[Posted on behalf of Steffen Oppel, wirebird guru]
The St Helena plover (or wirebird) nesting season is in full swing – although they can breed at pretty much any time throughout the year (the joys of living on a subtropical island), most of them lay eggs and raise their chicks during the hot and dry season from November through to March. In our current project, we are trying to locate all the wirebird nests in three major study areas – those where we also monitor the activity of cats and rats.
Fran and Denny scanning the pastures for nests
So far, the team has found 98 nests this season – a huge number given that the world population of adult birds is only around 350-400! However, the reason for this is very likely the rather poor breeding success: only 6 chicks have fledged so far, and 80-92% of all nests were predated before the chicks had grown up to fly away! As a consequence, many pairs are forced to lay another clutch of eggs when they lose the first one.
In many cases the predators remain unidentified, but at a few nests we monitored with stealthy cameras we saw cats and rats take the eggs. Cats are presumably also very capable of catching the chicks, which leave the nest when only 1-2 days old and follow their parents through the pastures to find food. Our monitoring shows that quite a few feral and domestic cats prowl the study areas, so it would be quite challenging for a small flightless chick to elude those predators for the 4-6 weeks it needs before it can fly.
The goal of our project is to increase the nesting success of the plover by removing the feral cats – a process that we started 3 weeks ago in one of the study areas. Given that there are no natural predators for the St Helena plover on the island, removing the non-native species that take such a heavy toll on the nests and chicks should provide an immediate boost to the population.
Map of this season's nests in the three main study areas
[Posted on behalf of Sheila and Chris Hillman, and Kevin George – St Helena National Trust Wirebird