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Sandy LK, Fanson KV, Griffiths SR, Robert KA, Palme R, Dimovski AM. Non-invasive monitoring of adrenocortical activity in the Gould's wattled bat (Chalinolobus gouldii). Gen Comp Endocrinol 2024:114619. [PMID: 39368757 DOI: 10.1016/j.ygcen.2024.114619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2024] [Revised: 10/01/2024] [Accepted: 10/02/2024] [Indexed: 10/07/2024]
Abstract
Although bats are the second most species-rich mammalian order, very little is known about their endocrine physiology. Glucocorticoids (GCs) are commonly associated with the stress response, but also modulate vital physiological functions which help animals adapt to their environment. Understanding normal patterns of adrenocortical activity can provide valuable insights into a species' fitness. Non-invasive hormone monitoring via faecal samples provides an integrated measure of adrenocortical activity while minimising stress on the animal but must be properly validated to ensure reliable results. The goal of this study was to validate an enzyme immunoassay for monitoring faecal glucocorticoid metabolites (FGMs) in a common Australian insectivorous bat species, the Gould's wattled bat (Chalinolobus gouldii). We compared the performance of five assays for monitoring changes in FGMs following capture and transfer of C.gouldii from the wild to captivity. Four of the five assays detected a significant increase in FGMs following capture, but the magnitude of the increase and consistency across individuals differed considerably. We selected the UVM-69a assay as the best performing assay to then describe normative patterns of adrenocortical activity in the species. Males had higher FGM levels than females, and juveniles had higher FGM levels than adults. Individuals with poorer body condition had higher FGM levels. We also demonstrate seasonal patterns of FGMs with higher levels in March and April corresponding with reproductive up-regulation and lower levels in May and November. Our study is the first of its kind to examine adrenocortical activity in an Australian insectivorous bat and provides a valuable tool for studying this species. Understanding adrenal function in common species such as the C.gouldii can shed light on the physiological mechanisms facilitating survival and success in changing environments.
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Affiliation(s)
- Lauren K Sandy
- School of Agriculture, Biomedicine & Environment, La Trobe University, Melbourne 3086, Australia
| | - Kerry V Fanson
- School of Agriculture, Biomedicine & Environment, La Trobe University, Melbourne 3086, Australia
| | - Stephen R Griffiths
- School of Agriculture, Biomedicine & Environment, La Trobe University, Melbourne 3086, Australia; Research Centre for Future Landscapes, La Trobe University, Melbourne 3086, Australia
| | - Kylie A Robert
- School of Agriculture, Biomedicine & Environment, La Trobe University, Melbourne 3086, Australia; Research Centre for Future Landscapes, La Trobe University, Melbourne 3086, Australia
| | - Rupert Palme
- Department of Bio Sciences and Pathobiology, University of Veterinary Medicine, 1210 Vienna, Austria
| | - Alicia M Dimovski
- School of Agriculture, Biomedicine & Environment, La Trobe University, Melbourne 3086, Australia; Research Centre for Future Landscapes, La Trobe University, Melbourne 3086, Australia.
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de Mel RK, Moseby KE, Stewart KA, Rankin KE, Czenze ZJ. The heat is on: Thermoregulatory and evaporative cooling patterns of desert-dwelling bats. J Therm Biol 2024; 123:103919. [PMID: 39024847 DOI: 10.1016/j.jtherbio.2024.103919] [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: 01/30/2024] [Revised: 07/07/2024] [Accepted: 07/08/2024] [Indexed: 07/20/2024]
Abstract
For small endotherms inhabiting desert ecosystems, defending body temperatures (Tb) is challenging as they contend with extremely high ambient temperatures (Ta) and limited standing water. In the arid zone, bats may thermoconform whereby Tb varies with Ta, or may evaporatively cool themselves to maintain Tb < Ta. We used an integrative approach that combined both temperature telemetry and flow through respirometry to investigate the ecological and physiological strategies of lesser long-eared bats (Nyctophilus geoffroyi) in Australia's arid zone. We predicted individuals would exhibit desert-adapted thermoregulatory patterns (i.e., thermoconform to prioritise water conservation), and that females would be more conservative with their water reserves for evaporative cooling compared to males. Temperature telemetry data indicated that free-ranging N. geoffroyi were heterothermic (Tskin = 18.9-44.9 °C) during summer and thermoconformed over a wide range of temperatures, likely to conserve water and energy during the day. Experimentally, at high Tas, females maintained significantly lower Tb and resting metabolic rates, despite lower evaporative water loss (EWL) rates compared to males. Females only increased EWL at experimental Ta = 42.5 °C, significantly higher than males (40.7 °C), and higher than any bat species yet recorded. During the hottest day of this study, our estimates suggest the water required for evaporative cooling ranged from 18.3% (females) and 25.5% (males) of body mass. However, if we extrapolate these results to a recent heatwave these values increase to 36.5% and 47.3%, which are likely beyond lethal limits. It appears this population is under selective pressures to conserve water reserves and that these pressures are more pronounced in females than males. Bats in arid ecosystems are threatened by both current and future heatwaves and we recommend future conservation efforts focus on protecting current roost trees and creating artificial standing water sites near vulnerable populations.
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Affiliation(s)
- Ruvinda K de Mel
- Centre for Behavioural and Physiological Ecology, University of New England, Armidale, NSW, 2351, Australia.
| | - Katherine E Moseby
- School of Biological, Earth and Environment Sciences, University of New South Wales, Kensington, NSW, Australia
| | - Kathleen A Stewart
- Centre for Behavioural and Physiological Ecology, University of New England, Armidale, NSW, 2351, Australia
| | - Kate E Rankin
- Centre for Behavioural and Physiological Ecology, University of New England, Armidale, NSW, 2351, Australia
| | - Zenon J Czenze
- Centre for Behavioural and Physiological Ecology, University of New England, Armidale, NSW, 2351, Australia
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3
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Chenery M, Geiser F, Stawski C. OUP accepted manuscript. J Mammal 2022; 103:826-834. [PMID: 36110387 PMCID: PMC9469929 DOI: 10.1093/jmammal/gyac022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 02/08/2022] [Indexed: 11/14/2022] Open
Abstract
Insectivorous bats are particularly susceptible to heat loss due to their relatively large surface area to volume ratio. Therefore, to maintain a high normothermic body temperature, bats require large amounts of energy for thermoregulation. This can be energetically challenging for small bats during cold periods as heat loss is augmented and insect prey is reduced. To conserve energy many bats enter a state of torpor characterized by a controlled reduction of metabolism and body temperature in combination with selecting roosts based upon thermal properties. Our study aimed to quantify torpor patterns and roost preferences of free-ranging little forest bats (Vespadelus vulturnus) during winter to identify physiological and behavioral mechanisms used by this species for survival of the cold season. All bats captured were male (body mass 4.9 ± 0.7 g, n = 6) and used torpor on every day monitored, with bouts lasting up to 187.58 h (mean = 35.5 ± 36.7 h, n = 6, total number of samples [N] = 61). Torpor bout duration was significantly correlated with daily minimum and maximum ambient temperature, mean skin temperature, insect mass, and body mass of individuals and the multiday torpor bouts recorded in the cold qualify as hibernation. The lowest skin temperature recorded was 5.2°C, which corresponded to the lowest ambient temperature measurement of −5.8°C. Most bats chose tall, large, live Eucalyptus trees for roosting and to leave their roost for foraging on warmer days. Many individuals often switched roosts (every 3–5 days) and movements increased as spring approached (every 1–2 days). Our data suggest that V. vulturnus are capable of using the environmental temperature to gauge potential foraging opportunities and as a cue to reenter torpor when conditions are unsuitable. Importantly, frequent use of torpor and appropriate roost selection form key roles in the winter survival of these tiny bats.
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Affiliation(s)
- Melissa Chenery
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia
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4
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Newman BA, Loeb SC, Jachowski DS. Winter roosting ecology of tricolored bats ( Perimyotis subflavus) in trees and bridges. J Mammal 2021. [DOI: 10.1093/jmammal/gyab080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Tricolored bats (Perimyotis subflavus) that roost in subterranean hibernacula have experienced precipitous declines from white-nose syndrome (WNS); however, understudied populations also use during winter non-subterranean roosts such as tree cavities, bridges, and foliage. Our objectives were to determine winter roost use by tricolored bats in an area devoid of subterranean roosts, determine roost microclimates to relate them to growth requirements of the fungal causal agent of WNS, and determine habitat factors influencing winter tree selection. From November to March 2017–2019, we used radiotelemetry to track 15 bats to their day roosts in the upper Coastal Plain of South Carolina and recorded microclimates in accessible tree cavities and bridges. We also characterized habitat and tree characteristics of 24 used trees and 153 random, available trees and used discrete choice models to determine selection. Roost structures included I-beam bridges, cavities in live trees, and foliage. Bridges were warmer and less humid than cavities. Roost temperatures often were amenable to fungal growth (< 19.5°C) but fluctuated widely depending on ambient temperatures. Bats used bridges on colder days (8.7°C ± 5.0 SD) and trees on warmer days (11.3°C ± 5.4). Bats selected low-decay trees closer to streams in areas with high canopy closure and cavity abundance. Bats also appeared to favor hardwood forests and avoid pine forests. Our results suggest that access to multiple roost microclimates might be important for tricolored bats during winter, and forest management practices that retain live trees near streams and foster cavity formation in hardwood forests likely will benefit this species. Our results also suggest tricolored bats using bridge and tree roosts might be less susceptible to WNS than bats using subterranean hibernaculum roosts. Thus, forests in areas without subterranean hibernacula in the southeastern United States that support bats during winter might represent important refugia from WNS for multiple species.
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Affiliation(s)
- Blaise A Newman
- Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, USA (BAN, DSJ)
| | - Susan C Loeb
- United States Department of Agriculture Forest Service, Southern Research Station, 233 Lehotsky Hall, Clemson University, Clemson, SC, USA (SCL)
| | - David S Jachowski
- Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC, USA (BAN, DSJ)
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Doty AC, Gonsalves L, Law BS. Activity patterns of insectivorous bats during a seasonal transition period from hibernation to reproduction. AUSTRALIAN MAMMALOGY 2020. [DOI: 10.1071/am18035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Bat activity is influenced by fluctuating environmental variables. It may also be influenced by energetic pressures related to pregnancy, lactation, and emergence following winter inactivity. We evaluated nightly changes in relative bat activity at Royal National Park in response to Julian date, ambient temperature, precipitation, wind speed and moon phase on a nightly scale for six weeks during spring, as insectivorous bats move out of hibernation or frequent, prolonged torpor, and into the maternal season. Interestingly, later Julian date (reflecting seasonal transition) was the sole variable that best predicted total nightly activity. In addition, we opportunistically assessed bat activity in response to a severe storm, considered a Category 1 cyclone, resulting in 96.4mm of rain in one night and wind speeds up to 94km h–1. Only one species of bat, Chalinolobus gouldii, was active during the storm, with activity restricted to the latter part of the evening when precipitation had reduced, indicating rapid resumption of activity following severe weather. The results of this research can be used as an indicator of emergence from winter inactivity and highlight activity patterns of bat species in relation to environmental variables to inform timing of monitoring programs, bat surveys, and targeted research.
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6
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Lumsden LF, Griffiths SR, Silins JE, Bennett AF. Roosting behaviour and the tree-hollow requirements of bats: insights from the lesser long-eared bat (Nyctophilus geoffroyi) and Gould’s wattled bat (Chalinolobus gouldii)
in south-eastern Australia. AUST J ZOOL 2020. [DOI: 10.1071/zo20072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Access to suitable roosts is critical for the conservation of tree-hollow roosting bats worldwide. Availability of roost sites is influenced by human land-use, but also by the roosting requirements and behaviour of species. We investigated roosting behaviour of the lesser long-eared bat (Nyctophilus geoffroyi) and Gould’s wattled bat (Chalinolobus gouldii) in a rural landscape in south-eastern Australia. Forty-five N. geoffroyi and 27 C. gouldii were fitted with radio-transmitters, resulting in the location of 139 and 89 roosts, respectively. Most (88%) roosts occupied by male N. geoffroyi contained only a single individual. During the breeding season female colonies were larger, with maternity roosts containing 18.3 ± 5.7 (s.e.) individuals. Mean colony sizes for C. gouldii were 8.7 ± 1.4 individuals. Both species shifted roosts frequently: on average, individual N. geoffroyi moved every 2.2 ± 0.23 days and C. gouldii every 2.2 ± 0.14 days. Notably, lactating female N. geoffroyi shifted roosts more frequently than non-breeding females. Individuals of both species roosted within a discrete area, with roosts typically <300 m apart; and consistently returned there from foraging up to 12 km distant. This roosting behaviour highlights three important requirements: (1) a relatively large overall number of hollows to support a population; (2) discrete roost areas with a high density of suitable hollows in close proximity; and (3) a range of hollow types to provide the specialised roosts required, particularly for breeding.
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Westerhuis EL, Schlesinger CA, Nano CEM, Morton SR, Christian KA. Characteristics of hollows and hollow-bearing trees in semi-arid river red gum woodland and potential limitations for hollow-dependent wildlife. AUSTRAL ECOL 2019. [DOI: 10.1111/aec.12765] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Erin L. Westerhuis
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Alice Springs Northern Territory 0870 Australia
| | - Christine A. Schlesinger
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Alice Springs Northern Territory 0870 Australia
| | - Catherine E. M. Nano
- Flora and Fauna, Department of Environment and Natural Resources; Alice Springs Australia
| | - Stephen R. Morton
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Alice Springs Northern Territory 0870 Australia
| | - Keith A. Christian
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Casuarina Northern Territory Australia
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8
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Greif S, Yovel Y. Using on-board sound recordings to infer behaviour of free-moving wild animals. ACTA ACUST UNITED AC 2019; 222:222/Suppl_1/jeb184689. [PMID: 30728226 DOI: 10.1242/jeb.184689] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Technological advances in the last 20 years have enabled researchers to develop increasingly sophisticated miniature devices (tags) that record an animal's behaviour not from an observational, external viewpoint, but directly on the animals themselves. So far, behavioural research with these tags has mostly been conducted using movement or acceleration data. But on-board audio recordings have become more and more common following pioneering work in marine mammal research. The first questions that come to mind when recording sound on-board animals concern their vocal behaviour. When are they calling? How do they adjust their behaviour? What acoustic parameters do they change and how? However, other topics like foraging behaviour, social interactions or environmental acoustics can now be addressed as well and offer detailed insight into the animals' daily life. In this Review, we discuss the possibilities, advantages and limitations of on-board acoustic recordings. We focus primarily on bats as their active-sensing, echolocating lifestyle allows many approaches to a multi-faceted acoustic assessment of their behaviour. The general ideas and concepts, however, are applicable to many animals and hopefully will demonstrate the versatility of on-board acoustic recordings and stimulate new research.
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Affiliation(s)
- Stefan Greif
- Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Yossi Yovel
- Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel .,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
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Geiser F, Bondarenco A, Currie SE, Doty AC, Körtner G, Law BS, Pavey CR, Riek A, Stawski C, Turbill C, Willis CKR, Brigham RM. Hibernation and daily torpor in Australian and New Zealand bats: does the climate zone matter? AUST J ZOOL 2019. [DOI: 10.1071/zo20025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We aim to summarise what is known about torpor use and patterns in Australian and New Zealand (ANZ) bats from temperate, tropical/subtropical and arid/semiarid regions and to identify whether and how they differ. ANZ bats comprise ~90 species from 10 families. Members of at least nine of these are known to use torpor, but detailed knowledge is currently restricted to the pteropodids, molossids, mystacinids, and vespertilionids. In temperate areas, several species can hibernate (use a sequence of multiday torpor bouts) in trees or caves mostly during winter and continue to use short bouts of torpor for the rest of the year, including while reproducing. Subtropical vespertilionids also use multiday torpor in winter and brief bouts of torpor in summer, which permit a reduction in foraging, probably in part to avoid predators. Like temperate-zone vespertilionids they show little or no seasonal change in thermal energetics during torpor, and observed changes in torpor patterns in the wild appear largely due to temperature effects. In contrast, subtropical blossom-bats (pteropodids) exhibit more pronounced daily torpor in summer than winter related to nectar availability, and this involves a seasonal change in physiology. Even in tropical areas, vespertilionids express short bouts of torpor lasting ~5 h in winter; summer data are not available. In the arid zone, molossids and vespertilionids use torpor throughout the year, including during desert heat waves. Given the same thermal conditions, torpor bouts in desert bats are longer in summer than in winter, probably to minimise water loss. Thus, torpor in ANZ bats is used by members of all or most families over the entire region, its regional and seasonal expression is often not pronounced or as expected, and it plays a key role in energy and water balance and other crucial biological functions that enhance long-term survival by individuals.
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10
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Lazzeroni ME, Burbrink FT, Simmons NB. Hibernation in bats (Mammalia: Chiroptera) did not evolve through positive selection of leptin. Ecol Evol 2018; 8:12576-12596. [PMID: 30619566 PMCID: PMC6308895 DOI: 10.1002/ece3.4674] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 09/10/2018] [Accepted: 09/14/2018] [Indexed: 01/25/2023] Open
Abstract
Temperature regulation is an indispensable physiological activity critical for animal survival. However, relatively little is known about the origin of thermoregulatory regimes in a phylogenetic context, or the genetic mechanisms driving the evolution of these regimes. Using bats as a study system, we examined the evolution of three thermoregulatory regimes (hibernation, daily heterothermy, and homeothermy) in relation to the evolution of leptin, a protein implicated in regulation of torpor bouts in mammals, including bats. A threshold model was used to test for a correlation between lineages with positively selected lep, the gene encoding leptin, and the thermoregulatory regimes of those lineages. Although evidence for episodic positive selection of lep was found, positive selection was not correlated with lineages of heterothermic bats, a finding that contradicts results from previous studies. Evidence from our ancestral state reconstructions suggests that the most recent common ancestor of bats used daily heterothermy and that the presence of hibernation is highly unlikely at this node. Hibernation likely evolved independently at least four times in bats-once in the common ancestor of Vespertilionidae and Molossidae, once in the clade containing Rhinolophidae and Rhinopomatidae, and again independently in the lineages leading to Taphozous melanopogon and Mystacina tuberculata. Our reconstructions revealed that thermoregulatory regimes never transitioned directly from hibernation to homeothermy, or the reverse, in the evolutionary history of bats. This, in addition to recent evidence that heterothermy is best described along a continuum, suggests that thermoregulatory regimes in mammals are best represented as an ordered continuous trait (homeothermy ← → daily torpor ← → hibernation) rather than as the three discrete regimes that evolve in an unordered fashion. These results have important implications for methodological approaches in future physiological and evolutionary research.
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Affiliation(s)
| | - Frank T. Burbrink
- Division of Vertebrate Zoology, Department of HerpetologyAmerican Museum of Natural HistoryNew YorkNew York
| | - Nancy B. Simmons
- Division of Vertebrate Zoology, Department of MammalogyAmerican Museum of Natural HistoryNew YorkNew York
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11
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McNab BK, O'Donnell C. The behavioral energetics of New Zealand's bats: Daily torpor and hibernation, a continuum. Comp Biochem Physiol A Mol Integr Physiol 2018; 223:18-22. [PMID: 29746908 DOI: 10.1016/j.cbpa.2018.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 05/01/2018] [Accepted: 05/01/2018] [Indexed: 01/14/2023]
Abstract
We examine the impact of behavior on the short-term energy expenditures of the only terrestrial mammals endemic to New Zealand, two bats, the long-tailed (Chalinolobus tuberculatus, family Vespertilionidae), and the lesser short-tailed (Mystacina tuberculata, family Mystacinidae). Vespertilionidae has a world-wide distribution. Mystacinidae is restricted to New Zealand, although related to five neotropical families and one in Madagascar reflecting a shared Gondwanan origin of their Noctilionoidea superfamily. Both species have highly variable body temperatures and rates of metabolism. They feed on flying insects, which requires them to be torpid in shelters during cold, wet periods. In dry weather Mystacina is active in winter at ambient temperatures as low as -1.0 °C, foraging for terrestrial invertebrates in leaf litter, even in the presence of snow, and consuming fruit, nectar, and pollen from endemic plants that bloom in winter. The behavior of Mystacina expands its presence in a cool, wet, temperate forest in a manner unlike any other bat, another example of the distinctive characteristics of the endemic New Zealand fauna. The use of torpor generally depends on a series of factors, including body mass, ambient temperature, latitude, reproductive cycle, sociality, and fat deposits. These factors result in a diversity of responses that range along a continuum from short-term torpor to hibernation.
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Affiliation(s)
- Brian K McNab
- Department of Biology, University of Florida, Gainesville, FL 32611, United States.
| | - Colin O'Donnell
- Department of Conservation, Government of New Zealand, Christchurch, New Zealand
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12
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Gonsalves L, Law B. Seasonal activity patterns of bats in North Sydney, New South Wales: implications for urban bat monitoring programs. AUSTRALIAN MAMMALOGY 2018. [DOI: 10.1071/am17031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Behavioural and physiological traits of bats may influence seasonal bat activity in urban areas. To examine this, we used acoustic surveys to monitor insectivorous bat activity in urban bushland and at two day-roosts of Miniopterus orianae oceanensis between September 2013 and August 2014. Day-roosts were also assessed for potential as swarming sites and monthly estimates of colony size were made at one of these, while radio-tracking was used to identify additional roosts. Acoustic surveys identified seven species, with Mi. o. oceanensis and Chalinolobus gouldii most commonly recorded. Nightly species richness was lower in winter than in other seasons, while total bat activity was greatest in autumn, reflecting increased activity by C. gouldii and Mi. o. oceanensis in this season. One Mi. o. oceanensis day-roost was used from autumn to early spring, with numbers of bats increasing from ~50 to 300 and high fidelity shown to this site by radio-tagged bats in autumn, while nightly activity at another day-roost was suggestive of swarming. Seasonal differences in bat activity were species-specific and, for Mi. o. oceanensis, corresponded to changes in population size as bats migrated to and from Sydney to meet reproductive and overwintering requirements. We recommend urban bat monitoring programs sample multiple seasons to adequately document trends in activity for all bat species.
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13
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Czenze ZJ, Brigham RM, Hickey AJR, Parsons S. Winter climate affects torpor patterns and roost choice in New Zealand lesser short‐tailed bats. J Zool (1987) 2017. [DOI: 10.1111/jzo.12486] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Z. J. Czenze
- School of Biological Sciences University of Auckland Auckland New Zealand
| | - R. M. Brigham
- Department of Biology University of Regina Regina SK Canada
| | - A. J. R. Hickey
- School of Biological Sciences University of Auckland Auckland New Zealand
| | - S. Parsons
- School of Biological Sciences University of Auckland Auckland New Zealand
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14
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Currie SE, Stawski C, Geiser F. Cold-hearted bats: uncoupling of heart rate and metabolism during torpor at subzero temperatures. J Exp Biol 2017; 221:jeb.170894. [DOI: 10.1242/jeb.170894] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/02/2017] [Indexed: 01/22/2023]
Abstract
Many hibernating animals thermoregulate during torpor and defend their body temperature (Tb) below 10°C by an increase in metabolic rate. Above a critical temperature (Tcrit) animals usually thermoconform. We investigated the physiological responses above and below Tcrit for a small tree dwelling bat (Chalinolobus gouldii, ∼14 g) that is often exposed to subzero temperatures during winter. Through simultaneous measurement of heart rate (HR) and oxygen consumption (V̇O2) we show that the relationship between oxygen transport and cardiac function is substantially altered in thermoregulating torpid bats between 1 and -2°C, compared with thermoconforming torpid bats at mild ambient temperatures (Ta 5-20°C). Tcrit for this species was Ta 0.7±0.4°C, with a corresponding Tb of 1.8±1.2°C. Below Tcrit animals began to thermoregulate, indicated by a considerable but disproportionate increase in both HR and V̇O2. The maximum increase in HR was only 4-fold greater than the average thermoconforming minimum, compared to a 46-fold increase in V̇O2. The differential response of HR and V̇O2 to low Ta was reflected in a 15-fold increase in oxygen delivery per heart beat (cardiac oxygen pulse). During torpor at low Ta, thermoregulating bats maintained a relatively slow HR and compensated for increased metabolic demands by significantly increasing stroke volume and tissue oxygen extraction. Our study provides new information on the relationship between metabolism and HR in an unstudied physiological state that may occur frequently in the wild and can be extremely costly for heterothermic animals.
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Affiliation(s)
- Shannon E. Currie
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, 2351, NSW, Australia
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany
| | - Clare Stawski
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, 2351, NSW, Australia
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, 2351, NSW, Australia
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