Environmental Statement volume 4 - Chiltern Evergreen3

Access was not obtained for Wolvercote Meadows SSSI and the site wasobserved from adjacent points. Of apparent low bird interest and lying morethan 500 metres from the railway, it was considered unnecessary to survey thesite further.The Islip to Brookfurlong Farm section of route was walked via publicfootpaths and was considered to be of low bird interest.All other sites received between three and four survey visits.Bird survey methodsWeather conditions throughout the survey periods were generally warm andcalm and highly suitable for surveying.Surveys mostly commenced about 0500 hours and continued to aroundmidday. The order in which areas were surveyed was varied over each of thefour rounds to ensure that each site received at least one early morning visit.Early morning is normally the most active period for birds, especially early inthe season. In general, song ceases earlier in the day as the breeding seasonprogresses. Early morning is also a relatively quiet time of day which makesthe detection of bird song and calls easier.However, only a proportion of the individuals of each species will be detectedon any single survey visit. Some birds, particularly secretive or low-densityspecies, can be especially elusive. For a survey to produce sufficient data toallow a reasonably accurate assessment of species diversity and the size ofpopulation of each species within an area, it is recommended that a minimumof eight survey visits be conducted (e.g. Gilbert et al, 1998) these commencingin late March or early April.The survey recorded all species and attempted to assess approximateestimates of the size of population (number of breeding territories) and thenumber of breeding species (diversity) in each of the areas.On each visit to an area it would be walked slowly and quietly. More timewould be spent in areas of potentially high interest, such as reed-beds orscrub, than in open grassland or arable land where birds are generally moreeasily detectable. Because of the late start to the survey and the need to locateany specially protected species that might occur, effort was frequentlytargeted at finding such species. Judgements were made on the knowledge ofparticular species’ requirements and the suitability of habitats in an area.The location and behaviour of each bird was recorded with the emphasis onterritorial males, family parties and other behaviour indicative of breedingsuch as anxiety displays or the carrying of food or nest material.ENVIRONMENTAL RESOURCES MANAGEMENTF2-5CHILTERN RAILWAYS