Emergence and Return Times in a Colonial, Cave‐Dwelling Bat: Age and Sex Differences Driven by Reproductive Cycle

ABSTRACT The time that bats emerge and subsequently return from a colonial roost determines their maximum foraging period and influences their exposure to mortality risks. The order in which different age and sex cohorts emerge and return reflects variation in these cohorts' resource requiremen...

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Main Authors: Nicola J. Bail, Lindy F. Lumsden, Terry Reardon, Emmi vanHarten, Paul Clissold, Thomas A. A. Prowse
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Ecology and Evolution
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Online Access:https://doi.org/10.1002/ece3.71281
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author Nicola J. Bail
Lindy F. Lumsden
Terry Reardon
Emmi vanHarten
Paul Clissold
Thomas A. A. Prowse
author_facet Nicola J. Bail
Lindy F. Lumsden
Terry Reardon
Emmi vanHarten
Paul Clissold
Thomas A. A. Prowse
author_sort Nicola J. Bail
collection DOAJ
description ABSTRACT The time that bats emerge and subsequently return from a colonial roost determines their maximum foraging period and influences their exposure to mortality risks. The order in which different age and sex cohorts emerge and return reflects variation in these cohorts' resource requirements. The critically endangered Southern Bent‐wing Bat (Miniopterus orianae bassanii) is an Australian insectivorous cave‐roosting colonial bat. Resource limitation is hypothesised to have contributed to its decline but may not affect all cohorts equally. We tagged and monitored 3462 wild Southern Bent‐wing Bats over 7 years with Passive Integrated Transponder technology. To infer resource requirements of different cohorts over the reproductive cycle, we estimated cohort‐specific peak emergence and return times and the frequency of nocturnal returns to the roost. The emergence and return behaviour varied with age, sex, and throughout the annual reproductive cycle. Although adult females and males behaved similarly during the non‐breeding period (winter), females emerged significantly (12–21 min) earlier and returned (27–62 min) later than males during pregnancy, lactation and weaning. Adult females were less likely than males to be detected overnight in the maternity roost while dependent young were present, suggesting that females prioritised maximising foraging over nocturnal nursing. When juveniles commenced flying, they delayed emergence until several hours after sunset (well after adults had departed the roost). During the 40‐day weaning period, they progressively emerged earlier, such that by the end of this period they emerged with the adults, then subsequently foraged for longer than adults over winter. Passive monitoring of emergence and return behaviour in colonial bats can provide valuable data to infer cohort‐specific resource requirements. Regular monitoring of a population's emergence and return times potentially allows for the early detection of changes in a resource requirements, and the use of PIT technology allows for the most vulnerable cohort(s) to be identified.
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spelling doaj-art-de577150d5014403ada8416979908a132025-08-20T03:10:10ZengWileyEcology and Evolution2045-77582025-05-01155n/an/a10.1002/ece3.71281Emergence and Return Times in a Colonial, Cave‐Dwelling Bat: Age and Sex Differences Driven by Reproductive CycleNicola J. Bail0Lindy F. Lumsden1Terry Reardon2Emmi vanHarten3Paul Clissold4Thomas A. A. Prowse5School of Biological Sciences The University of Adelaide Adelaide South Australia AustraliaDepartment of Energy, Environment and Climate Action Arthur Rylah Institute for Environmental Research Heidelberg Victoria AustraliaCudlee Creek South Australia AustraliaDepartment of Energy, Environment and Climate Action Arthur Rylah Institute for Environmental Research Heidelberg Victoria AustraliaHumbug Scrub South Australia AustraliaSchool of Biological Sciences The University of Adelaide Adelaide South Australia AustraliaABSTRACT The time that bats emerge and subsequently return from a colonial roost determines their maximum foraging period and influences their exposure to mortality risks. The order in which different age and sex cohorts emerge and return reflects variation in these cohorts' resource requirements. The critically endangered Southern Bent‐wing Bat (Miniopterus orianae bassanii) is an Australian insectivorous cave‐roosting colonial bat. Resource limitation is hypothesised to have contributed to its decline but may not affect all cohorts equally. We tagged and monitored 3462 wild Southern Bent‐wing Bats over 7 years with Passive Integrated Transponder technology. To infer resource requirements of different cohorts over the reproductive cycle, we estimated cohort‐specific peak emergence and return times and the frequency of nocturnal returns to the roost. The emergence and return behaviour varied with age, sex, and throughout the annual reproductive cycle. Although adult females and males behaved similarly during the non‐breeding period (winter), females emerged significantly (12–21 min) earlier and returned (27–62 min) later than males during pregnancy, lactation and weaning. Adult females were less likely than males to be detected overnight in the maternity roost while dependent young were present, suggesting that females prioritised maximising foraging over nocturnal nursing. When juveniles commenced flying, they delayed emergence until several hours after sunset (well after adults had departed the roost). During the 40‐day weaning period, they progressively emerged earlier, such that by the end of this period they emerged with the adults, then subsequently foraged for longer than adults over winter. Passive monitoring of emergence and return behaviour in colonial bats can provide valuable data to infer cohort‐specific resource requirements. Regular monitoring of a population's emergence and return times potentially allows for the early detection of changes in a resource requirements, and the use of PIT technology allows for the most vulnerable cohort(s) to be identified.https://doi.org/10.1002/ece3.71281cave‐dwelling batsChiropteraemergence and return timesMiniopterus orianae bassaniiPIT‐tagsreproduction
spellingShingle Nicola J. Bail
Lindy F. Lumsden
Terry Reardon
Emmi vanHarten
Paul Clissold
Thomas A. A. Prowse
Emergence and Return Times in a Colonial, Cave‐Dwelling Bat: Age and Sex Differences Driven by Reproductive Cycle
Ecology and Evolution
cave‐dwelling bats
Chiroptera
emergence and return times
Miniopterus orianae bassanii
PIT‐tags
reproduction
title Emergence and Return Times in a Colonial, Cave‐Dwelling Bat: Age and Sex Differences Driven by Reproductive Cycle
title_full Emergence and Return Times in a Colonial, Cave‐Dwelling Bat: Age and Sex Differences Driven by Reproductive Cycle
title_fullStr Emergence and Return Times in a Colonial, Cave‐Dwelling Bat: Age and Sex Differences Driven by Reproductive Cycle
title_full_unstemmed Emergence and Return Times in a Colonial, Cave‐Dwelling Bat: Age and Sex Differences Driven by Reproductive Cycle
title_short Emergence and Return Times in a Colonial, Cave‐Dwelling Bat: Age and Sex Differences Driven by Reproductive Cycle
title_sort emergence and return times in a colonial cave dwelling bat age and sex differences driven by reproductive cycle
topic cave‐dwelling bats
Chiroptera
emergence and return times
Miniopterus orianae bassanii
PIT‐tags
reproduction
url https://doi.org/10.1002/ece3.71281
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