You only have to compare this summer with last to realise how much things can change from one year to the next, both in terms of the weather and its effects on birds and other wildlife. Short term differences in bird populations and their breeding success are of interest to those studying such things but it is the longer term changes that are of wider interest. In the case of birds, information on how well the populations of many of our breeding species are doing comes from the BTO/JNCC/RSPB Breeding Bird Survey (BBS), the latest report from which has just been published.
As a volunteer myself, I appreciate the tremendous value of the survey and the importance of the information collected by the 2,592 volunteers who participate in BBS. Participation is simple enough, involving two visits to a survey square and the recording of what birds are seen and heard, and in what numbers. The survey, which began in 1995 as a replacement for the Common Birds Census operated by BTO, provides a measure of population change for a wide suite of species, highlighting those that have shown significant increases or decreases in their populations over time.
The latest report highlights the continued decline of turtle dove (down by 85% since 1995), cuckoo (down 50%), spotted flycatcher (down 49%) and starling (down 53%), among many others. Some species are, in contrast, increasing. These include: goldfinch (up 109%), blackcap (up 133%), nuthatch (up 88%) and great spotted woodpecker (up 139%). Not all of the increases are welcome, however, with Canada goose, greylag goose, ring-necked parakeet and red-legged partridge all showing sizeable increases in their populations.
One of the great strengths of the survey is that the information can be viewed at the regional level, something that has revealed some fascinating differences in how species have been doing. Cuckoo is one of several species in which populations in England are in decline but those in Scotland are stable or even increasing. There are a number of possible reasons why this might be happening, one of which is related to a changing climate, but more work is needed to be certain of what is going. Fortunately, the efforts of us volunteers provide the information needed to support this work.