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Aragona F, Rizzo M, Arfuso F, Acri G, Fazio F, Piccione G, Giannetto C. Eye Temperature Measured with Infrared Thermography to Assess Stress Responses to Road Transport in Horses. Animals (Basel) 2024; 14:1877. [PMID: 38997989 PMCID: PMC11240744 DOI: 10.3390/ani14131877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 06/21/2024] [Accepted: 06/25/2024] [Indexed: 07/14/2024] Open
Abstract
The aim of the present study was to investigate eye temperature modifications after road transport in athletic horses habituated to travel. Eight adult Italian saddle horses traveled 100 km and, two weeks later, 300 km. Eye temperature (ET), rectal temperature (RT) and serum cortisol concentration were assessed before (T1), after (T2) and 60 min (T3) after the road transport. ET was evaluated with infrared thermography (IRT) in three regions of interest: EL1 (medial canthus), EL2 (central cornea) and EL3 (lateral canthus). Two-way analysis of variance (ANOVA) for repeated measures showed statistically higher values at T2 and T3 for EL1 (p < 0.01), EL2 (p < 0.01) and EL3 (p < 0.01) following the 100 km journey. RT (p < 0.01) showed higher values at T2 and T3 after the 100 km journey and higher values at T2 (p < 0.01) following the 300 km journey. ET values were positively correlated with RT at T1, T2 and T3 following the 100 km journey and at T2 following the 300 km journey and positively correlated with serum cortisol concentration at T1, T2 and T3 following the 100 km journey and at T2 and T3 following the 300 km journey. Eye temperature monitoring with IRT allows quick and practical strategies to monitor an animal's physiological state and welfare during daily activities.
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Affiliation(s)
- Francesca Aragona
- Department of Veterinary Sciences, University of Messina, Polo Annunziata, 98168 Messina, Italy; (F.A.); (F.A.); (F.F.); (G.P.); (C.G.)
| | - Maria Rizzo
- Department of Veterinary Sciences, University of Messina, Polo Annunziata, 98168 Messina, Italy; (F.A.); (F.A.); (F.F.); (G.P.); (C.G.)
| | - Francesca Arfuso
- Department of Veterinary Sciences, University of Messina, Polo Annunziata, 98168 Messina, Italy; (F.A.); (F.A.); (F.F.); (G.P.); (C.G.)
| | - Giuseppe Acri
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Via Consolare Valeria, 98125 Messina, Italy;
| | - Francesco Fazio
- Department of Veterinary Sciences, University of Messina, Polo Annunziata, 98168 Messina, Italy; (F.A.); (F.A.); (F.F.); (G.P.); (C.G.)
| | - Giuseppe Piccione
- Department of Veterinary Sciences, University of Messina, Polo Annunziata, 98168 Messina, Italy; (F.A.); (F.A.); (F.F.); (G.P.); (C.G.)
| | - Claudia Giannetto
- Department of Veterinary Sciences, University of Messina, Polo Annunziata, 98168 Messina, Italy; (F.A.); (F.A.); (F.F.); (G.P.); (C.G.)
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Lewden A, Halna du Fretay T, Stier A. Changes in body surface temperature reveal the thermal challenge associated with catastrophic moult in captive gentoo penguins. J Exp Biol 2024; 227:jeb247332. [PMID: 38826104 PMCID: PMC11213523 DOI: 10.1242/jeb.247332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/12/2024] [Indexed: 06/04/2024]
Abstract
Once a year, penguins undergo a catastrophic moult, replacing their entire plumage during a fasting period on land or on sea-ice during which time individuals can lose 45% of their body mass. In penguins, new feather synthesis precedes the loss of old feathers, leading to an accumulation of two feather layers (double coat) before the old plumage is shed. We hypothesized that the combination of the high metabolism required for new feather synthesis and the potentially high thermal insulation linked to the double coat could lead to a thermal challenge requiring additional peripheral circulation to thermal windows to dissipate the extra heat. To test this hypothesis, we measured the surface temperature of different body regions of captive gentoo penguins (Pygoscelis papua) throughout the moult under constant environmental conditions. The surface temperature of the main body trunk decreased during the initial stages of the moult, suggesting greater thermal insulation. In contrast, the periorbital region, a potential proxy of core temperature in birds, increased during these same early moulting stages. The surface temperature of the bill, flipper and foot (thermal windows) tended to initially increase during the moult, highlighting the likely need for extra heat dissipation in moulting penguins. These results raise questions regarding the thermoregulatory capacities of penguins in the wild during the challenging period of moulting on land in the current context of global warming.
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Affiliation(s)
- Agnès Lewden
- Université de Brest - UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l'environnement marin – IUEM, Rue Dumont D'Urville, 29280 Plouzané, France
| | - Tristan Halna du Fretay
- Université de Brest - UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l'environnement marin – IUEM, Rue Dumont D'Urville, 29280 Plouzané, France
| | - Antoine Stier
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
- Department of Biology, University of Turku, FI-20014 Turku, Finland
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Lewden A, Ward C, Noiret A, Avril S, Abolivier L, Gérard C, Hammer TL, Raymond É, Robin JP, Viblanc VA, Bize P, Stier A. Surface temperatures are influenced by handling stress independently of corticosterone levels in wild king penguins (Aptenodytes patagonicus). J Therm Biol 2024; 121:103850. [PMID: 38608548 DOI: 10.1016/j.jtherbio.2024.103850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 03/17/2024] [Accepted: 03/17/2024] [Indexed: 04/14/2024]
Abstract
Assessing the physiological stress responses of wild animals opens a window for understanding how organisms cope with environmental challenges. Since stress response is associated with changes in body temperature, the use of body surface temperature through thermal imaging could help to measure acute and chronic stress responses non-invasively. We used thermal imaging, acute handling-stress protocol and an experimental manipulation of corticosterone (the main glucocorticoid hormone in birds) levels in breeding king penguins (Aptenodytes patagonicus), to assess: 1. The potential contribution of the Hypothalamo-Pituitary-Adrenal (HPA) axis in mediating chronic and acute stress-induced changes in adult surface temperature, 2. The influence of HPA axis manipulation on parental investment through thermal imaging of eggs and brooded chicks, and 3. The impact of parental treatment on offspring thermal's response to acute handling. Maximum eye temperature (Teye) increased and minimum beak temperature (Tbeak) decreased in response to handling stress in adults, but neither basal nor stress-induced surface temperatures were significantly affected by corticosterone implant. While egg temperature was not significantly influenced by parental treatment, we found a surprising pattern for chicks: chicks brooded by the (non-implanted) partner of corticosterone-implanted individuals exhibited higher surface temperature (both Teye and Tbeak) than those brooded by glucocorticoid-implanted or control parents. Chick's response to handling in terms of surface temperature was characterized by a drop in both Teye and Tbeak independently of parental treatment. We conclude that the HPA axis seems unlikely to play a major role in determining chronic or acute changes in surface temperature in king penguins. Changes in surface temperature may primarily be mediated by the Sympathetic-Adrenal-Medullary (SAM) axis in response to stressful situations. Our experiment did not reveal a direct impact of parental HPA axis manipulation on parental investment (egg or chick temperature), but a potential influence on the partner's brooding behaviour.
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Affiliation(s)
- Agnès Lewden
- Faculty of Biological Sciences, University of Leeds, Leeds, UK; Université de Brest - UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des Sciences de l'environnement Marin - IUEM, Rue Dumont D'Urville, 29280, Plouzané, France.
| | - Chelsea Ward
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Aude Noiret
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Sandra Avril
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000, Strasbourg, France
| | - Lucie Abolivier
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000, Strasbourg, France
| | - Caroline Gérard
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000, Strasbourg, France
| | - Tracey L Hammer
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000, Strasbourg, France
| | - Émilie Raymond
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France; Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000, Strasbourg, France
| | - Jean-Patrice Robin
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000, Strasbourg, France
| | - Vincent A Viblanc
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000, Strasbourg, France
| | - Pierre Bize
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK; Swiss Ornithological Institute, CH-6204, Sempach, Switzerland
| | - Antoine Stier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France; Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000, Strasbourg, France; Department of Biology, University of Turku, Turku, Finland.
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Tabh JKR, Hartjes M, Burness G. Endotherms trade body temperature regulation for the stress response. Proc Biol Sci 2023; 290:20231251. [PMID: 37909077 PMCID: PMC10618863 DOI: 10.1098/rspb.2023.1251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/06/2023] [Indexed: 11/02/2023] Open
Abstract
Responding to perceived threats is energetically expensive and can require animals to curtail somatic repair, immunity, and even reproduction to balance energy ledgers. In birds and mammals, energetic demands of thermoregulation are often immense, yet whether homeostatic body temperatures are also compromised to aid the stress response is not known. Using data sourced from over 60 years of literature and 24 endotherm species, we show that exposure to non-thermal challenges (e.g. human interaction, social threats) caused body temperatures to decrease in the cold and increase in the warmth, but particularly when species-specific costs of thermoregulation were high and surplus energy low. Biophysical models revealed that allowing body temperature to change in this way liberated up to 24% (mean = 5%) of resting energy expenditure for use towards coping. While useful to avoid energetic overload, these responses nevertheless heighten risks of cold- or heat-induced damage, particularly when coincident with cold- or heatwaves.
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Affiliation(s)
- Joshua K. R. Tabh
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada K9L 0G2
- Department of Biology, Lund University, Lund, 223 62, Sweden
| | - Mariah Hartjes
- Department of Biology, Trent University, Peterborough, Ontario, Canada K9L 0G2
| | - Gary Burness
- Department of Biology, Trent University, Peterborough, Ontario, Canada K9L 0G2
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Wongsaengchan C, McCafferty DJ, Lennox K, Nager RG, McKeegan DEF. Non-invasive assessment of positive affective state using infra-red thermography in rats. Anim Welf 2023; 32:e66. [PMID: 38510988 PMCID: PMC10951672 DOI: 10.1017/awf.2023.87] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 07/27/2023] [Accepted: 08/16/2023] [Indexed: 03/22/2024]
Abstract
With recent increased focus on positive welfare in animal welfare science, there is demand for objective positive welfare indicators. It is unclear whether changes in body surface temperature can be used to non-invasively identify and quantify positive states in mammals. We recorded continuous measurements of tail surface temperature using infra-red thermography (IRT) and concurrent behavioural observations in male and female Wistar rats (Rattus norvegicus). If tail surface temperature can differentiate between positive and negative experiences, we expect a qualitatively different response compared to negative experiences. Three groups of rats were presented with increasing magnitudes of food rewards (neutral/none, one and three rewards). The rats were placed in an arena to which they were habituated and filmed for 30 s before and 30 min after exposure to different rewards. Tail temperature initially decreased from the pre-reward baseline and subsequently returned towards baseline temperature. The overall pattern of the change was the same as for rats subjected to negative stimuli in previous studies. Nevertheless, dynamic changes in tail temperature, specifically the rate of recovery and the behavioural response (exploration), differed between neutral and rewarded rats but failed to distinguish reward magnitude. Sex differences were found in both thermal and behavioural responses, unrelated to reward magnitudes. Female rats exhibited a greater initial response with a slower recovery than male rats, emphasising the value of using of both sexes in animal welfare research. This study improves our understanding of the effects of positive emotions induced by food reward on peripheral body temperature and behaviour.
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Affiliation(s)
- Chanakarn Wongsaengchan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
- School of Psychology & Neuroscience, University of St Andrews, St Andrews, KY16 9JP, UK
| | - Dominic J McCafferty
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
| | - Katie Lennox
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
| | - Ruedi G Nager
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
| | - Dorothy EF McKeegan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
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Wongsaengchan C, McCafferty DJ, Evans NP, McKeegan DEF, Nager RG. Body surface temperature of rats reveals both magnitude and sex differences in the acute stress response. Physiol Behav 2023; 264:114138. [PMID: 36871696 DOI: 10.1016/j.physbeh.2023.114138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 02/09/2023] [Accepted: 02/24/2023] [Indexed: 03/07/2023]
Abstract
Understanding how biological markers of stress relate to stressor magnitude is much needed and can be used in welfare assessment. Changes in body surface temperature can be measured using infrared thermography (IRT) as a marker of a physiological response to acute stress. While an avian study has shown that changes in body surface temperature can reflect the intensity of acute stress, little is known about surface temperature responses to stressors of different magnitudes and its sex-specificity in mammals, and how they correlate with hormonal and behavioural responses. We used IRT to collect continuous surface temperature measurements of tail and eye of adult male and female rats (Rattus norvegicus), for 30 minutes after exposure to one of three stressors (small cage, encircling handling or rodent restraint cone) for one minute, and cross-validated the thermal response with plasma corticosterone (CORT) and behavioural assessment. To obtain individual baseline temperatures and thermal responses to stress, rats were imaged in a test arena (to which they were habituated) for 30 seconds before and 30 minutes after being exposed to the stressor. In response to the three stressors, tail temperature initially decreased and then recovered to, or overshot the baseline temperature. Tail temperature dynamics differed between stressors; being restrained in the small cage was associated with the smallest drop in temperature, in male rats, and the fastest thermal recovery, in both sexes. Increases in eye temperature only distinguished between stressors early in the response and only in females. The post stressor increase in eye temperature was greater in the right eye of males and the left eye of females. In both sexes encircling may have been associated with the fastest increase in CORT. These results were in line with observed behavioural changes, with greater movement in rats exposed to the small cage and higher immobility after encircling. The female tail and eye temperature, as well as the CORT concentrations did not return to pre-stressor levels in the observation period, in conjunction with the greater occurrence of escape-related behaviours in female rats. These results suggest that female rats are more vulnerable to acute restraint stress compared to male rats and emphasise the importance of using both sexes in future investigations of stressor magnitude. This study demonstrates that acute stress induced changes in mammalian surface temperature measured with IRT relate to the magnitude of restraint stress, indicate sex differences and correlate with hormonal and behavioural responses. Thus, IRT has the potential to become a non-invasive method of continuous welfare assessment in unrestrained mammals.
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Affiliation(s)
- Chanakarn Wongsaengchan
- School of Psychology & Neuroscience, University of St Andrews, St Andrews, KY16 9JP, United Kingdom
| | - Dominic J McCafferty
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Scottish Centre for Ecology and the Natural Environment, Rowardennan, G63 0AW, United Kingdom
| | - Neil P Evans
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Jarrett Building, Glasgow, G61 1QH, United Kingdom
| | - Dorothy E F McKeegan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Jarrett Building, Glasgow, G61 1QH, United Kingdom
| | - Ruedi G Nager
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, United Kingdom.
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Zuluaga JD, Danner RM. Acute stress and restricted diet reduce bill-mediated heat dissipation in the song sparrow (Melospiza melodia): implications for optimal thermoregulation. J Exp Biol 2023; 226:286688. [PMID: 36651227 DOI: 10.1242/jeb.245316] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 01/11/2023] [Indexed: 01/19/2023]
Abstract
We used thermal imaging to show that two environmental factors - acute stress and diet - influence thermoregulatory performance of a known thermal window, the avian bill. The bill plays important roles in thermoregulation and water balance. Given that heat loss through the bill is adjustable through vasoconstriction and vasodilation, and acute stress can cause vasoconstriction in peripheral body surfaces, we hypothesized that stress may influence the bill's role as a thermal window. We further hypothesized that diet influences heat dissipation from the bill, given that body condition influences the surface temperature of another body region (the eye region). We measured the surface temperature of the bills of song sparrows (Melospiza melodia) before, during and after handling by an observer at 37°C ambient temperature. We fed five birds a restricted diet intended to maintain body mass typical of wild birds, and we fed six birds an unrestricted diet for 5 months prior to experiments. Acute stress caused a decrease in the surface temperature of the bill, resulting in a 32.4% decrease in heat dissipation immediately following acute stress, before recovering over approximately 2.3 min. The initial reduction and subsequent recovery provide partial support for the hemoprotective and thermoprotective hypotheses, which predict a reduction or increase in peripheral blood flow, respectively. Birds with unrestricted diets had larger bills and dissipated more heat, indicating that diet and body condition influence bill-mediated heat dissipation and thermoregulation. These results indicate that stress-induced vascular changes and diet can influence mechanisms of heat loss and potentially inhibit optimal thermoregulation.
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Affiliation(s)
- Juan D Zuluaga
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403-5915, USA
| | - Raymond M Danner
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403-5915, USA.,Smithsonian Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, D.C. 20008, USA
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Bissonnette PB, Waterman JM, Petersen SD. The use of infrared thermography to noninvasively measure the surface temperature of polar bears during bouts of social play. Zoo Biol 2023; 42:38-44. [PMID: 35872605 DOI: 10.1002/zoo.21722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 04/10/2022] [Accepted: 07/13/2022] [Indexed: 11/11/2022]
Abstract
Infrared thermography or thermal imagery is a noninvasive tool that can be used to measure the temperature of surfaces. Typically, thermal imagery is used for construction or military purposes but is increasingly used as a noninvasive tool in wildlife studies. We investigated the use of thermal imagery to measure surface temperature changes as a proxy for energetic expenditure. We measured the surface temperature of polar bear (Ursus maritimus) eyes, while immobilized, to determine whether the eye is a thermal window that can accurately indicate internal temperature. We found a significant difference (2.68 ± 0.41°C) between the surface temperature of the eye measured with thermal imagery and the internal rectal temperature. Additionally, we measured surface temperature changes in polar bears after bouts of social play as a proxy for energy expenditure. Mean temperature of the eye increased by 1.34 ± 0.43°C after social play, indicating that this activity increased energy expenditure. During the fasting season, polar bears rely on fat stores, and any energy expenditure beyond what is required to travel may be costly to their survival, particularly in years of low resource availability. We conclude that thermal imagery is a useful tool to noninvasively investigate the energetics of social play.
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Affiliation(s)
- Paige B Bissonnette
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Jane M Waterman
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Stephen D Petersen
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.,Assiniboine Park Zoo, Winnipeg, Manitoba, Canada
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Soravia C, Ashton BJ, Ridley AR. Periorbital temperature responses to natural air temperature variation in wild birds. J Therm Biol 2022; 109:103323. [DOI: 10.1016/j.jtherbio.2022.103323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 08/10/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022]
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Di Giovanni J, Fawcett TW, Templeton CN, Raghav S, Boogert NJ. Urban gulls show similar thermographic and behavioral responses to human shouting and conspecific alarm calls. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.891985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Rapid population growth and the urbanization of modern environments are markedly increasing human-wildlife conflict. Wild animals in urban landscapes can benefit from exploiting human resources, but are also exposed to increased risk of human-caused injury, which should favor the ability to perceive and respond to human cues. Although it is well known that domesticated animals use human cues that may indicate threats, less is known about wild animals living in urban environments. Herring gulls (Larus argentatus) in urban landscapes have adapted kleptoparasitic behaviors to obtain human food, often resulting in negative interactions with humans. Here we quantified both the behavioral and physiological responses of free-living urban herring gulls to human shouting. We presented urban gulls with a fake human food item and played back recordings of either a man shouting, a natural stressor (i.e., conspecific alarm call), or a neutral stimulus (i.e., robin song). We recorded behavioral responses and used non-invasive infrared thermography to measure eye-region surface temperature changes associated with the avian physiological stress response. We found that gulls exposed to shouting and to conspecific alarm calls showed similar changes in behavior (indicating high levels of vigilance) and eye-region surface temperature (indicating physiological stress). Both responses were significantly stronger than the responses to robin song. Additionally, the behavioral and physiological responses were positively correlated across individuals. Our results demonstrate that urban-dwelling gulls respond to human shouting and conspecific alarm calls in a similar way, and suggest that infrared thermography is a viable technique to monitor stress responses in free-living birds.
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A Review of Non-Invasive Sampling in Wildlife Disease and Health Research: What’s New? Animals (Basel) 2022; 12:ani12131719. [PMID: 35804619 PMCID: PMC9265025 DOI: 10.3390/ani12131719] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 12/14/2022] Open
Abstract
Simple Summary The interest in wildlife research has increased in the last decades as more scientists work within a One Health framework that regards human, livestock and wildlife health as connected entities. To minimise the impact of research on wildlife, collecting samples with as little disturbance of the animals as possible is important. In our review, we assess the use of so-called non-invasive sampling and summarise which samples can be used successfully when carrying out research on wildlife diseases and health status. Our results show that interest in minimally invasive sampling has steadily increased since the 2010s. Topics able to employ these methods include disease research, but also stress and other hormone assessments, pollution studies, and dietary studies. At the moment, such methods are mainly used to collect samples from land mammals, however, they can also be used in a wide range of other animals. Ever more capable analytical methods will allow for an even wider use of such “animal-friendly” sampling methods. Abstract In the last decades, wildlife diseases and the health status of animal populations have gained increasing attention from the scientific community as part of a One Health framework. Furthermore, the need for non-invasive sampling methods with a minimal impact on wildlife has become paramount in complying with modern ethical standards and regulations, and to collect high-quality and unbiased data. We analysed the publication trends on non-invasive sampling in wildlife health and disease research and offer a comprehensive review on the different samples that can be collected non-invasively. We retrieved 272 articles spanning from 1998 to 2021, with a rapid increase in number from 2010. Thirty-nine percent of the papers were focussed on diseases, 58% on other health-related topics, and 3% on both. Stress and other physiological parameters were the most addressed research topics, followed by viruses, helminths, and bacterial infections. Terrestrial mammals accounted for 75% of all publications, and faeces were the most widely used sample. Our review of the sampling materials and collection methods highlights that, although the use of some types of samples for specific applications is now consolidated, others are perhaps still underutilised and new technologies may offer future opportunities for an even wider use of non-invasively collected samples.
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Vaz J, Bartley A, Hunt J. Personality matters: exploring the relationship between personality and stress physiology in captive African lions. BMC ZOOL 2022; 7:30. [PMID: 37170353 PMCID: PMC10127340 DOI: 10.1186/s40850-022-00126-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 04/20/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Considering animals as individuals and not as species is becoming increasingly essential to animal welfare management in captive settings. Recent studies on big cat personalities and coping strategies suggest personality can help big cats cope in their surroundings. Yet a large portion of the published literature focuses on understanding either the personality or stress physiology of big cats. Our research shows how integrating an improved understanding of the personality of big cats with stress physiology may enhance welfare, especially for endangered species like African lions. By using a wild cat personality checklist, this study compared the key personality dimensions of 22 African lions with its faecal glucocorticoids and assessed factors influencing their personality and stress physiology.
Results
We found two reliable personality dimensions for African lions (dominance and agreeableness) and identified key factors (sex, age and location) that may influence their personality. Further, on testing if these factors influenced the stress physiology through variations in glucocorticoid levels, there was no significant difference. However, there was a strong negative association between agreeableness and glucocorticoid levels. These results suggest that the behavioural traits loading positively and higher for agreeableness are associated with lower glucocorticoid stress levels, which may assist a lion to cope with stressors in its surroundings.
Conclusions
Our findings highlight this integrated approach of linking personality and stress physiology of big cats can be beneficial for caretakers. For example, during stressful veterinary procedures or in reintroduction programs, recognizing the personality of lions can help in designing or providing them with resources that will alleviate stress. Thus, there is a need for more interdisciplinary approaches that will contribute towards enhancing the individual and overall welfare of big cats.
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Blackburn G, Broom E, Ashton BJ, Thornton A, Ridley AR. Heat stress inhibits cognitive performance in wild Western Australian magpies, Cracticus tibicen dorsalis. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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14
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Mentesana L, Hau M. Glucocorticoids in a warming world: Do they help birds to cope with high environmental temperatures? Horm Behav 2022; 142:105178. [PMID: 35561643 DOI: 10.1016/j.yhbeh.2022.105178] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 04/09/2022] [Accepted: 04/16/2022] [Indexed: 11/04/2022]
Abstract
Climate change is threatening biodiversity world-wide. One of its most prominent manifestations are rising global temperatures and higher frequencies of heat waves. High environmental temperatures may be particularly challenging for endotherms, which expend considerable parts of their energy budget and water resources on thermoregulation. Thermoregulation involves phenotypic plasticity in behavioral and physiological traits. Information on causal mechanisms that support plastic thermoregulatory strategies is key to understand how environmental information is transmitted and whether they impose trade-offs or constraints that determine how endotherms cope with climate warming. In this review, we focus on glucocorticoids, metabolic hormones that orchestrate plastic responses to various environmental stimuli including temperature. To evaluate how they may mediate behavioral and physiological responses to high environmental temperatures, we 1) briefly review the major thermoregulatory strategies in birds; 2) summarize the functions of baseline and stress-induced glucocorticoid concentrations; 3) synthesize the current knowledge of the relationship between circulating glucocorticoids and high environmental temperatures in birds; 4) generate hypotheses for how glucocorticoids may support plastic thermoregulatory responses to high environmental temperatures that occur over different time-frames (i.e., acute, short- and longer-term); and 5) discuss open questions on how glucocorticoids, and their relationship with thermoregulation, may evolve. Throughout this review we highlight that our knowledge, particularly on free-living populations, is really limited and outline promising avenues for future research. As evolutionary endocrinologists we now need to step up and identify the costs, benefits, and evolution of glucocorticoid plasticity to elucidate how they may help birds cope with a warming world.
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Affiliation(s)
- Lucia Mentesana
- Max Planck Institute for Ornithology, Eberhard-Gwinner-Str., 82319 Seewiesen, Germany.
| | - Michaela Hau
- Max Planck Institute for Ornithology, Eberhard-Gwinner-Str., 82319 Seewiesen, Germany.
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15
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Arfuso F, Acri G, Piccione G, Sansotta C, Fazio F, Giudice E, Giannetto C. Eye surface infrared thermography usefulness as a noninvasive method of measuring stress response in sheep during shearing: Correlations with serum cortisol and rectal temperature values. Physiol Behav 2022; 250:113781. [PMID: 35314176 DOI: 10.1016/j.physbeh.2022.113781] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/03/2022] [Accepted: 03/10/2022] [Indexed: 01/03/2023]
Abstract
During shearing, animals' welfare is adversely affected and acute stress occurs. Once animal perceives a threat, it develops behavioral, autonomic, endocrine or immune responses to maintain homeostasis. This study aimed to investigate the usefulness of eye temperature assessment by infrared thermography (IRT) to evaluate acute stress response in sheep undergoing a shearing procedure. From each animal, blood sampling, rectal and eye temperature assessment were performed before shearing (TPRE), 5 (TPOST5) and 60 (TPOST60) minutes after the end of shearing procedure. On blood samples the serum cortisol concentrations were evaluated. Rectal temperature (TRECTAL) was measured using a digital thermometer. Thermographic acquisitions of eye temperature were performed from the eye total area (TEYE) and from three regions of interest (lateral canthus, TROI-1; central cornea, TROI-2; medial canthus, TROI-3). One-way analysis of variance showed a significant increase of serum cortisol concentration, TRECTAL, TEYE and TROI-3 (p < 0.001). Serum cortisol was positively correlated with TRECTAL and TROI-3 at TPOST5 and TPOST60. TRECTAL resulted positively correlated with TROI-3 at TPRE, TPOST5 and TPOST60. Agreement between TRECTAL and each eye temperature considered (TEYE, TROI-1, TROI-2, TROI-3) has been shown by Bland-Altman plots at each time point of monitoring period. The findings obtained in the current survey suggest that the medial canthus is the most suitable region for eye temperature measurement to asses stress response in animals. Moreover, this study highlighted the usefulness of IRT as an immediate and non-invasive physiological measure to assess stress response in sheep.
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Affiliation(s)
- Francesca Arfuso
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, 98168, Messina, Italy
| | - Giuseppe Acri
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Via Consolare Valeria, 98125, Messina, Italy
| | - Giuseppe Piccione
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, 98168, Messina, Italy.
| | - Carlo Sansotta
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Via Consolare Valeria, 98125, Messina, Italy
| | - Francesco Fazio
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, 98168, Messina, Italy
| | - Elisabetta Giudice
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, 98168, Messina, Italy
| | - Claudia Giannetto
- Department of Veterinary Sciences, University of Messina, Polo University Annunziata, 98168, Messina, Italy
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16
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Wellbrock AHJ, Eckhardt LRH, Kelsey NA, Heldmaier G, Rozman J, Witte K. Cool birds: first evidence of energy-saving nocturnal torpor in free-living common swifts Apus apus resting in their nests. Biol Lett 2022; 18:20210675. [PMID: 35414223 PMCID: PMC9006018 DOI: 10.1098/rsbl.2021.0675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Daily torpor is a means of saving energy by controlled lowering of the metabolic rate (MR) during resting, usually coupled with a decrease in body temperature. We studied nocturnal daily torpor under natural conditions in free-living common swifts Apus apus resting in their nests as a family using two non-invasive approaches. First, we monitored nest temperature (Tnest) in up to 50 occupied nests per breeding season in 2010-2015. Drops in Tnest were the first indication of torpor. Among 16 673 observations, we detected 423 events of substantial drops in Tnest of on average 8.6°C. Second, we measured MR of the families inside nest-boxes prepared for calorimetric measurements during cold periods in the breeding seasons of 2017 and 2018. We measured oxygen consumption and carbon dioxide production using a mobile indirect respirometer and calculated the percentage reduction in MR. During six torpor events observed, MR was gradually reduced by on average 56% from the reference value followed by a decrease in Tnest of on average 7.6°C. By contrast, MR only decreased by about 33% on nights without torpor. Our field data gave an indication of daily torpor, which is used as a strategy for energy saving in free-living common swifts.
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Affiliation(s)
- Arndt H J Wellbrock
- Research Group of Ecology and Behavioural Biology, Institute of Biology, University of Siegen, Siegen, Germany.,Institute of Avian Research 'Vogelwarte Helgoland', Wilhelmshaven, Germany
| | - Luca R H Eckhardt
- Research Group of Ecology and Behavioural Biology, Institute of Biology, University of Siegen, Siegen, Germany
| | - Natalie A Kelsey
- Research Group of Ecology and Behavioural Biology, Institute of Biology, University of Siegen, Siegen, Germany.,Institute of Avian Research 'Vogelwarte Helgoland', Wilhelmshaven, Germany
| | - Gerhard Heldmaier
- Animal Physiology, Faculty of Biology, Marburg University, Marburg, Germany
| | - Jan Rozman
- Research Group of Ecology and Behavioural Biology, Institute of Biology, University of Siegen, Siegen, Germany.,Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Klaudia Witte
- Research Group of Ecology and Behavioural Biology, Institute of Biology, University of Siegen, Siegen, Germany
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17
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Knoch S, Whiteside MA, Madden JR, Rose PE, Fawcett TW. Hot-headed peckers: thermographic changes during aggression among juvenile pheasants ( Phasianus colchicus). Philos Trans R Soc Lond B Biol Sci 2022; 377:20200442. [PMID: 35000453 PMCID: PMC8743885 DOI: 10.1098/rstb.2020.0442] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 10/28/2021] [Indexed: 12/16/2022] Open
Abstract
In group-living vertebrates, dominance status often covaries with physiological measurements (e.g. glucocorticoid levels), but it is unclear how dominance is linked to dynamic changes in physiological state over a shorter, behavioural timescale. In this observational study, we recorded spontaneous aggression among captive juvenile pheasants (Phasianus colchicus) alongside infrared thermographic measurements of their external temperature, a non-invasive technique previously used to examine stress responses in non-social contexts, where peripheral blood is redirected towards the body core. We found low but highly significant repeatability in maximum head temperature, suggesting individually consistent thermal profiles, and some indication of lower head temperatures in more active behavioural states (e.g. walking compared to resting). These individual differences were partly associated with sex, females being cooler on average than males, but unrelated to body size. During pairwise aggressive encounters, we observed a non-monotonic temperature change, with head temperature dropping rapidly immediately prior to an attack and increasing rapidly afterwards, before returning to baseline levels. This nonlinear pattern was similar for birds in aggressor and recipient roles, but aggressors were slightly hotter on average. Our findings show that aggressive interactions induce rapid temperature changes in dominants and subordinates alike, and highlight infrared thermography as a promising tool for investigating the physiological basis of pecking orders in galliforms. This article is part of the theme issue 'The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies'.
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Affiliation(s)
- Sophia Knoch
- Centre for Research in Animal Behaviour (CRAB), Washington Singer Laboratories, University of Exeter, Exeter EX4 4QG, UK
- Institute of Psychology, University of Freiburg, Engelbergerstr. 41, 79085 Freiburg, Germany
| | - Mark A. Whiteside
- Centre for Research in Animal Behaviour (CRAB), Washington Singer Laboratories, University of Exeter, Exeter EX4 4QG, UK
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
| | - Joah R. Madden
- Centre for Research in Animal Behaviour (CRAB), Washington Singer Laboratories, University of Exeter, Exeter EX4 4QG, UK
| | - Paul E. Rose
- Centre for Research in Animal Behaviour (CRAB), Washington Singer Laboratories, University of Exeter, Exeter EX4 4QG, UK
| | - Tim W. Fawcett
- Centre for Research in Animal Behaviour (CRAB), Washington Singer Laboratories, University of Exeter, Exeter EX4 4QG, UK
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18
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Eye Region Surface Temperature and Corticosterone Response to Acute Stress in a High-Arctic Seabird, the Little Auk. Animals (Basel) 2022; 12:ani12040499. [PMID: 35203208 PMCID: PMC8868316 DOI: 10.3390/ani12040499] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/31/2022] [Accepted: 02/12/2022] [Indexed: 02/05/2023] Open
Abstract
Measuring changes in surface body temperature (specifically in eye-region) in vertebrates using infrared thermography is increasingly applied for detection of the stress reaction. Here we investigated the relationship between the eye-region temperature (TEYE; measured with infrared thermography), the corticosterone level in blood (CORT; stress indicator in birds), and some covariates (ambient temperature, humidity, and sex/body size) in a High-Arctic seabird, the Little Auk Alle alle. The birds responded to the capture-restrain protocol (blood sampling at the moment of capturing, and after 30 min of restrain) by a significant TEYE and CORT increase. However, the strength of the TEYE and CORT response to acute stress were not correlated. It confirms the results of a recent study on other species and all together indicates that infrared thermography is a useful, non-invasive measure of hypothalamic-pituitary-adrenal (HPA) axis reactivity under acute activation, but it might not be a suitable proxy for natural variation of circulating glucocorticoid levels.
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19
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Tabh JKR, Mastromonaco GF, Burness G. Stress-induced changes in body surface temperature are repeatable, but do not differ between urban and rural birds. Oecologia 2022; 198:663-677. [PMID: 35138449 DOI: 10.1007/s00442-022-05120-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 01/18/2022] [Indexed: 11/29/2022]
Abstract
Urbanisation can alter local microclimates, thus creating new thermal challenges for resident species. However, urban environments also present residents with frequent, novel stressors (e.g., noise, human interaction) which may demand investment in costly, self-preserving responses (e.g., the fight-or-flight response). One way that urban residents might cope with this combination of demands is by using regional heterothermy to reduce costs of thermoregulation during the stress response. In this study, we used black-capped chickadees (nurban = 9; nrural = 10) to test whether known heterothermic responses to stress exposure (here, at the bare skin around the eye): (1) varied consistently among individuals (i.e., were repeatable), and (2) were most pronounced among urban individuals compared with rural individuals. Further, to gather evidence for selection on stress-induced heterothermic responses in urban settings, we tested: (3) whether repeatability of this response was lower among birds sampled from urban environments compared with those sampled from rural environments. For the first time, we show that heterothermic responses to stress exposures (i.e. changes in body surface temperature) were highly repeatable across chronic time periods (R = 0.58) but not acute time periods (R = 0.13). However, we also show that these responses did not differ between urban and rural birds, nor were our repeatability estimates any lower in our urban sample. Thus, while regional heterothermy during stress exposure may provide energetic benefits to some, but not all, individuals, enhanced use of this response to cope with urban pressures appears unlikely in our study species.
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Affiliation(s)
- Joshua K R Tabh
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, K9L 0G2, Canada. .,Department of Wildlife and Science, Toronto Zoo, Scarborough, ON, M1B 5K7, Canada.
| | | | - Gary Burness
- Department of Biology, Trent University, Peterborough, ON, K9L 0G2, Canada
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20
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Shankar A, Cisneros INH, Thompson S, Graham CH, Powers DR. A heterothermic spectrum in hummingbirds. J Exp Biol 2022; 225:273909. [PMID: 34989393 DOI: 10.1242/jeb.243208] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 12/29/2021] [Indexed: 11/20/2022]
Abstract
Many endotherms use torpor, saving energy by a controlled reduction of their body temperature and metabolic rate. Some species (e.g., arctic ground squirrels, hummingbirds) enter deep torpor, dropping their body temperatures by 23-37°C, while others can only enter shallow torpor (e.g., pigeons, 3-10°C reductions). However, deep torpor in mammals can increase predation risk (unless animals are in burrows or caves), inhibit immune function, and result in sleep deprivation, so even for species that can enter deep torpor, facultative shallow torpor might help balance energy savings with these potential costs. Deep torpor occurs in three avian orders, but the trade-offs of deep torpor in birds are unknown. Although the literature hints that some bird species (mousebirds and perhaps hummingbirds) can use both shallow and deep torpor, little empirical evidence of such an avian heterothermy spectrum within species exists. We infrared imaged three hummingbird species that are known to use deep torpor, under natural temperature and light cycles, to test if they were also capable of shallow torpor. All three species used both deep and shallow torpor, often on the same night. Depending on the species, they used shallow torpor for 5-35% of the night. The presence of a heterothermic spectrum in these bird species indicates a capacity for fine-scale physiological and genetic regulation of avian torpid metabolism.
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Affiliation(s)
- Anusha Shankar
- Stony Brook University, Stony Brook, NY 11794, USA.,Swiss Federal Research Institute (WSL), Birmensdorf, CH-8903, Switzerland
| | | | | | - Catherine H Graham
- Stony Brook University, Stony Brook, NY 11794, USA.,Swiss Federal Research Institute (WSL), Birmensdorf, CH-8903, Switzerland
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21
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Efficacy and Function of Feathers, Hair, and Glabrous Skin in the Thermoregulation Strategies of Domestic Animals. Animals (Basel) 2021; 11:ani11123472. [PMID: 34944249 PMCID: PMC8697956 DOI: 10.3390/ani11123472] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/28/2021] [Accepted: 11/29/2021] [Indexed: 12/13/2022] Open
Abstract
Simple Summary Animals adopt several strategies to regulate their body temperature by promoting heat loss or gain in hot and cold environments, respectively. This mechanism of heat loss or production is performed in thermal windows. A thermal window is a structure where many blood capillaries facilitate thermal exchange in this region. The presence of feathers, hair, or glabrous (hairless) skin and their structural characteristics greatly influence each species’ capacity to maintain thermal comfort. This factor needs to be considered when implementing new monitoring or measuring techniques such as infrared thermography since interpretations may vary due to the presence or absence of these structures. It is essential to recognize the effects of glabrous skin, hair, and feathers on thermoregulation to identify species-specific thermal windows that allow accurate evaluations of the thermal state of domestic animals. Abstract The objective of this review is to describe and analyze the effect of feathers, hair, and glabrous (hairless) skin on the thermoregulation of domestic and endotherm animals, especially concerning the uses and scope of infrared thermography (IRT), scientific findings on heat and cold stress, and differences among species of domestic animals. Clinical medicine considers thermoregulation a mechanism that allows animals to adapt to varying thermal environmental conditions, a process in which the presence of feathers, hair, or glabrous skin influences heat loss or heat retention, respectively, under hot and cold environmental conditions. Evaluating body temperature provides vital information on an individual’s physiological state and health status since variations in euthermia maintenance in vertebrates reflect a significant cellular metabolism deviation that needs to be assessed and quantified. IRT is a non-invasive tool for evaluating thermal responses under thermal stress conditions in animals, where the presence or absence of feathers, hair, and glabrous skin can affect readings and the differences detected. Therefore, anatomical regions, the characteristics of feathers, hair, glabrous skin such as structure, length, color, and extension, and strategies for dissipating or retaining heat together constitute a broad area of opportunity for future research into the phenomena of dermal thermoregulation in domestic species.
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22
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Ouyang JQ, Macaballug P, Chen H, Hodach K, Tang S, Francis JS. Infrared thermography is an effective, noninvasive measure of HPA activation. Stress 2021; 24:584-589. [PMID: 33480292 PMCID: PMC8295405 DOI: 10.1080/10253890.2020.1868431] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Infrared thermography (IRT) is increasingly applied as a noninvasive technique for measuring surface body temperature changes related to physiological stress. As a basis for validation of IRT as a tool for diagnostic use, we need to assess its potential to measure hypothalamic-pituitary-adrenal (HPA) axis reactivity. We used experimental manipulations of the HPA axis in house sparrows (Passer domesticus), i.e. adrenal tissue responsiveness to exogenous adrenocorticotropin (ACTH) and the efficacy of negative feedback using the synthetic glucocorticoid dexamethasone (DEX), to test whether IRT is an effective tool for measuring HPA reactivity. Experimental birds showed a pronounced decrease in skin temperatures after ACTH injection and an increase in temperature after DEX injection. However, individual variation in glucocorticoid levels were not related to skin temperatures except after ACTH injection in experimental birds. We show that IRT can be used to measure HPA reactivity but that skin-temperature is not a good index for glucocorticoid secretion at baseline levels. These results suggest that while IRT of skin temperatures is a useful, noninvasive measure of HPA axis reactivity under acute activation, this technique might not be suitable for measuring natural variation of circulating glucocorticoid levels.
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Affiliation(s)
- Jenny Q Ouyang
- Department of Biology, University of Nevada, Reno, NV, USA
| | | | - Hao Chen
- Department of Biology, University of Nevada, Reno, NV, USA
| | | | - Shelly Tang
- Department of Biology, University of Nevada, Reno, NV, USA
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23
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Infrared Thermography in the Study of Animals' Emotional Responses: A Critical Review. Animals (Basel) 2021; 11:ani11092510. [PMID: 34573476 PMCID: PMC8464846 DOI: 10.3390/ani11092510] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/19/2021] [Accepted: 08/23/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Assessing animal welfare has proven to be a challenging task with important consequences for their management. In the last few years, infrared thermography has gained increasing scientific consensus as a method to analyze emotional reactions to different stimuli in different taxa. This review aims to explore particularly the use of infrared thermography in the assessment of animals’ emotions, mainly focusing on pets, laboratory, and husbandry animals. If properly used, this technique has proven to be a noninvasive, reliable method to identify emotional activations. Abstract Whether animals have emotions was historically a long-lasting question but, today, nobody disputes that they do. However, how to assess them and how to guarantee animals their welfare have become important research topics in the last 20 years. Infrared thermography (IRT) is a method to record the electromagnetic radiation emitted by bodies. It can indirectly assess sympathetic and parasympathetic activity via the modification of temperature of different body areas, caused by different phenomena such as stress-induced hyperthermia or variation in blood flow. Compared to other emotional activation assessment methods, IRT has the advantage of being noninvasive, allowing use without the risk of influencing animals’ behavior or physiological responses. This review describes general principles of IRT functioning, as well as its applications in studies regarding emotional reactions of domestic animals, with a brief section dedicated to the experiments on wildlife; it analyzes potentialities and possible flaws, confronting the results obtained in different taxa, and discusses further opportunities for IRT in studies about animal emotions.
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24
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Tabh JKR, Burness G, Wearing OH, Tattersall GJ, Mastromonaco GF. Infrared thermography as a technique to measure physiological stress in birds: Body region and image angle matter. Physiol Rep 2021; 9:e14865. [PMID: 34057300 PMCID: PMC8165734 DOI: 10.14814/phy2.14865] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 03/31/2021] [Accepted: 04/13/2021] [Indexed: 11/24/2022] Open
Abstract
In vertebrates, changes in surface temperature following exposure to an acute stressor are thought to be promising indicators of the physiological stress response that may be captured noninvasively by infrared thermography. However, the efficacy of using stress-induced changes in surface temperature as indicators of physiological stress-responsiveness requires: (1) an understanding of how such responses vary across the body, (2) a magnitude of local, stress-induced thermal responses that is large enough to discriminate and quantify differences among individuals with conventional technologies, and (3) knowledge of how susceptible measurements across different body regions are to systematic error. In birds, temperature of the bare tissues surrounding the eye (the periorbital, or "eye," region) and covering the bill have each been speculated as possible predictors of stress physiological state. Using the domestic pigeon (Columba livia domestica; n = 9), we show that stress-induced changes in surface temperature are most pronounced at the bill and that thermal responses at only the bill have sufficient resolution to detect and quantify differences in responsiveness among individuals. More importantly, we show that surface temperature estimates at the eye region experience greater error due to changes in bird orientation than those at the bill. Such error concealed detection of stress-induced thermal responses at the eye region. Our results highlight that: (1) in some species, bill temperature may serve as a more robust indicator of autonomic stress-responsiveness than eye region temperature, and (2) future studies should account for spatial orientation of study individuals if inference is to be drawn from infrared thermographic images.
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Affiliation(s)
- Joshua K R Tabh
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada.,Department of Wildlife and Science, Toronto Zoo, Scarborough, ON, Canada
| | - Gary Burness
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - Oliver H Wearing
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Glenn J Tattersall
- Department of Biological Sciences, Brock University, St Catharines, ON, Canada
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25
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Hooper R, Meekins E, McIvor GE, Thornton A. Wild jackdaws respond to their partner's distress, but not with consolation. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210253. [PMID: 34234956 PMCID: PMC8242836 DOI: 10.1098/rsos.210253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 06/07/2021] [Indexed: 06/13/2023]
Abstract
Individuals are expected to manage their social relationships to maximize fitness returns. For example, reports of some mammals and birds offering unsolicited affiliation to distressed social partners (commonly termed 'consolation') are argued to illustrate convergent evolution of prosocial traits across divergent taxa. However, most studies cannot discriminate between consolation and alternative explanations such as self-soothing. Crucially, no study that controls for key confounds has examined consolation in the wild, where individuals face more complex and dangerous environments than in captivity. Controlling for common confounds, we find that male jackdaws (Corvus monedula) respond to their mate's stress-states, but not with consolation. Instead, they tended to decrease affiliation and partner visit rate in both experimental and natural contexts. This is striking because jackdaws have long-term monogamous relationships with highly interdependent fitness outcomes, which is precisely where theory predicts consolation should occur. Our findings challenge common conceptions about where consolation should evolve, and chime with concerns that current theory may be influenced by anthropomorphic expectations of how social relationships should be managed. To further our understanding of the evolution of such traits, we highlight the need for our current predictive frameworks to incorporate the behavioural trade-offs inherent to life in the wild.
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Affiliation(s)
- Rebecca Hooper
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | - Ella Meekins
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | - Guillam E. McIvor
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | - Alex Thornton
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
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26
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Ruuskanen S, Hsu BY, Nord A. Endocrinology of thermoregulation in birds in a changing climate. Mol Cell Endocrinol 2021; 519:111088. [PMID: 33227349 DOI: 10.1016/j.mce.2020.111088] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 11/13/2020] [Accepted: 11/17/2020] [Indexed: 02/06/2023]
Abstract
The ability to maintain a (relatively) stable body temperature in a wide range of thermal environments by use of endogenous heat production is a unique feature of endotherms such as birds. Endothermy is acquired and regulated via various endocrine and molecular pathways, and ultimately allows wide aerial, aquatic, and terrestrial distribution in variable environments. However, due to our changing climate, birds are faced with potential new challenges for thermoregulation, such as more frequent extreme weather events, lower predictability of climate, and increasing mean temperature. We provide an overview on thermoregulation in birds and its endocrine and molecular mechanisms, pinpointing gaps in current knowledge and recent developments, focusing especially on non-model species to understand the generality of, and variation in, mechanisms. We highlight plasticity of thermoregulation and underlying endocrine regulation, because thorough understanding of plasticity is key to predicting responses to changing environmental conditions. To this end, we discuss how changing climate is likely to affect avian thermoregulation and associated endocrine traits, and how the interplay between these physiological processes may play a role in facilitating or constraining adaptation to a changing climate. We conclude that while the general patterns of endocrine regulation of thermogenesis are quite well understood, at least in poultry, the molecular and endocrine mechanisms that regulate, e.g. mitochondrial function and plasticity of thermoregulation over different time scales (from transgenerational to daily variation), need to be unveiled. Plasticity may ameliorate climate change effects on thermoregulation to some extent, but the increased frequency of extreme weather events, and associated changes in resource availability, may be beyond the scope and/or speed for plastic responses. This could lead to selection for more tolerant phenotypes, if the underlying physiological traits harbour genetic and individual variation for selection to act on - a key question for future research.
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Affiliation(s)
| | - Bin-Yan Hsu
- Department of Biology, University of Turku, Finland
| | - Andreas Nord
- Lund University, Department of Biology, Section for Evolutionary Ecology, Ecology Building, Sölvegatan 37, SE-22362, Lund, Sweden
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Robertson JK, Mastromonaco GF, Burness G. Social hierarchy reveals thermoregulatory trade-offs in response to repeated stressors. J Exp Biol 2020; 223:jeb229047. [PMID: 32967999 DOI: 10.1242/jeb.229047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 09/09/2020] [Indexed: 11/20/2022]
Abstract
Coping with stressors can require substantial energetic investment, and when resources are limited, such investment can preclude simultaneous expenditure on other biological processes. Among endotherms, energetic demands of thermoregulation can also be immense, yet our understanding of whether a stress response is sufficient to induce changes in thermoregulatory investment is limited. Using the black-capped chickadee as a model species, we tested a hypothesis that stress-induced changes in surface temperature (Ts), a well-documented phenomenon across vertebrates, stem from trade-offs between thermoregulation and stress responsiveness. Because social subordination is known to constrain access to resources in this species, we predicted that Ts and dry heat loss of social subordinates, but not social dominants, would fall under stress exposure at low ambient temperatures (Ta), and rise under stress exposure at high Ta, thus permitting a reduction in total energetic expenditure toward thermoregulation. To test our predictions, we exposed four social groups of chickadees to repeated stressors and control conditions across a Ta gradient (n=30 days/treatment/group), whilst remotely monitoring social interactions and Ts Supporting our hypothesis, we show that: (1) social subordinates (n=12), who fed less than social dominants and alone experienced stress-induced mass-loss, displayed significantly larger changes in Ts following stress exposure than social dominants (n=8), and (2) stress-induced changes in Ts significantly increased heat conservation at low Ta and heat dissipation at high Ta among social subordinates alone. These results suggest that chickadees adjust their thermoregulatory strategies during stress exposure when resources are limited by ecologically relevant processes.
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Affiliation(s)
- Joshua K Robertson
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada K9L 0G2
- Department of Wildlife and Science, Toronto Zoo, Scarborough, ON, Canada M1B 5K7
| | | | - Gary Burness
- Department of Biology, Trent University, Peterborough, ON, Canada K9L 0G2
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Gormally BMG, Romero LM. What are you actually measuring? A review of techniques that integrate the stress response on distinct time‐scales. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13648] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Winder LA, White SA, Nord A, Helm B, McCafferty DJ. Body surface temperature responses to food restriction in wild and captive great tits. ACTA ACUST UNITED AC 2020; 223:223/8/jeb220046. [PMID: 32312718 DOI: 10.1242/jeb.220046] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/27/2020] [Indexed: 12/21/2022]
Abstract
During winter at temperate and high latitudes, the low ambient temperatures, limited food supplies and short foraging periods mean small passerines show behavioural, morphological and physiological adaptations to reduce the risk of facing energy shortages. Peripheral tissues vasoconstrict in low ambient temperatures to reduce heat loss and cold injury. Peripheral vasoconstriction has been observed with food restriction in captivity but has yet to be explored in free-ranging animals. We experimentally food restricted both wild and captive great tits (Parus major) during winter months and measured surface temperatures of the bill and eye region using thermal imaging, to investigate whether birds show rapid local heterothermic responses, which may reduce their thermoregulatory costs when facing a perceived imminent food shortage. Our results of a continuously filmed wild population showed that bill temperature was immediately reduced in response to food restriction compared with when food was available ad libitum, an apparent autonomic response. Such immediacy implies a 'pre-emptive' response before the bird experiences any shortfalls in energy reserves. We also demonstrate temporal variation in vasoconstriction of the bill, with bill temperature gradually rising throughout the food restriction after the initial drop. Eye-region temperature in the wild birds remained at similar levels throughout food restriction compared with unrestricted birds, possibly reflecting the need to maintain steady circulation to the central nervous and visual systems. Our findings provide evidence that birds selectively allow the bill to cool when a predictable food supply is suddenly disrupted, probably as a means of minimising depletion of body reserves for a perceived future shortage in energy.
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Affiliation(s)
- Lucy A Winder
- Scottish Centre for Ecology and the Natural Environment, Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Rowardennan G63 0AW, UK .,Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Stewart A White
- Scottish Centre for Ecology and the Natural Environment, Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Rowardennan G63 0AW, UK
| | - Andreas Nord
- Scottish Centre for Ecology and the Natural Environment, Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Rowardennan G63 0AW, UK.,Department of Biology, Section for Evolutionary Ecology, Lund University, SE-223 62 Lund, Sweden
| | - Barbara Helm
- Scottish Centre for Ecology and the Natural Environment, Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Rowardennan G63 0AW, UK.,Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, 9747 AG Groningen, The Netherlands
| | - Dominic J McCafferty
- Scottish Centre for Ecology and the Natural Environment, Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Rowardennan G63 0AW, UK
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Robertson JK, Mastromonaco G, Burness G. Evidence that stress-induced changes in surface temperature serve a thermoregulatory function. J Exp Biol 2020; 223:jeb213421. [PMID: 31974220 DOI: 10.1242/jeb.213421] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/20/2020] [Indexed: 08/26/2023]
Abstract
The fact that body temperature can rise or fall following exposure to stressors has been known for nearly two millennia; however, the functional value of this phenomenon remains poorly understood. We tested two competing hypotheses to explain stress-induced changes in temperature, with respect to surface tissues. Under the first hypothesis, changes in surface temperature are a consequence of vasoconstriction that occur to attenuate blood loss in the event of injury and serve no functional purpose per se; defined as the 'haemoprotective hypothesis'. Under the second hypothesis, changes in surface temperature reduce thermoregulatory burdens experienced during activation of a stress response, and thus hold a direct functional value: the 'thermoprotective hypothesis'. To understand whether stress-induced changes in surface temperature have functional consequences, we tested predictions of these two hypotheses by exposing black-capped chickadees (n=20) to rotating stressors across an ecologically relevant ambient temperature gradient, while non-invasively monitoring surface temperature (eye region temperature) using infrared thermography. Our results show that individuals exposed to rotating stressors reduce surface temperature and dry heat loss at low ambient temperature and increase surface temperature and dry heat loss at high ambient temperature, when compared with controls. These results support the thermoprotective hypothesis and suggest that changes in surface temperature following stress exposure have functional consequences and are consistent with an adaptation. Such findings emphasize the importance of the thermal environment in shaping physiological responses to stressors in vertebrates, and in doing so, raise questions about their suitability within the context of a changing climate.
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Affiliation(s)
- Joshua K Robertson
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada, K9L 0G2
- Department of Reproductive Physiology, The Toronto Zoo, Scarborough, Ontario, Canada, M1B 5K7
| | - Gabriela Mastromonaco
- Department of Reproductive Physiology, The Toronto Zoo, Scarborough, Ontario, Canada, M1B 5K7
| | - Gary Burness
- Department of Biology, Trent University, Peterborough, Ontario, Canada, K9L 0G2
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Jerem P, Jenni-Eiermann S, McKeegan D, McCafferty DJ, Nager RG. Eye region surface temperature dynamics during acute stress relate to baseline glucocorticoids independently of environmental conditions. Physiol Behav 2019; 210:112627. [PMID: 31348931 PMCID: PMC6739691 DOI: 10.1016/j.physbeh.2019.112627] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 07/22/2019] [Accepted: 07/22/2019] [Indexed: 02/06/2023]
Abstract
Reactions to acute stressors are critical for survival. Yet, the challenges of assessing underlying physiological processes in the field limit our understanding of how variation in the acute stress response relates to fitness in free-living animals. Glucocorticoid secretion during acute stress can be measured from blood plasma concentrations, but each blood sample can only provide information for one point in time. Also, the number of samples that can be extracted from an individual in the field is usually limited to avoid compromising welfare. This restricts capacity for repeated assessment, and therefore temporal resolution of findings within- and between-acute stress responses - both of which are important for determining links between acute stress and fitness. Acute stress induces additional body surface temperature changes that can be measured non-invasively, and at high frequencies using thermal imaging, offering opportunities to overcome these limitations. But, this method's usefulness in the field depends on the extent that environmental conditions affect the body surface temperature response, which remains poorly understood. We assessed the relative importance of individual physiology (baseline glucocorticoid concentrations) and environmental conditions (air temperature and relative humidity) in determining the eye region surface temperature (Teye) response to acute stress, in wild blue tits (Cyanistes caeruleus) during trapping, handling and blood sampling. When controlling for between-individual baseline variation, Teye initially dropped rapidly below, and then recovered above baseline, before declining more slowly until the end of the test, 160 s after trap closure. One measure of the amplitude of this response - the size of the initial drop in Teye - was dependent on environmental conditions, but not baseline corticosterone. Whereas, two properties defining response dynamics - the timing of the initial drop, and the slope of the subsequent recovery - were related to baseline corticosterone concentrations, independently of environmental conditions. This suggests inferring the acute stress response using thermal imaging of Teye will be practical under fluctuating environmental conditions in the field.
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Affiliation(s)
- Paul Jerem
- Department of Evolution, Behaviour and Environment, School of Life Sciences, University of Sussex, Falmer, UK.
| | | | - Dorothy McKeegan
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Dominic J McCafferty
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Ruedi G Nager
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
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Santos T, Gates R, Tinôco I, Zolnier S, Rocha K, Freitas L. Productive performance and surface temperatures of Japanese quail exposed to different environment conditions at start of lay. Poult Sci 2019; 98:2830-2839. [DOI: 10.3382/ps/pez068] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 01/29/2019] [Indexed: 12/17/2022] Open
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Edwards KL, Edes AN, Brown JL. Stress, Well-Being and Reproductive Success. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1200:91-162. [DOI: 10.1007/978-3-030-23633-5_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Surface temperature elevated by chronic and intermittent stress. Physiol Behav 2018; 191:47-55. [PMID: 29630961 PMCID: PMC5945995 DOI: 10.1016/j.physbeh.2018.04.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/03/2018] [Accepted: 04/03/2018] [Indexed: 11/24/2022]
Abstract
Stress in homeothermic animals is associated with raised body core temperature and altered patterns of peripheral blood flow. During acute stress, peripheral vasoconstriction causes a short-lived drop in surface temperature that can be detected non-invasively using infrared thermography (IRT). Whether and how skin temperature changes under chronic stress, and hence the potential of IRT in chronic stress detection, is unknown. We explored the impact of withdrawing environmental enrichments and intermittent routine handling on long-term skin temperature in laying hens (Gallus gallus domesticus). Immediately following enrichment withdrawal, comb, face and eye temperature dropped, suggesting this was acutely stressful. In the 3 weeks that followed, barren-housed hens displayed behavioural markers of frustration. Whilst control birds, housed in enriched conditions, showed a decline over weeks in both comb temperature and baseline corticosterone levels, barren-housed hens had no change in comb temperature and an increase in corticosterone. By the trial end, comb temperature (but not corticosterone) was significantly higher in barren-housed hens. This change in parameters over time may reflect cumulative impacts of enrichment withdrawal in barren pens and/or, as hens were young and maturing, age-related changes in controls. Comb, face and eye temperature were also higher on days following routine handling, and comb temperature higher on other days in hens that were regularly handled for blood sampling than for a less intensive weighing protocol. Together, these data support comb, face and eye surface temperature increase as a long-term marker of stress exposure in laying hens. It is important to recognise that the strength and even direction of these effects may vary with thermoregulatory and energetic context. However, in laboratory and indoor-reared farm animals that live in carefully managed environments, IRT of the skin can potentially be used to non-invasively monitor chronic and intermittent stress exposure. We measured surface temperature (ST) profile in hens subject to long term and intermittent stress. The impact of stressors was validated using established behavioural and hormonal markers. Enrichment withdrawal caused a short term drop in ST but living in a barren environment increased ST. Hens also had higher ST on days following handling or when subject to more intense handling methods. Thermal imaging of ST offers a non-invasive approach toward chronic stress monitoring.
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Nowack J. What eyes can tell. J Exp Biol 2018. [DOI: 10.1242/jeb.169961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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