Gunwalloe Swallow in Spain

We tend to ring a lot of Swallows at the roost at Gunwalloe, but the 'return' on these birds is rather small, with very few ever being found or recaught again. In fact, of the 2,007 Swallows ringed in the reedbed, four have been recaught in the reedbed within the same autumn, five have been caught a year after ringing and two have been recaught two years after ringing. Just one has been found dead (in Helston a year after ringing) and we've had two longer-distance movements.

One of these was a bird we ringed in August last year that then headed north, being recaught in Devon 26 days later! A rather more conventional movement has only just come to us via BTO, which was a bird ringed in July 2014 that was then recaught on southward passage in September in Guadalajara, central Spain. This is over 1,000km from Gunwalloe, but this bird obviously had a lot further still to go!

Tent-roosting Swallows

Instead of using our large wooden roosting box, last night we used a pop-up tent to roost some Swallows caught in the reedbed at Gunwalloe. The video below shows them being released at dawn, with all birds successfully dry and safe in the roomy tent.

Although the birds came in to roost very late, of the 350 birds present we caught 76, including a recapture of a bird we ringed in the Gunwalloe roost in July 2014 and also a bird ringed on the Isles of Scilly on 20th August, so heading completely the wrong way in autumn! What was equally surprising was that 24 out of the 76 birds caught were adults (32%), compared to 27 out of 284 (10%) ringed at roost earlier this year.

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

Swallow roost bonus

Having seen how much the reed had grown up at our sewage works site at Gwennap (check out the original reedbed in this blog post), last night we opted to see if any Swallows were roosting there. Bit of a long shot, but if you don't go and check you'll never know.

It didn't look too good as there weren't many birds around anyway, but we stuck up a few nets and hoped. We even added a speculative net alongside one of the settling tanks just in case one of the two regular Green Sandpipers there dropped in. So to cut a long story short, the roost only produced six Swallows and a Chiffchaff, but the extra net chipped in with three more Swallows that got the 'balancing-on-the-top-shelf-for-fun' game a bit wrong and also the hoped for Green Sand - the first ever caught by the group.

This was an adult in active wing moult, and apparently adults birds begin their complete moult on the breeding grounds and slowly moult through migration, finishing on their wintering grounds. Some will also suspend moult part-way through migration, continuing it later in the autumn. As in many waders, it is usually the female that departs first, leaving the male to raise the young which will then start to come through the UK later this month. Either way, a very smart bird indeed!

Our bird wasn't too far into the moult of its primaries
and hadn't started on the secondaries yet.