Food calling in ravens: are yells referential signals?

Citation
T. Bugnyar et al., Food calling in ravens: are yells referential signals?, ANIM BEHAV, 61, 2001, pp. 949-958
Citations number
54
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences","Neurosciences & Behavoir
Journal title
ANIMAL BEHAVIOUR
ISSN journal
0003-3472 → ACNP
Volume
61
Year of publication
2001
Part
5
Pages
949 - 958
Database
ISI
SICI code
0003-3472(200105)61:<949:FCIRAY>2.0.ZU;2-H
Abstract
Ravens, Corvus corax, yell when they approach rich but defended food source s. As in other species, such food-associated calls attract conspecifics. Th ese calls may provide information about the sender, such as its behaviour o r motivation, and about the type of stimuli to which the caller is respondi ng, such as the location, quality or quantity of a food source. We investig ated whether yells convey information about different types and amounts of food. We experimentally exposed a group of free-ranging ravens foraging in a game park near Grunau, Austria to six feeding situations. Food of one of three types (meat, kitchen leftovers, wild boar chow) and either of two qua ntities (one or three buckets) was shown to the ravens 10 min before they c ould gain access to it during the feeding of wild boars, Sus scrofa. Ravens responded to the sight of food with one type of yell, the long haa call. H aa calling rates varied with the type but not with the amount of food, and decreased during feeding. Although juveniles produced long yells (chii call s) in response to food they changed the context of calling with increasing independence from their parents. Ravens gave short 'who' yells when approac hing the food. Who calling was thus not affected by the sight of food but b y the feeding situation in general. This is comparable to other calls given in a foraging context, such as appeasement and intimidation calls. The dif ferent use of long and short yells relative to food availability suggests t hat who calls provide information about the caller, such as its behaviour a t food, whereas haa calls may also provide information about the food itsel f. Our data are consistent with the idea that haa calls are functionally re ferential. (C) 2001 The Association for the Study of Animal Behaviour.