Intra-population variation in many fitness-related traits (e.g. clutch size) is often attributed to variation in individual parental quality. One possible component of quality is the level at which each individual can expend energy while provisioning dependent young. We used breeding tree swallows (Tachycineta bicolor) to test whether adults with large, natural-sized broods and/or nestlings in good nutritional condition had relatively high daily energy expenditures (DEEs). Adults with high DEEs were predicted to have large internal organs and high metabolic capacities. We first measured the growth rate of nestlings in natural broods of five, six and seven over a 4-day period and then measured parental DEE using doubly labelled water. Adults were then dissected for analyses of body composition and to determine maximum enzyme activities in the pectoral muscle. Although the total mass gain of large broods was greater than that of small broods, parental DEE was independent of brood size. We hypothesize that adults matched their clutch size (and consequently, brood size) to their individual foraging efficiencies. When statistically controlling for the effects of brood size, in one of two years there was a positive correlation between DEE and brood mass. This suggests that among individuals rearing the same-sized broods there were reproductive benefits of a relatively high DEE. There was no correlation between either brood size or DEE and the mass of any internal organ or the metabolic capacity of the pectoral muscle.
Physiological and biochemical correlates of brood size and energy expenditure in tree swallows
G.P. Burness, R.C. Ydenberg, P.W. Hochachka; Physiological and biochemical correlates of brood size and energy expenditure in tree swallows. J Exp Biol 15 April 2001; 204 (8): 1491–1501. doi: https://doi.org/10.1242/jeb.204.8.1491
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The Forest of Biologists
We are excited to announce the launch of The Forest of Biologists, a new biodiversity initiative created with support from the Woodland Trust, aiming to counteract nature loss and safeguard some of the most critically endangered ecosystems for future generations. Do take a look around our virtual forest. For every Research Article and Review/Commentary article that is published in JEB, a native tree is planted in a forest in the UK.
Celebrating 100 years of discovery
We are proud to be celebrating 100 years of discovery in Journal of Experimental Biology. Visit our centenary webpage to find out more about how we are marking this historic milestone.
Looking back on the first issue of JEB
Journal of Experimental Biology launched in 1923 as The British Journal of Experimental Biology. As we celebrate our centenary, we look back at that first issue and the zoologists publishing their work in the new journal.
In our new Conversation series JEB@100, JEB Editor-in-Chief Craig Franklin talks about the big outstanding questions in the field of physiological plasticity and why he thinks a sense of community is key to the journal's success. Find out more here.
Deer mice overheat and struggle to run in high temperatures
Matthew Eizenga and colleagues show that deer mice run comfortably at 25C, but as the temperature rises the tiny rodents start to struggle and they begin overheating at air temperatures of 38C, which could be a big problem for the animals in future climate scenarios.
Propose new workshop for 2025
Do you have an idea for a Workshop? We are now accepting proposals for our 2025 Biologists Workshops programme. As the scientific organiser, your involvement will be focused on the science. We'll take care of all the logistics. In 2025 we'll continue our efforts to diversify our Workshop programme and will be reserving one of our Workshops for an application from a Global South (GS) country to host an event overseas.