May, June & July are the busiest months on Skomer, for visitors, jobs to be done and, most importantly, birds on the island. (Why I’m only just getting round to talking about the seabird monitoring in August!!) Just counting the seabirds takes up a good three weeks, but we also monitor the colonies to collect much more detailed data – a much bigger job, which Will, the Trust’s fieldworker, does an excellent job at.
Skomer Island is one of four key sites in the Seabird Monitoring Programme. This joint programme between the BTO and JNCC aims to monitor seabirds all across the UK, Channel Islands and the Isle of Man. All coastline can be monitored, but the four key sites are large seabird colonies, spread geographically to give us more detailed information about the state of our seabirds. As Skomer is a key site, we have to collect breeding success, adult survival and population data every year for all our seabird species. Will does an incredible job of collecting this data, spending hundreds of hours staring at the cliffs across the busy season, meaning he is very rarely seen anywhere else!
As part of my role as Seasonal Assistant Warden, I have
taken on one of Will’s Razorbill study plots at Bull Hole. With only Razorbills
studied at Bull Hole, and most of the other plots at the Wick, High Cliff and
South Stream, it makes sense to split this one off, and I was very happy to
take on the challenge.
Most of the seabirds follow a similar methodology for their
monitoring, though as the timing and behaviour of breeding changes between
species, there is some variation. For Razorbills, it starts in mid-May. Over a
series of visits, all the breeding sites in the plot area are marked onto a map
and numbered. Then, between late May and mid-July, I visited the plot every day
(weather depending!), looked at every nest site and recorded adults attending,
the presence of an egg or chick, or whether the bird was incubating.
In principle, this is very simple, and it’s easy when the
adults are helpful and move to give you a lovely view of an egg or small chick.
Unfortunately, that is rarely the case, and with 120 sites plotted, there was
an awful lot of staring at birds that seemed to be having a lovely little
sleep. But seeing a bird finally stand up and rejig itself was pretty exciting
– can you see what’s underneath before it settles back down?!
Once the eggs started hatching in early June, things get
easier – it’s much harder to sit still for hours on end when you have a wriggly
little chick to look at! The valuable information is how old the chick is, so
we can then predict the day it will be ready to fledge. Ageing a chick is
reliant on getting a decent view, and they can still be very sneaky, tucked
under parents or into a tiny crevice. So we rely on the small glimpses we get,
often just the end of a bill protruding from an adult’s back (incredibly cute
when they poke out to see the view!).
The days fly by, and nearing the end of June we had the first Razorbill fledge. Over the next couple of weeks, fledging increased until the cliffs got very quiet by mid-July. Visiting Bull Hole every day and watching the same birds, you really root for all of them to succeed. Not all do, but when a chick disappears after 15 days, you know they’re probably off out to sea and (hopefully) okay!
Once the cliffs get quiet, we look at the overall data and work out the numbers. All those hours of watching end up as one small number, less than 1, which tells us how many breeding attempts were successful. The success rate varies across the sites and across the years but usually sits somewhere around half (0.5). It’s quite strange for all that time spent watching to end up as something so tiny, but these numbers, built up over the years, paint a clear picture of what’s happening to our seabirds. And with this data feeding into the Seabird Monitoring Programme, we know it’s contributing to the national picture too. That means it will help evidence the changes we’re seeing and, hopefully, contribute to wider changes needed to conserve these populations.
It was a
joy to spend so much time studying the Razorbills, even on days when I didn’t get
there until evening, the views of the sun setting and watching the Manxies streaming
by made the long days worth it. As I write this, nearing the end of my time
this season, I already miss those long, hot days with the smell and racket of a
busy seabird colony!
Izzy –
Seasonal Assistant Warden
Nature Networks
This project is funded by the Nature Networks Programme. It is being delivered by the Heritage Fund, on behalf of the Welsh Government.
Ariennir y prosiect yma gan y Rhaglen Rhwydweithiau Natur. Mae'n cael ei ddarparu gan y Gronfa Treftadaeth, ar ran Llywodraeth Cymru.
