Journal article
The small-bat-in-summer paradigm: Energetics and adaptive behavioural routines of bats investigated through a stochastic dynamic model
Journal of Animal Ecology, Vol.92(10), pp.2078-2093
2023
PMID: 37661664
Abstract
Strong seasonality at high latitudes represents a major challenge for many endotherms as they must balance survival and reproduction in an environment that varies widely in food availability and temperature. To avoid energetic mismatches caused by limited foraging time and stochastic weather conditions, bats employ the energy-saving state of torpor during summer to save accumulated energy reserves. However, at high-latitude small-bats-in-summer face a particular challenge: as nocturnal foragers, they rely on the darkness at night to avoid predators and/or interspecific competition, but live in an environment with short, light summer nights, and even a lack of true night at the northernmost distributions of some bat species. To predict optimal behaviour in relation to latitudinal variation in diurnal cycles, we constructed a stochastic dynamic programming model of bats living at high latitudes. Using a stochastic dynamic programming framework with values that are representative for our study system, we show that individual energetic reserves are a strong driver of daytime use of torpor and night-time foraging behaviour alike, with these linked effects being both temperature- and photoperiod-dependent. We further used the model to predict survival probabilities at five locations across a latitudinal gradient (60.1° N to 70.9° N), finding that combinations of photoperiod and temperature conditions limited population distributions in the model. To verify our model results, we compared predictions for optimal decisions with our own empirical data collected on northern bats (Eptesicus nilssonii) from two latitudes in Norway. The similarities between our predictions and observations provide strong evidence that this model framework incorporates the most important drivers of diurnal decision-making in bat physiology and behaviour. Comparing empirical data and model predictions also revealed that bats facing lighter night conditions further north restrict their mass gain, which strengthens the hypothesis that predation threat is a main driver of bat nocturnality. Our model findings regarding state-dependent decisions in bats should contribute to the understanding of how bats cope with the summer challenges at high latitudes.
Details
- Title
- The small-bat-in-summer paradigm: Energetics and adaptive behavioural routines of bats investigated through a stochastic dynamic model
- Authors
- Mari Aas Fjelldal (Corresponding Author) - Norwegian University of Science and TechnologyAmandine Sophie Muller (Author) - Norwegian University of Science and TechnologyIrja Ida Ratikainen (Author) - Norwegian University of Science and TechnologyClare Stawski (Author) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringJonathan Wright (Author) - Norwegian University of Science and Technology
- Publication details
- Journal of Animal Ecology, Vol.92(10), pp.2078-2093
- Publisher
- Wiley-Blackwell Publishing Ltd.
- Date published
- 2023
- DOI
- 10.1111/1365-2656.13999
- ISSN
- 1365-2656
- PMID
- 37661664
- Copyright note
- This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2023 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.
- Grant note
- 223257 / Norges Forskningsråd Norges TekniskNaturvitenskapelige Universitet
- Organisation Unit
- University of the Sunshine Coast, Queensland; School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 99966898502621
- Output Type
- Journal article
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