Overview

Title

Wintering Blackcaps 1945/46 – 1953/54

Description and Summary of Results 

It was becoming increasingly obvious that a few individuals of some species, normally considered as summer visitors, were remaining through the winter. The most common of these was the Blackcap Sylvia atricapilla with the Chiffchaff Phylloscopus collybita and Stone Curlew Burhinus oedicnemus being another two reported quite commonly, especially in southern England. Most records of other species were considered accidental or even if regular until December were thought unlikely to be able survive through the winter. It was already known that the main wintering range of the Blackcap was not very far to the south of Britain. A total of 302 records were received of Blackcaps from 1 November to 31 March in 1945/46-1953/54, but only 256 could be accepted without question. The main concentration was in the southwestern counties of England and around Dublin in Ireland, with lesser concentrations in other parts of southern England and in Yorkshire. There were 6 records in Scotland. There was a slight but definite increase in numbers from December to March, and this coincided with a northward movement taking place through the winter period. On average there were about 25 records each winter, with no apparent correlation with weather conditions. Blackcaps were observed to feed on household scraps (often on bird tables) as well as apples, other fruits and insects when they could find them. They also were observed being quite aggressive to other species. Of 79 records where the sex was definitely stated there were 51 males and 28 females. All 6 Scottish birds were female, in northern England females tended to predominate but males were more predominant further south and, along the south coast, records of males were commoner than females. Six records were of pairs, all in February in the south and southwest of England, with a seventh pair in Ireland. (At the time it was assumed that the wintering Blackcaps were simply birds which had not migrated south. Now it is known that most or all wintering birds are actually from a population breeding in and around SW Germany and that British breeding birds move south for the winter.)

Methods of Data Capture 

The survey was based on casual records of wintering birds sent in as a result of publicity. There was no questionnaire or or other form used and so the amount of data gathered for each record varied.

Purpose of Data Capture 

To determine the numbers and distribution of Blackcaps wintering in Britain and Ireland.

Geographic Coverage 

All of Britain and Ireland.

Temporal Coverage 

All records within the period 1 November to 31 March from the winters 1945/46 to 1953/54 were asked for.

Other Interested parties 

The survey was organised and run by John Stafford for the BTO as a Trust-aided enquiry.