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3 Acta Chiropterologica

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Sugar composition of fruit and nectar and preferences of bats: causes and consequences

100%

Herrera M. L. G.

Acta Chiropterologica

1999

tom 01

nr 2

Cranial shape and diet variation in Myotis species (Chiroptera: Vespertilionidae): testing the relationship between form and function

51%

Ospina-Garces S. M. , De Luna E. , Herrera M L. G. , Flores-Martinez J. J.

Acta Chiropterologica

2016

tom 18

nr 1

The relationship between cranial morphology and diet has long been investigated in bats. Bats of the genus Myotis include insectivorous, facultatively piscivorous, and piscivorous species. We tested the hypothesis that facultatively piscivorous (five Myotis species) and piscivorous species (M. vivesi) present cranial morphological and functional changes with respect to insectivorous taxa (16 Myotis species). Cranial shapes in skull and mandible modules were described with four geometric landmark configurations in these dietary groups. Gape capacity was measured with the stretch factors for temporal and masseter muscles. Geometric configurations from two skull and two mandible shapes were analyzed to detect differences in cranial morphology in relation to diet. Differences in cranial morphology were found between piscivorous and insectivorous species involving the mandibular process where masticatory muscles are attached. Linear regression analysis of Procrustes distances and gape capacity showed that the shape of the mandibular process region was highly correlated with the stretch factor of the masseter muscle in piscivorous and facultatively piscivorous species. These results suggest differences in cranial morphology and performance among diets but the hypothesis of gradual changes in cranial shape among diets was only accepted for the mandible and not for the skull. Myotis vivesi appears to improve mechanical advantage of masticatory muscles at lower gapes, presumably allowing more efficient chewing of slippery prey.

Winter and summer torpor in a free-ranging subtropical desert bat: the fishing myotis (Myotis vivesi)

51%

Salinas R. V. B. , Herrera M. L. G. , Flores-Martinez J. J. , Johnston D. S.

Acta Chiropterologica

2014

tom 16

nr 2

Use of torpor likely favors the survival of subtropical bats in harsh environments. The fishing myotis (Myotis vivesi) is a species endemic to desert islands in the Gulf of California, where summers are extremely hot and winters are cold and windy. We explored thermoregulating abilities of M. vivesi measuring skin temperature (Tskin) on free-ranging individuals in winter 2010 and 2011, and in summer 2010. We also measured ambient (Ta) and roost (Troost) temperatures during the study, and we obtained data for wind speed at night time during winter periods. We found that all bats entered torpor in both winters and that at least three individuals hibernated for several days, which had not been reported previously for bats in subtropical deserts. In summer, three individuals entered short bouts of shallow torpor in early mornings. Roosts were slightly warmer than Ta in winter at nightime, and in summer they never reached temperatures > 38.7°C, even at Ta ≈ 45°C. Roost occupancy in winter was higher during windy nights in 2010 but no pattern was found in 2011. Therefore, in winter fishing myotis were more likely to remain in their night roosts and enter torpor when ambient conditions (e.g., strong winds) limit fishing on marine waters. In summer, roosts provide good insulation against high Ta, and bats might not need to resort to torpor to lower their metabolic rate except for a brief period during early mornings. When resources are limited the use of torpor may increase this insular species' chances of survival.