Deer are bad news for birds

Deer may be affecting some bird species on far larger scales than previously appreciated, new research has found. The study, published this week in the British Ecological Society's Journal of Applied Ecology, provides evidence that the populations of several woodland bird populations fare worse in areas that have high, rather than low, numbers of deer.

The research led by Dr Stuart Newson from the British Trust for Ornithology (BTO) applied new methods of analysis to large national bird and deer monitoring data. The study focused on eleven woodland bird species in lowland England and their relationships with three widespread and abundant deer species: muntjac (Muntiacus reevesi), roe deer (Capreolus capreolus) and fallow deer (Dama dama). The eleven bird species depend on low dense vegetation in woodland and scrub, and are therefore potentially vulnerable to browsing by deer which tends to reduce this vegetation.

There was evidence that increases in deer have been associated with large-scale population declines for five of the eleven bird species. Of these, it was suggested that the impacts of deer are likely to have been greatest for two species of conservation concern, the amber listed Nightingale and the red listed Willow Tit. These two birds have declined by 54% and 65% respectively over the last ten years.

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