Ontogeny of nesting habitat recognition and preference in neonatal herring gull chicks, Larus Argentatus Pontoppidan

Abstract

This investigation was designed to examine the development of nesting habitat recognition and preferences as a function of habitat and social stimuli in neonatal Herring Gull chicks. The initial experiment studied the daily development of nest site preference during the first week post-hatch and thereafter weekly development until fledging the test procedure, which was essentially the same for all experiments, consisted of relocating chicks 20m from the nest and observing their movements. During these observations, latency, time moving, initial orientation, final distance from the nest, and initial and final vegetation characteristics were recorded. Results indicate that Herring Gull chicks exhibit a preference for the nest site area during the first week post-hatch and this preference wanes after the first week until fledging. Chicks of all ages showed a preference for vegetation similar to that of the nest site area. Nest site preferences are ecotypically controlled since foster-reared chicks exhibited the same preference for their foster nest as did normal-reared chicks for their natural nests. -- Several experiments examined the effect of vegetation characteristics and social stimuli provided by other chicks on nest site attachment and recognition. Vegetation type and the presence of siblings were found to be important stimulus properties of the nest situation in nest area attachment. Chicks exhibited a preference for vegetation similar to that at the nest site and for siblings over non-siblings. Nest site recognition appeared to be predominantly a visual response, at least in visually experienced animals. Vegetation characteristics, landmarks and the presence of other chicks were found to be among the cues used to recognize the nest site. The results of these experiments were interpreted as supporting the hypotheses that nesting habitat preferences are evident in Herring Gulls during the prefledging period and that habitat and social stimuli are important in the development of nest site preferences and recognition. These neonatal habitat preferences may be influential in determining later preferences for nesting sites and may be responsible for the observed stereotypy in adult habitat preferences.