2024 Barn Owl update

We thought that 2023 was an odd year for Barn Owls, but 2024 seemed to continue the trend! The very wet spring was perhaps a boom for early grass growth, with a consequent increase in vole numbers. So 2024 saw our highest ever average clutch size (5.4), with three clutches of eight eggs being found.

This didn't necessarily feed through into large broods though, with the average (3.2) very much in line with the last couple of years:

	2015	2016	2017	2018	2019	2020	2021	2022	2023	2024
Sites visited	41	47	64	85	87	106	93	112	127	150
Unoccupied	11	12	23	34	36	43	35	34	29	66
Occupied, no breeding	7	8	5	4	3	4	5	4	10	4
Average clutch size (where observed)	4.6	4.6	5.3	5.2	4.7	4.6	4.5	4.5	4.6	5.4
Average brood size (where observed)	3.5	2.8	3.0	3.3	3.0	3.2	2.8	3.1	3.2	3.2
Chicks ringed	70	47	90	132	119	177	133	189	193	209
Adults ringed/recaught	17/8	14/9	21/14	18/14	16/15	22/17	19/17	20/22	30/24	22/35

The most productive area seemed to be Penwith (average of 4.0 chicks per brood) with the lowest being Roseland (2.4) and East Cornwall (2.9). For only the second year, we also recaught more ringed adults than we ringed new birds, which is very satisfying.

As for movements, the map below shows the origins of birds recaught as breeding birds in nestboxes during the 2024 season. As expected, most of these is short distance dispersal of young birds, on average 8.5km but ranging from 1.7km up to 37.2km.

This only relates to recaptures though, but we unfortunately also hear of many of our birds found dead. In 2024, 11 of our birds were reported dead, including three hit by cars and one that hit wires.

Barn Owl throuple and other odd goings on

Over the long bank holiday weekend we had a chance to make our first visits to Barn Owl nestboxes across part of our patch. It was a long slog, with plenty of sites covered and overall it seems to be an early season with several broods of good-sized chicks and even some not too far off ringing age. But of more interest were some of the 28 adults caught over the weekend (just eight were new, unringed birds), which had some surprising histories.

Overall, there were plenty of short movements, which is what we'd expect from dispersing juveniles, but you can see from the map below that these birds generally don't go too far. The longest movement of the weekend was a bird ringed as a chick in 2023 near Probus and now residing in a new box put up at the National Trust offices on the Roseland!

The strangest happenings were saved for the Lizard though. On the expected end of the spectrum was the new pairing at one site, with both of the pair ringed locally as chicks, in 2022 and 2023. In the middle of the spectrum was a breeding female ringed near the Helford river in 2020, then recaught breeding down near Goonhilly Downs in 2022, was then back up near the Helford to breed in 2023, and now breeding in another box near Goonhilly Downs again this year (below), so four sites in five years!

The far end of the weird spectrum though was at another site near the Helford, where the nestbox camera showed two birds in the box, but we could also hear chicks hissing on a nearby ledge. As we put a ladder up to check the ledge a female flew off, with the ledge home to an impressive seven chicks and an egg, which may well still hatch. We don't see many clutches of eight, but this was our fourth of the weekend. So who was in the box? Well one bird was the regular male that's been breeding there since 2020, but the other was a male ringed as a chick at a site 10km away in 2022. It'll be intriguing how this throuple get on and I must admit it's a first for me.

We couldn't have a Barn Owl post without a photo of a Barn Owl, so here's a few of the various stages we found, including just some of the largest larder we've probably ever seen.

Spanish Black-head and record Cormorant numbers

Mullion Island Cormorants are already well into their breeding season now, with some chicks almost ready to fledge. Our regular count from photos found a reciord 75 nests across the front of the island, beating the 73 nests in 2021 and 72 in 1999.

Annoyingly, photographs also showed an interloper in the colony. This white- (or blue-) ringed bird is likely to be from Wales or Ireland, but without being able to read the ring we'll never know. We're currently investigating the options for remote pan-tilt-zoom cameras, so watch this space.

The highlight from this weekend was a great sighting by Shaun Grose at Hayle. This Black-headed Gull (black ring N016) is actually the first Spanish-ringed bird to be seen in Cornwall, so quite special. In fact only 30 have ever been seen in the UK, so even at a national level this is notable.

It was ringed as an adult on the north coast of Spain in January 2022 and was regular there until 11th March 2022, then seen again in March 2023. It returned in January 2024 and was last seen there on 26th February, before being seen at Hayle. Presumably it's breeding somewhere in the UK, so one to look out for in future years.

Start of the winter Chiffs

It's not often we start our winter sewage works ringing in December, but a couple of weekends of cold weather recently gave us the chance to venture out to a couple of sites.

Gwennap is often our most productive site and a few hours last weekend saw us catch 101 birds, including 59 Chiffchaffs. Of these, just four were birds ringed in previous winters, predictably all at the site. The highlight though was a smart Grey Wagtail which was already carrying a ring, but not one of ours. It had actually been ringed as one of three chicks in a nest in Budock Water in April, 9km from Gwennap.

The Grey Wagtails in the nest (Sam Pitt Miller)

This last weekend we were then able to get into Brew sewage works, near Sennen, right down in the far west. It needs a calm day to net this exposed site, so we have to make the most of the chance. A short morning produced 61 birds, of which 45 were Chiffchaffs. Being so close to the autumn ringing site at Nanjizal, several of these were already ringed, which gives a nice insight into the arrival timing of wintering birds (more on that later). Most were from this same autumn, but four were ringed at Nanjizal in autumn 2022, so were returning birds.

Brew is also our best site for Siberian Chiffchaffs (tristis race) of which we caught two, both of which were quite subtle birds (as below), not the cold grey birds we sometimes see.

Barn Owl 2023 update

After one of the strangest springs weather-wise, the Barn Owl season seemed to be all over the place in 2023. We had regular sites unoccupied, non-breeding birds at some sites and some exceptionally late broods. Even now we have a few sites where we need to revisit to ring chicks!

With some new funding from the FiPL project (Farming in Protected Landscapes) managed by the Cornwall AONB, we are continuing to expand our monitoring, this year onto the Roseland peninsula, with some new ringer recruits this year as well from the National Trust.

Our totals for the year were still quite impressive (note we've knocked off a couple of the early years to make space):

	2015	2016	2017	2018	2019	2020	2021	2022	2023
Sites visited	41	47	64	85	87	106	93	112	127
Unoccupied	11	12	23	34	36	43	35	34	29
Occupied, no breeding	7	8	5	4	3	4	5	4	10
Average clutch size (where observed)	4.6	4.6	5.3	5.2	4.7	4.6	4.5	4.5	4.6
Average brood size (where observed)	3.5	2.8	3.0	3.3	3.0	3.2	2.8	3.1	3.2
Chicks ringed	70	47	90	132	119	177	133	189	193
Adults ringed/recaught	17/8	14/9	21/14	18/14	16/15	22/17	19/17	20/22	30/24

Unsurprisingly there was again some variety in the brood sizes across the area, with the highest average again along the north coast fared the best though (average brood size of 3.7), followed by the east of the county (3.5, compared to just 2.3 last year) and then 3.0-3.1 elsewhere.

There seemed to be more movement between sites this year, with one adult even on its third site in as many years! The movements between bixes (mostly birds ringed as chicks dispersing) are shown here.

Stormies on the move

Last month saw us able to mist net Storm Petrels down at Porthgwarra on two nights, catching a total of 119 birds. Of these, 113 were unringed, three were ringed by us in previous years and three were already wearing rings from elsewhere:

• ringed on Great Saltee Island (Co Wexford) three days earlier
• ringed on Little Saltee Island (Co Wexford) in July 2022
• ringed at Torre de Hercules in northern Spain in July 2015, although since then it had managed to lose a foot, a surprisingly regular phenomenon in Storm Petrels!

Two birds we ringed on the same night were also recaught 21 days later on Bardsey, also on the same night! Another was then recaught on Lundy Island 29 days later, alongside birds we'd ringed here in July 2016, June 2017 and August 2020, which may well now be recruited as breeding birds on the island.

Hopefully more Stormies to come next week, with a public ringing session likely to be on Monday or Tuesday, so see here for details.

Strange goings on at Mullion Island

We took the opportunity of a fine evening to do a quick Great Black-backed Gull nest count on Mullion Island yesterday. Quite bizarrely, almost the first breeding bird we saw on landing was this Canada Goose, which actually had a nest with six eggs.

Nest with a view!

This is the first time we've even seen Canada Goose on the island, so quite a aurprise. At the other end of the island, we also found a second pair, but with an apparently failed nest with just one egg found near the empty nest.

As for the gulls, we covered most of the island, bar two areas close to nesting Shags, with a final count of 64 nests (178 eggs/chicks). Most were clutches of three eggs, some of which were just hatching, with just two small chicks seen.

Surprisingly we only saw one colour-ringed bird (L:DD2), which was a chick ringed on the island in 2018. Since then, it's been on its travels, seen on Ares beach in northern Spain in January, September and December 2020 and then at the nearby Playa de Santa Cruz in January 2021, so nice to see it back breeding.

Coincidentally, on a non-birding kayak earlier in the day (but always with camera at hand) we also recorded L:DD1 near Rosemullion Head, which is the first time it's been seen since being ringed on the island in 2018.

Herring Gull and Kittiwake wanderings

We've not blogged anything for a while, but with a quiet winter devoid of Siberian Chiffchaffs there's not much to report! But this week we've had a couple of exciting colour ring sightings, so thought we'd share.

On 4th May we heard from the assistant warden at the newly-accredited Lundy Bird Observatory, with news of one of our blue-ringed Herring Gulls; W:377, which was ringed as a chick on a roof at Tregoniggie Industrial Estate, Falmouth in June 2020. It is a bit of an explorer though, having been seen locally until August 2021, before being report on the French coast in February 2022. The next winter (January 2023), it was reported from a French landfill site, before returning to the coast in March. It was last reported there on 6th April before swapping France for Lundy.

W377 at Stithians in August 2021

W377 at Marais de Suscinio in February 2022 (Catherine and Michel Marcaul)

Newly-moulted W377 back at Marais de Suscinio in March 2023 (Anne-Sophie Hochet)

W377 on Lundy in May 2023 (Luke Marriner)

Then on 15th May, we had a report of one of our Trewavas Head Kittiwakes, seen pair bonding and attending the beginnings of a nest maintenance on Skellig Michael, Co. Kerry, Ireland. KJ was ringed as an adult at Trewavas Head in 2017 and bred there (when the site was doing well) until 2020. As the main site started to fail, it then moved a short distance along the coast to Trequean Zawn in 2021, but then wasn't seen in 2022.

KJ on its travels (Brian Power)

We rarely see movements between our sites and Wales/Ireland as it's far more likely for us to share birds with the French colonies. In fact, this is our first Kittiwake to be found in Ireland and only the second Cornish-ringed bird to make the trip.

Barn Owl 2022 update

It's been a strange summer for lots of our regular projects, with freak weather, bird flu and remnants of Covid still making life difficult. Some of our birds have fared particularly badly, with Kittiwake reduced to just one successful sitre across Cornwall, a crying shame.

Our Barn Owl monitoring continued pretty much unaffected though and despite the drought, birds actually seemed to do OK. The project continued to grow and we personally visited over 100 boxes for the first time, which is no mean feat. Despite clutch sizes being nothing special, birds survived quite well and were about average.

	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	2022
Sites visited	34	32	44	41	47	64	85	87	106	93	112
Unoccupied	7	12	11	11	12	23	34	36	43	35	34
Occupied, no breeding	2	7	7	7	8	5	4	3	4	5	4
Average clutch size (where observed)	4.1	3.6	4.6	4.6	4.6	5.3	5.2	4.7	4.6	4.5	4.5
Average brood size (where observed)	3.1	2.4	3.5	3.5	2.8	3.0	3.3	3.0	3.2	2.8	3.1
Chicks ringed	46	20	63	70	47	90	132	119	177	133	189
Adults ringed/recaught	11/9	3/4	9/13	17/8	14/9	21/14	18/14	16/15	22/17	19/17	20/22

It did seem that pairs along the north coast fared the best though (average brood size of 3.7), followed by Lizard and Penwith (3.4), central Cornwall (3.0), whilst those in the east of the county suffered most in the dry weather (just 2.3).

We continued our run of bizarre movements as well, with a non-breeding male (with a regular female) in an established site in Penwith having been ringed as a chick in 2017 in Northumberland. This is our furthest movement to date (at 587km) and it'll be interesting to see if it stays to breed now.

We sadly also received three reports of ringed birds dead on the A30 during the year, all on the open dual carriageway between Carland Cross and Fraddon. Along with a bird that had to be put to sleep after becoming tangled in a barrbed wire fence, this was a poor year for our chicks.

Portreath Kittiwakes

With spring migrants back in earnest and everything singing and nest-buiilding, it was a good time to have another look at the Portreath Kittiwakes.

Probably only 75% of the birds were back on ledges, with plenty of space left to fill, so hopefully birds just aren't settled yet. Despite the sun, a bit of hazy sea fret made life a bit difficult ring-reading but we still managed to pick up three of our regular French-ringed birds.

OBM-WLN was ringed as a chick at Pointe du Raz in 2011
and has been seen regularly at Portreath ever since

RYM-ROO is a 2014 chick, first seen at Porthmissen (near Padstow)
in June 2018, then at Portreath in July 2018 and regularly since

The third bird avoided being photographed, but NRL-ROM was a 2015 chick and has been at Portreath since 2018. All useful information of course on how our birds roam around the Channel between breeding sites, so fingers crossed this will be the start of a productive season.

So the breeding season starts

With the run of fine weather this week, it's the perfect chance to have a first look at some of our breeding seabirds. First stop yesterday was Mullion Island, where a few photographs from the cliffs revealed that the Cormorants were well into the breeding season, with some nests even having half-grown chicks exercising their wings. A scan of the photos revealed at least 69 nests, which is on a par with last year's record 73 nests.

We then sat on the cliffs overlooking Rinsey zawn and waited patiently for sitting Shags to shuffle and show us what they're up to. In total there were 11 occupied nests, but of these just one had laid, with three eggs present. This compares to well to previous years, with first eggs noted (from 2013-19) on 8th March, 22nd April, 13th March, 1st April, 22nd March, 9th April and 25th March.

Storm Eunice delivers a lost swan

Storm Eunice brought a fair amount of destruction to the southwest, but there was one arrival that was a rather unexpected. When going out onto their farm near Lelant, one family were surprised to find an exhausted young swan in one of their fields. They picked it up and found that it was ringed, with both a metal ring and a yellow colour ring: CDBH.

CDBH recovering on a Cornish farm (Selena Richards)

With a bit of detective work, it was found to be a bird ringed as a cygnet in a park in Dublin in September 2021. It was quite happily seen in the park over the winter, last seen on 4th January, but then perhaps got caught up in the storm and ended up in a Cornish field on 24th February. The Dublin project has ringed 800 Mute Swans since 2015 but have never before had a sightings in England. The 353km this bird travelled (wind-asssited) is also a record for the project.

This is the first record of an Irish Mute Swan in Cornwall and in fact there have been very few ringing records of Irish Mute Swans making the Irish Sea crossing at all. There have previously been eight records in England (strangely mostly in and around the West Midlands), five in wales and two in Scotland.

Many thanks to Selena Richards and family for finding and reporting CDBH, Mark Whittaker for tracking it down and Graham Prole from the Irish Midland Ringing Group for the quick reply with the details.

Our ninth Herring Gull visits France

Perhaps it's the fact that the weather is so wet and windy in Cornwall at the moment that another of our juvenile gulls has made the trip across the Channel to France. On Friday, W:377 was seen on the southern coast of Brittany near Sarzeau, loafing on a raft (for terns) with other juvenile gulls.

W:377 at Marais de Suscinio

Ringed as a chick in Falmouth in 2020 it hasn't been far before, last seen at Stithians Reservoir in August last year. See below it's short history, very helpfully prduced by the app created for us by Stephen Vickers, which you can use to report gulls to us here.

This is the ninth of our colour-ringed birds to have been seen in France, so it'll be interesting to see if it returns in the spring. Many thanks to Catherine and Michel Marcaultfor reporting W:377 and also for the photos.

W:377 at Stithians Reservoir in August 2021

Sibe Chiff overload at the sewage works

The middle of January 2022 saw the first spell of cold, calm weather, perfect to start our winter ringing at our local sewage treatment works (STWs). These sites are a haven for insects in the cold weather and where there are insects there are always going to be birds. In winter, the resident wagtails, Wrens and Robins are joined by large numnbers of Chiffchaffs, including Siberian 'tristis' Chiffchaffs, possibly from as far east as the Urals. Once considered a rarity in the UK, it's now become more apparent how frequent they are, especially in the far southwest.

Over the week of cold weather we managed to ring at four of our regular sites, all of which produced plenty of birds. We've ringed at these sites for several years, so recatching birds from previous winters is always interesting and it's rare to see a bird ringed at one site moving to a different one in a subsequent winter. In fact one of the birds recaught at Constantine had been ringed there five years previously, in January 2017! We do also catch birds from elsewhere which again gives us an insight into where these winter birds come from.

The table below shows the total number of Chiffs caught at the sites over the week, including new birds and those already ringed:

	Chiffchaff	Siberian Chiffchaff
Gwennap STW	44	7
Brew STW	39	12
Ponsanooth STW	31	2
Constantine STW	21	-
TOTAL	135	21

 

It's fascinating to see how the proportion of 'tristis' birds varies across the sites, with almost a quarter of birds caught at Brew, down to none at Constantine. This may be due to the surrounding habitat to some degree, as Constantine is very much an inland wooded valley, whereas Brew sits right down near Lands End on a scrubby hill. What's also interesting at Brew STW is that it sits at the top of the Nanjizal valley, where large numbers of Chiffs are ringed on autumn migration. Some of these stay for the winter, so it's interesting to look at when these birds first arrived in the valley. The Nanjizal Chiffs recaught at Brew this week were ringed in February 2020, October 2020, November 2020, and from 2021, on 22nd September (a surprisingly early date), 10th October, 5th and 11th November. As for the 'tristis' Chiffs, they were all ringed much later in the autumn in November 2021, on 18th, 20th and 24th. Some Nanjizal-ringed birds do also move through and winter elsewhere, with birds ringed on 25th October and 11th November recaught at Ponsanooth (44km), and a bird ringed on 6th November recaught at Gwennap (43km).

 

As for birds from further afield, we saw just one of these, with a Chiff ringed on Hartlepool Headland on 19th October recaught at Gwennap, 565km as the Chiff flies.

We're back to mild, wet weather now so fingers crossed for some more cold settled weather and we can get back to the works and see what we missed this week!

Eight colour-ringed gull species from eight countries!

We recently received details from BTO of some colour-ringed gulls reported to us over the last cpouple of weeks and it's quite an amazing selection! In total we received details of eight different species from eight different countries:

• Common Gull from Norway on the Asda roof in Penryn
• Yellow-legged Gull from Switzerland on Hayle estuary
• Caspian Gull from Poland at Coverack
• Mediterranean Gull from Belgium at Swanpool, Falmouth
• Black-headed Gull from Denmark at Helston boating lake
  
• Herring Gull from Wales at Coverack
• Lesser Black-backed Gull from Portugal on Hayle estuary
  
• Great Black-backed Gull from Loee Island in Newlyn harbour

This again goes to show a) how important Cornwall is to wintering birds from right across Europe and b) how important colour-ringing is in showing this.

It also shows that these birds can turn up pretty much anywhere, all seen by local birders with a decent 'scope or camera. So if you're out birding over the winter do keep an eye out for anything out there sporting a shiny colour ring and get reporting.