Predator – prey interactions are less specialised in urban parks compared to peri-urban forests

Species diversity is positively associated with specialisation and complexity of interaction networks and the delivery of related ecosystem functions. However, anthropogenic environments, such as urban areas, can have altered species diversity which may affect species interaction networks. For example, urban parks can be important for supporting bird diversity in cities, but their predatory interactions with arthropods may be weaker, along with reduced delivery of ecosystem functions such as insect control or pest removal. Here, in a case study of four sites, we compared networks of insectivorous birds and their prey from urban parks and peri-urban forests, using high-throughput DNA metabarcoding of bird faecal samples. We compared prey taxonomical diversity and composition, and network properties between the two habitats. We built predator – prey networks with 50 individual birds of eleven species whose faecal samples returned more than 100 million sequence reads of 1363 arthropod zOTUs assigned to 489 species. We found that the diversity of prey was lower in urban parks than in forests, and prey composition between urban sites overlapped more and had a lower turnover, indicating a more homogeneous prey community, than forest sites. Urban bird – arthropod networks were less specialised, more nested and more functionally redundant than their forest counterparts. Our results show a loss of specialisation in predator – prey interactions in urban areas as a consequence of increased overlap in prey species among predators. However, given the limited sample size, our reconstructed networks cannot fully characterise the local bird assemblages, even though the main species were sampled. Despite the limited scope of inference, the observed loss of specialisation could have broader implications for urban ecosystem services, such as insect control, but extensive further replication is needed to test these potential consequences.