THE British Trust for Ornithology (BTO) is seeking volunteers for its annual house-martin survey. Despite building their nests close to humans, much of the behaviour of these summer visitors from Africa— which the Rev Gilbert White once believed hibernated in the UK over winter, under rocks—remains a mystery. So do the reasons for a longterm 69% population decline, leading to the house martin’s amber listing on the UK list for Birds of Conservation Concern. The BTO hopes its survey of nests will provide information on breeding and habitat preferences, and more accurate population estimates (www.bto.org/housemartins).
New volunteers are also sought for the annual Breeding Bird Survey (BBS) (www.bto.org/bbs), the findings of which make a major contribution to monitoring species population trends. For example, it’s the BBS that has shown that, although tree sparrows, whose numbers plunged in the immediate post Second World War decades, have increased by 12% in recent years, the current population remains at about one for every 30 found in the 1970s.
Participants are being asked to carry out first nest surveys from early April to mid May, with a second survey from mid May to the end of June.
The BTO is hoping that data from volunteers can help explain the reasons behind the 69% decline in the housemartin population