Birds in woodland can be affected by increasing deer populations through changes to the vegetation structure and the potential impacts on foraging resources; these effects need to be better understood. This work, carried out over three years by the BTO and the University of East Anglia, used experimental exclusion of deer to look at the effects of deer browsing in English coppiced woodland. Deer browsing strongly altered the vegetation structure by reducing canopy cover and the density of shrub layer foliage. However, deer did not affect the invertebrate density per unit of foliage. Significantly more ground and understorey foraging birds were captured where deer were excluded, and negative responses to browsing were more marked for migrant birds than for residents. At the species level, especially pronounced negative effects were found for Dunnock (Prunella modularis) and Garden Warbler (Sylvia borin); for instance approximately five times more Dunnocks were captured in deer exclosures than in browsed vegetation. Negative responses to browsing were also found for Nightingale (Luscinia megarhynchos) and Long-tailed Tit (Aegithalos caudatus). No significant positive responses to browsing were detected. For some species the use of young re-growth increased post breeding relative to the breeding period. This included a marked shift by resident birds that involved a disproportionate number of juveniles. This work shows that by modifying the vegetation, deer activity can alter woodland bird assemblages. As far as we are aware this is the first experimental demonstration of such effects in Europe, and at low to moderate browsing intensity typical of the wider landscape scale.

Research by the BTO and the JNCC shows that the regions used by policy makers in monitoring and protecting the UK’s internationally important seabird populations are not necessarily meaningful on an ecological level. Consequently, the effects of man’s marine activities, such as fishing, dredging and shipping, on seabirds could be overlooked. The research used data collected at seabird colonies in the UK and Ireland since 1986 to identify monitoring regions that better reflect the areas of coast and sea used by 11 species. The number of areas determined varied between species, from two for Northern Gannet, a highly mobile species, to seven for the more sedentary Great Cormorant. Current regions used for monitoring are mostly based on features such as seabed habitat and tidal fronts. This research suggests that knowledge of seabird ecology is crucial for better understanding population changes in these charismatic species. As top predators, seabirds are key indicators of the health of marine ecosystems. A similar approach placing ecology at the heart of monitoring could perhaps benefit other marine predators, for example dolphins and seals.

Since its emergence in 2005, the parasitic disease trichomonosis has caused epidemic mortality and significant population declines in British Greenfinches and Chaffinches. This began in western England and Wales, but spread to eastern England, and more recently, southern Fennoscandia. An international team of experts, including BTO scientists, has used molecular, epidemiological and ringing data, to show that the parasitic strain is identical in all cases, and that migration, primarily of Chaffinches, has been responsible for its spread. This is the first documented case of a protozoal parasitic infection being transmitted in this way.