Social dominance and cooperation in female vampire bats

AbstractStable social bonds in group-living animals can provide greater access to food. A striking example is that female vampire bats often regurgitate blood to socially bonded kin and nonkin that failed in their nightly hunt. Food-sharing relationships form via preferred associations and social grooming within roosts. However, it remains unclear whether these cooperative relationships extend beyond the roost. To evaluate if long-term cooperative relationships in vampire bats play a role in foraging, we tested if foraging encounters measured by proximity sensors could be explained by wild roosting proximity, kinship, or rates of co-feeding, social grooming, and food sharing during 22 months in captivity. We assessed evidence for six hypothetical scenarios of social foraging, ranging from individual to collective hunting. We found that female vampire bats departed their roost individually, but often re-united far outside the roost. Nonrandomly repeating foraging encounters were predicted by within-roost association and histories of cooperation in captivity, even when controlling for kinship. Foraging bats demonstrated both affiliative and competitive interactions and a previously undescribed call type. We suggest that social foraging could have implications for social evolution if ‘local’ cooperation within the roost and ‘global’ competition outside the roost enhances fitness interdependence between frequent roostmates.

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Social foraging in vampire bats is predicted by long-term cooperative relationships

PLoS Biology ◽

10.1371/journal.pbio.3001366 ◽

2021 ◽

Vol 19 (9) ◽

pp. e3001366

Author(s):

Simon P. Ripperger ◽

Gerald G. Carter

Keyword(s):

Social Evolution ◽

Group Living ◽

Food Sharing ◽

Social Foraging ◽

Social Grooming ◽

Cooperative Relationships ◽

Vampire Bats ◽

In Captivity ◽

Access To Food

Stable social bonds in group-living animals can provide greater access to food. A striking example is that female vampire bats often regurgitate blood to socially bonded kin and nonkin that failed in their nightly hunt. Food-sharing relationships form via preferred associations and social grooming within roosts. However, it remains unclear whether these cooperative relationships extend beyond the roost. To evaluate if long-term cooperative relationships in vampire bats play a role in foraging, we tested if foraging encounters measured by proximity sensors could be explained by wild roosting proximity, kinship, or rates of co-feeding, social grooming, and food sharing during 21 months in captivity. We assessed evidence for 6 hypothetical scenarios of social foraging, ranging from individual to collective hunting. We found that closely bonded female vampire bats departed their roost separately, but often reunited far outside the roost. Repeating foraging encounters were predicted by within-roost association and histories of cooperation in captivity, even when accounting for kinship. Foraging bats demonstrated both affiliative and competitive interactions with different social calls linked to each interaction type. We suggest that social foraging could have implications for social evolution if “local” within-roost cooperation and “global” outside-roost competition enhances fitness interdependence between frequent roostmates.

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The season for peace: reconciliation in a despotic species (Lemur catta)

10.7287/peerj.preprints.568 ◽

2014 ◽

Author(s):

Elisabetta Palagi ◽

Ivan Norscia

Keyword(s):

Conflicts Of Interest ◽

Group Living ◽

Lemur Catta ◽

Female Dominance ◽

Captive Group ◽

Post Conflict ◽

Group Cooperation ◽

In Captivity ◽

In The Wild ◽

The Right

However despotic a social group may be, managing conflicts of interest is crucial to preserve group living benefits, mainly based on cooperation. In fact, in despotic groups post-conflict management via reconciliation (the first post-conflict reunion between former opponents) can occur, even if at variable levels. In the despotic Lemur catta reconciliation was reported in one out of four captive groups. We used this species as a model to understand what variables influence the occurrence of the reconciliation in despotic groups. We analyzed 2339 PC-MC collected on eight groups (five in the Berenty forest, Madagascar; three hosted at the Pistoia Zoo, Italy). Since Lemur catta is characterized by rigid female dominance but show female-female coalitionary support, we expected to find reconciliation in the wild, other than in captivity. Consistently, we found the phenomenon to be present in one captive group and two wild groups, thus providing the first evidence of the presence of reconciliation in wild Lemur catta. Being this species a seasonal breeder (with mating occurring once a year), we expected that the season more than other variables (wild/captivity setting, rank, or individual features) would influence reconciliation levels. Via GLMM we found that the season was indeed the only variable significantly explaining reconciliation rates, lowest during mating and highest during the pregnancy period. We posit that reconciliation can be present in despotic species but not when the advantages of intra-group cooperation are annihilated by competition, as it occurs in seasonal breeders when reproduction is at stake. By comparing our results with literature, we conclude that in despotic social groups in which coalitions are observed, the right question is not if but when reconciliation can be present.

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Development of new food-sharing relationships among nonkin vampire bats

10.1101/534321 ◽

2019 ◽

Cited By ~ 2

Author(s):

Gerald G. Carter ◽

Damien R. Farine ◽

Rachel J. Crisp ◽

Julia K. Vrtilek ◽

Simon P. Ripperger ◽

...

Keyword(s):

Social Bonds ◽

Low Cost ◽

Food Sharing ◽

Cooperative Relationships ◽

Vampire Bats ◽

Term Pair ◽

Show Evidence ◽

Survival And Reproduction ◽

High Investment

AbstractIn an individualized animal society, social bonds can foster cooperation and enhance survival and reproduction. Cooperative bonds often exist among kin, but nonkin can also develop high-investment cooperative bonds that share similarities with human friendship. How do such bonds form? One theory suggests that strangers should ‘test the waters’ of a new relationship by making small initial cooperative investments and gradually escalating them with good partners. This ‘raising-the-stakes’ strategy is demonstrated by human strangers in short-term economic games, but it remains unclear whether it applies to helping in a natural long-term social bond. Here we show evidence that unfamiliar vampire bats (Desmodus rotundus) selectively escalate low-cost investments in allogrooming before developing higher-cost food-sharing relationships. We introduced females from geographically distant sites in pairs or groups and observed that bats established new reciprocal grooming relationships, and that increasing grooming rates predicted the occurrence of first food donations, at which point grooming rates no longer increased. New food-sharing relationships emerged reciprocally in 14% of female pairs, typically over 10-15 months, and developed faster when strangers lacked alternative familiar partners. A gradual grooming-to-sharing transition among past strangers suggests that ‘raising the stakes’ might be more evident when tracking multiple cooperative behaviours as new relationships form, rather than measuring a single behavior in an established relationship. ‘Raising the stakes’ could play a similar underappreciated role across a broader spectrum of social decisions with long-term consequences, such as joining a new social group or forming a long-term pair-bond.Significance statementVampire bats form long-term cooperative social bonds that involve reciprocal food sharing. How do two unrelated bats go from being strangers to having a high-investment food-sharing relationship? We introduced unfamiliar bats and found evidence that low-cost grooming paves the way for higher-cost food donations. Food sharing emerged in a reciprocal fashion and it emerged faster when two strangers did not have access to their original groupmates. The bats that formed new food-sharing relationships had a history of escalating reciprocal grooming up until the food sharing began. Our finding that unfamiliar nonkin vampire bats appear to gradually and selectively transition from low-cost to high-cost cooperative behaviors is the first evidence that nonhuman individuals ‘raise the stakes’ when forming new cooperative relationships.

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The season for peace: reconciliation in a despotic species (Lemur catta)

10.7287/peerj.preprints.568v1 ◽

2014 ◽

Author(s):

Elisabetta Palagi ◽

Ivan Norscia

Keyword(s):

Conflicts Of Interest ◽

Group Living ◽

Lemur Catta ◽

Female Dominance ◽

Captive Group ◽

Post Conflict ◽

Group Cooperation ◽

In Captivity ◽

In The Wild ◽

The Right

However despotic a social group may be, managing conflicts of interest is crucial to preserve group living benefits, mainly based on cooperation. In fact, in despotic groups post-conflict management via reconciliation (the first post-conflict reunion between former opponents) can occur, even if at variable levels. In the despotic Lemur catta reconciliation was reported in one out of four captive groups. We used this species as a model to understand what variables influence the occurrence of the reconciliation in despotic groups. We analyzed 2339 PC-MC collected on eight groups (five in the Berenty forest, Madagascar; three hosted at the Pistoia Zoo, Italy). Since Lemur catta is characterized by rigid female dominance but show female-female coalitionary support, we expected to find reconciliation in the wild, other than in captivity. Consistently, we found the phenomenon to be present in one captive group and two wild groups, thus providing the first evidence of the presence of reconciliation in wild Lemur catta. Being this species a seasonal breeder (with mating occurring once a year), we expected that the season more than other variables (wild/captivity setting, rank, or individual features) would influence reconciliation levels. Via GLMM we found that the season was indeed the only variable significantly explaining reconciliation rates, lowest during mating and highest during the pregnancy period. We posit that reconciliation can be present in despotic species but not when the advantages of intra-group cooperation are annihilated by competition, as it occurs in seasonal breeders when reproduction is at stake. By comparing our results with literature, we conclude that in despotic social groups in which coalitions are observed, the right question is not if but when reconciliation can be present.

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Non-random associations in group housed rats (Rattus norvegicus)

Scientific Reports ◽

10.1038/s41598-021-94608-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Leanne Proops ◽

Camille A. Troisi ◽

Tanja K. Kleinhappel ◽

Teresa Romero

Keyword(s):

Network Analysis ◽

Empirical Evidence ◽

Rattus Norvegicus ◽

Dominance Hierarchy ◽

Group Living ◽

Ecological Factors ◽

Limited Evidence ◽

Rat Strains ◽

Social Species ◽

Over Time

AbstractEcological factors, such as predation, have traditionally been used to explain sociability. However, it is increasingly recognised that individuals within a group do not associate randomly, and that these non-random associations can generate fitness advantages. The majority of the empirical evidence on differentiated associations in group-living mammals, however, comes from a limited number of taxa and we still know very little about their occurrence and characteristics in some highly social species, such as rats (Rattus spp.). Here, using network analysis, we quantified association patterns in four groups of male fancy rats. We found that the associations between rats were not randomly distributed and that most individuals had significantly more preferred/avoided associates than expected by random. We also found that these preferences can be stable over time, and that they were not influenced by individuals’ rank position in the dominance hierarchy. Our findings are consistent with work in other mammals, but contrast with the limited evidence available for other rat strains. While further studies in groups with different demographic composition are warranted to confirm our findings, the occurrence of differentiated associations in all male groups of rats have important implications for the management and welfare of captive rat populations.

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