This short note describes the derivation of maps of abundance and change in abundance for the two species, from the late 1990s to the present day. This short BTO Research Note illustrates recent changes in distribution and abundance and discusses interpretation of the data presented.
The BTO/JNCC/RSPB Breeding Bird Survey (BBS) is the main scheme for monitoring the population changes of the UK’s common breeding birds. It is a national volunteer project aimed at keeping track of changes in the breeding populations of widespread bird species in the UK. Wild bird populations are an important indicator of the health of the countryside, and knowing to what extent bird populations are increasing or decreasing is fundamental to bird conservation.
Mammal recording was introduced to the BBS in 1995 with a view to help improve our knowledge of the distribution and population trends of some of our commoner mammals. Compared with birds, the population trends of mammals are relatively poorly known. Even though mammal recording has always been a voluntary addition to the scheme, 90% of BBS observers now actively look for them during their BBS visits.