Homosexual behaviour in birds: frequency of expression is related to parental care disparity between the sexes

  title={Homosexual behaviour in birds: frequency of expression is related to parental care disparity between the sexes},
  author={Geoff R. MacFarlane and Simon Phillip Blomberg and Paul L. Vasey},
  journal={Animal Behaviour},

Effect of Female-Biased Sex Ratios on Female Homosexual Behavior in Japanese Macaques: Evidence for the “Bisexual Preference Hypothesis”

It is concluded that when a female targets another female as a mate, it is an active choice for a female sexual partner over available male alternatives, rather than a by-default situation that occurs because males are not available as sexual partners, or because females are better able to access female sexual partners due to a scarcity of male sexual competitors.

Promiscuous primates engage in same-sex genital interactions

Neuroendocrine contributions to sexual partner preference in birds

Investigating parental care behaviour in same-sex pairing of zoo greater flamingo (Phoenicopterus roseus)

In greater flamingos the behaviour of the female–female pairs seems to be equivalent to that of male-female bonds, and this research provides more insight into flamingo social behaviour, and their reproductive cycle, and provides information on why pair bonds may form and how these affect the wider breeding behaviours of the flock.

Experimentally evoked same-sex sexual behaviour in pigeons: better to be in a female-female pair than alone

These results are the first obtained under controlled experimental conditions which demonstrate that the sex ratio of a population can shift the social structure and cause cooperative same-sex breeding behaviour to arise in a monogamous species.

Nice guys finish last: same-sex sexual behavior and pairing success in male budgerigars

It is hypothesized that the tendency of males to engage in same-sex interactions may represent a mechanism of mutual assessment of male abilities, especially those involved in group foraging efforts (the "leader assessment hypothesis") and suggested that increased investigation of allopreening and other seemingly affiliative behaviors that occur outside the heterosexual pair bond may advance understanding of social organization in flocking birds.

Same-sex pair-bonds are equivalent to male–female bonds in a life-long socially monogamous songbird

It is proposed that same-sex pairing in the zebra finch may result from the pressure to find a social partner, and the quality and stability of social interactions were equivalent in same- sex and male–female pairs.



Same-sex sexual behavior in birds: expression is related to social mating system and state of development at hatching

It is suggested that requirement of biparental care in monogamous species may influence the greater expression of FF sexual behavior and longer term associations, and both spatial and behavioral dispersion of females and engagement in uniparental Care may be important in explaining the lower incidence of FFSexual behavior in polygynous species.

Same-Sex Mounting in Birds: Comparative Test of a Synthetic Reproductive Skew Model of Homosexuality

A novel model, the Synthetic Reproductive Skew Model of Homosexuality, is introduced that aims at understand- ing same-sex mounting as a result of the combined effect of a set of variables and processes that affect both sexual and sociosexual aspects of behaviour.

Development of Sexual Partner Preference in the Zebra Finch: A Socially Monogamous, Pair-Bonding Animal

Removal of adult males from breeding cages, so that young birds were not exposed to males or to male–female pairs during development, eliminated sex-typical partner preferences; these birds were equally interested in both sexes and were more likely than controls to pair with a same-sex partner.

Parental conflict in birds: comparative analyses of offspring development, ecology and mating opportunities

The results suggest that sexual conflict is a key element in the evolution of parental care systems and support the view that the major correlates of the intersexual conflict are mating opportunities for both sexes, rather than the breeding environment.

Are parental care trade‐offs in shorebirds driven by parental investment or sexual selection?

Changes in parental care and sexual selection intensity were tightly correlated, and the results from the analyses were consistent with both PIH and SSH, although the patterns in male transition were sensitive to model values.

Homosexual behaviour in animals : an evolutionary perspective

This chapter discusses the evolution of male homosexuality and its implications for human psychological and cultural variations among Indian Ocean bottlenose dolphins, as well as the development of homosexual behavior in male mountain gorillas.

Successful same-sex pairing in Laysan albatross

It is demonstrated how changes in the sex ratio of a population can shift the social structure and cause cooperative behaviour to arise in a monogamous species, and the importance of genetically sexing monomorphic species is underscored.


Sexual selection in Lawes' Parotia, a lek‐mating bird of paradise, during 1981–1983 in Papua New Guinea is studied to confirm an important role of female choice in sexual selection in birds of paradise but also suggests that female choice may be unrelated to the process of lek-initiation in this species.

Parental investment, sexual selection and sex ratios

An integrative model shows how factors interact to generate sex roles and underscores the need to distinguish between the ASR and the operational sex ratio (OSR) if mortality is higher when caring than competing this diminishes the likelihood of sex role divergence.

Induced homosexual behaviour in male house finches (Carpodacus mexicanus): the “Prisoner Effect”

It is presumed that the regulation of sociosexual tension is another potential function of the male homosexual behaviour observed in this study.