Acorn woodpeckers vocally discriminate current and former group members from nongroup members

2020 ◽  
Vol 31 (5) ◽  
pp. 1120-1128 ◽  
Author(s):  
Michael A Pardo ◽  
Casey E Hayes ◽  
Eric L Walters ◽  
Walter D Koenig
Keyword(s):  
Social Relationships ◽  
Group Living ◽  
Current Group ◽  
Breeding Bird ◽  
Cooperatively Breeding ◽  
Melanerpes Formicivorus ◽  
Group Members ◽  
Valuable Relationships ◽  
Acorn Woodpeckers

Abstract In species with long-term social relationships, the ability to recognize individuals after extended separation and the ability to discriminate between former social affiliates that have died and those that have left the group but may return are likely to be beneficial. Few studies, however, have investigated whether animals can make these discriminations. We presented acorn woodpeckers (Melanerpes formicivorus), a group-living, cooperatively breeding bird, with playbacks of current group members, former group members still living nearby, former group members that had died or left the study area, and familiar nongroup members. Subjects responded more quickly to the calls of nongroup members than to the calls of current group members or former group members still living in the study area but did not discriminate between nongroup members and former group members that had died or disappeared. This suggests that acorn woodpeckers can vocally recognize both current group members and former group members that have dispersed to nearby groups and that they either forget former group members that no longer live in the vicinity or classify them differently from former group members that still live nearby. This study suggests an important role for vocal recognition in maintaining valuable relationships with social affiliates postdispersal.

Experimental evidence that acorn woodpeckers recognize relationships among third parties no longer living together

2020 ◽  
Vol 31 (5) ◽  
pp. 1257-1265 ◽  
Author(s):  
Michael A Pardo ◽  
Eric L Walters ◽  
Walter D Koenig
Keyword(s):  
Experimental Evidence ◽  
Social Group ◽  
Third Parties ◽  
Social Species ◽  
Living Together ◽  
Melanerpes Formicivorus ◽  
Group Members ◽  
The Subject ◽  
Acorn Woodpeckers ◽  
Group Relationships

Abstract Triadic awareness, or knowledge of the relationships between others, is essential to navigating many complex social interactions. While some animals maintain relationships with former group members post-dispersal, recognizing cross-group relationships between others may be more cognitively challenging than simply recognizing relationships between members of a single group because there is typically much less opportunity to observe interactions between individuals that do not live together. We presented acorn woodpeckers (Melanerpes formicivorus), a highly social species, with playback stimuli consisting of a simulated chorus between two different individuals, a behavior that only occurs naturally between social affiliates. Subjects were expected to respond less rapidly if they perceived the callers as having an affiliative relationship. Females responded more rapidly to a pair of callers that never co-occurred in the same social group, and responded less rapidly to callers that were members of the same social group at the time of the experiment and to callers that last lived in the same group before the subject had hatched. This suggests that female acorn woodpeckers can infer the existence of relationships between conspecifics that live in separate groups by observing them interact after the conspecifics in question no longer live in the same group as each other. This study provides experimental evidence that nonhuman animals may recognize relationships between third parties that no longer live together and emphasizes the potential importance of social knowledge about distant social affiliates.

scholarly journals Temporal variability and cooperative breeding: testing the bet-hedging hypothesis in the acorn woodpecker

2015 ◽  
Vol 282 (1816) ◽  
pp. 20151742 ◽  
Author(s):  
Walter D. Koenig ◽  
Eric L. Walters
Keyword(s):  
Reproductive Success ◽  
Cooperative Breeding ◽  
Group Living ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Ecological Conditions ◽  
Variable Environments ◽  
Melanerpes Formicivorus ◽  
Mean Fitness

Cooperative breeding is generally considered an adaptation to ecological constraints on dispersal and independent breeding, usually due to limited breeding opportunities. Although benefits of cooperative breeding are typically thought of in terms of increased mean reproductive success, it has recently been proposed that this phenomenon may be a bet-hedging strategy that reduces variance in reproductive success (fecundity variance) in populations living in highly variable environments. We tested this hypothesis using long-term data on the polygynandrous acorn woodpecker ( Melanerpes formicivorus ). In general, fecundity variance decreased with increasing sociality, at least when controlling for annual variation in ecological conditions. Nonetheless, decreased fecundity variance was insufficient to compensate for reduced per capita reproductive success of larger, more social groups, which typically suffered lower estimated mean fitness. We did, however, find evidence that sociality in the form of larger group size resulted in increased fitness in years following a small acorn crop due to reduced fecundity variance. Bet-hedging, although not the factor driving sociality in general, may play a role in driving acorn woodpecker group living when acorns are scarce and ecological conditions are poor.

scholarly journals Spontaneous abortion as a response to reproductive conflict in the banded mongoose

2019 ◽  
Vol 15 (12) ◽  
pp. 20190529
Author(s):  
E. Inzani ◽  
H. H. Marshall ◽  
F. J. Thompson ◽  
G. Kalema-Zikusoka ◽  
M. A. Cant ◽  
...  
Keyword(s):  
Spontaneous Abortion ◽  
Group Living ◽  
Reproductive Competition ◽  
Reproductive Conflict ◽  
Future Fertility ◽  
Banded Mongoose ◽  
Living Species ◽  
Group Members ◽  
Term Data

When breeding females compete for limited resources, the intensity of this reproductive conflict can determine whether the fitness benefits of current reproductive effort exceed the potential costs to survival and future fertility. In group-living species, reproductive competition can occur through post-natal competition among the offspring of co-breeding females. Spontaneous abortion could be a response to such competition, allowing females to curtail reproductive expenditure on offspring that are unlikely to survive and to conserve resources for future breeding opportunities. We tested this hypothesis using long-term data on banded mongooses, Mungos mungo , in which multiple females within a group give birth synchronously to a communal litter that is cared for by other group members. As predicted, abortions were more likely during dry periods when food is scarce, and in breeding attempts with more intense reproductive competition. Within breeding events, younger, lighter females carrying smaller fetuses were more likely to abort, particularly those that were also of lower rank. Our results suggest that abortion may be a means by which disadvantaged females conserve resources for future breeding attempts in more benign conditions, and highlight that female reproductive competition may be resolved long before the production of offspring.

Social status influences responses to unfamiliar conspecifics in a cooperatively breeding fish

Behaviour ◽  
2015 ◽  
Vol 152 (12-13) ◽  
pp. 1821-1839 ◽  
Author(s):  
Isaac Y. Ligocki ◽  
Adam R. Reddon ◽  
Jennifer K. Hellmann ◽  
Constance M. O’Connor ◽  
Susan Marsh-Rollo ◽  
...  
Keyword(s):  
Social Status ◽  
Cichlid Fish ◽  
Group Living ◽  
Costs And Benefits ◽  
Control Groups ◽  
High Ranking ◽  
The Social ◽  
Cooperatively Breeding ◽  
Group Members ◽  
Group Member

In group living animals, individuals may visit other groups. The costs and benefits of such visits for the members of a group will depend on the attributes and intentions of the visitor, and the social status of responding group members. Using wild groups of the cooperatively breeding cichlid fish (Neolamprologus pulcher), we compared group member responses to unfamiliar ‘visiting’ conspecifics in control groups and in experimentally manipulated groups from which a subordinate the same size and sex as the visitor was removed. High-ranking fish were less aggressive towards visitors in removal groups than in control groups; low-ranking subordinates were more aggressive in the removal treatment. High-ranking females and subordinates the same size and sex as the visitor responded most aggressively toward the visitor in control groups. These results suggest that visitors are perceived as potential group joiners, and that such visits impose different costs and benefits on current group members.

scholarly journals Stable social relationships between unrelated females increase individual fitness in a cooperative bird

2018 ◽  
Vol 285 (1876) ◽  
pp. 20180130 ◽  
Author(s):  
Christina Riehl ◽  
Meghan J. Strong
Keyword(s):  
Social Relationships ◽  
Social Bonds ◽  
Field Research ◽  
Breeding Bird ◽  
Reproductive Synchrony ◽  
Individual Fitness ◽  
Direct Benefits ◽  
Social Familiarity ◽  
Greater Ani

Social animals often form long-lasting relationships with fellow group members, usually with close kin. In primates, strong social bonds have been associated with increased longevity, offspring survival and reproductive success. However, little is known about the fitness effects of social bonds between non-kin, especially outside of mammals. In this study, we use long-term field research on a cooperatively breeding bird, the greater ani ( Crotophaga major ), to ask whether adult females benefit by remaining in long-term associations with unrelated, co-breeding females. We find that females that have previously nested together synchronize their reproduction more rapidly than those nesting with unfamiliar partners, which leads to lower competition and higher fledging success. Importantly, although previous experience with a co-breeding female influenced reproductive synchrony, the degree of reproductive synchrony did not influence whether co-breeding females remained together in subsequent years, ruling out the alternate hypothesis that highly synchronized females are simply more likely to remain together. These results indicate that switching groups is costly to females, and that social familiarity improves reproductive coordination. Stable social relationships therefore have significant fitness consequences for cooperatively nesting female birds, suggesting that direct benefits alone may favour the evolution of associations between non-relatives and contribute to long-term group stability.

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