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O'Connor RS, Love OP, Régimbald L, Le Pogam A, Gerson AR, Elliott KH, Hargreaves AL, Vézina F. An arctic breeding songbird overheats during intense activity even at low air temperatures. Sci Rep 2024; 14:15193. [PMID: 38956145 PMCID: PMC11219724 DOI: 10.1038/s41598-024-65208-9] [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: 11/17/2023] [Accepted: 06/18/2024] [Indexed: 07/04/2024] Open
Abstract
Birds maintain some of the highest body temperatures among endothermic animals. Often deemed a selective advantage for heat tolerance, high body temperatures also limits birds' thermal safety margin before reaching lethal levels. Recent modelling suggests that sustained effort in Arctic birds might be restricted at mild air temperatures, which may require reductions in activity to avoid overheating, with expected negative impacts on reproductive performance. We measured within-individual changes in body temperature in calm birds and then in response to an experimental increase in activity in an outdoor captive population of Arctic, cold-specialised snow buntings (Plectrophenax nivalis), exposed to naturally varying air temperatures (- 15 to 36 °C). Calm buntings exhibited a modal body temperature range from 39.9 to 42.6 °C. However, we detected a significant increase in body temperature within minutes of shifting calm birds to active flight, with strong evidence for a positive effect of air temperature on body temperature (slope = 0.04 °C/ °C). Importantly, by an ambient temperature of 9 °C, flying buntings were already generating body temperatures ≥ 45 °C, approaching the upper thermal limits of organismal performance (45-47 °C). With known limited evaporative heat dissipation capacities in these birds, our results support the recent prediction that free-living buntings operating at maximal sustainable rates will increasingly need to rely on behavioural thermoregulatory strategies to regulate body temperature, to the detriment of nestling growth and survival.
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Affiliation(s)
- Ryan S O'Connor
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada.
- Groupe de Recherche sur les Environnements Nordiques BORÉAS, Rimouski, Canada.
- Centre d'études Nordiques, Rimouski, Canada.
- Centre de la Science de la Biodiversité du Québec, Rimouski, Canada.
| | - Oliver P Love
- Department of Integrative Biology, University of Windsor, Windsor, ON, N9B 3P4, Canada
| | - Lyette Régimbald
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada
| | - Audrey Le Pogam
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada
- Groupe de Recherche sur les Environnements Nordiques BORÉAS, Rimouski, Canada
- Centre d'études Nordiques, Rimouski, Canada
- Centre de la Science de la Biodiversité du Québec, Rimouski, Canada
| | - Alexander R Gerson
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Kyle H Elliott
- Department of Natural Resource Sciences, McGill University, Sainte Anne de Bellevue, QC, H9X 3V90, Canada
| | - Anna L Hargreaves
- Department of Biological Sciences, McGill University, Montréal, QC, H3A 1B1, Canada
| | - François Vézina
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada
- Groupe de Recherche sur les Environnements Nordiques BORÉAS, Rimouski, Canada
- Centre d'études Nordiques, Rimouski, Canada
- Centre de la Science de la Biodiversité du Québec, Rimouski, Canada
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2
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Neumann LK, Davis CA, Fuhlendorf SD, Elmore RD. Does weather drive habitat use and movement of a nonmigratory bird? Ecosphere 2023. [DOI: 10.1002/ecs2.4407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Affiliation(s)
- L. K. Neumann
- Natural Resource Ecology and Management Oklahoma State University Stillwater Oklahoma USA
| | - C. A. Davis
- Natural Resource Ecology and Management Oklahoma State University Stillwater Oklahoma USA
| | - S. D. Fuhlendorf
- Natural Resource Ecology and Management Oklahoma State University Stillwater Oklahoma USA
| | - R. D. Elmore
- Natural Resource Ecology and Management Oklahoma State University Stillwater Oklahoma USA
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3
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Neumann LK, Fuhlendorf SD, Davis CD, Wilder SM. Climate alters the movement ecology of a non-migratory bird. Ecol Evol 2022; 12:e8869. [PMID: 35475174 PMCID: PMC9034450 DOI: 10.1002/ece3.8869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/01/2022] [Accepted: 04/08/2022] [Indexed: 11/11/2022] Open
Abstract
Global climate change is causing increased climate extremes threatening biodiversity and altering ecosystems. Climate is comprised of many variables including air temperature, barometric pressure, solar radiation, wind, relative humidity, and precipitation that interact with each other. As movement connects various aspects of an animal's life, understanding how climate influences movement at a fine-temporal scale will be critical to the long-term conservation of species impacted by climate change. The sedentary nature of non-migratory species could increase some species risk of extirpation caused by climate change. We used Northern Bobwhite (Colinus virginianus; hereafter bobwhite) as a model to better understand the relationship between climate and the movement ecology of a non-migratory species at a fine-temporal scale. We collected movement data on bobwhite from across western Oklahoma during 2019-2020 and paired these data with meteorological data. We analyzed movement in three different ways (probability of movement, hourly distance moved, and sinuosity) using two calculated movement metrics: hourly movement (displacement between two consecutive fixes an hour apart) and sinuosity (a form of tortuosity that determines the amount of curvature of a random search path). We used generalized linear-mixed models to analyze probability of movement and hourly distance moved, and used linear-mixed models to analyze sinuosity. The interaction between air temperature and solar radiation affected probability of movement and hourly distance moved. Bobwhite movement increased as air temperature increased beyond 10°C during low solar radiation. During medium and high solar radiation, bobwhite moved farther as air temperature increased until 25-30°C when hourly distance moved plateaued. Bobwhite sinuosity increased as solar radiation increased. Our results show that specific climate variables alter the fine-scale movement of a non-migratory species. Understanding the link between climate and movement is important to determining how climate change may impact a species' space use and fitness now and in the future.
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Affiliation(s)
- Landon K. Neumann
- Oklahoma State UniversityStillwaterOklahomaUSA,Natural Resource Ecology and ManagementOklahoma State UniversityStillwaterOklahomaUSA
| | - Samuel D. Fuhlendorf
- Natural Resource Ecology and ManagementOklahoma State UniversityStillwaterOklahomaUSA
| | - Craig D. Davis
- Natural Resource Ecology and ManagementOklahoma State UniversityStillwaterOklahomaUSA
| | - Shawn M. Wilder
- Department of Integrative BiologyOklahoma State UniversityStillwaterOklahomaUSA
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4
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Udino E, Mariette MM. How to Stay Cool: Early Acoustic and Thermal Experience Alters Individual Behavioural Thermoregulation in the Heat. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.818278] [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
Climate change is pushing organisms closer to their physiological limits. Animals can reduce heat exposure – and the associated risks of lethal hyperthermia and dehydration – by retreating into thermal refuges. Refuge use nonetheless reduces foraging and reproductive activities, and thereby potentially fitness. Behavioural responses to heat thus define the selection pressures to which individuals are exposed. However, whether and why such behavioural responses vary between individuals remains largely unknown. Here, we tested whether early-life experience generates inter-individual differences in behavioural responses to heat at adulthood. In the arid-adapted zebra finch, parents incubating at high temperatures emit “heat-calls,” which adaptively alter offspring growth. We experimentally manipulated individual early life acoustic and thermal experience. At adulthood, across two summers, we then repeatedly recorded individual panting behaviour, microsite use, activity (N = 2,402 observations for 184 birds), and (for a small subset, N = 23 birds) body temperature, over a gradient of air temperatures (26–38°C), in outdoor aviaries. We found consistent inter-individual variation in behavioural thermoregulation, and show for the first time in endotherms that early-life experience contributes to such variation. Birds exposed prenatally to heat-calls started panting at lower temperatures than controls but panted less at high temperatures. It is possible that this corresponds to a heat-regulation strategy to improve water saving at high temperature extremes, and/or, allow maintaining high activity levels, since heat-call birds were also more active across the temperature gradient. In addition, microsite use varied with the interaction between early acoustic and thermal experiences, control-call birds from cooler nests using the cooler microsite more than their hot-nest counterparts, whereas the opposite pattern was observed in heat-call birds. Overall, our study demonstrates that a prenatal acoustic signal of heat alters how individuals adjust behaviourally to thermal challenges at adulthood. This suggests that there is scope for selection pressures to act differently across individuals, and potentially strengthen the long-term fitness impact of early-life effects.
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Playà‐Montmany N, González‐Medina E, Cabello‐Vergel J, Parejo M, Abad‐Gómez JM, Sánchez‐Guzmán JM, Villegas A, Masero JA. The thermoregulatory role of relative bill and leg surface areas in a Mediterranean population of Great tit ( Parus major). Ecol Evol 2021; 11:15936-15946. [PMID: 34824801 PMCID: PMC8601919 DOI: 10.1002/ece3.8263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 09/15/2021] [Accepted: 10/07/2021] [Indexed: 11/07/2022] Open
Abstract
There is growing evidence on the role of legs and bill as 'thermal windows' in birds coping with heat stress. However, there is a lack of empirical work examining the relationship between the relative bill and/or leg surface areas and key thermoregulatory traits such as the limits of the thermoneutral zone (TNZ) or the cooling efficiency at high temperatures. Here, we explored this relationship in a Mediterranean population of Great tit (Parus major) facing increasing thermal stress in its environment. The lower and upper critical limits of the TNZ were found to be 17.7 ± 1.6ºC and 34.5 ± 0.7°C, respectively, and the basal metabolic rate was 0.96 ± 0.12 ml O2 min-1 on average. The evaporative water loss (EWL) inflection point was established at 31.85 ± 0.27°C and was not significantly different from the value of the upper critical limit. No significant relationship was observed between the relative bill or tarsi size and TNZ critical limits, breadth, mass-independent VO2, or mass-independent EWL at any environmental temperature (from 10 to 40°C). However, Great tit males (but not females) with larger tarsi areas (a proxy of leg surface area) showed higher cooling efficiencies at 40°C. We found no support for the hypothesis that the bill surface area plays a significant role as a thermal window in Great tits, but the leg surface areas may play a role in males' physiological responses to high temperatures. On the one hand, we argue that the studied population occupies habitats with available microclimates and fresh water for drinking during summer, so active heat dissipation by EWL might be favored instead of dry heat loss through the bill surface. Conversely, male dominance behaviors could imply a greater dependence on cutaneous EWL through the upper leg surfaces as a consequence of higher exposure to harsh environmental conditions than faced by females.
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Affiliation(s)
- Núria Playà‐Montmany
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Erick González‐Medina
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Julián Cabello‐Vergel
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Manuel Parejo
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - José M. Abad‐Gómez
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Juan M. Sánchez‐Guzmán
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
- Ecology in the AnthropoceneAssociated Unit CSIC‐UEXFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Auxiliadora Villegas
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
- Ecology in the AnthropoceneAssociated Unit CSIC‐UEXFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - José A. Masero
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
- Ecology in the AnthropoceneAssociated Unit CSIC‐UEXFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
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Neate‐Clegg MHC, Horns JJ, Buchert M, Pope TL, Norvell R, Parrish JR, Howe F, Şekercioğlu ÇH. The effects of climate change and fluctuations on the riparian bird communities of the arid Intermountain West. Anim Conserv 2021. [DOI: 10.1111/acv.12755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
| | - J. J. Horns
- School of Biological Sciences University of Utah Salt Lake City UT USA
| | - M. Buchert
- Department of City and Metropolitan Planning University of Utah Salt Lake City UT USA
| | - T. L. Pope
- Utah Division of Wildlife Resources Salt Lake City UT USA
| | - R. Norvell
- Utah Division of Wildlife Resources Salt Lake City UT USA
| | - J. R. Parrish
- Utah Division of Wildlife Resources Salt Lake City UT USA
| | - F. Howe
- College of Natural Resources Utah State University Logan UT USA
| | - Ç. H. Şekercioğlu
- School of Biological Sciences University of Utah Salt Lake City UT USA
- Faculty of Sciences Koç University Istanbul Turkey
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Bourne AR, Ridley AR, McKechnie AE, Spottiswoode CN, Cunningham SJ. Dehydration risk is associated with reduced nest attendance and hatching success in a cooperatively breeding bird, the southern pied babbler Turdoides bicolor. CONSERVATION PHYSIOLOGY 2021; 9:coab043. [PMID: 34150211 PMCID: PMC8208672 DOI: 10.1093/conphys/coab043] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 03/26/2021] [Accepted: 06/09/2021] [Indexed: 05/12/2023]
Abstract
High air temperatures have measurable negative impacts on reproduction in wild animal populations, including during incubation in birds. Understanding the mechanisms driving these impacts requires comprehensive knowledge of animal physiology and behaviour under natural conditions. We used a novel combination of a non-invasive doubly labelled water (DLW) technique, nest temperature data and field-based behaviour observations to test effects of temperature, rainfall and group size on physiology and behaviour during incubation in southern pied babblers Turdoides bicolor, a cooperatively breeding passerine endemic to the arid savanna regions of southern Africa. The proportion of time that clutches were incubated declined as air temperatures increased, a behavioural pattern traditionally interpreted as a benefit of ambient incubation. However, we show that (i) clutches had a <50% chance of hatching when exposed to daily maximum air temperatures of >35.3°C; (ii) pied babbler groups incubated their nests almost constantly (99% of daylight hours) except on hot days; (iii) operative temperatures in unattended nests frequently exceeded 40.5°C, above which bird embryos are at risk of death; (iv) pied babblers incubating for long periods of time failed to maintain water balance on hot days; and (v) pied babblers from incubating groups lost mass on hot days. These results suggest that pied babblers might leave their nests during hot periods to lower the risk of dehydration associated with prolonged incubation at high operative temperatures. As mean air temperatures increase and extreme heat events become more frequent under climate change, birds will likely incur ever greater thermoregulatory costs of incubation, leading to compromised nest attendance and increased potential for eggs to overheat, with implications for nest success and, ultimately, population persistence.
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Affiliation(s)
- Amanda R Bourne
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
- Corresponding author: FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
| | - Amanda R Ridley
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley 6009, Australia
| | - Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria 0184, South Africa
- DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield 0002, South Africa
| | - Claire N Spottiswoode
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Susan J Cunningham
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
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Ruth JM, Talbot WA, Smith EK. Behavioral Response to High Temperatures in a Desert Grassland Bird: Use of Shrubs as Thermal Refugia. WEST N AM NATURALIST 2020. [DOI: 10.3398/064.080.0215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Janet M. Ruth
- U.S. Geological Survey, Fort Collins Science Center, New Mexico Landscapes Field Station, Albuquerque, NM 87131
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9
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Oswald KN, Smit B, Lee AT, Cunningham SJ. Behaviour of an alpine range-restricted species is described by interactions between microsite use and temperature. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.09.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Chronic, sublethal effects of high temperatures will cause severe declines in southern African arid-zone birds during the 21st century. Proc Natl Acad Sci U S A 2019; 116:14065-14070. [PMID: 31235571 DOI: 10.1073/pnas.1821312116] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Birds inhabiting hot, arid regions are among the terrestrial organisms most vulnerable to climate change. The potential for increasingly frequent and intense heat waves to cause lethal dehydration and hyperthermia is well documented, but the consequences of sublethal fitness costs associated with chronic exposure to sustained hot weather remain unclear. Using data for species occurring in southern Africa's Kalahari Desert, we mapped exposure to acute lethal risks and chronic sublethal fitness costs under past, present, and future climates. For inactive birds in shaded microsites, the risks of lethal dehydration and hyperthermia will remain low during the 21st century. In contrast, exposure to conditions associated with chronic, sublethal costs related to progressive body mass loss, reduced nestling growth rates, or increased breeding failure will expand dramatically. For example, by the 2080s the region will experience 10-20 consecutive days per year on which Southern Pied Babblers (Turdoides bicolor) will lose ∼4% of body mass per day, conditions under which this species' persistence will be extremely unlikely. Similarly, exposure to air temperature maxima associated with delayed fledging, reduced fledgling size, and breeding failure will increase several-fold in Southern Yellow-billed Hornbills (Tockus leucomelas) and Southern Fiscals (Lanius collaris). Our analysis reveals that sublethal costs of chronic heat exposure are likely to drive large declines in avian diversity in the southern African arid zone by the end of the century.
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Kline HN, Fulbright TE, Grahmann ED, Hernández F, Wester DB, Brennan LA, Hehman MW. Temperature influences resource use by chestnut-bellied scaled quail. Ecosphere 2019. [DOI: 10.1002/ecs2.2599] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Holley N. Kline
- Caesar Kleberg Wildlife Research Institute; Texas A&M University-Kingsville; MSC 218 Kingsville Texas 78363 USA
| | - Timothy E. Fulbright
- Caesar Kleberg Wildlife Research Institute; Texas A&M University-Kingsville; MSC 218 Kingsville Texas 78363 USA
| | - Eric D. Grahmann
- Caesar Kleberg Wildlife Research Institute; Texas A&M University-Kingsville; MSC 218 Kingsville Texas 78363 USA
| | - Fidel Hernández
- Caesar Kleberg Wildlife Research Institute; Texas A&M University-Kingsville; MSC 218 Kingsville Texas 78363 USA
| | - David B. Wester
- Caesar Kleberg Wildlife Research Institute; Texas A&M University-Kingsville; MSC 218 Kingsville Texas 78363 USA
| | - Leonard A. Brennan
- Caesar Kleberg Wildlife Research Institute; Texas A&M University-Kingsville; MSC 218 Kingsville Texas 78363 USA
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O’Connor R, Brigham R, McKechnie A. Extreme operative temperatures in exposed microsites used by roosting Rufous-cheeked Nightjars (Caprimulgus rufigena): implications for water balance under current and future climate conditions. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0310] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Nocturnally active birds roosting in exposed microsites can experience operative temperatures (Te) that markedly differ from air temperature (Ta). Thus, quantifying Te becomes important for accurately modeling energy and water balance. We measured Te at roost and nest sites used by Rufous-cheeked Nightjars (Caprimulgus rufigena A. Smith, 1845) (mean body mass = 57.1 g) with three-dimensionally printed models covered with the plumage of a bird. Additionally, we estimated site-specific diurnal water requirements for evaporative cooling by integrating Te and Ta profiles with evaporative water loss (EWL) data for Rufous-cheeked Nightjars. Between the hours of 12:00 and 15:00, representing maximum solar radiation, mean Te at roost sites varied from 33.1 to 49.9 °C, whereas at the single nest site, Te averaged 51.4 °C. Mean diurnal EWL, estimated using Te, ranged from 2.8 to 10.5 g among roosts, values 1.2- and 3.6-fold greater, respectively, than Ta estimates. At the nest site, total EWL estimated using Te was 11.3 g, 4.0-fold greater than the corresponding estimate based on Ta. Consequently, Rufous-cheeked Nightjars can experience EWL potentially approaching their limits of dehydration tolerance. In the absence of microsite changes, climate change during the 21st century could perhaps create thermal conditions under which Rufous-cheeked Nightjars exceed dehydration tolerance limits before the onset of their nocturnal active phase.
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Affiliation(s)
- R.S. O’Connor
- DST–NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - R.M. Brigham
- Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada
| | - A.E. McKechnie
- DST–NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa; South African Research Chair in Conservation Physiology, National Zoological Garden, South African National Biodiversity Institute, P.O. Box 754, Pretoria 0001, South Africa
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Abstract
Deserts, already defined by climatic extremes, have warmed and dried more than other regions in the contiguous United States due to climate change. Our resurveys of sites originally visited in the early 20th century found Mojave Desert birds strongly declined in occupancy and sites lost nearly half of their species. Declines were associated with climate change, particularly decreased precipitation. The magnitude of the decline in the avian community and the absence of species that were local climatological “winners” are exceptional. Our results provide evidence that bird communities in the Mojave Desert have collapsed to a new, lower baseline. Declines could accelerate with future climate change, as this region is predicted to become drier and hotter by the end of the century. Climate change has caused deserts, already defined by climatic extremes, to warm and dry more rapidly than other ecoregions in the contiguous United States over the last 50 years. Desert birds persist near the edge of their physiological limits, and climate change could cause lethal dehydration and hyperthermia, leading to decline or extirpation of some species. We evaluated how desert birds have responded to climate and habitat change by resurveying historic sites throughout the Mojave Desert that were originally surveyed for avian diversity during the early 20th century by Joseph Grinnell and colleagues. We found strong evidence of an avian community in collapse. Sites lost on average 43% of their species, and occupancy probability declined significantly for 39 of 135 breeding birds. The common raven was the only native species to substantially increase across survey sites. Climate change, particularly decline in precipitation, was the most important driver of site-level persistence, while habitat change had a secondary influence. Habitat preference and diet were the two most important species traits associated with occupancy change. The presence of surface water reduced the loss of site-level richness, creating refugia. The collapse of the avian community over the past century may indicate a larger imbalance in the Mojave and provide an early warning of future ecosystem disintegration, given climate models unanimously predict an increasingly dry and hot future.
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