Conservation Science in the RSPB 2006

16
Repeat Woodland Birds Survey
Several woodland species have
shown substantial declines over
the last 25 years and three
species (lesser spotted
woodpecker, marsh tit and
willow tit) have been added to
the red list of birds of
conservation concern. However, it
was unclear whether national
monitoring schemes were
providing representative data for
all woodland species. Therefore,
to establish population trends of
the key species within this
habitat, in 2003–2004 in
partnership with the British Trust
for Ornithology (BTO), we resurveyed
more than 400 woods
distributed throughout Britain
that had been originally surveyed
in the mid 1980s and before. The
methods were an exact match of
those used in the original
surveys, with the RSPB using
point counts and the BTO
territory mapping. In order to test
the potential causes of these
declines, we also gathered data
on woodland habitat and other
environmental measures, such as
climate change, the summer
activity of deer and the
abundance of grey squirrel dreys.
scarcer and more localised resident
species, such as the hawfinch,
lesser spotted woodpecker, lesser
redpoll and willow tit, had also
suffered substantial declines. These
findings are broadly in line with
those of national monitoring
schemes but have provided a much
clearer picture of the scale and
geographical pattern of changes.
Hawfinches
Analyses showed that many of the
declines appeared to be related to
changes in woodland structure.
Although factors driving these
structural changes themselves are
not clear, potential causes include
increase in woodland age, reduction
in active management and increased
grazing and browsing by deer. For
only two species, hawfinch and
David Kjaer (rspb-images.com)
Population changes revealed a
mixed picture, with 11 of the 34
species showing large increases
(>25%), eight large decreases
(>25%), and a further two worrying
indications of overall decline. The
survey confirmed declines in all the
long-distance migrants, such as
willow warbler and spotted
flycatcher, and found that several