27 April 2015

RAS double century

The Retrapping Adults for Survival (RAS) scheme was established in 1998 and uses bird ringing to monitor survival rates of a range of bird species. Coverage is particularly aimed at species which, due to their behaviour or the habitats they occupy, are not often caught by standard mist netting activities in woodland, wetland or scrub, such as Swallows, Dippers, Pied Flycatchers and many seabirds and raptors.

With the RAS season already underway for many species, registrations for new projects have been arriving thick and fast here at BTO HQ. At the time of writing, a fantastic 19 new projects, covering 16 species, have registered to start in 2015. A milestone was reached a few days ago with the registration of a new Tree Sparrow project in Cleveland which became the 200th active RAS project.

Tree Sparrows are a species of high conservation concern due to a spectacular crash in numbers of breeding birds between the late 1970s and early 1990s. Whilst BBS data suggest a significant increase in numbers since 1994, maps from the latest Bird Atlas show breeding Tree Sparrows as being absent from much of the south and west of the country and also declining in abundance south of the Midlands.

Maps reproduced from Bird Atlas 2007–11, which is a joint project between, BTO, BirdWatch Ireland and the Scottish Ornithologists’ Club. Map reproduced with permission from the British Trust for Ornithology.

Tree Sparrow is one of the RAS target species identified in the demographic targeting strategy. Currently, only one project, a study in Durham, has been running for long enough to contribute to the RAS survival trend, and the results suggest that, on average, about half of all adult Tree Sparrows breeding in 2015 will still be alive in 2016. But is this the case at other sites across Britain & Ireland? With two new RAS projects starting in 2015, the total number of active studies will increase to six, giving a much better idea of the national picture.

One project currently contributes to the national survival rate trend for Tree Sparrow (solid line), which shows that around half of the birds alive in one year currently survive to the next; the quality of the trend is considered to be 'uncertain' as the errors (dotted lines around the solid line) are relatively large – addition of more projects will help to reduce the size of these errors. 

There have been recent increases in the number of projects for Mute Swan (now three active projects), Starling (now 10 active and five historical projects), Swift (now three active and two historical projects) and House Sparrow (now 21 active and 12 historical projects) which is fantastic. It would also be beneficial to have a few more projects on species such as Tawny Owl, Barn Owl and House Martin to allow us to produce more accurate trends for these species.

It is rare for all active projects to run in a given year and there are always a few projects that have to end for one reason or another. That said, with more projects still registering for 2015, it would represent an incredible effort if the number that submit data this year hits the 200 mark for the first time.

A massive thank you to all current, past and soon-to-be RAS ringers for their tremendous efforts. Keep an eye on the website for the 2014 results which will be published soon.

24 April 2015

Chiff-ful start to the nesting season

Over in Cambridgeshire there’s been wonderful sunshine, but accompanied by overnight frosts. Thankfully this hasn’t put off the resident birds at the National Trust’s Wicken Fen National Nature Reserve, where members of the ringing and nest recording group are getting ready to ring the first broods of Blackbirds. Also, our first Coot brood has just hatched, Long-tailed Tit clutches are about to hatch, Blue Tits and Great Tits are laying, and we’ve started monitoring our first finch nests: an almost fully-built Chaffinch nest was found a week ago and a pair of Goldfinches were spotted building last Thursday.

Water birds such as Coot (pictured) and Moorhen commonly hatch their first broods in mid-April

As for summer migrants, arrivals have been stalled by strong north-westerly winds, according to the BTO migration blog, and indeed Blackcaps at Wicken have been singing on territory for only a week and Willow Warblers still seem thin on the ground. One short-distance migrant, though, has been getting off to a flying start this season and keeping our nest finders very busy: Chiffchaff!

During Easter weekend we saw plenty of male Chiffchaffs singing from tree tops but no birds skulking lower down (a tell-tale sign of a female getting ready to build). Last Monday, things had got busier: males were singing back-to-back and chasing each other off territories and ‘hueet’ contact calls could be heard everywhere. Then, on Tuesday 14, we caught our first glimpse of a bird with a beakful of long grass—a building female! Early next morning we spotted another bird building and then on Thursday 16, Anne, our main nest finder, found five more nests, some almost fully formed (a characteristic domed construction). By Monday 20, we had found 11 nests, two lined with feathers, and that morning we found nest number 12 at an early stage, the female pinging back-and-forth with large bits of material.

Chiffchaff nest at Wicken Fen in 2014. Built just above the ground, the nest is dome shaped, made from reeds and some finer grasses, and lined with feathers. c.200 Chiffchaff nests are monitored across the country for NRS each year.

So what to expect this weekend? Those lined nests will probably have eggs, though females may still be building on other territories. Nest recorders elsewhere have begun reporting Blackcaps on eggs, Whitethroats and Willow Warblers building, and Chaffinches on full clutches.

How far along are nesting birds on your patch? Help the BTO collect vital data on nest productivity and timing of breeding by taking part in the Nest Record Scheme.

21 April 2015

Elusive Hawfinch 'shows a bit of leg'

Chris McGuigan writes:

I recently received an email from Barry Farquharson, a local birdwatcher who has become rather good at reading - and photographing - colour-ringed birds (usually gulls).

This one was different though, it read: "Going through some fairly poor photos from Scone Palace, Perth, I've managed to find a ringed Hawfinch in one, although unfortunately only one leg is visible. I assume it will be a local bird, but just in case.... Looks like red over orange on the right leg."

In actual fact, in the photograph (see below) you could just see the other leg too which looked like 'black over metal'.

Colour ringed Hawfinch. Photo by Barry Farquharson

Armed with this information and suspecting it had been ringed locally (but some time ago) I contacted Neil Morrison as well as the BTO 'Hawfinch colour-ring data coordinators'. Neil confirmed that he hadn't ringed any in recent years but that his records were all in storage. Eventually he was able to confirm that this female bird had been ringed at Scone Palace on 17th February 2007, as a probable first-year bird. Thus 2 days short of 8 years had elapsed from capture to re-sighting, becoming one of the oldest Hawfinch recorded in the BTO Ringing Scheme.

Well done to Barry who I'm sure will be pointing his camera at birds' legs even more in future!

Ed. note - the Online Ringing Report (ORR) shows that only 58 Hawfinches were ringed in 2007 so this is a great record. The ORR, including the longevity records, will be updated in July to include 2014's data. It remains to be seen whether this bird will become the longevity record holder at that point!

15 April 2015

First BTO-ringed Mediterranean Gull recorded in Morocco

Sean Kingston, the British & Irish Mediterranean Gull colour ring coordinator, recently contacted us with the following story:

The breeding population of Mediterranean Gulls in the UK has gone from strength to strength in recent years with the number of breeding pairs breaching the 1,000 mark for the first time in 2010 (Holling et al 2012). 2014 was the first year that Mediterranean Gulls were recorded successfully breeding in Cambridgeshire. A pair fledged two chicks which were colour ringed by Tony Martin on 8th June 2014 as 2XL0 and 2XL1.

2XL1, the sibling of 2XL0, ringed in Cambridgeshire in 2014. Photo by Tony Martin

On Monday 30th March 2015, 2XL0 was re-sighted by Brian Small of Limosa Holidays among a flock of 15 Med Gulls at Oued Souss, about 40 minutes south of Agadir in Morocco. This is the first sighting of a BTO-ringed Mediterranean Gull in Morocco. 2XL0 had flown 1,600 miles, or 2,600 kilometres, from its birth site in Cambridgeshire to its wintering grounds in Morocco.

Photographic proof of 2XL0 in Morocco. Photo by Brian Small

Over two thirds of the Western European population of Mediterranean Gulls head south each autumn and winter primarily along the Atlantic Coast of Portugal between Lisbon and the Algarve. So while it is not unusual for Mediterranean Gulls to leave the UK in winter, it is unusual for a bird to fly as far south as Morocco, as this is close to the southern end of the wintering range for Western European Mediterranean Gulls. Renaud Flamant, international Mediterranean Gull colour ring programme coordinator, does receive occasional reports from traveling birders of European-ringed Mediterranean Gulls as far south as the Gambia and Mauritania.

Fledged Mediterranean Gulls have an annual survival rate of over 80% per annum so it is possible that 2XL0 may be around for at least the next ten years (the longevity record is held by a bird that was ringed as an adult in 1991 and caught again 15 years, 3 months and 7 days later - ed.). Hopefully 2XL0 will have sense and continue to winter in beautiful warm Morocco however this is by no means certain as many juvenile Mediterranean Gulls change their wintering location from year to year and really only become site faithful upon reaching adulthood at three years of age.

Many thanks to Tony Martin, Brian Small and Renaud Flamant.

Further reading
Holling, M., & the Rare Breeding Birds Panel. 2012. Rare breeding birds in the United Kingdom in 2010. British Birds 105: 351–430.

10 April 2015

Blackcap making touch down

This is an exciting time of year with our resident birds starting to nest and 'our' summer migrants winging their way back to Britain and Ireland. On the BTO reserve in Thetford in Norfolk, there are at least four singing male Blackcaps that have returned and more are surely on the way.

Male Blackcap - Mike Dawson

We recently received an email regarding a first year male Blackcap that had been ringed by West Wilts Ringing Group on 28 Sept 2010 (6am) near South Marston, Swindon (see blue point on map below). The finder mentioned it hit an airport window at Pamplona, Navarra, Spain (red point, 980km from ringing site), presumably on it's migration towards the UK. Interestingly this seemed to be the only British/Irish ringed bird found under that window, out of the whole 400 strong flock that was found dead!

We reported last year on the large exodus of Blackcap being caught in the autumn (click here), so it is good to hear that large numbers are now coming back towards the UK, however grim the outcome for these individual birds was.