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

Browse

Browsing Mark Brigham by Author "Hickey, Anthony J.R."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Stressful summers? Torpor expression differs between high- and low-latitude populations of bats
    (American Society of Mammalogists, 2017) Czenze, Zenon J,; Brigham, R. Mark; Hickey, Anthony J.R.; Parsons, Stuart
    Variation in weather and food availability impacts the energy budgets of endotherms, with some species using torpor as an energy-saving strategy during periods of negative energy balance. We evaluated how latitudinal differences in energy balance relate to variation in torpor expression and roosting sociality between populations. We monitored summer skin temperatures (Tsk) of individuals from 2 populations of New Zealand lesser shorttailed bats (Mystacina tuberculata) separated by 6° of latitude using temperature telemetry. Although mean summer Ta was only < 1°C lower for the higher-latitude than lower-latitude population, individuals living at the higher-latitude site used torpor on 36% of observation days compared to 11% for lower-latitude bats. None of the recorded weather variables affected the propensity to enter torpor or torpor bout duration; however, the minimum torpid Tsk of bats positively correlated with daily minimum Ta. Roosts occupied by solitary bats were warmer than Ta, and temperatures within them fluctuated less than Ta. Higher-latitude individuals roosted solitarily (38%) more frequently than lower-latitude individuals (17%) and individuals from both populations exclusively used torpor while roosting solitarily. Arousals from torpor by higher-latitude bats coincided with sunset and not daily Ta maxima suggesting that bats were not fully exploiting advantages of passive rewarming. Site-specific roost choice and torpor patterns were apparent between M. tuberculata populations during summer, demonstrating that small differences in Ta differentially affect energetic strategy. The thermoregulatory behavior of species inhabiting latitudinal gradients in climate is highly plastic, likely to meet the specific challenges of their environment.
  • Thumbnail Image
    ItemOpen Access
    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.