MAROM, S.; WOJCIECHOWSKI , M.; KORINE, C.; PINSHOW, B.; BEN GURION UNIVERSITY OF THE NEGEV; BEN GURION UNIVERSITY OF THE NEGEV; BEN GURION UNIVERSITY OF THE NEGEV; BEN GURION UNIVERSITY OF THE NEGEV: Energy metabolism and water loss in two sympatric microchiropteran species – a day:night comparison
In this study, we compared body temperature, metabolic rate (MR) and evaporative water loss (EWL) in two sympatric insectivorous bats that are common in the Negev desert, Tadarida teniotis and Otonycteris hemprichii. Body temperature (Tb by indwelling thermocouple over the interscapular brown adipose tissue), MR and EWL were measured at ambient temperatures (Ta) ranging from 15 �C to 40 �C using indirect calorimetry in an open flow system. Measurements were made during daytime and nighttime, representing the resting and active phases, respectively. During the day, both species became torpid at Ta < 25 �C, while at night they were normothermic, with concomitant adjustments in MR. While torpid, Tb in both species remained 1 �C to 2 �C above Ta, and MR was correspondingly reduced. Non-torpid bats always maintained Tb at 30 �C to 36 �C, and their MR was greater at low than at high Ta. The thermoneutral zones of both species were from ~32 �C to ~35 �C. At high Ta, EWL increased markedly, but was lower in O. hemprichii than in T. teniotis. Torpid bats had lower EWL than awake bats. Torpor may thus be regarded as a water-conserving as well as an energy-conserving mechanism in desert dwelling bats. Funded by Israel Science Foundation grant # 653/01-1 and a student support grant to SM from the Mitrani Department for Desert Ecology.
