Meeting Abstract

P3.67A  Wednesday, Jan. 6  Seasonal variability in urine concentration and fecal water content of free-ranging bats in a tropical deciduous forest PILOSOF, S.; MUNOZ-GARCIA, A.*; PINSHOW, B.; HERRERA, M. L.G.; Ben Gurion University of the Negev; Universidad Nacional Autonomoa de Mexico; Ben Gurion University of the Negev; Ben Gurion University of the Negev shainova@gmail.com

Small mammals inhabiting highly seasonal environments often compensate for reduced water availability by producing highly concentrated urine, by reducing fecal water content (FWC), or by both. We examined seasonal variations in urine concentration (U_osm) and FWC of free-ranging bats inhabiting the tropical deciduous forest of the Chamela-Cuixmala biosphere reserve, Mexico, which is characterized by marked dry and rainy seasons. We hypothesized that bats inhabiting this forest would have seasonal physiological changes to maintain water balance. To test the predictions that bats would have (1) higher U_osm and (2) reduced FWC during the dry season compared to the rainy, we measured U_osm and FWC of samples collected from free-ranging bats in both seasons. Our first prediction was supported for the insectivorous Pteronotus parnellii (dry season U_osm = 2130 ± 122 mOsmol/kgH₂O, N = 24; rainy season U_osm = 1731 ± 72 mOsmol/kgH₂O, N = 42), but not for three frugivorous (Artibeus intermedius, A. hirsutus and A. jamaicensis), one hematophagous (Desmodus rotundus) and one mixed diet (insects and nectar, Glossophaga soricina) bat species. Our second prediction was supported for P. parnellii (dry season FWC = 51.6 ± 2.3%, N = 41; rainy season FWC = 71.1 ± 0.7%, N = 108) and G. soricina (dry season FWC = 45.2 ± 5.6%, N = 7; rainy season FWC = 84.9 ± 4.3% N = 11), but not for A. jamaicensis and A. intermedius. We conclude that the frugivorous and hematophagous bats are not water stressed in either season because their diets are water-rich all year round, and that P. parnellii copes with decreased water availability in the dry season by increasing U_osm and decreasing FWC. G. soricina also reduced FWC in the dry season, perhaps because of increased insect consumption.