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The Journal of Experimental Biology 205, 3571-3575 (2002)
Copyright © 2002 The Company of Biologists Limited

Seasonal daily, daytime and night-time field metabolic rates in Arabian babblers (Turdoides squamiceps)

Avner Anava1, Michael Kam2, Amiram Shkolnik3 and A. Allan Degen2,*

1 Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
2 Desert Animal Adaptations and Husbandry, Wyler Department of Dryland Agriculture, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
3 Department of Zoology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel

* Author for correspondence (e-mail: degen{at}bgumail.bgu.ac.il)

Accepted 14 August 2002

Arabian babblers (Turdoides squamiceps; mean adult body mass=72.5 g) inhabit extreme deserts of Israel. Previous studies have shown that their daily field metabolic rates are similar in winter and summer and that there is an increase during the breeding season. We hypothesized that the difference in seasonal daily field metabolic rate would be a consequence of differences in daytime metabolic rate, and that night-time metabolic rate would be similar during the three seasons. We used doubly labelled water to determine daily, daytime and night-time field metabolic and water-influx rates in breeding babblers in spring and nonbreeding babblers in winter and summer.

Daily and daytime energy expenditure rates were higher during the breeding season than during either summer or winter, but there was no difference among seasons in night-time energy expenditure rates. Thus, our hypothesis was supported. The daytime field metabolic rates in summer and winter nonbreeding babblers were 3.92x and 4.32x the resting metabolic rate (RMR), respectively, and in breeding babblers was 5.04x RMR, whereas the night-time field metabolic rates ranged between 1.26x RMR and 1.35x RMR in the three seasons. Daily and daytime water-influx rates were highest in winter, intermediate during the breeding season and lowest in summer, but there was no difference among seasons in night-time water-influx rate. Daytime water-influx rate was greater than night-time water-influx rate by 2.5-fold in summer, 3.9-fold in the breeding season and 6.75-fold in winter.

Seasonal patterns of daily and daytime energy expenditure were similar, as were seasonal patterns of daily and daytime water influx. Daily and daytime energy expenditure and water-influx rates differed among seasons whereas night-time rates of both did not. Daily and daytime field metabolic rates of babblers were highest during the breeding season, whereas daily and daytime water-influx rates were highest in winter.

Key words: Arabian babbler, Turdoides squamiceps, doubly labelled water, daily field metabolic rate, daytime field metabolic rate, night-time field metabolic rate, water-influx rate






© The Company of Biologists Ltd 2002