Conservation Science in the RSPB 2006

18
The 2004 nightjar survey
Restoration of lowland heathland from mature conifer plantations at
Farnham Heath and elsewhere is likely to continue to benefit nightjars.
Mike Coates (RSPB)
The nightjar is an evocative bird of
heathland and forests, but its
crepuscular behaviour makes it
difficult to survey. Since the 1950s,
large-scale losses of heathland to
agriculture, built development and
afforestation have led to overall
contractions in range and numbers.
Nightjars are surveyed by counting
males making churring calls at dusk.
The first national survey in 1981 gave
an estimate of 2,100 churring males in
Britain in 241 10-km squares and the
second, in 1992, an estimated 3,400 in
268 10-km squares. Although this is an
encouraging sign of recovery, the atlas
of breeding birds in 1970 had recorded
nightjars in 562 10-km squares.
The 2004 survey aimed to estimate
the size of the current population and
assess whether there had been any
further changes in size and range.
Observers covered more than 3,250
1-km sample squares and counted
4,131 churring males. Allowing for
potentially suitable habitat in
unsurveyed squares, the total
population was estimated at 4,606
(95% confidence limits ± 913) – a
36% increase since 1992.
Nightjars were recorded in 275 10-km
squares, 2.6% up on 1992. There
was, however, evidence of localised
declines and range contractions in
north Wales, northern England and
Scotland. For instance, numbers in
Northumberland declined by 78%
between 1992 and 2004, and the
number of occupied 10-km squares in
Scotland dropped from 18 to seven.
Habitat recorded within a 50-metre
radius of each churring male showed
that, in 2004, 57% of nightjars
were associated with forest
plantations (similar to 1992) and
59% with heathland (slightly higher
than in 1992).
The UK Biodiversity Action Plan
objectives for population increase
(4,000 churring males by 2003) and
maintaining range (at least 268
occupied 10-km squares) have
been reached, but the target for a
5% range increase has not. Overall,
the continued increase in the
national population is probably
attributable to habitat protection,
management and restoration of
heathlands, and the continued
availability of clearfell and young
forest plantations.
Contact:
simon.wotton@rspb.org.uk