This year was our 38th year of monitoring the cereal-crop flora, the invertebrate fauna and partrige number on the Sussex study area and our 40th year of counting the partridges. In spite of poor weather it was one of the best years we have had for a long time in Sussex. The chick survival rate in 2007 was 40% overall, higher than the 33% needed to maintain numbers. In contrast to 2004, when we counted only 33 pairs of greypartridges across the whole 8,000-acre study area, this autumn we found 83 pairs of grey partridges.
After the long-running decline in numbers of grey partridges on our Sussex study area, there has recently been an increase in the numbers of breeding pairs (see Figure 1). There are signs of a slight increase in the supply of chick-food insects since the early 1990s, but the overall picture is one of little long-term change since the early 1970s (see Figure 2). This is remarkable in view of the changes in agriculture. As a result of the slightly improved insect situation, owing partly to fewer insecticides being used, there has been a steady increase in chick survival rate over the whole area (see Figure 3). All of these changes indicate that things are improving for grey partridges in this area of Sussex.
Several farms have also started to increase nesting cover and the quality of the chick-rearing habitat. By 2006 they had already installed 15 kilmetres of beetle banks, 13 kilometres of conservation headlands and eight kilometeres of 10-20 metre-wide strips of brood-rearing cover. Some of this has attracted funding from the new Environmental Stewardship Scheme (ESS), with the rest funded directly by the farmers themselves.
There is evidence that this effort is working, with the average chick survival rate being 47% over the last four years on the area with new management compared with 33% on the area without it. Further improvements are under way and the prospects of grey partridges in Sussex are the best we have seen for four decades.
|Figure 1. Grey partridge spring pair density on the Sussex study site 1970-2007. In the last three years, the density of pairs of grey partridges on the Sussex study area has been higher than in the preceding six.|
|Figure 2. Changes in the average level of chick-food insects across the Sussex study area, 1970-2007. The general picture is of an increase ind chick-food insects since the 1990s.|
|Figure 3. Changes in chick survival rate over the Sussex study area, 1970-2007. Over the last seven years, there has been the beginnings of an increase in the number of chicks that survive throught the summer.|