|ognizant Communication Corporation|
VOLUME 15, NUMBER 2
Bird Behavior, Vol. 15, pp. 33-42
1056-1383/03 $20.00 + .00
Copyright © 2003 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.
Pecking and Respiration Rhythms of Pigeons (Columba livia)
Wolfgang Hörster, Li Xia, and Juan D. Delius
University of Konstanz, Germany
The production and coordination of rhythmic activities in birds is seldom investigated. Here we describe the pecking and breathing rhythms of pigeons under different conditions. When feeding from a heap of small grains, hungry pigeons pecked at regular intervals of about 0.3 s. The pecking rhythm was slightly slower in the afternoon. The pecking rhythm induced by the dopaminergic drug apomorphine was somewhat faster but some overt pecks were skipped. The mean respiratory cycle during a nonpecking baseline condition lasted about 2.5 s. Breathing was slightly faster in the afternoon. During bouts of grain pecking, the breathing cycle shortened to about 1.7 s but returned to baseline soon afterwards. Under the influence of apomorphine, the respiration cycle duration was reduced to about 0.8 s. There was a relative interaction between the pecking and breathing rhythms, the pecks tending to occur at particular points of the inspiration and expiration phases. This partial entrainment was less pronounced during apomorphine-induced than grain-induced pecking. The mechanisms and functions that might be involved are discussed.
Key words: Pecking; Feeding; Apomorphine; Respiration; Rhythms; Coupling; Pigeons
Prey Choice in Pied Kingfishers (Ceryle rudis L.): Prey Size and Prey Depth
Gadi Katzir,1 Zev Labinger,2 And Yoav Benjamini3
1Department of Biology, University of Haifa at Oranim, Israel
2Department of Zoology, Tel Aviv University, Israel
3Department of Statistics, Tel Aviv University, Israel
Pied kingfishers (Ceryle rudis) forage for fish using intermittent stationary hovers and plunge dives into shallow water. Prior to the dive the kingfishers must determine aspects of both prey (e.g., size) and environment (e.g., water depth). In a previous study kingfishers were tested for choice of different sized prey at a given depth. The purpose of this study was to test for the combined effect of prey size and prey depth. The subjects were captive, hand-reared pied kingfishers and they were tested in a simultaneous, two-prey choice situation in which both prey size and prey depth could be varied. When prey of different size were presented at unequal depth, the larger prey was presented deeper. The probability of choosing the larger prey (selectivity) was positively correlated with the relative size. Selectivity decreased with the increased difference in prey depth. When prey of equal size were presented at unequal depth, the kingfishers chose the shallower prey more frequently. Latency to capture was negatively correlated with selectivity. While in most trials the kingfishers dove directly from the perch, the frequency of hover-dives increased with increased prey depth. Our results support predictions derived from foraging models of simultaneous prey encounters. Proximate mechanisms of prey choice are discussed in view of the pied kingfisher's unique foraging behavior.
Key words: Prey choice; Pied kingfisher; Plunge diving; Piscivoury
Cultural Evolution and Song Stereotypy in an Isolated Population of Montane White-Crowned Sparrows (Zonotrichia leucophrys oriantha)
Department of Biology, St. Mary's College, 14500 Bannister Road, S.E., Calgary, Alberta, T2X 1Z4, Canada
In songbirds, song is a culturally transmitted trait. A geographically isolated population may also be isolated culturally, with few immigrants to introduce novel song variants. If so, an isolated population may show less variation in song among males. Montane white-crowned sparrows (Zonotrichia leucophrys oriantha) breeding in the Cypress Hills of Alberta and Saskatchewan are separated from other breeding populations by 250 km of grassland habitat, unsuitable for breeding by this species. Recordings of 51 males in the Cypress Hills showed very little variation in song among males. These results were compared to less isolated populations of the same and different subspecies of white-crowned sparrow. In general, the songs of Z. leucophrys oriantha populations studied showed less variation among males in such attributes as complex syllables and terminal trills than populations of either Z. leucophrys gambelii or Z. leucophrys pugetensis white-crowned sparrows. It is not clear whether song stereotypy in the Cypress Hills is a result of cultural isolation or is an attribute of the subspecies. Songs of the Cypress Hills population have been sampled four times in 22 years. Although the local song type has survived essentially unchanged, one phrase is now different in all males recorded. This population-wide change occurred over an interval of less than 10 years.
Key words: Cultural evolution; White-crowned sparrows; Zonotrichia leucophyrs oriantha
Kinship and Association in Social Foraging Northwestern Crows (Corvus caurinus)
Renee Robinette Ha,1 Paul Bentzen,2 Jennifer Marsh,1 and James C. Ha1
1Department of Psychology and 2School of Aquatic and Fishery Sciences & Marine Molecular Biotechnology Laboratory, University of Washington, Seattle, WA 98195
The producer-scrounger model suggests that the number of producers (animals that search for food) and scroungers (animals that consume food found by producers) may be an evolutionarily stable strategy. We investigated the role of kinship and social affiliation on these strategies by combining microsatellite DNA-based measures of relatedness with focal animal behavioral sampling of northwestern crows in the field. Scrounges were either passive (quiet ground approach without pursuit) or aggressive (noisy approach with pursuit). The combination of individually marked animals and information on relatedness allowed investigation of the roles of dominance and kinship in scrounging, including the target and form of the scrounge. Crows in foraging groups were more likely to be associated (i.e., socially affiliated) than were birds in the background population, but were not more likely to be genetically related than were birds in the background population. There was no difference between the average association of the foraging group and the average association between the scrounge interactors. There was also no difference in the average association between passive and aggressive scrounge interactions. Adults were more likely than juveniles to demonstrate a preference for social companions, and males were more likely than females to demonstrate a preference for social companions. Within foraging groups, passive scrounges tended to occur between more closely related individuals, and aggressive scrounges among less closely related individuals. Thus, scroungers modulate their mode of scrounging according to relatedness, or producers modulate their response, or both. They discriminate close from more distant relatives or unrelated individuals by adjusting the level of aggressiveness associated with theft.
Key words: Association; Producer; Relatedness; Scrounger
Parental Care and Aggression During Incubation in Captive California Condors (Gymnogyps californianus)
Nancy C. Harvey, Susan M. Farabaugh, Cindy D. Woodward, and Kristin McCaffree
Center for Reproduction of Endangered Species, Zoological Society of San Diego, San Diego, CA 92112-0551
Before 1994, the California condor (Gymnogyps californianus) captive program relied upon egg removal, double clutching, and hand rearing for the rapid increase of the captive population and subsequent reintroduction. Problems encountered with the first hand-reared released birds resulted in modification of the captive condor program to initiate parent rearing whenever possible. From 1994 through 1999, we examined incubation behavior in eight captive pairs of California condors at the San Diego Wild Animal Park using time-lapsed, dawn-to-dusk video recordings. Known pedigrees were the basis for pair formation rather than free choice. For males and females, we calculated the percent of time spent incubating, frequency of nest box entry with distinction between entries into a vacant or occupied nest box, egg manipulation, number of incubation bouts, nudge mate, egg pull, and aggressive interactions. There were no sex differences in the percent of time spent in incubation. Males entered occupied nest boxes significantly more often than females and such entries frequently resulted in aggression. Females had a higher mean rate of aggression than did males, but the difference was not significant. Because some pairs had higher combined rates of male/female aggression than others we categorized pairs as "compatible" or "incompatible" based on the results of paired sign tests. Incompatible pairs had a significantly greater proportion of entry into occupied nests, rates of nudge mate, and egg pull than the compatible pairs. Observed differences found within particular pairs in their daily time spent on nest and rates of aggression suggest that some of the forced pairs were less cooperative in their parental care duties. As more birds become available for captive propagation, there will be greater flexibility in establishing cooperative condor pairs and potentially increasing the number of parent-reared birds for release.
Key words: California condor; Parental care; Incubation; Captive breeding