Postfledging Dispersal, Habitat Imprinting, and Philopatry in a Montane, Migratory Sparrow

Abstract

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Postfledging dispersal in the endangered Lesser KestrelFalco naumanni

“…Why do they move long distances towards the north from their breeding sites prior to a southerly migration? It has been suggested that before migration young migratory birds disperse to find favourable areas (living space, food and shelter; Morton et al 1991, Baker 1993. They may therefore avoid competition with adults, enhance survival and improve body condition in preparation for migration (Morton et al 1991, Baker 1993.…”

“…It has been suggested that before migration young migratory birds disperse to find favourable areas (living space, food and shelter; Morton et al 1991, Baker 1993. They may therefore avoid competition with adults, enhance survival and improve body condition in preparation for migration (Morton et al 1991, Baker 1993. Ultimate factors could be to collect information to identify a future breeding site (hereafter IBS hypothesis) or create a navigational target or a mental map (hereafter CNT hypothesis) to return the following spring (Morton et al 1991;Baker 1993).…”

“…They may therefore avoid competition with adults, enhance survival and improve body condition in preparation for migration (Morton et al 1991, Baker 1993. Ultimate factors could be to collect information to identify a future breeding site (hereafter IBS hypothesis) or create a navigational target or a mental map (hereafter CNT hypothesis) to return the following spring (Morton et al 1991;Baker 1993). These possible explanations are not mutually exclusive.…”

“…Postnatal dispersal by juveniles once they have reached independence from adults up to first migration or settling in a winter area seems usual in most birds (Morton et al 1991). The factors that lead to this type of dispersal are not well understood.…”

Predictive models for lesser kestrel Falco naumanni distribution, abundance and extinction in southern Spain

“…Don~izar and F. Hiraldo, unpublished data). If kestrels, like other raptors (Cade & Bird, 1990;Cade & Jones, 1993) and, in general, other birds (Klopfer & Ganzhorn, 1985;Morton et al, 1991), have an imprinted image of the habitat in which they were born it could be expected that individuals will tend to breed in urban areas even if the quality of the surrounding foraging habitats has declined. It would be interesting to find out if adequate foraging habitat is present far from villages and if these areas are not colonized because of low availability of adequate nesting sites.…”