Foraging behaviour of brown-hooded kingfishers (Halcyon albiventris) in the East Usambara Mountains, Tanzania

Abstract

We report metrics of foraging behaviour of the brown-hooded kingfisher (Halcyon albiventris) at field sites near Amani, Tanzania. We also test whether the relationships between perch height, search time, sally distance and handling times are consistent with predictions of opportunistic foraging. The time spent at a perch when the bird attempts prey capture should be shorter than give-up times when birds are taking the first thing detected. Hence, survival distribution functions and non-parametric rank statistics were used to test for differences between give-up and attempt perches. Since an exponential model appropriately described the perch survival distribution function, the time that a bird leaves a perch is independent from time already at the location. At any given time during a search for prey items, the probability that a kingfisher stayed at a perch was significantly lower when the bird made an attempt at the item than if it gave up on a location. Additionally, there were no relationships between search time and perch height, sally distance and handling times. This may be explained by an energetic trade-off with large prey handling costs, opportunistic feeding of the more abundant  small prey items, or prey-specific familiarity by local kingfishers.

Key words: opportunist, search behaviour, search time.