POPULATION CHANGES IN FARMLAND BIRDS – Kemerton Estate
– 1998-2002 (John Clarke 2002) |
Background Since the 1950’s there has been a steady decline in the
populations of most birds using farmland. In some instances a British population is under severe threat
whilst many more are giving cause for serious concern. Red Data Lists and Biodiversity Action Plans include
many farmland species.
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Male Whitethroat |
Kestrel - Large Young |
At Kemerton, early conservation work appeared to be unable to prevent local populations
following national trends. However, since the mid-1990’s various changes in agricultural practices at
Kemerton have apparently coincided with a reversal in fortune of several species of bird. Personal
observations and comparisons with work carried out in the early 1980’s gave cause for optimism and in 1998
population-monitoring trials were started.
Initially the trials focused primarily on two typical local
species – the Skylark and the Yellowhammer – using a strict methodology to obtain an annual ‘snapshot’ population
assessment. Restrictions of time and resources limited the main effort to these two species. However, it was
possible to monitor additional species in a less formal, but nonetheless consistent way. Thus species such as
Whitethroat and Linnet were included – and it is on these four species that this report
focuses.
In 2000 Kemerton Estate entered into a whole-farm Countryside Stewardship Agreement and as part
of that scheme began implementing changes to the management of field margins and of hedgerows. These were in
addition to earlier changes introduced by the farm manager since the mid-1990’s. The changes at Kemerton that
may have most improved the wildlife include a general increase in the ‘volume’ of each hedgerow (height and
width), stricter control of chemical drift into field margins and hedge bottoms, and the provision of rough
grass margins.
While these changes were taking place at Kemerton, since 1992 The Allington Research and
Educational Trust had been monitoring similar changes taking place on their farm at Loddington. Since 1994
the British Trust for Ornithology has been monitoring farmland bird populations on a regional and national
basis.
In 2000 Kemerton Conservation Trust, as part of a much farm-wide monitoring
scheme included monitoring populations of the four ‘target’ bird species. Kemerton’s results could then be compared
with trends identified locally by Loddington and nationally by the BTO. Close comparison of the local populations
would not be practical: varying agricultural practices and differing amounts of available wildlife habitat would be
affecting population numbers.
Results Although the methodologies used by Kemerton, Loddington and the BTO
differ considerably, so long as each is consistent then the various trends can be
compared.
Trends recorded
1. Linnet
BTO |
Shows 19% decline over 7 years |
Loddington |
Shows 150% increase over 10 years |
Kemerton |
Shows 216% increase over 5 years |
2. Skylark
BTO |
Shows 19% decline over 7 years |
Loddington |
Shows 3% increase over 10 years |
Kemerton |
Shows 83% increase over 5 years |
3. Whitethroat
BTO |
Shows 25% decline over 7 years |
Loddington |
Shows 80% increase over 10 years |
Kemerton |
Shows 69% increase over 5 years |
4. Yellowhammer
BTO |
Shows 13% decline over 7 years |
Loddington |
Shows 5% increase over 10 years |
Kemerton |
Shows 300% increase over 5 years |
Conclusions
- For three of the species Kemerton appears to have reversed the national decline - and for
the fourth species has far exceeded the national figure for increase
- For all species Loddington has either reversed or considerably reduced the national declines
(Like Kemerton, Loddington has been implementing changes aimed at improving the conservation value of
various farmland habitats)
- From the Kemerton results and from personal comments received from Loddington staff, it
would appear that these significant gains for wildlife have been achieved as a result of comparatively
small changes in agricultural practices.
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