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Protected areas show mixed results in supporting avian food webs

Just how effective protected areas are at safeguarding habitats and the species that live within them is the focus of a new Swansea University study.

Establishing protected areas has become a conservation priority to mitigate the extinction crisis. The strategy has improved distinct aspects of biodiversity, including species richness and abundance across ecosystems. However, researchers from the Department of Biosciences wanted to gain a better understanding of how these areas are helping with the conservation of entire food webs: the networks of ecological interactions that focus on predator-prey relationships.

Their study analyzed hundreds of thousands of observational citizen science records from online databases such as eBird of 509 bird species distributed across 45 networks of European PAs located from Spain to Finland. They combined these observational data with information on predator-prey relationships between these species.

The team compared food webs in protected versus non-protected environments, relating any differences to environmental, geographical, and conservation status conditions of the protected areas. These included factors such as remoteness, habitat diversity, percentage cover of forests, agriculture, human pressure, or the specific designation of the protected areas.

have just been published in the journal Proceedings of the Royal Society B: Biological Sciences.

The scientists discovered that whereas for some food web properties the effects of protection were positive, in general these effects were mixed across European bioregions, with no consistent trends in whether food webs were better off inside rather than outside protected areas.

In general, protected food webs had more species, with a larger fraction of those at intermediate levels of the food web. Importantly, the body size of both intermediate and top predator species was larger inside protected areas. However, for other relevant food web properties such as the mean length of food chains or the connectivity of the network, there were no clear trends.

In terms of drivers behind these patterns, the authors found that the remoteness of the protected areas, their habitat diversity, human pressure and fraction of agricultural land were highly correlated with changes in food webs. Interestingly, the effects of protection were stronger in protected areas designated as part of the European Bird Directives initiative, highlighting the importance of having clear management goals in mind when setting up protected areas.

Co-author Dr. Miguel Lurgi, lead of the Computational Ecology Lab said, "Studies like ours highlight the complexity of conservation action and the importance of considering key aspects of biodiversity beyond species richness, such as ecological interactions and the tangled networks that they form, into biodiversity assessments.

"These networks not only structure communities and enable their persistence, but they also play important roles in the functions that ecosystems fulfill in nature."