24 July 2016

Trewavas Kittiwakes 2016

You might have seen a few posts from us over the summer with various photos of Kittiwakes at our study site at Trewavas/Rinsey, but yesterday saw effectively our last trip to the colony. With many failed breeders now departed and numerous chicks fledged, the colony has become rather quiet, or in the case of Rinsey deserted!

So what better time to offer a brief summary of the year. On the good side, the two sites at Trewavas Head fared pretty well, holding over 120 pairs of birds. This compares to around 70 in previous years so was a welcome increase. Some of these birds may have relocated from Rinsey though, where numbers were again very low (more on that later). Records of colour-ringed birds give us a little bit of insight into these movements and this year we saw six birds at Trewavas that had been recorded previously at Rinsey. Two of these were actually ringed as chicks in France (in 2007 and 2008), giving yet more insight into how these birds move around.

Part of the colony at Trewavas Head

Other French-ringed birds at Trewavas included birds ringed as chicks in 2002 and 2005. We also recorded 16 birds ringed at Trewavas in previous years, including a bird also photographed at sea in 2014 (see pics here), and also a bird originally ringed on the Isles of Scilly in 1996, caught and colour-ringed here in 2015.

At Rinsey, the only colour-ringed birds seen were a French bird ringed as a chick in 2005 and seen quite regularly and a lone bird ringed by us in 2013, which visited just once in February 2016. Breeding at Rinsey was also a write-off, with just nine pairs attempting to nest but all failing before the end of the season.

So a season of good and bad across the sites, but with some interesting stories building...

4 July 2016

Full day of seabirds (and some cannibalism)

You know it's seabird time of year when you're heading out ringing for the day and your roof rack looks like this! Add to that a back seat full of paddles, buoyancy aids, drybag, VHF radio and an assortment of rings and colour rings and we were in for a long day...

First port of call was to take two boats over to Mullion Island to try to track down some of the 203 Great Black-backed Gull chicks/eggs we'd counted earlier in the year. Very few birds make it to a ringable size though, but with a record count this year hopes were high. The vegetation was, as ever, challenging and wading through the mallow and sea kale looking for chicks is a laborious job.

Even large chicks are remarkably good at hiding in low vegetation
True to form we found very few birds, which is always a bit depressing; a full sweep of the island found just 13 birds! These were all a good size to ring and colour ring, so it'll be interesting to see where these birds go wandering.

Some birds aren't quite so good at hide-and-seek though

Part of the reason so few birds survive to this stage was evident all around the island though, with at least 16 relatively freshly-dead chicks found. Some of these were pretty well-grown so it does look like predation (or more accurately cannibalism) remains a driver of the low productivity on the island. We're not sure how commonplace this is, but it doesn't seem to be the best strategy for a colonial-nesting bird!

Once we were back over from Mullion, we headed straight round to Praa Sands for the long paddle round to Trewavas Head to the second of our Kittiwake sites (only accessible by kayak). Unfortunately, the swell was way higher than forecast, so it wasn't safe to land and in any case the tide was really high which would have made accessing nest sites rather treacherous! This isn't the easiest of jobs at the best of times, as kayaking round the headlands with a double-ladder strapped to the side of your kayak is tiring to say the least. Makes landing interesting as well and I must admit we did get barrelled by a wave coming back in to Praa Sands.

Last job of the day (after an impromptu ringing group BBQ in the evening sun) was to make the most of a calm, new moon night to get nets up for Storm Petrels. The first net round before midnight produced over 25 birds so we knew we were in for a busy night, but sadly the Cornish mizzle came in at 1am and we had to beat a hasty retreat before the rocks got too slippy. But although we'd not made it to the busiest time of the night the total of 55 new birds was pretty good. It was a bit surprising to find these were all new birds, so we'll just have to go out again on Tuesday night and hope to recatch some ringed birds...

2 July 2016

Better Kittiwake news but bad for Barn Owls

The last few days have been rather busy, so only a quick update for now! In essence, Barn Owls seem to be doing quite badly (deserted clutches, stunted growth and massively reduced broods) whilst the Kittiwakes at Trewavas Head seem to be doing OK. We've also managed a ringing demonstration at Gunwalloe and hosted a visiting ringer from Devon.

More details to follow once we've caught up after Great Black-backed Gulls, Kittiwakes and Storm Petrels tomorrow, but for now enjoy a few Kittiwake pics from Trewavas Head...

We counted at least 71 nests which is the most we've ever had here:
birds from the crashing Rinsey colony perhaps?
Most birds were a good size for ringing,
but some were too small even for a metal ring
AU is an interesting bird. Now breeding at Trewavas Head,
it was ringed as a breeding bird at Rinsey in 2012 and seen there
three times in 2013 but not seen in either 2014 or 2015.