Patterns of Panting and Gular Flutter in Cormorants, Pelicans, Owls, and Doves

Abstract

Most birds pant when subjected to heat stress, but some supplement evaporation from the respiratory tract by fluttering the gular area. Gular flutter occurs in at least the following taxa: cormorants, pelicans, boobies, anhingas, frigate-birds, herons, owls, doves, roadrunners, colies, and many gallinaceous species. The mechanics of gular flutter have been examined only in the Poor-will, Phalaenoptilus nuttallii (Lasiewski and Bartholomew 1966), but data on rates of gular flutter are available for a number of species, including the Common Nighthawk, Chordeiles minor (Lasiewski and Dawson 1964), Domestic Pigeon (Columba livia (Calder and Schmidt-Nielsen 1966), Bobwhite (Colinus virginianus), Gambel's and California Quail (Lophortyx gambelii and L. californicus), Painted Quail, Excalfactoria chinensis, Screech Owl, Otus asio, and Mourning Dove, Zenaidura macroura (Lasiewski et al. 1966b). The ability of birds that employ gular flutter to dissipate all of their metabolic heat through evaporation has been demonstrated in the Poor-will (Bartholomew et al. 1962), Common Nighthawk (Lasiewski and Dawson 1964), Domestic Pigeon (Calder and Schmidt-Nielsen 1966), Inca Dove, Scardafella inca (MacMillen and Trost 1967), and the Painted Quail (Lasiewski et al. 1966a). In caprimulgids the rate of flutter is independent of heat load and appears to be determined by the resonant properties of the gular area, just as the panting rate of dogs is determined by the resonant properties of the thoraco-abdominal region (Crawford 1962). The present study was undertaken to examine aspects of gular flutter and breathing in several birds of widely differing morphology and behavior. Through the cooperation of the staff of the San Diego Zoological Gardens, we were able to make measurements on a Double-crested Cormorant (Phalacrocorax auritus), a Brown Pelican (Pelecanus occidentalis), a Homed Owl (Bubo virginianus), and a Barn Owl (Tyto alba). Mourning doves (Zenaidura macroura) and a Horned Owl were studied on the Los Angeles Campus of the University of California.