Social Dominance, Mating and Spacing Systems, Female Fecundity, and Vocal Dialects in Captive and Free-Ranging Brown-Headed Cowbirds

Rothstein, Stephen I.; Yokel, David A.; Fleischer, Robert C.

doi:10.1007/978-1-4615-6784-4_3

Cited by 128 publications

(97 citation statements)

References 51 publications

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“…Other than nests located within the same Phoebe territory (distance: 0 km), all other nests were 1-50 km apart, which was deemed far enough to be beyond the dimensions of the breeding range of individual female Cowbirds (*200 m diameter, following Gibbs et al 1997). This scale of minimal distances between different individual female Cowbirds' territories had also been suggested by other published work from Ithaca (Friedmann 1929), from other upstate New York study sites (Dufty 1982;Hahn et al 1999), and from other regions within the Cowbird's range (Darley 1983;Rothstein et al 1986;Raim 2000). Our sampling paradigm, therefore, implies that parasitism events in separate host nest sites were likely owing to eggs laid by different Cowbird females.…”

Section: Methodssupporting

confidence: 73%

Indirect estimates of breeding and natal philopatry in an obligate avian brood parasite

et al. 2011

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In theory, obligate brood parasitic birds are freed from several of the temporal and spatial constraints of parental care for dependent young. Yet, similar to parental bird species, adults in several avian brood parasites show a territorial spacing system while breeding, including site fidelity within and across years. Banding-based capture and sighting studies are also suggestive of non-parasite-like lower levels of natal philopatry in avian brood parasites. We analyzed the potential correlation of physical distance with genetic structure of a Brown-headed Cowbird Molothrus ater population, sampling parasitic chicks from nests across different temporal and spatial scales of its common host, the Eastern Phoebe Sayornis phoebe, near Ithaca, New York, USA. In support of extensive breeding but not historical patterns of natal philopatry, we detected no significant covariation of genetic similarity by distance of nestling parasites at the scale beyond that of individual host nest sites. These results contribute towards a baseline for future behavioral and genetic comparisons of whether and how parasitic versus parental reproductive strategies impact patterns of avian population genetic structure across space and time.

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Section: Methodssupporting

confidence: 73%

Indirect estimates of breeding and natal philopatry in an obligate avian brood parasite

et al. 2011

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“…In the wild, both male and female cowbirds have dominance hierarchies. In captivity, the dominant male in a cage (Dufty & Wingfield, 1986) shows mate guarding and excludes subordinate males from courting females (Rothstein et al, 1986). Females show less clearly defined dominance in captivity (Rothstein et al, 1986), possibly because the resources that they normally defend, host nests, are absent.…”

Section: Behavioral Variables Altered By Captivitymentioning

confidence: 99%

“…Obviously, more research is needed to isolate why we found sexspecific effects of captivity on Hp volume in M. a. obscurus despite a lack of sex-specific Hp size in wild birds of the population we studied. Future studies should consider subspecies and within-subspecies population differences as cowbird space use appears to depend on a number of habitat, habitat use, and population size dimensions (Darley, 1982(Darley, , 1983Dufty, 1982;Lowther, 1993;Rothstein, Verner, & Steven, 1984;Rothstein et al, 1986). Precedents for such within-species population differences are found in black-capped chickadees (P. atricapilla).…”

Section: Cowbird Population Differencesmentioning

confidence: 99%

Sex differences in the effects of captivity on hippocampus size in brown-headed cowbirds (Molothrus ater obscurus).

Day

Guerra²,

Schlinger³

et al. 2008

Behavioral Neuroscience

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In brood parasitic cowbirds, hippocampus (Hp) size is correlated with environmental spatial memory demands. Searching for host nests is the presumed causal factor influencing cowbird Hp size, because Hp volumes vary across species, sexes, and seasons according to nest-searching participation. Brownheaded cowbirds have female-only nest searching and, at least in the eastern subspecies, a larger Hp in females than in males, suggesting that nest searching influences cowbird Hp size. We predicted that female brown-headed cowbirds housed in aviaries lacking host nests would have a smaller Hp than wild-caught females whereas males would be unaffected. We found that the Hp was smaller in captive females, but not males, compared to their wild-caught counterparts. This did not appear to be due to general effects of an impoverished environment on all brain regions. Our results imply that interruption of nest searching in cowbirds prevents seasonal increase in Hp size in females. Future studies should isolate which behavioral differences between wild and captive birds contributed to captivity-induced changes in Hp volume in females while not affecting males. Keywordscowbird; hippocampus; sex differences; brain plasticity; brood parasitism Variation in environmental spatial demands is related to variation in hippocampus (Hp) size among closely related species, between sexes, and across seasons in mammalian, avian, and reptilian species. For example, food-storing behaviors in birds (Clayton, 1995a;Hampton, Sherry, Shettleworth, Kurgel, & Ivy, 1995;Hampton & Shettleworth, 1996;Healy & Krebs, 1992;Krebs, Sherry, Healy, Perry, & Vaccarion, 1989;Sherry, Vaccarino, Buckenham, & Herz, 1989;Volman, Grubb, & Schuett, 1997) and rodents (Jacobs, 1992;Jacobs & Spencer, 1994), foraging-related rate of movement in lacertid lizards (Day, Crews, & Wilczynski, 1999), home-range size in voles (Gaulin, 1992;Jacobs, Gaulin, Sherry, & Hoffman, 1990 Sherry, Jacobs, & Gaulin, 1992), and breeding-habitat complexity in petrels (Abbott, Walsh, Storey, Stenhause, & Harley, 1999) are all associated with enlarged Hp size, presumably due to the demands of spatial memory. In addition, seasonal variation in food-storing demands is associated with seasonal changes in Hp volume (Smulders, Sasson, & DeVoogd, 1995) in black-capped chickadees and rodents (Jacobs, 1996). Males have a larger Hp than females in a vole species in which males have larger home ranges but not in vole species that do not have sex differences in home range (Gaulin, 1992). These results provide evidence that environmental or experiential seasonal changes can alter Hp volume and that natural and sexual selection on a variety of spatial-related skills has produced a larger Hp in some species or sexes than in others.Although correlations of Hp volume with ecological demands for spatial ability are numerous, the specific mechanisms that contribute to such adult variation in the volume of the Hp are not well understood. We do know that species-specific reactions to spatial experience...

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“…We collected data that past field and laboratory research had indicated were important for effective social, vocal and reproductive functioning [29,30,40,41]. In 15 min time blocks, we occasionsampled males for vocalizations, noting each male that vocalized along with information on the social context surrounding the vocalization.…”

Section: (C) Data Collectionmentioning

confidence: 99%

“…What was more surprising, however, was that there were a variety of effects on aspects of the juvenile males' social behaviour apart from song structure. While JA juveniles developed social behaviour typical of wild cowbirds (competitive, aggressive singing bouts with other males, pair-bonding with females and monogamous mating patterns [30][31][32]), J juveniles engaged in atypical social interactions: they were not aggressive, they did not engage in many social singing interactions with males or with females, they did not pair-bond or mate-guard females and they mated promiscuously. Thus, a minor manipulation to the demographics of flocks revealed the pronounced flexibility in the vocal and social repertoires of juvenile male cowbirds.…”

Section: Introductionmentioning

confidence: 99%

Social networks and the development of social skills in cowbirds

White

Gersick

Snyder‐Mackler

2012

Phil. Trans. R. Soc. B

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The complex interrelationships among individuals within social environments can exert selection pressures on social skills: those behaviours and cognitive processes that allow animals to manipulate and out-reproduce others. Social complexity can also have a developmental effect on social skills by providing individuals with opportunities to hone their skills by dealing with the challenges posed in within-group interactions. We examined how social skills develop in captive, adult male brownheaded cowbirds (Molothrus ater) that were exposed to differing levels of 'social complexity' across a 2-year experiment. After each year, subjects housed in groups with dynamic social structure (where many individuals entered and exited the groups during the year) outcompeted birds who had been housed in static groups. Exposure to dynamic structure subsequently led to substantial changes to the social networks of the home conditions during the breeding season. Static groups were characterized by a predictable relationship between singing and reproductive success that was stable across years. In dynamic conditions, however, males showed significant variability in their dominance status, their courting and even in their mating success. Reproductive success of males varied dramatically across years and was responsive to social learning in adulthood, and socially dynamic environments 'trained' individuals to be better competitors, even at an age when the development of many traits important for breeding (like song quality) had ended.

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Social Dominance, Mating and Spacing Systems, Female Fecundity, and Vocal Dialects in Captive and Free-Ranging Brown-Headed Cowbirds

Cited by 128 publications

References 51 publications

Indirect estimates of breeding and natal philopatry in an obligate avian brood parasite

Indirect estimates of breeding and natal philopatry in an obligate avian brood parasite

Sex differences in the effects of captivity on hippocampus size in brown-headed cowbirds (Molothrus ater obscurus).

Social networks and the development of social skills in cowbirds

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