Mark Brigham

Permanent URI for this collectionhttps://hdl.handle.net/10294/8900

Professor

Office: LB 242
E-mail: Mark.Brigham@uregina.ca
Phone: 306-585-4255 or 306-585-4562
Fax: 306-337-2410

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Browsing Mark Brigham by Author "Czenze, Zenon J."

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    Cold and alone? Roost choice and season affect torpor patterns in lesser short‑tailed bats
    (Springer, 2017) Brigham, R. Mark; HIckey, Anthony J.R.; Parsons, Stuart; Czenze, Zenon J.
    Seasonal changes in weather and food availability differentially impact energy budgets of small mammals such as bats. While most thermal physiological research has focused on species that experience extreme seasonal temperature variations, knowledge is lacking from less variable temperate to subtropical climates. We quantified ambient temperature (Ta) and skin temperature (Tsk) responses by individuals from a population of New Zealand lesser shorttailed bats (Mystacina tuberculata) during summer and winter using temperature telemetry. During summer, communal roosts were more thermally stable than Ta. During winter, solitary roosts were warmer than Ta indicating significant thermal buffering. Communal roost trees were used on 83 % of observation days during summer, and individuals occupying them rarely entered torpor. Solitary roosts were occupied on 93 % of observation days during winter, and 100 % of individuals occupying them used torpor. During summer and winter, bats employed torpor on 11 and 95 % of observation days, respectively. Maximum torpor bout duration was 120.8 h and winter torpor bout duration correlated negatively with mean Ta. Torpor bout duration did not differ between sexes, although female minimum Tsk was significantly lower than males. The summer Heterothermy Index varied, and was also significantly affected by Ta. Mean arousal time was correlated with sunset time and arousals occurred most frequently on significantly warmer evenings, which are likely associated with an increased probability of foraging success. We provide the first evidence that torpor is used flexibly throughout the year by M. tuberculata, demonstrating that roost choice and season impact torpor patterns. Our results add to the growing knowledge that even small changes in seasonal climate can have large effects on the energy balance of small mammals.
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    Winter climate affects torpor patterns and roost choice in New Zealand lesser short-tailed bats
    (Wiley-Blackwell (Zoological Society of London), 2017) Czenze, Zenon J.; Brigham, R. Mark; Hickey, Anthony J.R.; Parsons, Stuart
    Variation in winter conditions differentially impacts thermoregulation of endotherms, with some species using torpor as an energy-saving strategy during periods of negative energy balance. We evaluated how differences in energy balance due to winter ambient temperatures (Ta), would lead to differing torpor expression and roost choice between populations. Here, we monitored Ta and skin temperatures (Tsk) of New Zealand lesser short-tailed bats (Mystacina tuberculata) using temperature telemetry from an inland population from Pureora, North Island and another from Hauturu/Little Barrier Island (Hauturu), an offshore island. Relative to Pureora, all recorded Ta variables were higher in Hauturu. Hauturu bats used short torpor (<24 h) more frequently (51% of observational days) than their Pureora conspecifics (33%). Furthermore, minimum Tsk of Hauturu bats correlated positively with mean Ta and Hauturu bats were more likely to arouse on nights with warmer sunset Ta. No correlation was found for Pureora bats. Torpor bout duration did not differ between sites. On Hauturu, bats preferred thermally unstable roosts and preferentially roosted inside dead punga/silver fern-trees (Cyathea dealbata). As punga thermal characteristics did not differ from Ta, Hauturu bats may take advantage of warm Ta to reduce rewarming costs. We did not observe differences in any thermoregulatory variables between sexes in Hauturu. Differences in winter Ta may differentially impact populations across a latitudinal gradient. Although bat populations in warmer climates are under less thermoregulatory stress, site and climate specific adaptations appear to be employed that affect roost choice and torpor patterns.