MSBO UK Twite Study Project

MSBO UK Twite Study Project

Introduction…

Spring 2011

During late summer 2010, Machrihanish Seabird Observatory (MSBO) joined the UK Twite Study Project.

Historical data at MSBO reveals a light passage of Twite (carduelis flavirostris) in spring then, throughout summer, a small breeding population has always been obvious.

However, autumn (mid-August through to October) is prime time for the appearance of many passage birds from the north; presumably from numerous W coast islands and possibly also mainland Argyll.

Over many years, assemblies of up to 200 Twite have been logged in the area and in recent years migrant flocks have been attracted to the immediate vicinity of MSBO (just a few metres from observers) to gorge on nyjer seed.

On-going passage has always been assumed (see comment on retraps below).

This conclusion has often been reinforced by highly variable maximum daily counts at the station coupled by brief sightings of loads of colour-ringed birds (majority photographed) that originated mainly from ringing sites in NW England (Cumbria and Lancashire) in previous winters.

A Twite colour-ringed in County Donegal in winter 2007 was photographed at MSBO during autumn 2008.

Catching Twite at MSBO…

The trapping method involves a rather simple, near circular pull net (2m x 1.5m).

The back edge of the net is attached to a lead that is linked to a 1m high post. A pull line is connected to the opposite end. The net is furled neatly in a semi-circle and when the pull line is activated (from MSBO) it rises nippily, closing efficiently, almost 1m high over the birds (forming a tent shape) and is then lowered carefully.

No pegs are used; the net is 2m deep but rises only 1m allowing the net that remains furled on the ground to act as a very capable barricade. In addition, a small drystone dyke-type wall was built as a shelter to aid trapping operations.

The successful pull system was designed by the warden and constructed (very professionally and at low cost) by Derek Goode (MSBO occasional assistant and ex Campbeltown fisherman). The largest batch caught was around 30 birds.

Ringing totals at MSBO…

Trapping Twite began in earnest on 12th August 2010 and by the end of the month a total of almost 200 birds sported our unique colour rings (sequence described below). Throughout September the total rose (rather slowly) to 300 colour-ringed.

During October, very obvious passage/influxes of unringed birds occurred almost daily; a further 194 were captured during this rousing period bringing the total colour-ringed this autumn (August – October) to 494 (our anticipated ringing total was 500+).

MSBO colour ring sequence…

All Twite captured were fitted with a green over white split ring on each leg along with a statutory BTO metal ring which is positioned on the left leg above colour ring (project identifier).

Winter destinations…

The project has verified that MSBO is unquestionably an outstanding passage site for this species.

So, what has been discovered so far?

As at March 2011, we have received confirmation of birds in Ayrshire (2), Dumfries and Galloway (3), Cumbria (1), Lancashire (1), Isle of Man (2) and Co Antrim, N Ireland (2).

A total of 5 Twite were also controlled at MSBO during autumn 2010; these included birds from Sanda Island (1), Cumbria (1), Lancashire (2) and Suffolk (1); see Recoveries, Controls and Sightings below.

The controls reveal significant information on probable wintering areas and notably, our first indication of natal origin; see Recoveries, Controls and Sightings below.

Retraps at MSBO…

Many birds acquired retrap histories; for example, a few retrapped in October had been ringed in August.

This implied that the regular supply of nyjer seed was undoubtedly encouraging some birds to adopt MSBO feeding station as a lengthy staging post (many adults were in wing moult August/early September).

However, by the end of October, the majority had moved on and by early November only a ‘handful’ of birds (<10: majority MSBO colour-ringed) were exploiting the feeding station.

Five of our colour-ringed birds remained at the feeding station throughout November-December but, throughout January, none were present (J. McGlynn pers. comm.).

Recoveries…

V879672 ringed on 28th August and retrapped at MSBO on 21st September was controlled at Heysham Harbour North Wall (Lancashire) on 24th/25th October 2010 (‘most unusual for a controlled bird to be caught on consecutive days’; Pete Marsh pers. com).
V879943 ringed on 11th October was controlled at Point of Ayre, Isle of Man on 10th January 2011 (Sean Gray) (145 Km SE).
V879195 ringed on 23rd October was controlled at Point of Ayre, Isle of Man on 17th January 2011 (Sean Grey).

Controls…

X459621 (female) ringed at Corporation Marsh, Dunwich, Suffolk on 3rd January 2009 was controlled at MSBO on 27th June 2010 (597 Km NW – apparently the longest movement of a UK ringed Twite).
X351628 (juvenile) ringed at Sanda Island BO off S Kintyre on 5th July 2010 was controlled at MSBO on 27th August 2010 (21 Km NNW).
R687990 (male) ringed at Askam in Furness, Cumbria on 27th November 2009 was controlled at MSBO on 25th October 2010 (213 Km NW).

Sightings of MSBO colour-rings 2010 / early 2011…

One was photographed at Ramsey, Isle of Man on 16th October (Sean Gray).
One was seen very well at Walney Island BO (Cumbria) on 29th-30th October and 5th November with further sightings of 2 birds on 17th November and singles on 19th, 26th and 29th December 2010 (‘a most unusual colour combination’; Colin Raven – warden).
One definite was photographed at The Wig, Loch Ryan, Dumfries and Galloway on 19th November 2010 (‘however, at least threewith green/white rings were present in a large flock’;Gavin Chambers).
One was at Carsethorn Bay (Nith estuary) Dumfries and Galloway (inner Solway) on 7th December and two were seen well there on 22nd December 2010 (‘both birds in the ‘scope at the same time’; Richard and BarbaraMearns).
One was photographed at Doonfoot, Ayrshire on 7th December 2010 (Chas Moonie).
One was at Crook of Baldoon, Dumfries and Galloway on 11th January 2011 (Paul Tarling – warden).
One (c/r sequence confirmed three times) appears to be wintering on Bird Island (Kircubbin), Strangford Loch, Co Down, N Ireland; ‘colour rings seen very well’; dates included10th and 28th February and 14th March 2011 (HughThurgate/ warden).
One was photographed at Black Neuk, Girvan, Ayrshire on 19th April 2011 (Angus Hogg).
One was photographed on Rathlin Island, Co Antrim, N. Ireland on 22nd April 2011 (Neal Warnock).

Notes; the majority of sightings reveal a SSE movement; however, the Doonfoot bird moved directly east and the controlled Sanda ringed juvenile undertook a most unexpected / extremely rapid post natal dispersal to the NW.

The birds observed well at Strangford Loch (photographed) and on Rathlin Island (photographed) reveal that we still have much to discover about the potential winter and possible breeding distribution of Twite in Northern Ireland.

X459621 a control from Suffokwas very likely breeding by MSBO. Remarkably, this female now has the distinction of undertaking one of the longest UK movements of this species.

Twite sporting MSBO unique colour-ring sequence (October 2010)

Note metal above colour ring on left leg = project identifier

Askam in Furness (Cumbria) colour-ringed Twite at MSBO (October 2010)