Food, friends or family: What drives delayed dispersal in group-living animals?

Abstract Cooperative breeding, in which more than two individuals live in a group and raise offspring, usually in a single nest, is found in only 3% of avian species. On the basis of a review of the literature, we found reports of groups (usually trios) at nest sites in 42 species of diurnal raptors. At least one example of cooperative breeding was found in 29% of genera and 14% of species, distributed in both Accipitridae and Falconidae. Given the difficulty of obtaining behavioral observations necessary to detect cooperative breeding in most raptor species, combined with the large number of species that have been poorly studied, cooperative breeding in diurnal raptors may be more common than our data indicate. However, when data on the sex of the extra bird(s) or relationships among group members were available, patterns were quite varied. For 7 of 13 species, groups primarily contained multiple adult males, though three of those species also had groups formed from offspring that had delayed dispersal; three species had a low, but regular, occurrence of multiple females (females of groups laid eggs in the same nest); and the remaining three species were characterized by having extra birds that were yearlings or subadults. In over half of species, groups did not appear to be composed of related individuals, contrary to many cooperatively breeding passerine species where groups are primarily composed of offspring that have delayed dispersal. Our review suggests that the evolution of group living in many raptors may be independent of delayed dispersal, and that the factors important in explaining the evolution of that behavior depend upon the benefits of group living.

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Demography and social organisation of the red-winged fairy-wren, Malurus elegans

Australian Journal of Zoology ◽

10.1071/zo99066 ◽

2000 ◽

Vol 48 (2) ◽

pp. 161 ◽

Cited By ~ 27

Author(s):

Eleanor Russell ◽

Ian Rowley

Keyword(s):

Western Australia ◽

Group Living ◽

Delayed Dispersal ◽

Important Benefit ◽

The Social ◽

Mean Size ◽

Work Done ◽

Large Groups ◽

Rainfall Region ◽

Eucalyptus Diversicolor

The red-winged fairy-wren, Malurus elegans, is endemic to the high-rainfall region of south-western Australia. We studied it in Eucalyptus diversicolor (karri) forest near Manjimup, Western Australia from 1980 to 1995. After a detailed study of breeding biology during 1980–86, we monitored dispersal and survival in known groups during 1987–95. M. elegans bred cooperatively, with 83% of groups (mean size 4.1) including one or more non-breeding males or females that helped to rear young and defend the territory. Survival of breeding adults (78%) and helper males (76%) was high. Territories and groups persisted from year to year, even though one or other of the breeding pair was replaced. Most known dispersals were to a group only 1–2 territories distant. Dispersal was female-biased, mostly in their third or fourth year. A behaviour not recorded in other Malurus spp. was that some birds, chiefly females, joined groups as helpers. The feeding rate of nestlings was not related to group size, but in larger groups the share of work done by the breeding female decreased. Helpers did not enhance the survival of breeding females, and had little overall effect on the production of fledglings. Females produced a mean of 2.4 fledglings, 1.8 independent young and 1.1 yearlings per year; survival of fledglings to the start of the following breeding season was44.2% (31–61%). We argue that the high levels of adult and juvenile survival influence many aspects of the social system in M. elegans, such as large groups, the presence of female helpers, occurrence of immigrant helpers and delayed dispersal. We suggest that an important benefit of delayed dispersal and group living is in promoting the survival of young birds, and increasing their chance of acquiring a territory.

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H. KRUUK. The social badger. Ecology and behaviour of a group-living carnivore (Meies meles). Oxford University Press, Oxford: 1989. Pp xii, 155 + [12 pp colour plates]; illustrated. Price: £15.95. ISBN 0-19-858703-1.

Archives of Natural History ◽

10.3366/anh.1991.18.1.131b ◽

1991 ◽

Vol 18 (1) ◽

pp. 131-132

Author(s):

D. P. SLEEMAN

Keyword(s):

Group Living ◽

Oxford University ◽

The Social ◽

Oxford University Press

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Subjective Fear Dilutes as Group Size Increases

10.31234/osf.io/r2yhn ◽

2020 ◽

Author(s):

dean mobbs ◽

Ellen Tedeschi ◽

Anastasia Buyalskaya ◽

Brian Silston

Keyword(s):

Group Size ◽

Real World ◽

Survival Benefit ◽

Group Living ◽

External Factors ◽

Threat Perception ◽

Perception Of Threat ◽

Threat Level ◽

Internal States ◽

Risk Dilution

According to Hamilton’s Selfish Herd Theory, a crucial survival benefit of group living is that it provides a ‘risk dilution’ function against predation. Despite a large literature on group living benefits in animals, few studies have been conducted on how group size alters subjective fear or threat perception in humans, and on what factors drive preferences for being in groups when facing threats. We conducted seven experiments (N=3,838) to test (A) if the presence of others decreases perception of threat under a variety of conditions. In studies 1 to 3, we experimentally manipulated group size in hypothetical and real-world situations, to show that fear responses decreased as group size increased. In studies 4 to 7 we again used a combination of hypothetical, virtual and real-world decisions to test (B) how internal states (e.g. anxiety) and external factors (e.g. threat level, availability of help) affected participants’ preference for groups. Participants consistently chose larger groups when threat and anxiety were high. Overall, our findings show that group size provides a salient signal of protection and safety.

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Affiliations, aggressions and an adoption: Male–male relationships in wild bonobos

10.1093/oso/9780198728511.003.0003 ◽

2018 ◽

Author(s):

Martin Surbeck ◽

Gottfried Hohmann

Keyword(s):

Close Relationships ◽

Group Living ◽

Mate Competition ◽

Male Group ◽

Cooperative Hunting ◽

Sexual Behaviours ◽

Study Population ◽

Living Species ◽

The Way

The nature of the relationships between males is a characteristic trait of many multi-male group living species with implications for the individuals. In our study population of bonobos, certain male dyads exhibit clear preferences for ranging in the same party and sitting in proximity. These preferences are not reflected in the frequency of aggression towards each other and only to some extent in their affiliative and socio-sexual behaviours. While bonobo males at LuiKotale clearly do not benefit from close relationships in the way chimpanzee males do (cooperative hunting, territorial patrol, mate competition), some relationships might result from close associations between their mothers. In some particular situations, these male relationships can be very important as in the case of an orphan adopted by his older maternal brother. La nature des relations entre mâles est un trait caractéristique de plusieurs groupes qui ont plusieurs mâles, avec des implications au niveau d’individus. Dans notre étude des populations de bonobos, certains dyades mâles montrent une préférence à aller dans le même groupe et s’asseoir proche l’un de l’autre. Cette préférence n’est pas reflétée dans la fréquence d’agression entre eux et est seulement lié, à degrés, à leur comportements socio-sexuels et d’appartenance. Tandis que les mâles bonobos à LuiKotale ne profitent pas de leur fortes relations comme les chimpanzés mâles (chasse coopérative, patrouille territoriale, compétition pour compagnon), ils peuvent aider leur partenaires à supporter le stress de la vie en groupe et peuvent en conséquence contribuer au bien-être des individus. Quelques proches associations entre les mâles peuvent provenir d’associations entre leurs mères. Dans quelques situations particulières, ces relations mâles prouvent leur importance comme dans le cas d’un orphelin adopté par son grand frère maternel.

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Social ethology of the wolverine

10.1093/oso/9780198759805.003.0018 ◽

2018 ◽

Author(s):

Jeffrey P. Copeland ◽

Arild Landa ◽

Kimberly Heinemeyer ◽

Keith B. Aubry ◽

Jiska van Dijk ◽

...

Keyword(s):

Social Organization ◽

Social Interactions ◽

Resource Availability ◽

Social Behaviour ◽

Social System ◽

Group Living ◽

Field Studies ◽

Ecological Framework ◽

The Social ◽

Living Species

Social behaviour in solitary carnivores has long been an active area of investigation but for many species remains largely founded in conjecture compared to our understanding of sociality in group-living species. The social organization of the wolverine has, until now, received little attention beyond its portrayal as a typical mustelid social system. In this chapter the authors compile observations of social interactions from multiple wolverine field studies, which are integrated into an ecological framework. An ethological model for the wolverine is proposed that reveals an intricate social organization, which is driven by variable resource availability within extremely large territories and supports social behaviour that underpins offspring development.

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Retirement Age and Housing Consumption: The Case of South Korea

Sustainability ◽

10.3390/su13031286 ◽

2021 ◽

Vol 13 (3) ◽

pp. 1286

Author(s):

Chunil Kim ◽

Hyobi Choi ◽

Yeol Choi

Keyword(s):

South Korea ◽

Group Living ◽

Peripheral Region ◽

Housing Tenure ◽

Housing Consumption ◽

Household Expenditures ◽

Housing Tenure Choice ◽

Populated Region ◽

The Impact ◽

Real Assets

South Korea became an aging society in 2000 and will become a super-aged nation in 2026. The extended life expectancy and earlier retirement make workers’ preparation for retirement more difficult, and that hardship might lead to poorer living conditions after retirement. As annuity payments are, in general, not enough for retirees to maintain their previous standard of living after retirement, retired households would have to liquidate their financial and real assets to cover household expenditures. As housing takes the biggest share of households’ total assets in Korea, it seems to be natural for retirees to downsize their houses. However, there is no consensus in the housing literature on housing downsizing, and the debate is still ongoing. In order to understand whether or not housing downsizing by retirees occurs in Korea, this paper examines the impact of the timing of retirement on housing consumption using an econometric model of housing tenure choice and the consumption for housing. The results show that the early retirement group living in more populated region does not downsize the house, while the timing of retirement is negatively associated with housing consumption for the late retirement group living in the peripheral region.

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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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