29 August 2016

Green 0T0

We've been finding it quite difficult to catch up with any significant numbers of Mediterranean Gulls at our regular sites (Men-aver beach and Gillan Creek), so colour-ring sightings have been few and far between. But yesterday we did catch up with Green 0T0 which is an occasional visitor to Portscatho and the Helford river.

Distance and poor light weren't conducive to a decent photo of 0T0

Ringed as a chick in Vendée, France in 2011 Green 0T0 was first seen in Cornwall in September 2011, then again in October 2012. By December 2012 it was down in Portugal, moving east to Spain in February 2013. It was then back in France before being seen in southern Portugal the next winter. Since then it's only been seen in France, before returning to Cornwall in August 2014 and now August 2016.

This is one of the wider-ranging of the birds we've seen in the county, so hopefully it will continue to wander!

27 August 2016

Chats and pipits

Just two of us ventured out yesterday to make the most of the calm weather at Gunwalloe. As we've not been able to run the CES this year (due to an inaccessible net ride) we could use 'tape' lures to increase our catch of migrant warblers. It worked!

Our catch of 104 birds was excellent, especially considering most of these came from a single 40' net and a net right out in the open at the edge of the new turnip field. The main species were Whitethroat (19), Sedge Warbler (17) and Chiffchaff (10), though the highlights were three Tree Pipits (the first we've ever caught here) and three Stonechats (two juveniles and an adult male).

Other sessions this weekend have seen the group ringing Spotted Flycatcher and a dozen Grasshopper Warblers at Nanjizal and a very smart Whinchat at Marazion.

21 August 2016

2016 Barn Owl numbers

With all the monitoring of first-brood Barn Owls now finished, we can get a good picture of how the season went. The table shows the standard figures we work out every year and it's clear that 2016 was a pretty dismal affair.

2011 2012 2013 2014 2015 2016
Sites visited 32 34 32 44 41 47
Unoccupied 2 (6%) 7 (21%) 12 (38%) 11 (27%) 11 (27%) 12 (26%)
Occupied but no breeding 13 (41%) 2 (6%) 7 (22%) 7 (18%) 7 (12%) 8 (17%)
Average clutch size (where observed) 4.8 4.1 3.6 4.6 4.6 4.6
Average brood size (where observed) 3.1 3.1 2.4 3.5 3.5 2.8
Number of chicks ringed 33 46 19 63 70 47

Whilst the number of sites we monitor has increased (and will increase more with some very generous funding from Paradise Park), and occupancy remained average, productivity was very low. The average clutch size was similar to previous years but brood sizes were lower than the last couple of years. We also saw four complete failures which is still very unusual in the county.

We think this is due to the cold, wet spring weather, which meant that many birds were either not in good enough condition to breed, or did breed but didn't find the food to raise larger broods. We also found that many birds were developing very slowly, so several visits to ring chicks found that they were just too small, so extra visits were needed. This also meant that there were quite a few 'abandoned' chicks brought in to the Screech Owl Sanctuary; not all survived to fuully-grown, but those that did were also ringed by the group before release.

This poor season seems to have been mirrored across the west of the UK and we can only hope that this will improve in future years.

19 August 2016

Injured Peregrines, Portland Stormies and a super-fat Sedge Warbler

We recently received details of some of our ringed birds that had been found elsewhere, both recaptured alive and found dead.

The saddest was the finding of two injured Peregrines, both ringed as chicks in the same nest near Botallack in May. One was found grounded with a broken metacarpal near Helston on 15th August and a second was found the next day near St Just, with a broken humerus and ulna. Both are now receiving veterinary care and we hope they'll recover enough to be released again.

Another interesting set of movements involved three Storm Petrels, all moving between Hot Point, Lizard and Portland Bird Observatory in Dorset (just over 200km). Over the summer we caught two birds originally ringed at Portland Bill (2699028 and 2699030) and have just heard that a bird we ringed on 5th July was recaught there on 19th July. These are the first movements of Stormies between us and Portland, so to have three in a summer is rather coincidental!

Last but not least was a more expected recapture of one of our Reed Warblers on the Isles of Scilly. D791823 was ringed at Marazion Marsh on 8th August 2015 and recaught at Porthellick, St Mary's on 10th June 2016.

Movements of the Peregrines (red), Storm Petrels (blue) and Reed Warbler (green)
On the ringing front, we've been battling the wind and Cornish mizzle to fit in some mist-netting sessions, but have only really managed a couple of Swallow roost catches (totalling 144 birds (and one Sand Martin)) and a couple of mornings in the reedbed, ringing 70 warblers and Reed Buntings. You know migration is well underway though when you catch a Sedge Warbler completely covered in fat. The bird below (excuse the rubbish photo) felt like a tube of butter, being completely covered in stored fat. Considering the fat-free weight of a Sedge Warble can be as little as 9.5g, this bird weighed in at 19.8g!

6 August 2016

Not often you get four controls in one net

Last night our numbers were swollen by visitors from up-country, allowing us to us divide our time between nocturnal netting sites on the Lizard. First stop was Gunwalloe where we netted the Swallow roost for the first time, starting off well catching a decent number of warblers and a couple of Reed Buntings (very much lacking in recent years). Numbers of Swallows soon increased, but the roost was rather disrupted by a pack of Starlings also choosing to roost close to the nets, of which we caught a small number. But once these were cleared, Swallows dropped back in and we ended the night with 50 Swallows (along with nine Reed and eight Sedge Warblers).

With most of the team staying to process Swallows, two decamped to Hot Point, Lizard to set nets for Storm Petrels. In amongst a very eerie sea fret, we netted through to 3am, catching 60 birds. The highlight though was one net round which produced five ringed birds (in the same net)! These included birds from Portland Bill (Dorset), Dingle peninsula (Co Kerry), a recapture of a bird we ringed in July 2015 and incredibly two birds carrying rings from the Channel Islands Ringing Scheme.

These birds will almost certainly have been ringed on the small island of Burhou, but we'll have to wait for confirmation. This is rather exceptional though, as to the end of 2015 only 12 Channel Islands ringed Storm Petrels had been recaptured in Britain & Ireland (four of which have unsurprisingly been in Cornwall).

Just for a brief distraction we also caught a bat, which we think was a Pipistrelle... ***UPDATE*** It was apparently a Whiskered Bat!

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.

21 June 2016

Highs and lows in the Kittiwake world

Just for a change of scenery I headed up to look for some colour-ringed birds in the Kittiwake colony at Porthmissen, Trevone this afternoon. In many ways this was a day of highs and lows, quite nicely reflecting the life of a Kittiwake.

The first high was the site, as this part of the north Cornwall coast really is quite stunning! The birds are best viewed from across a narrow isthmus looking back into the colony, nesting along a series of narrow ledges across the sheer face.

The high was soon replaced with a low though, as on scanning through the colony it soon became apparent that a vast majority of the nests were empty, some with attendant adults, some abandoned. This has recently been one of the key sites in the county for Kittiwake and to see it so devoid of new life was quite depressing. The last few years have seen huge declines in Kittiwakes across the whole south of their range, so we're just hoping that the big declines in key sites in Cornwall are just temporary blips.

The next high came when scanning through the core of the colony, waiting for birds to stand or and shuffle to check them for rings. I was expecting to find one or two French-ringed bird, but found none. But far more interesting to me was a bird that leap out at me as having one of our rings from the Lizard (60km away)! Thankfully it wasn't too far away to read and it turns out that 'AL' has a far from mundane history. It was actually ringed as a chick on Gugh, on the Isles of Scilly, in 1999 and was recaught by us at Rinsey in June 2012, when we added one of our colour rings. It was then seen three more times at Rinsey in 2012, six times in 2013 and just once in 2014 which was the year the colony crashed there. So we don't really know when it first moved to Porthmissen, but it is certainly one to look out for there in future.

The world's worst digi-scoped photo, with the 17-year-old AL on the right
After that quite special high, I was then plunged into a rather depressing low with the arrival of a juvenile (female?) Peregrine. After a short while visiting empty parts of the colony, it then happened upon a ledge with four nests on it, all with attendant adults. The first brooding Kittiwake put up quite a fight, but with the adults soon displaced, the Peregrine proceeded to jump from nest to nest along the ledge, taking all four chicks from these nests (all were broods of one) over 45 minutes. The first three were eaten at the nest, with only feeble mobbing from the parents, though one adult did manage to knock the Peregrine off the ledge, which then carried the last chick off to the clifftop to eat.

Juvenile Peregrine predating the first of the four Kittiwakes nests in this photo,
with other attendant adults unable to intervene

Whether this is a new behaviour or a regular occurrence is unknown, but this may go part way to explain why there were so many empty nests in other parts of the colony. That's nature though, even if it is mightily depressing!

8 June 2016

Breeding Stormies on the Brisons

The Brisons lie just off Cape Cornwall and really haven't been visited for a decade, so it was about time we made the effort and went and had a look! Thanks to the good fishing folk of Sennen Cove we were able to hitch a lift over for a couple of hours and ring a good number of birds and also try to get a handle on the number of breeding birds over there.

In total we were able to ring 42 Shags (two adults), 13 Razorbill (seven adults) and an unexpected 11 Guillemot (eight adults). Many auks were still on eggs, with a few abandoned Shag nests and several still with small chicks.

More significantly though, we also heard at least two Storm Petrels calling (or singing) from one of the boulder fields. This remains the only site in the county that Storm Petrel have been presumed to breed, although we're sure that other several other sites must exist but are just hard to access.

Very cute Razorbill chick, many of which are somewhat
difficult to get at in the boulder fields (below)!
Most Shag nests had broods of two, but a few had three feisty chicks
Adult Razorbill