The areas of highest breeding season species richness are in the river valleys, in which many tetrads have a wide diversity of habitats. They also contain a number of nature reserves that attract both birds and bird-watchers. The highest summer species richness in the 2007/11 period were 125 in SU77W (Lavell’s Lake, Dinton Pastures), 126 in SU56T (Woolhampton Gravel Pits) and 129 in SU46Y (Lower Farm Gravel Pit, Newbury).
The median number of confirmed plus probable breeding species in the 2007/11 survey was 42, a little lower than the 46 for the 11987/9 survey. However, the difference is not uniform across the county: the losses being mostly in woodland and arable land species.
The areas of highest species richness are in the river valleys, in which many tetrads have a wide diversity of habitats. They also contain a number of nature reserves that attract both birds and bird-watchers.
The median number of confirmed plus probable breeding species in the 2007/11 survey was 42, a little lower than the 46 for the 11987/9 survey. However, the difference is not uniform across the county: the losses being mostly in woodland and arable land species.
The map shows the change in the number of confirmed plus probable breeding species. Although there has been a small overall increase in this measure of richness between 1987/9 and 2007/11, there has been a substantial fall in the number of amber and particularly in red-list species. This is most obvious in the arable farming areas of the county, though apparent improvements on parts of the Downs may be encouraging.
Note: this change measure is particularly susceptible to differences in the efficacy of surveying between the two survey periods. Analysis of the data indicates that for the county as a whole efficacy was similar in 1987/9 and 2007/11, however, this does not apply to individual tetrads and some of the change displayed here may reflect more or less effective surveying.
The highest winter species diversity is found along the river valleys and in areas with expanses of open water. Nine tetrads recorded 100 or more species, with 109 in SU77W (Lavell’s Lake, Dinton Pastures) and SU97J (Dorney Wetlands), and 113 in TQ07D (Queen mother Reservoir). Away from the wet areas, most tetrads fell in the range of 41 – 60 species.