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| Autori principali: | , , |
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| Natura: | Recurso digital |
| Lingua: | |
| Pubblicazione: |
Zenodo
1986
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| Soggetti: | |
| Accesso online: | https://doi.org/10.5281/zenodo.19669945 |
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Sommario:
- (Uploaded by Plazi for the Bat Literature Project) Energy metabolism, thermoregulation, and water flux of Macrotus californicus, the most northerly representative of the Phyllostomidae, were studied in the laboratory using standard methods, and energy metabolism and water fluxes were studied in the field using the doubly labelled water method together with a time budget. Daily energy expenditures of free-living bats averaged 22.8 kJ during the winter study period. Approximately 60% of this was allocated to resting metabolism costs while in the primary roosts (22 h/day). Macrotus californicus is unable to use torpor. The thermoneutral zone (TNZ) in this species is narrow (33 to 40 ~ and metabolic rate increased rapidly as ambient temperature decreased below the TNZ. Basal metabolic rate was 1.25 ml O2/g' h, or 24 J/ g.h. Total thermal conductance below the TNZ was 1.8 mW/g. ~ similar to values measured for other bats. Evaporative water loss showed a hyperbolic increase with increasing ambient temperature, and was approximately 1% of total body mass/h in the TNZ. The success of these bats as year-round residents in deserts in the southwestern United States is probably not due to special physiological adaptations, but to roosting and foraging behavior. They use geothermally-heated winter roost sites (stable year-round temperatures of approximately 29 ~ which minimize energy expenditures, and they have an energetically frugal pattern of foraging that relies on visual prey location. These seem to be the two major factors which have allowed M. californicus to invade the temperate zone.