Genetic diversity and the implications of captive rearing for a small population of Black‐tailed Godwits

Headstarting is a captive rearing intervention where eggs are taken from
the wild, artificially incubated and chicks are reared in captivity to
fledging before being released into the wild. From an imperiled
Black-tailed Godwit population in the UK, clutches have been collected for
headstarting. While this conservation measure has reduced local extinction
risk, it may have impacts on genetic diversity and population viability,
especially when wild-sourced eggs must be collected from a small
population. Here, we compare genetic diversity and relatedness of the UK
population of 42 pairs with the much larger breeding population in the
Netherlands (~30,000 pairs). We found that levels of heterozygosity and
inbreeding are not currently compromised, but allelic richness in the UK
population was 8.5% lower than in the Dutch population, and relatedness
estimates suggest that 6.1% of the individuals in the UK population are
closely related, at the level of half sibling and up, compared to 1.9% in
the Dutch population.  Increasing levels of relatedness could in
the future deplete genetic variation further in the absence of immigration
or wild-sourced eggs from other populations.