Biology subjects

Peterson, C. C.

Publications and source records attributed to Peterson, C. C..

3 recordsLinked to original sources

bioRxiv2024

Group composition and dynamics in American Crows: insights into an unusual cooperative breeder

Breeding pairs of American Crows (Corvus brachyrhynchos) in Stillwater, OK, lived with 0-10 auxil-iaries in territories distributed throughout public, campus, commercial, and residential areas. Unpaired crows moved easily among groups throughout the year, but commonly did so during the two months or so preceding the onset of nesting across the population, and the week or so preceding hatching within groups. In 2001 and 2002, pre-hatch group size ranged from 2-10 (mean = 4.5 in both years), and auxiliaries included a male sibling, social and genetic offspring, step-offspring, half-siblings, and unrelated immigrants of both sexes, ranging in age from 1 to at least five years old. Twenty nine percent of pre-hatch auxiliaries dispersed out of groups at hatch-ing (for half, only temporarily), including all females unrelated to female breeders. Post-hatch group size ranged from 2-6, with means of 3.7 in both years, and the post-hatch auxiliary popula-tion differed in composition from the pre-hatch population: whereas post-hatch male auxiliaries included a sibling, half siblings, and unrelated immigrants in addition to social and genetic sons, all post-hatch female auxiliaries were the social and genetic daughters of female breeders, and all but one (the same individual in both years) were also the social and genetic daughters of male breeders. Crows in Stillwater delayed breeding for one or more years beyond sexual maturity, despite the availability of space and members of the opposite sex. Individual dispersal decisions by unpaired crows, and the behavior of paired territory owners, did not follow patterns described for other cooperative breeders. We found little support for extant theories regarding the formation, com-position, and maintenance of avian groups, and discuss aspects of the lives of crows that may have contributed to the complex and benign nature of this populations society. How to Cite: Caffrey, C. and C. C. Peterson. 2015. Group composition and dynamics in American Crows: insights into an unusual cooperative breeder. Friesen Press.

ecology↗

bioRxiv2024

Individual contributions to nest building and incubation by cooperatively breeding American Crows

American Crows (Corvus brachyrhynchos brachyrhynchos) are long-lived birds with pair bonds that may last many years. Pairs in Stillwater, OK, nested singly or in groups with up to 10 auxiliaries (Caffrey and Peterson 2015). Breeders did most of the nest building. Pair members contributed at approximately equal rates, although the sexes differed slightly in details: males tended to carry sticks and hand off materials more often, and females spent more time at and in nests. Both sexes worked faster on second and third attempts than on first attempts of the season. We found no evidence that pair members were (sexually) signaling to each other via their contributions. Incubation periods were characterized by low levels of activity at nests, where females spent most of their time and were fed once every 3-4 hours, mostly by their mates. Contributions to both stages of nesting by auxiliaries varied widely and exhibited no patterns with respect to any measured phenotypic characteristics.

ecology↗

bioRxiv2024

Nestling-care decisions by cooperatively breeding American Crows

During the nestling stage of breeding seasons in Stillwater, OK, pairs of American Crows (Corvus brachyrhynchos brachyrhynchos) lived alone or in groups of variable composition; auxiliaries included individuals that had delayed dispersal, immigrated into groups, or returned to natal territories after having lived elsewhere. Most, but not all, auxiliaries contributed to feeding nestlings, and their contributions varied considerably. On average, breeders fed nestlings at greater rates than did auxiliaries, and female breeders spent more time at nests than did other group members. Breeders compensated for auxiliary contributions by reducing their own; this and breeder responses to the disappearance of auxiliary feeding group members provide evidence that these long-lived, iteroparous animals were managing energy budgets so as to maximize fitness over the long term. Female breeders in larger groups spent more time at nests than did those in smaller groups, but not for expected reasons and not to any reproductive benefit. A few female auxiliaries spent increasing amounts of time at nests as nestlings aged. No other measured phenotypic characteristic of individuals was found to explain any of the wide variation in the patterns of nestling care exhibited by members of our population.

ecology↗