In the first project, records from intensive surveys revealed that seven bird and butterfly species have colonized PAs more than four times more frequently than expected from the availability of PAs in the landscapes colonized.
Records of an additional 256 invertebrate species with less-intensive surveys supported these findings and showed that 98 per cent of species are disproportionately associated with PAs in newly colonized parts of their ranges.
Although colonizing species favoured PAs in general, species vary greatly in their reliance on PAs, reflecting differences in the dependence of individual species on particular habitats and other conditions that are available only in PAs.
In the second project, known by the acronym ‘Chainspan’, climate–abundance models were developed which were able to explain 56 per cent of the variation in recent 30-year population trends of a range of bird species. With confidence that the models could be used to hind-cast in this way, we then used the models to investigate how future populations might change under climate conditions corresponding to a 4:0 º C change in average global temperature.
This was projected to cause UK declines of at least 25 per cent for more than half of the internationally important populations considered. Despite this, most EU Special Protection Areas in the UK were projected to retain species in sufficient abundances to maintain their legal status and generally sites which are important now were still projected to be important in the future.
Whilst declines in vulnerable northern species seem likely, management to improve site-quality and reduce the severity of other pressures may reduce the magnitude of such reductions. Management to increase site-size and quality may also increase the ability of sites to accommodate change. In general, the implementation of existing legal and policy mechanisms may be adapted to enable such changes to occur on the ground and therefore maximise the opportunities for appropriate steps to help birds in the UK to adapt to climate change.
In the third project, we have examined the extent to which wetland bird species colonizing the UK since 1960 have exploited PAs. Colonization commenced in a PA for all six species which established permanent (greater than 10 years) breeding populations in the UK during this period. Subsequently, birds started to breed outside as well as inside PAs: the colonizing species showing declining fractions of breeding within PAs over time, a trend not seen in already-resident species. This led us to conclude that PAs were valuable as ‘landing pads’ for range-shifting species first arriving in a new region, and then as ‘establishment centres’ from which viable populations spread.