Rare and declining bird species benefit most from designating protected areas for conservation in the UK

Answering this question is not as easy as it first seems, since the goals of protection can vary – protecting a particular bit of habitat or increasing the numbers of an endangered species, for example. There is also a lot of variation in how this protection is translated into on-the-ground management, so it can be difficult to determine whether protected areas are having the desired effect. The evidence published on the effectiveness of protected areas is mixed, and the causal links between the use of protected areas and conservation outcomes are rarely tested. The work reported in this paper uses data collected by BTO volunteers to address the lack of understanding around the underlying processes that determine effectiveness and, through this, increases our chances of delivering protected areas that truly benefit biodiversity conservation.

The authors use data from three large-scale UK citizen science programmes monitoring bird populations – the BTO/JNCC/RSPB Breeding Bird Survey, two Bird Atlas projects led by BTO, and the Constant Effort Sites ringing scheme – to test whether protected areas i) are associated with greater abundance and probability of occurrence, ii) deliver more positive (or less negative) trends in abundance, iii) affect breeding productivity, and iv) enable better outcomes for priority species. 

The results reveal that species occur more often and in higher numbers, and are more likely to colonise and persist at sites with a greater extent of protected area coverage. However, there is no evidence that changes in abundance (trend) are more positive around protected areas.Importantly, the most effective protected areas for birds were found to be those designated (and hence likely managed) specifically for them – i.e. Special Protection Areas (SPA), rather than Sites of Special Scientific Interest (SSSI) or Special Areas of Conservation (SAC).

Uniquely, the use of ringing data enabled the BTO team to test whether protected areas supported increased productivity (i.e. a greater number of young birds fledged per adult) and, through this, led to an increase in abundance over time. The results revealed that higher productivity in protected areas was associated with more positive trends in abundance.

Importantly, examining the variation in species responses revealed that habitat specialists and rare species were more likely to benefit from protected areas than common species and habitat generalists. By controlling for large-scale variation in land-cover, topography and climate, the authors show that species are not only more likely to occur in protected areas, over and above the surrounding land (a much-debated question), but also that the benefits of this network are greatest for those species most in need of conservation action.

Whilst protected areas have, on average, reduced species diversity (many are in upland areas), they support communities of more specialist and cold-adapted species. Furthermore, the results showed that protected area networks can also buffer community-level responses to climate change, particularly by facilitating climate-driven colonisation of new sites. 

This is an unusually comprehensive assessment of the effects of protected sites on a national avifauna, and it is evident that the UK’s protected area network has had a positive impact on bird conservation over the last three decades. There is, however, the potential to do more; the UK is one of the least biodiverse nations globally and suffers from a significant shortfall in the extent of protected area coverage. The research also underlines the value of designating sites specifically for target species, as is evident in the results for Special Protection Areas, and this provides vital evidence that can be used to direct future policy decisions around the nature and designation of protected areas, both in the UK and elsewhere.