Why Do Eggs Fail? An investigation into hatching failure in wild and managed bird populations

Many conservation programmes incorporate managed wild and captive bird populations as
part of their strategies to preserve endangered species and bring them "back from the brink",
but these populations often exhibit high rates of hatching failure. Hatching failure affects
approximately 10% of avian eggs overall, but much higher incidence rates can occur in
endangered species. Reproductive success is therefore of major interest to conservation
programmes, with previous research showing that infertility is typically the main cause of
hatching failure in captive populations, while early embryo mortality (EEM) is more common
in wild populations. Still, little is known about the drivers leading to hatching failure, with the
differences between wild and captive populations indicating that factors may be environment
and/or management dependent.
I aim to investigate why managed bird populations often exhibit high levels of hatching failure,
working with wild and captive managed populations in the UK and New Zealand to establish
the key factors underlying infertility and EEM. I will review the current interventions
implemented by different programmes for managed populations and will identify patterns of
infertility and EEM within and between species, then investigate the intrinsic and extrinsic
causes, with a focus on behaviour, environment, disease, and egg microbiomes.