Worcestershire Record No. 5 Nov 1998 p. 20

WINTERING BLACKCAPS SURVEY - HELP WANTED

Reprinted from Worcestershire Wildlife News No. 82 September 1998. See also Worcestershire Record May 1998 page 14.

Dave Ratcliffe

For those lucky enough to have had wintering Blackcaps Sylvia atricapilla in their gardens, they will not be a new phenomena, but just how many are there in Worcestershire during the winter months? This is a question I am going to try and answer by asking interested observers to report their sightings of Blackcaps during the forthcoming winter.

Wintering Blackcaps were last surveyed in Worcestershire during 1978/9 as part of the BTO national survey conducted by Iain H. Leach and reported in Bird Study 28:5-14 March 1981. The total reported for Worcestershire was 39. I am interested to discover what has happened in the twenty years since that survey and will use his methodology, albeit on a county rather than national scale. In addition to a simple count I will be asking for details of place, dates, number, sex, feeding habits and any observations on aggression towards other Blackcaps or other species.

According to the Atlas of Wintering Birds in Britain & Ireland wintering Blackcaps arrive in the east in late autumn after the breeding population has left. It is thought that these winter visitors travel from northern and eastern Europe. It seems that in the early winter they manage to survive on the remaining natural food in the countryside, moving to gardens and suburban settings in late December, supplementing their diet with bird table foods and garden berries.

Blackcaps are omnivorous, taking fat, bread, cheese, and I have even seen a male trying suspended birdcake and peanut feeders! Re-trapping has shown that they are able to maintain or even increase their weight during these cold spells which demonstrates just how effective their strategy is. Aggression towards other species as well as other Blackcaps has been recorded, and they seem well able to defend a food source.

A well recorded tendency to winter in built up areas has been noted. Clearly visits to gardens are more likely to he recorded than rural sites, but as Leach noted "nearly all the winter records of Chiffchaff in south -west England are from rural habitats and few are seen in gardens (R.L.Bland and R.D.Penhallurick in litt.) indicates warblers are recorded in rural habitats when present, and hence the bias is less than might be expected". It is probably worth considering whether this bias has been further diminished by the 'bird pagers' and 'birdlines' now available. Against this however Andrew Cannon of the British Trust for Ornithology, informs me that there are 72 Worcestershire participants of the BTO Garden Birdwatch survey, which could certainly influence a small scale county survey.

Clearly this winter's survey can only be "snapshot"' of our Blackcap population , but one I hope you can get involved. I would like to receive any records made between October 1998 and March 1999.