The effect of housing development and roads on the distribution of stone curlews in the Brecks Evidence to support the Appropriate Assessment of development plans and projects in Breckland

The effect of housing development and roads on the distribution of stone curlews in the Brecks. The effect of housing development and roads on the distribution of stone curlew 3 Summary We combine data describing the nest location of stone curlews with data on the locations of new housing, road data and traffic data to explore the effect of housing and roads on the spatial distribution of stone curlews over the period 1988-2006. This work has been commissioned by Breckland District Council to inform the potential impact of new housing within the district, and in particular in the vicinity of Thetford. We differentiate between arable and semi-natural habitats and focus on stone curlews breeding on arable land, as this habitat is likely to be more uniform and less subject to variation in habitat quality, management etc. Over the study period the number of stone curlew nests has increased steadily (from 83 in 1988 to 246 in 2006). This increase is most marked on arable land, while birds nesting on SSSIs have shown a slight decline since 2002. On arable land the birds occur at relatively low densities and there has been considerable turnover and change in the precise areas which hold nests in each year. During the study period the number of houses within and around the study area has also increased, from c.150,000 houses in 1988 to c.210,000 houses in 2006. Within every single year from 1988 to 2006, the stone curlew nest density (per ha of suitable arable land) was significantly lower on land within 0-500m of the nearest settlement than in successive distance bands. Annual nest densities on arable land 500-1000m from settlements were also lower than densities at subsequent distance bands in 14 of the 18 years over the period 1988-2006. This consistency across the whole study period provides strong long-term evidence of some negative impacts or association of housing on stone curlews densities on arable land. The proportion of all nests (within a given year) which are nesting within 500m or within 500-1000m of any " settlement " has steadily increased over the past two decades, indicating that the avoidance of housing, while always highly significant, has decreased in more recent years. We also found a significant avoidance of trunk roads. We grouped yearly data into four different and for all four periods, the nest density on arable land within 500m of a trunk road …