Extrapair Copulations Predict Extrapair Fertilizations in the American Crow

Townsend, Andrea K.

doi:10.1525/cond.2009.090010

Cited by 11 publications

(13 citation statements)

References 26 publications

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“…review in Gowaty and Buschhaus 1998 ). Among corvids, forced copulations has been recorded in the colonially breeding Rook C. frugilegus , where similar to the present study, a multimale group attempted to mount females (Roskaft 1983 ), and in the cooperatively breeding American Crow C. brachyrhynchos , where extra pair copulation attempts were initiated by males, and mostly appeared to be resisted by females (Townsend 2009 ). Similarly, in this paper we describe a previously unreported and untypical aggressive social behaviour in the hooded crow.…”

Section: Discussionsupporting

confidence: 84%

Sexual aggression by intruders in hooded crow Corvus cornix

Zduniak

Kosicki

Yosef³

2015

acta ethol

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The hooded crow Corvus cornix is a west Palaearctic, solitary nesting, monogamous corvid. In the breeding season, populations are characterized by a social organization wherein breeding pairs are territorial and non-breeding individuals, called floaters, live in flocks. During a study of the breeding ecology of the hooded crow, conducted in a protected flooded area, we monitored nests with video cameras. We recorded two separate incidents when intruders attacked a female at the nest. We believe that she remained in the nest in order to prevent the strangers cannibalizing the nestlings by mantling over the brood. The spatio-temporal occurrence of these attacks suggests that the observed behaviour is intraspecific sexual aggression wherein non-breeding males mounted an immobilized female.Electronic supplementary materialThe online version of this article (doi:10.1007/s10211-015-0222-z) contains supplementary material, which is available to authorized users.

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Section: Discussionsupporting

confidence: 84%

Sexual aggression by intruders in hooded crow Corvus cornix

Zduniak

Kosicki

Yosef³

2015

acta ethol

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“…The elevated paternity loss of injured male breeders to within-group auxiliary males in our study can be interpreted in light of reproductive skew theory. Previously, we suggested that American Crows meet the assumptions of tug-of-war reproductive skew models in that breeders and auxiliaries appear to struggle over reproductive shares, and neither appears to have complete control over reproductive partitioning in groups (Townsend 2009, J. Field Ornithol.…”

Section: Discussionmentioning

confidence: 99%

“…The elevated paternity loss of injured male breeders to within‐group auxiliary males in our study can be interpreted in light of reproductive skew theory. Previously, we suggested that American Crows meet the assumptions of tug‐of‐war reproductive skew models in that breeders and auxiliaries appear to struggle over reproductive shares, and neither appears to have complete control over reproductive partitioning in groups (Townsend 2009, Townsend et al 2009b), although male breeders have some control over group membership (Townsend et al 2009b). The tug‐of‐war model of reproductive skew predicts that a reduction in the competitive asymmetry between dominants and subordinates (which we would expect in groups with injured male breeders) will increase the reproductive share of subordinates and, because of heightened conflict over reproductive shares, negatively impact overall group output (Reeve et al 1998).…”

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confidence: 98%

“…Finally, females paired to injured male breeders might be more likely to accept fertilizations from extrapair males because of increased benefits of fertility insurance (Sheldon 1994), for provisioning benefits gained from extrapair auxiliary males (Townsend et al 2010), or for evaluation of future breeding partners in case of mate loss (Petrie and Kempenaers 1998). However, female American Crows generally appear to resist extrapair copulations, as do females in other species in the genus Corvus (Townsend 2009), suggesting that the occurrence and distribution of extrapair paternity might not be female‐driven in this system (Townsend 2009, Townsend et al 2010).…”

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confidence: 99%

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Injury and paternity loss in cooperatively breeding American Crows

Townsend

Clark

McGowan

2011

Journal of Field Ornithology

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Although survivable injuries have been documented in several species of birds, little is known about the social and reproductive consequences of such injuries. We examined relationships between injuries and group composition, reproductive output, and paternity of male breeders in 27 family groups of American Crows (Corvus brachyrhynchos) using 96 broods sampled from 2004 to 2009. Injuries and permanent disfigurement of wings or feet were sustained by 25.9% (7/27) of dominant male breeders. Injured male breeders had smaller broods (2.13 vs. 3.38 nestlings per brood for injured vs. uninjured breeders), lost more paternity (48% vs. 13% extrapair young per brood), and had more adult male auxiliaries in their groups (1.63 vs. 0.65 auxiliaries per group) than uninjured birds. Some of the variation in reproductive partitioning, extrapair paternity rates, and group composition among American Crow family groups can therefore be explained by injuries to male breeders. These results suggest that injuries could account for some of the unexplained variation in the rates and distribution of extrapair paternity across populations and taxa, as well as some of the variation in reproductive skew among cooperatively breeding birds.

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“…Among crows, interactions may also be simply extensions of typical scavenging behaviours that include interest in dead animals. Alternatively, given that crows defend territory boundaries and female mates, particularly during the period of peak female sexual receptiveness between March and April, it is possible that contact with dead crows is the result of attempts to evict intruders [20,21]. Through two controlled experiments, we seek to determine if tactile interactions between wild crows and dead conspecifics are a defining feature of crows' response repertoire, and if food, information acquisition or territoriality are motivating factors.…”

Section: Introductionmentioning

confidence: 99%

Occurrence and variability of tactile interactions between wild American crows and dead conspecifics

Swift¹,

Marzluff²

2018

Phil. Trans. R. Soc. B

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Observations of some mammals and birds touching their dead provoke questions about the motivation and adaptive value of this potentially risky behaviour. Here, we use controlled experiments to determine if tactile interactions are characteristic of wild American crow responses to dead crows, and what the prevalence and nature of tactile interactions suggests about their motivations. In Experiment 1, we test if food or information acquisition motivates contact by presenting crows with taxidermy-prepared dead crows, and two species crows are known to scavenge: dead pigeons and dead squirrels. In Experiment 2, we test if territoriality motivates tactile interactions by presenting crows with taxidermy crows prepared to look either dead or upright and life-like. In Experiment 1, we find that crows are significantly less likely to make contact but more likely to alarm call and recruit other birds in response to dead crows than to dead pigeons and squirrels. In addition, we find that aggressive and sexual encounters with dead crows are seasonally biased. These findings are inconsistent with feeding or information acquisition-based motivation. In Experiment 2, we find that crows rarely dive-bomb and more often alarm call and recruit other crows to dead than to life-like crows, behaviours inconsistent with responses given to live intruders. Consistent with a danger response hypothesis, our results show that alarm calling and neighbour recruitment occur more frequently in response to dead crows than other stimuli, and that touching dead crows is atypical. Occasional contacts, which take a variety of aggressive and sexual forms, may result from an inability to mediate conflicting stimuli.This article is part of the theme issue 'Evolutionary thanatology: impacts of the dead on the living in humans and other animals'.

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Extrapair Copulations Predict Extrapair Fertilizations in the American Crow

Cited by 11 publications

References 26 publications

Sexual aggression by intruders in hooded crow Corvus cornix

Sexual aggression by intruders in hooded crow Corvus cornix

Injury and paternity loss in cooperatively breeding American Crows

Occurrence and variability of tactile interactions between wild American crows and dead conspecifics

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