Migration movements of four common passerines

With the publication of the British Trust for Ornithology's Migration Atlas that illustrates and analyses all ringing recoveries relevant to Britain and Ireland it seems appropriate to highlight four Cumbrian related recoveries that have come to light this year.

The four selected are relatively common and may not be considered to be migrants to some people. Robin; Blackbird and Stonechat can be seen all the year round, as can Blackcap, however ringing recoveries have shown that there is a transient part of each species.

Robin

Ringed 28th October 2001, Eskmeals, Cumbria; juvenile. Recovered 13th June 2002, Hill of Fortrose, Highland, Scotland; caught by ringer.

Many Scottish-born Robins (especially juveniles) move south to avoid the northern winter; this recovery is an example in case. At Eskmeals during September and October there is obvious Robin migration: up to 30 juveniles have been caught on several days. It is quite usual to visit a mist-net holding several Robins, including the resident territorial bird, caught no doubt giving chase to the incomers. There have been no recoveries of summer Robins outside Eskmeals. However there are a number of more southerly winter recoveries in England and Wales from the autumn movements. This recovery highlighted here is the first to pinpoint the geographical origin of these autumn Robins.

The most recent edition of Ringing and Migration (BTO Journal for ringers); gives a Humberside October-ringed Robin recovered in Sweden in mid-May.

Blackcap

Ringed 17th November 2001, Eskmeals, Cumbria; juvenile male. Recovered 19th April 2002, Oberbayern, near Austrian/German border; killed by cat.

Until as recently as fifty years ago our winters were very largely void of Blackcaps, the summer population having emigrated by the end of September. Towards the middle of the last century winter sightings of Blackcaps started to increase, with many visiting garden feeding-stations.

At first it was thought that some may have been over-wintering breeding birds, perhaps due to the warming of British winters. However, ringing proved that in fact the British wintering population was from birds of eastern European origin. This population was undergoing a change in its winter migration strategy: from being a migrant to North Africa to one that travelled a shorter distance to the increasingly temperate British Isles: evolution in action! Time - and more ringing-returns - will see the full development or otherwise of this remarkable 'in our lifetime' event.

There are presently no recoveries of summer (April-August) ringed Blackcaps at Eskmeals during the winter period.

The recent edition of Ringing and Migration gives recoveries of Slovenian-ringed birds in Lancashire in January and Gwent in March.

Blackbird

Ringed 6th January 2002, Eskmeals, Cumbria; 2nd-year male. Recovered 31st January, St Ola, Orkney; killed by cat.

At Eskmeals there is a large-scale autumn influx of thrushes, the acres of sea buckthorn and its berried fruit offering a reliable annual source of food until the end of the winter, and a safe place to roost during the long dark winter nights.

From October onwards Blackbirds of continental origin (recognisable in the hand by their longer wing-length) start to appear. There have been several recoveries of German- and Dutch-ringed birds at Eskmeals, and recoveries from Norway and Sweden in the summer from autumn-ringed Eskmeals birds.

This recovery is a puzzle: to move so far in the midst of winter is unexplained, unless it was a Scandinavian bird making an early return to its breeding grounds.

The recent edition of Ringing and Migration gives recoveries of German- and Dutch-ringed birds on the east coast of England in November and December. Note, however,

that these birds were ringed at bird observatories; it is likely they originated from further east or north in Europe.

Stonechat

Ringed 20th May 2001, Parton, near Whitehaven, Cumbria; nestling. Recovered 7th May 2002, Huesca, Spain; killed by car.

Stonechats remain an enigma. The continental (German and Dutch) populations are totally migratory, wintering in countries both north and south of the western Mediterranean inlet. The British and Irish population is largely sedentary with a small, unknown, percentage taking the option of avoiding the British winter and moving to the same general area as the continental birds.

There has been one previous foreign Cumbrian-ringed recovery, a Mosedale (NY33) nestling being recovered near the Loire in early January 1996. There have however been several recoveries of Cumbrian-ringed birds at coastal areas of Kent and Dorset in October, the peak exit time for migrants. Presently there have been approximately forty foreign recoveries of British-ringed Stonechats.

Remarkably, Ringing and Migration gives a recovery of an individual ringed at Huesca in late November recovered breeding in Gwent in June.

The very late date of the Parton bird in Spain is without precedent: migrant Stonechats would be expected to be back on their breeding grounds towards the end of March.

Although cats, and to lesser extent cars, bring in information which would otherwise be lost, the total impact of losses from these two factors on populations of small passerines must be significant.

John Callion

(See also John's account on Stonechat in the Migration Atlas, just published.)