TY - JOUR
T1 - Seasonal patterns in behavior and glucocorticoid secretion of a specialist Holarctic tree squirrel (Sciurus aberti)
AU - Zhang, Victor Y.
AU - Buck, C. Loren
N1 - Funding Information:
Research reported in this publication was supported by grants from the National Science Foundation (NSF) to C. Loren Buck (IOS-1558056) and from the Arizona Board of Regents Technology Research Initiative Fund, administered by Northern Arizona University.
Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2022/7
Y1 - 2022/7
N2 - Seasonally breeding mammals must make constant adjustments in behavior and physiology to manage energetic trade-offs between survival and reproduction. Despite encountering high levels of climate and resource variability across the year, specialist Abert’s squirrels (Sciurus aberti), lack the capacity to express hibernation or pronounced morphological adaptations to seasonality. Using accelerometer and GPS devices, we assessed how abiotic environmental factors, reproduction, and resource abundance influenced levels of activity and daily range size in a rural and food-supplemented suburban population of squirrels. We also quantified fecal cortisol metabolites (FCM) in squirrels to assess patterns of glucocorticoid secretion. While changes in weather predicted activity levels in both populations, seasonal variation in activity levels were reduced in food-supplemented compared to rural squirrels. In contrast to activity, daily range size was not affected by weather but was a better predictor of sex-specific reproductive investment. Comparisons between populations suggest that food-supplemented squirrels forage more efficiently within smaller areas. Across both sexes and populations, squirrels showed no sexual dimorphism in body size, no major patterns of seasonal weight change, and no associations between body mass and FCM concentrations; however, FCMs were lower in the food-supplemented compared to rural population during late-spring. Taken together, activity levels and FCM concentrations appear primarily influenced by weather and seasonal fluctuations in food availability, whereas daily range size reflects sexual asymmetries in seasonal reproductive investment. Overall, squirrels appear to rely largely on behavioral adjustments to cope with novel environmental heterogeneity, rather than changes in morphology or GC secretion.
AB - Seasonally breeding mammals must make constant adjustments in behavior and physiology to manage energetic trade-offs between survival and reproduction. Despite encountering high levels of climate and resource variability across the year, specialist Abert’s squirrels (Sciurus aberti), lack the capacity to express hibernation or pronounced morphological adaptations to seasonality. Using accelerometer and GPS devices, we assessed how abiotic environmental factors, reproduction, and resource abundance influenced levels of activity and daily range size in a rural and food-supplemented suburban population of squirrels. We also quantified fecal cortisol metabolites (FCM) in squirrels to assess patterns of glucocorticoid secretion. While changes in weather predicted activity levels in both populations, seasonal variation in activity levels were reduced in food-supplemented compared to rural squirrels. In contrast to activity, daily range size was not affected by weather but was a better predictor of sex-specific reproductive investment. Comparisons between populations suggest that food-supplemented squirrels forage more efficiently within smaller areas. Across both sexes and populations, squirrels showed no sexual dimorphism in body size, no major patterns of seasonal weight change, and no associations between body mass and FCM concentrations; however, FCMs were lower in the food-supplemented compared to rural population during late-spring. Taken together, activity levels and FCM concentrations appear primarily influenced by weather and seasonal fluctuations in food availability, whereas daily range size reflects sexual asymmetries in seasonal reproductive investment. Overall, squirrels appear to rely largely on behavioral adjustments to cope with novel environmental heterogeneity, rather than changes in morphology or GC secretion.
KW - Accelerometer
KW - Biologger
KW - Fecal glucocorticoid metabolites
KW - Home range
KW - Reproductive investment
KW - Sciurid
UR - http://www.scopus.com/inward/record.url?scp=85124552933&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85124552933&partnerID=8YFLogxK
U2 - 10.1007/s00360-022-01429-6
DO - 10.1007/s00360-022-01429-6
M3 - Article
C2 - 35157127
AN - SCOPUS:85124552933
SN - 0174-1578
VL - 192
SP - 541
EP - 559
JO - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
JF - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
IS - 3-4
ER -