Suffolk tourists visit the county

It's that time of year in sunny Cornwall where the roads slow down and lots of new faces arrive in the county on their summer holidays. Apparently this isn't just restricted to people though (emmits as we call them down here), with some birds from 'up-country' also finding Cornwall to their liking.

This might not be too surprising when we're talking migrants, but even we're surprised sometimes by the arrivals we find. Whilst recently checking Barn Owl boxes in the far west of Cornwall, we came across a ringed female in a box with her chicks, but the ring number was unfamiliar. It turns out this bird had been ringed as a chick the previous year in east Suffolk, which is quite remarkable! The box is monitored by the Suffolk Community Barn Owl Project and this looks to be by far the furthest movement they've heard of from their hundreds of boxes.

Many thanks to the National Trust West Cornwall Barn Owl Project for helping monitor these boxes in Penwith and to the Suffolk project for providing us with some quick feedback.

Most of our Barn Owls seem to be at this stage, with chicks mostly under two weeks old

As if this was surprising enough, I was emailed by Sue Sayer (Cornwall Seal Group) the very next day with details of a colour-ringed Kittiwake photographed during one of their boat-based surveys at Porthmissen earlier in the year. In a strange coincidence, this bird was also from Suffolk, ringed as a chick in Lowestoft in 2014. It was seen again in Lowestoft in June 2016 but not since and may well be a young bird prospecting new nest sites.

The movements of these two birds are not quite unprecedented, although the only Barn Owls to have travelled further to Cornwall were ringed in Germany and The Netherlands. The only Kittiwakes to have travelled further were from Northumberland (x2), Northern Ireland (x2) and Norway.

Origins of our two visitors: K (Kittiwake) and B (Barn Owl)

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.

Reedbeds, Dippers and an interesting Barn Owl movement

With summer vaguely arriving in Cornwall, this week saw us dusting off the mist nets to start the 2015 CES (Constant Effort Site) season at Gunwalloe. This is now the fifth year we've run the scheme, adding to the BTO's national dataset monitoring the breeding performance of a range of species.

The so-called 'dry ride' at Gunwalloe

The first few visits of the season are always a bit quiet, as we are mostly targeting reedbed migrants here, yet to arrive in big numbers. Those that have arrived are busy setting up territory and not flying round the reedbed, so the catch of just 16 birds was expected. This was mostly Reed and Sedge Warblers though, including two of the former ringed in 2013. We also retrapped Reed Warbler Y101100, originally ringed as an adult at Gunwalloe in June 2011 and retrapped seven times since on site. This is even more impressive when you consider this bird has now crossed the Sahara desert at least 10 times!

We are now also just starting the main nestbox checks of the year, with the first chicks ringed this week in the form of our usual Dippers in Idless Woods. We probably missed one brood that fledged quite early, but the second box had two fat chicks (from four eggs) at the perfect size for ringing.

Two Dipper chicks tucked up in their not-so-cosy-looking nest

Last but far from least was another morning spent doing Barn Owl box checks, this time in the west of the county with National Trust ranger Shaun Boyns. Once again birds seemed to be doing pretty well down here, with two pairs already with chicks hatched! One interesting National Trust story was the male in the box at Trevean (an NT farm), which the nestbox camera had shown was ringed. We presumed it was a bird from one of our sites locally, but was in fact a bird that we'd ringed as a chick at Treveal (an NT farm) in 2014. At 8km, this isn't the longest movement we've seen, but it's great to see a bird breeding in its first year, and one we know very well indeed.

GR80993 in his new home at Trevean

GR80993 and two siblings when ringed at Treveal in 2014 (we're not sure who's who though!)

Next stop are Cormorant chicks on Mullion Island tomorrow and hopefully retrieving the remaining GPS data-loggers from our Herring Gulls in St Ives...

Dire CES and our first Kittiwake chick

The last few days have been busy as ever, including a very poor CES visit to Gunwalloe. The graph below shows how our catches in the reedbed have been pretty poor this year (shown in black) in comparison to the previous three and our recent session was barely any better, with 17 birds only a slight improvement on last year. The catch was mostly Reed Warblers, but here's hoping it'll pick up soon...

On a slightly better note, a quick visit to Rinsey yesterday found our first Kittiwake chick of the year. Not so good news was the fact that there are very few pairs in the zawn and that two birds that were on eggs have now lost them...

I do wonder if the apparent decline in Kittiwake numbers has something to do with the concurrent increase in the number of pairs of Herring Gulls in the zawn. From only a couple of pairs a few years ago there are now as many as 15 pairs, which must have some impact on the Kittiwakes.

Herring Gulls are much earlier breeders than Kittiwakes,
with pairs already with well-grown young

We've also recently met up with Shaun Boyns who runs the National Trust's West Cornwall Barn Owl Project and hopefully in the future we'll be able to work with Shaun to monitor their nestboxes. The project is just taking off now, with 18 new boxes going up this year, so this would be an exciting addition to our network of sites.

Three Barn Owl chicks at the National Trust offices at Treveal