Calling behavior of band-tailed pigeons in reference to a census technique

Graduation date: 1968Calling of captive and free-living band-tailed pigeons (Columba fasciata, Say) was studied between June, 1965, and June, 1967, in western Oregon. Vocalizations of captive band-tails were observed during mornings and afternoons in 1965 and 1966; calling of free-living band-tails was observed in mornings during call-counts and point observations in 1966. Data were collected on types of vocalizations, effects of certain physical and biological factors on calling, and variation in band-tailed pigeon call-counts. The perch-call normally uttered by adult male band-tails was the only vocalization heard which was considered sufficiently audible for use in an audio-census. Captive and free-living band-tails called most frequently from approximately 1/2 hour before sunrise to 1 1/2 hours after sunrise in mornings. In afternoons, captive pigeons called most frequently from 3 1/2 to 1 1/2 hours before sunset. Calling of captive pigeons lacked a definite seasonal trend. Free-living band-tails heard during call-counts began calling between May 18 and June 10, and continued calling until mid-August. There were no significant linear correlations at the 95 percent level between each of several weather factors and calling of captive band-tails or numbers of pigeons heard during call-counts. Calling of captive male band-tails in different stages of the reproductive cycle was observed. Unmated males called at least eight times more frequently than mated males in mornings (P < 0.01), and significantly more frequently than mated males in afternoons (P < 0.01). The probability of hearing an unmated captive male pigeon call during a 3-minute interval was at least seven times that of hearing a mated male in mornings (P < 0.01). The probability of hearing an unmated male was significantly. higher than that of hearing a mated male in. afternoons (P < 0.02). Although no quantitative data were collected on audibility of the perch-call, the maximum audible range of the call was estimated to be 1/4 mile. Numbers of band-tails heard, calls heard, and pigeons seen during 3l call-counts on seven routes in western Oregon in 1966 were subjected to analysis of variance. Estimates of variance between routes were higher than estimates of variance among counts within routes. Based on these data, the sample arrangement resulting in least variance or highest precision for a fixed total number of counts was one count per route. Numbers of band-tails seen varied more than numbers of pigeons heard or numbers of calls heard. It was estimated that numbers of band-tails heard or numbers of calls heard during one call-count on each of 40 routes annually would allow detection at the 95 percent level of approximately a 25 percent change in numbers of pigeons present. A recommended procedure for conducting band-tailed pigeon call-counts was outlined