A behavioral ecology of the Belted Kingfisher (Ceryle alcyon)

The Belted Kingfisher is a non-passerine aerial piscivore of relatively recent tropical descent that breeds in earthen burrows along watercourses throughout the temperate zone of North America. In the following chapters I explore the ways in which this suite of life history traits may influence patterns of mortality and fecundity among individuals and thus help to shape the overall behavioral ecology of this species. All kingfishers defending territories in the Connecticut River valley during the winters of 1992–1998 were males. These overwintering males were adults that previously bred in the area and juveniles that dispersed into the area the preceding autumn. Banding and museum-skin data suggest that this pattern of unequal sex distribution during the winter occurs across North America at latitudes north of approximately 40–45°N. Because males and females are equal in body size and social dominance, it appears that advantages associated with year-round breeding-site occupation outweigh the potential costs of overwintering more often for males than for females. One way that males may reduce the potential costs of overwintering at high latitudes is to roost at night in earthen burrows, a habit that I found can reduce a bird\u27s nocturnal thermoregulatory costs by ∼20%. The enhanced probability for burrow-roosting kingfishers to survive climatic extremes may represent an adaptation allowing this species to extend the northerly limit of its non-breeding geographic range. Like many temperate-breeding birds that nest in cavities, nesting success for kingfishers along the Connecticut River was high; females almost invariably laid 7 eggs, few of these eggs failed to hatch (\u3c10%), and few nestlings failed to fledge (\u3c15%). Like many socially monogamous non-passerines, males and females shared all phases of parental care more or less equally, including incubation. Testosterone levels of males peaked during the sexual phase of breeding and remained both high and variable until dropping abruptly once nestlings hatched. Perhaps reflecting differences in post-breeding agendas, the sexual differences in “parental motivation” that I did observe among kingfishers tended to occur late in the nestling period, when males fed the young more often and females more often abandoned