Female brown-headed cowbirds' (Molothrus ater) social assortment changes in response to male song: A potential source of public information

Department of Psychology, Indiana University, 1101 E.10th St., IN 47405, Bloomington, USA
Behavioral Ecology and Sociobiology (Impact Factor: 2.35). 01/2003; 53(3):163-173. DOI: 10.1007/s00265-002-0560-5


In many species, females' behavior appears to be influenced by that of other females, particularly regarding mate choice. Females theoretically can reduce the costs associated with independent male assessment by observing conspecifics. Studies of brown-headed cowbirds suggest that females pay attention to other females' behavior. Group-housed females modify their song preferences, whereas females housed in pairs do not. What information is available to females in a group environment? To address this question, we studied two groups of juvenile (i.e. hatch-year birds) and adult female cowbirds in a naturalistic group setting. We used a longitudinal ABA design, consecutively introducing and removing males that differed in age, amount of song production and stage of song development, to isolate the male characteristics that related to changes in female behavior. Juvenile and adult females assorted by age class when singing adult males were in the aviary, but not when singing juveniles or silent males of any age class were in the aviary. Results from playback tests confirmed that adult male song alone influenced female age class assortment. Videotape analysis from playback tests revealed that females also wing stroked in response to male song. Other females sometimes approached females who wing stroked and observed them. We hypothesize that group-level changes in social organization and individual females' responses can serve as visual signals for other individuals.


Available from: David J White
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    • "Recurrent associations will facilitate information exchange, especially when signals can only be assessed through close social interaction (McGregor, 2005 ). In autumn, females use visual signals , known as wing-strokes, to communicate mate preferences with both males and females (Dohme, King, Meredith, & West, 2014; Gros-Louis, White, King, & West, 2003; West & King, 1988). In spring, female cowbirds assess and adopt the mate choices of other females by attending to their 'chatter' vocalizations (FreedBrown & White, 2009 ). "
    [Show abstract] [Hide abstract] ABSTRACT: Many vertebrates inhabit dynamic and loosely structured groups where group size and social composition continually fluctuates. The ability to sustain nonrandom interaction preferences across group changes is an important aspect in maintaining social organization. In two experiments, we explored the strength and persistence of social preferences for familiar conspecifics in brown-headed cowbirds. In the first experiment, we demonstrated that females preferentially associate with familiar females when introduced into a flock containing novel individuals. In the second experiment we investigated the consistency of familiarity preferences across a series of social introductions. Females maintained preferences to approach familiar conspecifics, and the individual strength of those preferences remained consistent across introductions. Male preferences changed across the introductions. In the first introduction, males showed a significant preference to approach familiar conspecifics, but increased their approaches towards novel conspecifics in subsequent introductions. Our findings suggest that female cowbirds are an important factor in maintaining social organization through their enduring associations with familiar individuals, whereas males facilitate social integration by extending connections towards novel individuals during periods of change.
    Full-text · Article · Jul 2015 · Animal Behaviour
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    • "Social interaction during the autumn and winter has been shown to shape later female reproductive behaviour and mate preferences (Freeberg 1997, 1998; Freeberg et al. 1999). In particular, sex assortment in cowbird flocks is high (Kohn et al. 2011), and close interaction with other females during autumn may expose individuals to cues regarding the quality of male song displays (Gros-Louis et al. 2003) and shape later mate preferences (West et al. 2006). During the spring, cowbirds focus on courtship and sustaining consortships with preferred mates (Friedmann 1929; Ortega 1998). "
    [Show abstract] [Hide abstract] ABSTRACT: Individuals often show predictable variation in social tendencies over time and across contexts. In species that rely on social interaction for the development of courtship behaviours, predictable variation in juvenile social behaviour may influence the ontogeny of courtship skills by exposing young individuals to different levels of contact with conspecifics. During the autumn and winter, brown-headed cowbirds utilize a social display known as the head-down to facilitate close social interaction with others. In this study we investigated whether head-downs rates are correlated across social contexts, and thus constitute a social temperament trait, and whether variation in head-down rates predicts subsequent courtship behaviour in juvenile cowbirds. During the autumn, we used a fission-fusion perturbation on a flock of juvenile females and males, and recorded the number of approaches and head-downs across social contexts. All individuals were then followed into the breeding season, where we recorded male singing behaviour, female chatter vocalization and consort status. We found that female head-down rates were correlated across contexts during the autumn, and that females that engaged in more head-down displays received more songs from males, responded to more songs with chatter vocalizations and were more likely to be in a consortship during the breeding season. As far as we know, this study presents the first demonstration that a social temperament trait can predict competent adult-like courtship behaviour in juvenile birds, and suggests that juvenile sociability may be an important developmental mechanism in the emergence of reproductive competence.
    Full-text · Article · Apr 2013 · Animal Behaviour
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    • "If at all, they can only infer risk from experiences gained somewhere else which may vary greatly between locations and may not allow generalization. Instead of relying on own experience, migrants may use public information [47], [48] by observing resident birds. Migrants are already known to use residents as a cue for breeding habitat selection (heterospecific attraction hypothesis; [49]). "
    [Show abstract] [Hide abstract] ABSTRACT: Environments undergo short-term and long-term changes due to natural or human-induced events. Animals differ in their ability to cope with such changes which can be related to their ecology. Changes in the environment often elicit avoidance reactions (neophobia) which protect animals from dangerous situations but can also inhibit exploration and familiarization with novel situations and thus, learning about new resources. Studies investigating the relationship between a species' ecology and its neophobia have so far been restricted to comparing only a few species and mainly in captivity. The current study investigated neophobia reactions to experimentally-induced changes in the natural environment of six closely-related blackbird species (Icteridae), including two species represented by two distinct populations. For analyses, neophobic reactions (difference in number of birds feeding and time spent feeding with and without novel objects) were related to several measures of ecological plasticity and the migratory strategy (resident or migratory) of the population. Phylogenetic relationships were incorporated into the analysis. The degree of neophobia was related to migratory strategy with migrants expressing much higher neophobia (fewer birds feeding and for a shorter time with objects present) than residents. Furthermore, neophobia showed a relationship to diet breadth with fewer individuals of diet generalists than specialists returning when objects were present supporting the dangerous niche hypothesis. Residents may have evolved lower neophobia as costs of missing out on opportunities may be higher for residents than migrants as the former are restricted to a smaller area. Lower neophobia allows them approaching changes in the environment (e.g. novel objects) quickly, thereby securing access to resources. Additionally, residents have a greater familiarity with similar situations in the area than migrants and the latter may, therefore, initially stay behind resident species.
    Full-text · Article · Feb 2013 · PLoS ONE
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