• Wellcome Trust close
• 1998 close
• 2003 close

Brood parasitism is a form of breeding in which the parasite lays its eggs in the nests of other species, the host, which incubates and rears the young. In avian brood parasites, the habit imposes behavioural and cognitive demands that differ among the sexes, among times of the year and among related species, providing a suitable model to investigate neural adaptations and plasticity. In species of cowbirds (Molothrus sp), parasitism involves patrolling the home range and remembering the location of status of potential hosts' nests, updating this information after each egg is laid. Recent findings include:- Parasitic bird species have larger hippocampal formations (relative to telencephalon) than related non-parasitic species (Reboreda et al. 1996). Within parasitic species where females do all the host nest book-keeping (M.bonariensis), they have larger hippocampus:telencephalon ratios than males, while in species where there isn't such behavioural dimorphism no neuroanatomic dimorphism is present (Reboreda et al. 1996). This neuroanatomical sex dimorphism is found during the breeding season only (Clayton et al. 1997). In a sexually dimorphic species, sexes have been shown to differ in their performance of a memory-testing task in the laboratory (Astie et al. 1998). The histological correlates of these anatomical observations remain unexplored and, together with a better ethological understanding of the nature of the behavioural differences, constitute the topic of this project. Targets include the definition of the functional boundaries of the cowbird hoppocampal formation, the comparison of hippocampal cytoarchitecture across sex and seasons, and the analysis of adult neurogenesis and cell death. While the neurohistological work will be the nucleus of the project, the student will be involved in field research aimed at characterising the temporal and spatial parameters of "book-keeping" and in laboratory tests investigating memory traits associated with brood parasitism.