Angeborene und erfahrungsbedingte Komponenten der Habitatwahl der Tannenmeise (Parus ater)

Zusammenfassung

Mit handaufgezogenen Tannenmeisen, die in verschiedenen Habitattypen aufwuchsen, wurde untersucht, inwieweit Umwelt und genetische Prädisposition die spätere Habitatwahl beeinflussen. Eine optimale Periode für das Entstehen einer Bindung an das umgebende Habitat scheint zu existieren. Der Grad der entstehenden Bevorzugung ist davon abhängig, wie gut die umgebenden Habitatstrukturen einem angeborenen inneren Bild des arttypischen Koniferenlebensraums entsprechen. In den neophoben Reaktionen auf verschiedene Pflanzentypen bestehen angeborene Unterschiede, die eventuell ebenfalls durch unterschiedliches Übereinstimmen mit dem angeborenen Habitatschema erklärbar sind.

Summary

We examined the mechanisms which lead to the establishment of habitat preferences during the ontogeny of the Coal Tit. Hand-reared birds were raised under different conditions: in differing sequence two groups were held in deciduous and coniferous habitat, successively; a third group was kept in a deciduous habitat. Subsequently, the development of preferences for one or the other habitat type was studied in a choice experiment (Fig. 1). In addition, trials on neophobia were carried out (Fig. 2) to investigate, if differences in neophobia towards different plants were correlated with innate or learned preferences. The results show that both innate dispositions and early experience influence habitat preferences. Juvenile experience is the decisive factor, determining habitat preference in a way similar to imprinting. A genetically preprogrammed time frame seems to exist which constitutes the optimal period for the development of habitat preference. The degree of the developing preference is dependent on an interior template of species-specific coniferous habitat and on how well the surrounding habitat structures fit this innate template. Due to innate differences in neophobic reactions to different plant types, Coal Tits probably have to overcome little or no neophobia when encountering species-typical coniferous habitat.