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City life offers surprising opportunities for some endangered species

DAILY SCIENCE

City life offers surprising opportunities for some endangered species

Two new studies in widely varying environments—southern England and southern California—argue against writing off urban areas as arks of biodiversity
June 11, 2024

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Cities can be surprising havens for animals that are usually thought of as intolerant of urban environments and even endangered species, according to a pair of new studies. The analyses add heft to a growing body of evidence on the importance of cities for protecting and maintaining native biodiversity.

More than half the world’s population lives in urban areas, and the extent of built-up areas worldwide is predicted to triple from 2000 to 2050. Urbanization fragments habitat; alters vegetation; introduces disturbances by humans and pets; increases noise, light, and air pollution; and exposes animals to mortality from traffic collisions.

Not surprisingly, then, urbanization is considered a major threat to biodiversity worldwide. Yet recent studies have also shown that sensitive native species can persist in cities under certain conditions.

“As urban areas are rapidly growing worldwide, there is a need to integrate conservation management into town policies to ensure species can thrive in those new environments,” says Emilie Hardouin, a conservation geneticist at Bournemouth University in the UK and a member of one of the study teams. “Conservation shouldn’t just happen in ‘pristine’ and ‘untouched’ landscapes, but in areas where wildlife have used and adapted to the human-induced changes in habitats.”

Hardouin and her collaborators analyzed nearly 11,000 sightings of 27 mammal species, collected largely by community scientists, between 2000 and 2018 in the area around Bournemouth, Christchurch, and Poole in southern England [1].

The researchers compared the presence of mammal communities in urban landscapes to those of nearby farmland, grassland, woodland, and heath. The different landscapes harbored different communities of mammal species, with urban mammal communities especially distinct from those of the other landscapes, the researchers report in the journal Urban Ecosystems.

Still, four out of the five vulnerable and endangered mammal species recorded in the study were seen in urban areas: the European rabbit, hazel dormouse, West European hedgehog, and European water vole. Only the Eurasian red squirrel was absent from cities.

 

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The West European Hedgehog was present in all environments, but was actually observed most often in urban areas, a finding consistent with other studies that have shown hedgehogs can thrive in cities. Urban areas could provide even better habitat for creatures like hedgehogs with better connectivity between backyards and other green spaces, the researchers point out.

“We are currently investigating the general public’s attitude toward biodiversity in towns, as their support will be crucial for the successful implementation of any policies” to protect native wildlife and foster endangered species, Hardouin says. “Additionally, we need to investigate urban area biodiversity in more depth. For this study, we used ad-hoc citizen science data collection, which tends to have a reporting bias toward charismatic species. In the future, we aim to adopt a more systematic approach to studying biodiversity in urban areas, such as eDNA metabarcoding, which would allow us to investigate vertebrate biodiversity, not just mammals.”

A second study of urban wildlife also made use of data collected by community scientists – in this case, more than 500,000 observations of 967 native species recorded in the iNaturalist app by 71,000 different individuals within 93 miles of Los Angeles, California [2]. The research team used these observations to measure how 12 different taxonomic groups ranging from snails and wasps to birds and mammals respond to urbanization, as well as the urban tolerance of the animal community as a whole at different locations across the city.

City managers could use these newly developed metrics to plan and evaluate urban conservation efforts in the future, the researchers say.

Overall, native species were more likely to be observed in natural areas than in urban parts of the city, the researchers report in the journal PLoS ONE. Yet some species actually seemed to benefit from urban development.

Slugs and snails are the most urban-tolerant group, and were seen more often in the more built-up areas compared to more natural areas around Los Angeles. These humidity-loving animals may benefit from people’s tendency to add water to their yards and gardens year-round in the arid climate of southern California.

Meanwhile, butterflies and moths were the least urban-tolerant group. This may reflect a lack of host plants for these species in the most built-up areas – but this could be remedied with careful planning and restoration, the researchers argue.

Surprisingly, the team found that “there were regions in urbanized areas of L.A. that were composed of native species that are considered more urban intolerant/wildland associated,” says study team member Joseph Curti, a graduate student at the University of California, Los Angeles. “These pockets of native species indicate that there are still regions of the city where we see interesting and diverse native species communities.”

Source: [1] Boakes Z. et al.  “The importance of urban areas in supporting vulnerable and endangered mammals.” Urban Ecosystems 2024.

[2] Curti J.N. et al.Using unstructured crowd-sourced data to evaluate urban tolerance of terrestrial native animal species within a California Mega-City.” PLoS ONE 2024.

Image: Envato Elements.

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