St Ives Herring Gulls back on the TV

For anyone that missed the original airing of the programme, some of our gull-tracking work that featured on the BBC is available again on iPlayer for the next couple of weeks. The programme 'Nature's Boldest Thieves' looked at the food-snatching behaviour of birds in St Ives and included some work on birds that we colour-ringed and also tracked using GPS data-loggers.

The programme can be viewed on iPlayer here, or just click on the image below.

The bits to look out for on our work are at 14:30, 32:15 and 41:50. The work is still ongoing, so if anyone comes across any of our blue-ringed gulls then do let us know (details on the contacts page).

Why so many adult Sedge Warblers?

We've noticed this month that we seem to have been catching more adult Sedge Warbles than normal, so we thought we'd have a look back through our data from previous years and see if this is correct... So we compared the percentage of adults in our reedbed catches at Marazion/Gunwalloe and also at the migration site at Nanjizal.

We couldn't find a photo of adult/juvenile Sedge Warblers side by side,
so this wing shot of will have to suffice,
but the difference in wear on the flight feathers is obvious,
hence these birds are easy to age

 So the August percentages look like this (with total number of birds caught in brackets)...

	Gunwalloe/Marazion	Nanjizal
2011	10% (375)
2012	16% (125)
2013	8% (198)	7% (215)
2014	12% (87)	8% (657)
2015	24% (128)	15% (907)

From this cursory glance at the data it looks like we were in fact correct, with a much higher percentage of adults in our catch this autumn. Why this might be is a bit of a mystery and it'll be interesting to see how this compares to other sites in the southwest and beyond.

Alderney Stormies and our first foreign Cormorant sighting

In the past we've only shared a single Storm Petrel with the Channel Islands; a bird ringed on Burhou, Alderney in June 2008 that we recaught at The Lizard in August 2013. So it was a pleasant surprise to receive news from the BTO two of our birds from The Lizard had been recaught on Burhou in July. One of these had been ringed in July 2012 and the other was ringed on 16th July this year, recaught there just two nights later.

This got me thinking about the differences between the birds we caught at Porthgwarra in 2011 and the birds we now catch at Lizard (2012-15). The pattern of movements always struck me as being a bit different between the two sites, but is there really anything in it? In 2011 we ringed 190 birds at Porthgwarra (with 6 controls) and since then we've ringed 565 birds at Lizard (with 20 controls). The movements these sessions have generated re shown below:

	From Lizard	To Lizard	From Porthgwarra	To Porthgwarra
France	9	5	4	1
Wales	13	1
Channel Islands	2	1
Ireland			2	1
Isles of Scilly		3		2
Scotland	1			1
Dorset				1
Isle of Man			1
Portugal		1

Some of the differences are interesting, with numerous movements between Porthgwarra and Ireland (Counties Wexford, Sligo and Mayo), but none to/from Lizard. But our ringing at Lizard has shared many birds with Welsh sites, whereas we never traded a Porthgwarra bird with Wales. The obvious explanation for the Welsh movements is the increased ringing activity on the Welsh Islands in recent years, in particular on Skokholm. The table below shows the national ringing totals from the BTO's online ringing report and the big increase in effort in Wales is pretty obvious! But there's no real change in effort in Ireland (the figures here are for the Republic of Ireland), so the fact that none of our Lizard birds have been found there is unusual.

	Wales	Ireland	Scotland	England (non-Cornwall)
2010	87	2144	3997	114
2011	78	1896	5090	170
2012	140	1255	5602	146
2013	553	2682	4312	73

Whilst I was looking at all these recoveries, I thought I'd also look at the length of time between ringing and finding. It is generally thought that birds attracted to 'tapes' are non-breeding, prospecting birds in the first few years of life. This fits with our captures, with most birds being recaught in the next summer or sooner. Obviously there are some very quick movements between sites (we've had one day movement to/from both south Wales and France), but recaptures after more than two years are unusual. In fact, the longest time elapsed was the Burhou-ringed bird mentioned right at the start, recaught five years after ringing.

1 week	5
1 month	10
Same year	9
1 year	16
2 years	5
3 years	2
4 years	1
5 years	1

So whilst a quick look at the data doesn't really answer many questions, it certainly poses a few more questions and we'll just have to keep ringing birds to find the answers!

In other news, we have also just received a sighting of one of our Cormorants in France: our first foreign movement! TBD was ringed on Mullion Island in May (see blog post here) and was seen yesterday on Banneg in the Molene archipelago.

Thanks to Helen Maheo for the photo of TBD on Banneg

Interestingly, this isn't the first Mullion Island Cormorant to be found in France, as there appears to be an old record of a chick ringed on the island in 1969 that was found dead in Loire-Atlantique in 1971. We're not sure who would have ringed this bird, but watch this space for further details...

Early autumn at Nanjizal

August is always an interesting and busy time at Nanjizal, with the first big push of migrant warblers coming through. Where other Cornish sites are catching <100 birds in a session, the valley at Nanjizal regularly produces catches three times this number. Just over the last week, morning catches of 341 and 281 have been dominated by Sedge Warblers (201 on one morning alone), but in amongst them have been a few more interesting species.

Wednesday morning produced an early Melodious Warbler (above) and also Nightingale (below),
actually a much rarer species in the county!

Anyone still stuck for an autumn ringing trip away might want to consider a trip down to Cornwall, so check out some extra info here.

Reedbed roost and ruins

With a small break in the weather we finally managed to fit in a CES session at Guwalloe Marsh on Saturday, so while we were there we did a Swallow roost in the reedbed the night before. With well over a thousand Swallows gathering, the birds looked good, the weather looked good and we had our first big Swallow catch of the autumn.

After a long night processing, we ended up with 174 Swallows (inc 14 adults), four Sand Martins and some odds and sods, so a good (if late) start to the hirundine season.

Swallows ready to be processed and put to bed in our roost box

Poor night-time pic, but nice comparison of adult and juvenile Sand Martin

And an even worse photo of them going in the morning!

We followed the roost up by sleeping over by the marsh and then getting up for CES in the morning. The weather was kind for a change and with an extra net the final total of 89 birds was pretty acceptable, including 32 Sedge Warblers and 14 Reed Warblers. Only 69 of these were from standard nets, but this total is our highest ever for Visit 10.

What was apparent was that birds were already fattening up for migration, with several Sedge Warblers carrying lots of fuel: compare the Fat 0 bird weighing 9.1g to the Fat 7 bird weighing 16.7g and you'll get the idea. It was also interesting that it was the adult birds that were the fattest, with the average juvenile weight being 10.8g compared to 13.1g for adults.

Yet another dire photo, this time of a Fat 7 Sedge Warbler

Just to add a bit of culture to the day, we also stopped off to have a nose round the ongoing archaeological dig on the clifftop. The site is a mediaeval settlement and would have been the largest in the Kerrier area, so a bit of a change from the single farm and holiday shop here now! But with some fascinating archaeology on show it was a rather interesting aside...

Apparently these are two walls of an old iron age building

Interrupted Barn Owl brood

A couple of days ago we ringed the last of our first-brood Barn Owls, this time out at a National Trust farm in Penwith. This is a great example of the value of monitoring, with the male of this pair being a first-year bird ringed a few miles up the coast at another National Trust farm. As a young breeding pair, they had a faltering start... Their first nesting attempt was just three eggs, two of which looked like they were never incubated, with the female sitting on a single egg at the front of the box. They soon decided to start over, moving to another box on the farm, laying three eggs in quick succession but then waiting a week to lay a further two! It was presumably these late two that never made it beyond hatching, but three did survive big enough to look like fledging (below being ringed).

With all the first broods now ringed, we can tally up the year and see how it compares to the last few...

	2011	2012	2013	2014	2015
Sites visited	32	34	32	44	40
Unoccupied	2	7	12	12	12
Occupied but no breeding	13	2	7	8	4
Occupied but no breeding	13	2	7	8	4
Failures	0	0	3	0	4
Average brood size (where observed)	3.1	3.1	2.4	3.5	3.5
Number of chicks ringed	33	46	19	63	70

So whilst we checked fewer sites than last year, we saw good rates of occupation and similar clutch and brood sizes to 2014, but managed to ring more chicks than any other year. What was different this year was the high number of failed attempts. Of these, two failed at the egg stage (the young pair above and another where the female was found dead mid-incubation) and two at the chicks stage.

One of the failures saw five large chicks found decapitated in the box. We've seen this once before and presumed it was predation by a Stoat, but we've since heard that adults under stress can sometimes kill their own chicks in this manner, so it was perhaps food stress that caused this particular loss. This happened overnight, being a grisly find for the barn owners when they turned on their nestbox camera in the morning.

But with more boxes being put up and monitored, we hope to have more interesting and enlightening stories to share over the coming years. Thanks as ever to the many landowners who let us into their barns and houses to monitor these birds and in particular to Shaun Boyns at the National Trust for coordinating all of the monitoring in Penwith.

More Storm Petrel news from France

Last month we blogged about the 'rush' of four French-ringed Storm Petrels we caught on one night (see the post here), but we had no such luck in July, but our catch of 75 birds on one night was a bit of a Lizard record! But we've also heard a bit more about the Storm Petrel ringing in France, courtesy of Bernard Cadiou.

He confirmed that the four birds we caught last month were all ringed in 2014 on the Molene archipelago, where he's been running the ringing programme since 1997. In that time he's ringed over 18,000 birds and on just three nights last month they caught 688 birds - all in two nets without a tape-lure! But these are breeding birds and he was able to confirm that most of the birds we are catching in Cornwall are wandering non-breeders, which once settled at a colony will rarely wander far from it. One good example is 2683074, ringed at Lizard on 8th July 2013 and recaught on Banneg in the Molene archipelago just three nights later. Interestingly, it was then caught incubating an egg on the nearby colony of Enez Kreiz in 2014 and was also recaught there by Bernard just yesterday, this time incubating a small chick!

The Molene archipelago lies off the French coast and is home to France's largest breeding population of Storm Petrels. The three main islands are shown below, with the density of breeding birds shown by the coloured grids (or kernel maps for the two right-hand maps).

 

Many thanks to Bernard for the update on their ringing programme on the islands and it certainly inspires us to ring more birds here!

Foreign gulls and legless gulls

The blog has been a bit quiet recently, but that's mainly due to a long overdue holiday in Turkey! But I came back to a bit of a flurry of gull reports, all of which were quite interesting...

The first two were a bit sad, as Herring Gull W:062 appears to have lost a leg! It was seen with both legs intact in amongst the thousand other gulls in Cadgwith Bay in January, so has obviously suffered a mishap since then. It was reported from Swanpool, having been ringed locally in Falmouth in 2014.

We also heard that W:197 from St Ives had been found with a broken wing and broken leg in St Ives, so had to be euthanased by a local vet. Better news came in the form of W:060, originally ringed on Falmouth High Street, which is now also on it's holidays, being seen in France. This is the first foreign sighting of one of our Herring Gulls, so was great news!

We've also only ever had one previous foreign sighting of one of our Great Black-backed Gulls, so receiving two in a week was a surprise. Our only other foreign sighting was L:BF8, ringed in Falmouth and seen in France in October 2014, and it apparently liked France as it was reported from a different site again at the start of May (delayed as reported by letter). Also heading south was L:BJ3, ringed on Mullion Island in 2014 and seen at Lizard Point twice in August 2014. It was seen on Chouet Landfill, Guernsey on 13th July and it's about time one of our birds made it to the Channel Islands.

Apart from this, since the last blog update we've been doing some ringing, so below are a few highlights in the form of pretty pics!

It was another year of low productivity for our Great Black-backed Gulls on Mullion Island, with just nine chicks making it to an old enough age to colour-ringed

Our Kittiwakes have been doing slightly better, with 25 chicks and 15 adults now ringed at Trewavas Head

It's not been such a good year for resightings of French-ringed birds though, with just five birds seen. This bird was ringed at Ponte du Raz, France in 2002 and has been seen at Trewavas Head in 2012 and 2015.

This is also a French bird, ringed as a chick in 2007 and seen for the first time at Trewavas Head this year. Caught inadvertently, we noticed that the colour rings (in particular yellow) were starting to fade so we replaced them with one of our numbered rings.

Away from seabirds, we are also continuing to ring rehabilitated owls at the Screech Owl Sanctuary, these being some of the eight young Tawny Owls ringed recently.

Tit-tastic

Hopefully this won't be blocked by too many browsers, but our latest CES visit at Gunwalloe was a bit of a Blue Tit festival, with several broods apparently converging on the reedbed for the morning!

The total for the day of 87 birds (24 from an extra non-CES 30' net) was dominated by Blue Tits, with 32 caught, including several adults. But most were noisy, newly-fledged juveniles testing out their biting skills for the first time!

If ever there was an individual that demonstrated why birds
need an annual feather moult, this was it!

The rest of the catch included 13 newly-fledged Reed Warblers (and 7 adults), 10 Sedge Warblers and a scattering of Bkackcap, Bullfinch, Reed Bunting etc... We were also reunited with Y101092, a female Cetti's Warbler ringed in June 2011 and only recaught twice since (in July 2011 and June 2014).

In other news, we also recently had a kayak expedition out to Trewavas Head and Rinsey to ring a few more adult Kittiwakes. In an eventful day, including losing a kayak and capsizing a kayak, we colour-ringed a further 15 adult birds as part of our RAS study. We were also able to resight a few birds from previous year, including a single French-ringed bird.

It's rare to see a first-summer Kittiwakes back at a colony,
so this bird at Trewavas Head was a surprise

On the way back we stopped off to ring a few Herring Gull chicks at Rinsey: our natural 'control' site for the Falmouth urban gull work. We rounded up nine birds, so it was depressing to see broods of three later in the week with just two ringed!

Rush of French Stormies

After the success of Storm Petrel ringing the previous night, we headed out to Hot Point again last night, this time in perfect still conditions. With just two of us out, we managed a very respectable 65 birds, but the make up of these made for one of the best nights we've had!

We often deliberate over the ageing of Stormies, so this bird with a single
recently-moulted inner greater covert made us scratch our heads!

64 of these birds were, unsurprisingly, Storm Petrels, which compares well to the 40-50 we normally ring in the whole of June... but what was interesting was some of the recaptures of ringed birds. No less than four of these were French-ringed birds, all ringed above the 'knee'. The latest BTO Online Ringing Report (for 2013) shows just three French-ringed Storm Petrels recaptured in Britain and Ireland, so four on one night is quite notable!

We also recaptured two birds ringed on the Isles of Scilly (in 2011 and 2014) and one of our own birds ringed last year which is interesting. The fact that one of the Scilly birds was ringed as an adult in 2011 contradicts the commonly-held belief that tape-luring only draws in young non-breeding birds...

A final hoorah for the night though was a very smart Manx Shearwater that blundered into one of the nets. We'd had one bounce out of a net the previous evening, but this one flopped in whilst we were extracting Stormies, so managed to get to it before it too bounced. Whilst half-hoping to find it was a ringed bird from one of the west coast breeding sites, it was an interesting training event fitting the overlapped and ellipsed ring!

Ringing marathon

Not quite a 26-mile marathon, but a pretty full 24 hours of ringing was had yesterday. In the morning three of us kayak-ed out to Mullion Island to check on the progress of our Great Black-backed Gull chicks. These were, as expected, a bit behind the Looe Island birds, with most chicks being quite small. We ringed a token gesture four birds (and colour-ringed the only large-ish one), with our main ringing visit now planned for the end of the month.

The only chick big enough to ring, sporting one of our improved colour rings

The island also produced a few surprises in the form of an adult Cormorant sporting an orange ring (presumably one of ours from a few years ago), a metal-ringed Shag (presumably local), a pair of Guillemots with a chick (and possibly four pairs of Razorbills) and this Oystercatcher nest.

Later in the day we headed out to Hot Point, Lizard, for our first Storm Petrels of the year. In slightly too windy conditions, we managed 28 birds, including one from the Isles of Scilly and the obligatory bird missing a foot. With a few Manx Shearwaters buzzing round we also switched the tape-lure for a while, but despite five birds coming close none came quite close enough!

With dawn rapidly approaching, we switched location to Gunwalloe to get a pre-dawn net over the new cliff-top Sand Martin colony there. Must have been a bit cold, as birds were rather reluctant to get up, but as dawn arrived we managed to catch 17 birds, including two very fresh juveniles.

Our Sand Martin net was a bit of a Heath Robinson affair...

Juvenile (left) and adult (right) Sand Martins

Wandering Red Kite

Whilst not really a ringing group sighting, we've just heard of a wing-tagged Red Kite in the county so thought we'd help track it down.

Whilst the mid-summer influx of Red Kites into west Cornwall is an annual spectacle, this year it's been quite exceptional. The last few days have seen large numbers of birds across Penwith, with the top spot going to Nanjizal, where 202 birds were counted on the 9th. On the same day, Linton Proctor was lucky enough to photograph a wing-tagged bird at Polgigga (below) and this proved to be rather exciting!

The pink tag indicates that this bird is actually from NE England, with the orange bar indicating it was a 2014 nestling. Thanks to the guys at Friends of Red Kites, we now know that this bird was ringed in the nest just a couple of miles from Gateshead Metro Shopping Centre in June 2014 and was last seen in the communal roost in the Derwent Valley in October. So why it should now be wandering so far from home is a mystery, but fingers crossed it will be seen again on it's way back north!

First CES juveniles of the year

This morning we braved the mud at Gunwalloe again to do CES visit 3, and were pleasantly surprised by the results. After a few years of quite low early-season catches, the standard nets (400' of them) produced 28 birds with an additional 30' net producing an impressive 15 birds!

Captures so far by CES visit in 2015 (shown in red) look quite good compared to the last couple of years

Aside from the standard warbler fare (including both Reed and Sedge Warbler originally ringed in 2011), we caught our first recently-fledged juveniles of the year, in the form of a Robin and a Dunnock...

...with the additional highlight of two controls (birds ringed elsewhere). The Blackcap below was ringed at Nanjizal, near Land's End (see more here), in September last year and we also caught a Reed Warbler originally ringed as a breeding male on the Isles of Scilly in June 2013. The latter bird is interesting as it appears to have switched breeding site by quite a way north.

One last distraction whilst on the way to check out a small Sand Martin colony was a female Stonechat carrying food that we eventually pinned down to a small area of open dune grassland. A quick search revealed a brood of two half-grown chicks which were duly ringed and returned to home.

Rather small Stonechat chick

19-year-old Kittiwake and a few Shags

RAS is the BTO's Retrapping Adults for Survival scheme, where regular monitoring of a breeding population of ringed or marked birds gives a better understanding of between-year survival rates. The group carries out RAS studies on House Sparrow, Jackdaw and Kittiwake and yesterday we headed out in wetsuits and a ladder on a kayak (yes, a ladder bungied onto a kayak) to check on some of our seabirds.

First stop was Trewavas Head where we we have a small colour-ringed population of Kittiwakes. We were able to read a couple of our own rings, including a bird that had moved from the now-struggling colony at Rinsey, now resident at Trewavas Head, and another French-ringed bird from Finisterre. We also colour-ringed eight more adult birds, including one already carrying a metal ring: ES19858 was originally ringed as a chick on Gugh, Isles of Scilly, in 1996, so is already a good age! This is the third Scillies bird we've caught in the area, with the others ringed in 1998 and 1999.

ES19858 looking good for 19 years old!

On the way back we were able to stop off at Rinsey to ring a couple of accessible broods of Shag chicks, also managing to catch a single adult bird. They're surprisingly small in the hand, but still pack a punch with that hooked bill!

Guernsey tip gulls

It's that time of year again when a few members of the ringing group head over to Guernsey to help out with the cannon-netting and colour-ringing of gulls on the tip there. This is probably the final year of tip trips, which have been run by Paul Veron and North Thames Gull Group. For more info on the project, check out the video from a couple of years ago:

 

Over the week we've caught just over 1,400 gulls, most of which were Herring Gulls, but also good numbers of Lesser Black-backed Gulls and a few other odds and sods. So below are just a few pics from the trip, perhaps useful for people to get to grips with ageing these birds.

 

A variety of ages of Herring Gull awaiting extraction

The Guernsey gull team for 2015

Herring Gull

 

First-summer bird (age code 5): no grey on the mantle and uniformly dark secondaries

Second-summer bird (age code 7): grey on the mantle and some mottling on the secondaries

Third-summer bird (age code 9): grey coming through on the wing coverts and adult-type primaries moulting in

Fourth-summer bird or older (age code 8i): mostly adult-type primaries and secondaries, with some remnants of immature plumage

Lesser Black-backed Gull 

 

First-summer bird (age code 5)

First-summer bird (right) and second-summer bird (left)

Second-summer bird (age code 7)

Third-summer bird (age code 9)

 

Yellow-legged Gull

 

We were lucky enough to also catch a Yellow-legged Gull; only the third we've caught on the tip. This second-summer bird can be identified by the darker grey mantle, more orange orbital ring (around the eye), a very deep long bill and a much more delineated white rump.