Summary: Mateos (2005)

In vertebrates, the relationship between glucocorticoids, testosterone, social and sexual behaviours is often complicated and incompletely understood. The subordination stress paradigm predicts that subordinate individuals should show higher levels of glucocorticoids, dominants should have higher levels of testosterone and there should be an inverse relationship between glucocorticoid concentration and testosterone. Mateos (2005) studied male ring-necked  pheasants, Phasianus colchicus, and found that dominants and  high-displaying males had higher levels of testosterone, but, in contrast to expectations, also had higher levels of corticosterone. This indicates a positive correlation between testosterone and glucocorticoids. She suggests that the results support a stress-mediated version of the immunocompetence handicap hypothesis.

Summary: Mateos (2005)

The relationship between testosterone, glucocorticoids, social and sexual behaviour is complicated and poorly understood in vertebrates. It is thought that subordinates should have higher glucocorticoid levels (known as the subordination stress paradigm) and that dominant, more active, males should have higher concentrations of testosterone during the breeding season. It has thus been suggested that glucocorticoid and testosterone concentration should be inversely related. Mateos (2005) investigated the relationship between behaviour and hormone concentration in male ring-necked pheasants, Phasianus colchicus. She found that dominant and high-displaying males had higher levels of testosterone and corticosterone (a glucocorticoid) throughout the mating period, indicating that these two hormones are positively correlated. Mateos (2005) indicates that the results do not support the subordination stress paradigm, but she indicates that they may support the immunocompetence handicap hypothesis (through stress-mediation).

Summary: Garcia-Fernandez et al. (2010)

Eggs constitute most of the maternal investment in precocial birds as parents do not feed young post-hatching. The embryo and chick development are influenced by maternal testosterone in the yolk. Testosterone is deposited in eggs by females in response to the environment experienced during the laying period, which includes the quality of the mate. Garcia-Fernandez et al. (2010) assessed the relevance of female mate choice on egg characteristics in the grey partridge Perdix perdix. Females were allowed to choose between males in choice trials and were then mated with either preferred or non-preferred males. They found that eggs from both groups did not differ significantly in mass, but females mated to preferred males produced eggs with higher testosterone levels. They suggest that partner attractiveness is important in the transfer of maternally derived egg components.

Summary: Ulyan et al. (2006)

Ulyan et al. (2006) evaluated the responses of group living capuchins (Cebus apella) to different feeding schedules. They fed animals a predictable schedule for 6 weeks, then an unpredictable schedule for another 6 weeks. They sampled behaviour using scan sampling (1 minute intervals) for 1 hour pre- and post-feed. Ulyan et al. (2006) hypothesized that behaviour and faecal cortisol concentration would be influenced by meal unpredictability. They did not find any major differences in behaviours typically associated with stress or anticipation, but suggest that differences in other behavioural measures indicates that predictable feeding regimes is better for the animals' well being. Their results suggest that the anticipation of feeding is pronounced when feeding time is delayed in an unpredictable manner and cortisol concentration increases during this time. Ulyan et al. (2006) propose that a predictable feeding schedule is more beneficial for the well being of captive capuchins.

Summary: Chapuis & Bshary (2010)

Signals alter the behaviour of receivers, thereby increasing the sender's fitness. When individuals interact cooperatively, signal strength may be linked to supply and demand (biological market theory). Hunger level in cleaner shrimps (Periclimenes longicarpus) is linked to advertisement of their services to client reef fish. To test more detailed predictions of biological market theory, Chapuis & Bshary (2010) investigated signalling by wild cleaner shrimps. Shrimps increased claw clapping when they were food deprived and were more likely to clean than non-clapping shrimp. Chapuis & Bshary (2010) however did not find evidence that signalling was target-specific to visiting client species, and shrimps signalled more frequently to predatory species. They conclude that signal conveys information about identity in order to avoid predation, rather than to attract choosy clients.

Summary: Stetina et al. (2011)

Recognition of emotions is required for interpersonal interactions and emotional competencies. Stetina et al. (2011) explored the possibility of enhancing emotion recognition of children (5-7 years) and adults (19-45 years) by using animal-assisted intervention, focusing on the emotional expression of dogs. Their results showed that the highest changes in both the adult and children groups related to the correct identification of fear and anger. Adults also showed an increase in the overall number of correctly identified facial expressions, as well as a decrease in the latency to respond. Children also increased their capacity for the recognition of disgust and neutral facial expressions, identified 5 more emotions correctly after training and decreased their response latency. Stetina et al. (2011) suggest that a generalization process from human-dog interaction to human-human interaction seems to occur. They indicate that the implied learning effects of animal-assisted interventions are a promising and essential aspect of psychological and psychosocial treatment.

Summary: Townsend & Moger (1987)

Male Puerto Rican frogs Eleutherodactylus coqui are paternal throughout embryonic development of the eggs. Males stop calling (which is necessary for attracting mates) and reduce egg cannibalism during this period. Townsend & Moger (1987) analyzed the relationship between parental behaviour and androgens by analysing blood plasma from males captured in the field. They found that paternal males had lower androgen levels than males that were nonpaternal, calling or amplectant. They noted that the decline in circulating androgens between the sexually active state and the paternal care state was rapid, but also that androgen levels did not differ between males that were at differing stages of the paternal care period. Townsend & Moger's (1987) results suggest a relationship between circulating androgen levels, mating behaviour and the development of paternal care.