Excretion patterns of coccidian oocysts and nematode eggs during the reproductive season in Northern Bald Ibis ().

Individual reproductive success largely depends on the ability to optimize behaviour, immune function and the physiological stress response. We have investigated correlations between behaviour, faecal steroid metabolites, immune parameters, parasite excretion patterns and reproductive output in a critically endangered avian species, the Northern Bald Ibis (). In particular, we related haematocrit, heterophil/lymphocyte ratio, excreted immune-reactive corticosterone metabolites and social behaviour with parasite excretion and two individual fitness parameters, namely, number of eggs laid and number of fledglings.

Familiarity with the experimenter influences the performance of Common ravens (Corvus corax) and Carrion crows (Corvus corone corone) in cognitive tasks.

When humans and animals interact with one another over an extended time span they familiarise and may develop a relationship, which can exert an influence on both partners. For example, the behaviour of an animal in experiments may be affected by its relationship to the human experimenter. However, few studies have systematically examined the impact of human-animal relationships on experimental results.