Evol Ecol Res 4: 1177-1189 (2002) Full PDF if your library subscribes.
Senior and junior nestlings in asynchronous bluethroat broods differ in their effectiveness of begging
Per T. Smiseth* and Trond Amundsen
Department of Zoology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
Address all correspondence to Per T. Smiseth, School of Biological Sciences, 3.614 Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
In accordance with theoretical models of begging as an honest signal, empirical studies have found that begging by nestlings reflects need and that parent birds respond to variation in begging activity. However, parent birds hatch their broods asynchronously and the resulting within-brood size-asymmetries might induce differences in the begging tactics of senior and junior nestlings. In the present study, we tested for long-term effects of initial variation in size-asymmetry on food allocation, visual begging and physical competition among siblings by experimentally generating asynchronous and synchronous bluethroat (Luscinia s. svecica) broods. Seniors were fed more often than juniors. However, there were no differences in the pre-feeding begging behaviour of seniors and juniors. Thus, seniors were more effective at begging (i.e. had higher returns for a given level of begging) than juniors. There was no evidence that the higher effectiveness of seniors was due to juniors being excluded from the most favourable positions in the nest. Seniors in asynchronous broods might have been more effective at begging because they controlled food distribution through other behaviours than those analysed by us, or because parents preferentially fed seniors. Finally, we found that juniors begged for longer than seniors in asynchronous broods. This suggests that juniors compensated for their less effective begging by increasing their post-feeding begging effort. Our results provide evidence that marked initial size-asymmetries lead to a divergence in the begging behaviour of seniors and juniors.
Keywords: asynchronous hatching, food distribution, nestling begging, sibling competition, signalling of need.
DOWNLOAD A FREE, FULL PDF COPY
IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.
© 2002 Per T. Smiseth. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.
Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.
All copies of abstracts and articles must preserve their copyright notice without modification.