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Candidates for conservation listing
The new analyses presented
in this report suggest that several species should be considered as potential
candidates for addition to the revised conservation lists currently being developed
by the conservation agencies and conservation Non-Governmental Organisations (NGOs).
Yellowhammer and Lesser Spotted Woodpecker have both exhibited rapid population
declines of greater than 50% over the last 25 years, and Mistle Thrush, Cuckoo,
Willow Warbler and House Sparrow have all exhibited population declines of greater
than 25% over this period.
While the above species
are obvious candidates for addition to the conservation lists, the status of other
species is less clear. The Waterways Birds Survey (WBS) has identified rapid (>50%)
declines for Little Grebe, Grey Wagtail and Yellow Wagtail populations, but as
only 24 years of data are presently available from this scheme, the current acceptance
criteria, which specify a 25 year trend, exclude them from the conservation lists.
Other BTO monitoring schemes have identified population decreases of greater than
50% for Lesser Redpoll, Goldcrest and Tree Pipit, and of between 25% and 49% for
Meadow Pipit and Lapwing. However, as the populations of these species may only
be partially sampled by the respective schemes, the reported trends may not be
representative of the conservation status of these species at a national level.
for changed conservation listing
Three species - Starlings,
Willow Tits and Marsh Tits - previously listed as exhibiting moderate declines
(>25%) now appear to be declining rapidly, decreasing in number by greater
than 50% over the last 25 years. Conversely, the population trajectories of two
species - Swallow and Goldfinch - have changed sufficiently to justify their removal
from the conservation listings. Both species exhibit relatively large-scale medium-term
population fluctuations that resulted in their previous listings, but populations
have since recovered to the extent that no long-term trend is detectable over
the last 25 years.
A source of considerable
concern is that several species that appear on conservation lists have actually
accelerated their decline since the lists were drawn up in 1996 (JNCC
1996, Gibbons et al.
1996), despite the presence of costed government Biodiversity Action Plans
for some of them. Thus the Red-listed Grey Partridge, Bullfinch
and Corn Bunting all show population declines of greater than 25% on CBC
or BBS plots over the last 5 and 6 years respectively. Starling and Willow
Tit also show declines of greater than 25% over the past 5 or 6 years respectively
on CBC or BBS plots.
In addition, two species
that have been in decline for several years, but were not considered sufficiently
well-monitored throughout the UK to be listed previously, have exhibited declines
of >25% over the last 5 years on CBC plots (Redpoll) and WBS plots (Yellow
role of breeding performance
In general, breeding performance
appears to show a density dependent response to population changes. As populations
decline, breeding performance tends to improve, but as populations increase, breeding
performance tends to decline.
However, there are a number
of species for which declines in breeding performance are likely to be driving
the population declines (Linnet and Lapwing) or helping to inhibit
recovery (possibly Reed Bunting and Whitethroat). The importance
of decreases in breeding performance for declining Redpoll and Yellow
Wagtail populations and for farmland Moorhen populations is, as
Increasing breeding performance
may be helping to drive population expansion of a number of species: the predatory
Grey Heron, Sparrowhawk and Buzzard; the corvids Jackdaw,
Magpie, Crow and Rook; the seed-eaters Collared Dove,
Stock Dove and Woodlark; and the insectivores Robin, Redstart,
Nuthatch, Great Tit, Blue Tit and Long-tailed Tit.
For a few species, long-term
population data are not available and changes in breeding performance from the
Nest Record Scheme may provide a potential warning of population declines, either
because they have the potential to drive population declines (Red-throated
Diver and Ringed Plover) or because they are the result of density
dependent changes (Stonechat, Whinchat, Wheatear, Tawny Owl
and Ring Ouzel). The importance of the substantial declines in productivity
of Greenfinch, Blue Tit, Sedge Warbler and Garden Warbler
is unclear at the moment, but warrants close attention.
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