Corticosterone and Dispersal in Western Screech-Owls (Otus kennicottii)

Abstract

Belthoff and Dufty (in press) posed a model for dispersal in screech-owls and similar nonmigratory birds. The model is based on interactions among hormonal changes, body condition, and locomotor activity patterns. It predicts that corticosterone increases in blood plasma prior to dispersal under endogenous and exogenous influences, and this increase mediates the locomotor activity that underlies dispersal. Juveniles in good body condition (i.e., those with sufficient fat reserves) will disperse at that time, while birds in poor body condition will not. The latter will increase their foraging activity under the influence of corticosterone and disperse later. This paper presents preliminary data that show that locomotor activity levels are reduced in captive Western Screech-owls at the time of dispersal under the influence of a corticosterone-blocking drug.

Parent Publication

• Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium

Citation

Belthoff, James R.; Dufty, Alfred M., Jr. 1997. Corticosterone and Dispersal in Western Screech-Owls (Otus kennicottii). In: Duncan, James R.; Johnson, David H.; Nicholls, Thomas H., eds. Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium. Gen. Tech. Rep. NC-190. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Forest Experiment Station. 62-67.