Saturday, 14 June 2014

A preview of the Big Count!

Over the last three days we've carried out the annual nest census - systematically finding, counting and marking every single nest/clutch of every species on Rockabill - that means every patch of ground, every nestbox, every hole in a wall and under every bit of vegetation! Thankfully the weather was on our side which made the whole thing a little bit easier.

In our daily checks of the study areas we've noticed the number of new nests appearing has slowed considerably - most pairs have laid eggs now so it's the perfect time to do the nest census. Doing it now also means we should avoid counting any late nests, which are treated separately in our results as they are often laid by young inexperienced Terns and so their clutch size and productivity is generally lower than the main population. Doing it now also means we should minimise the chances of including re-laid clutches in our results, which could otherwise create some bias in our results.

Common Terns usually lay 2-3 eggs - this is a 'super-normal clutch' with 7 eggs (and an 8th was added later!) - it's likely to be the result of two females laying in the same place and putting their eggs together, and probably 'stealing' another egg or two that they thought might ahve been theirs. (Picture taken under NPWS license)

We have thousands of Terns here, and a lot of Kittiwakes and Black Guillemots too, so we have a lot of adding up to do over the next couple of days. We'll also be doing another count of everything at the end of this coming week, but we should have some provisional counts to share in the next few days to give a snapshot of how things are faring here compared to previous years - so keep an eye out for that blog post over the next few days. As a bit of a teaser I can also tell you we found our first chicks of the year during the census - so stay tuned!

And finally, we had a visit from some Porpoises - a mother and calf, and another adult - who were obviously enjoying the calm conditions over the last few days!

Harbour Porpoises - a mother and calf - paid us a visit during our census!

Keep an eye out for our nest census update in the coming days!
Until then!

- Brian & Donnacha

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