Land‐sharing vs. land‐sparing urban development modulate predator–prey interactions in Europe

Abstract

Urban areas are expanding globally as a consequence of human population increases, with overall negative effects on biodiversity. To prevent the further loss of biodiversity, it is urgent to understand the mechanisms behind this loss to develop evidence‐based sustainable solutions to preserve biodiversity in urban landscapes. The two extreme urban development types along a continuum, land‐sparing (large, continuous green areas and high‐density housing) and land‐sharing (small, fragmented green areas and low‐density housing) have been the recent focus of debates regarding the pattern of urban development. However, in this context, there is no information on the mechanisms behind the observed biodiversity changes. One of the main mechanisms proposed to explain urban biodiversity loss is the alteration of predator–prey interactions. Using ground‐nesting birds as a model system and data from nine European cities, we experimentally tested the effects of these two extreme urban development types on artificial ground nest survival and whether nest survival correlates with the local abundance of ground‐nesting birds and their nest predators. Nest survival (n = 554) was lower in land‐sharing than in land‐sparing urban areas. Nest survival decreased with increasing numbers of local predators (cats and corvids) and with nest visibility. Correspondingly, relative abundance of ground‐nesting birds was greater in land‐sparing than in land‐sharing urban areas, though overall bird species richness was unaffected by the pattern of urban development. We provide the first evidence that predator–prey interactions differ between the two extreme urban development types. Changing interactions may explain the higher proportion of ground‐nesting birds in land‐sparing areas, and suggest a limitation of the land‐sharing model. Nest predator control and the provision of more green‐covered urban habitats may also improve conservation of sensitive birds in cities. Our findings provide information on how to further expand our cities without severe loss of urban‐sensitive species and give support for land‐sparing over land‐sharing urban development.

Niche Analysis and Conservation of Bird Species Using Urban Core Areas

“…However, birds face novel conditions in cities, mostly due to the destruction and fragmentation of natural habitats, especially forests, which are replaced by open habitats and impervious surfaces [14]. Moreover, birds in cities are generally more susceptible to predation, by both natural (e.g., corvids, hawks) and domestic (e.g., cats, dogs) predators [15,16], and disease due to anthropogenic pollution (e.g., organic, air, noise [17,18]). Such novel conditions induced by urbanization act as ecological filters, altering bird species distribution and community composition along the urbanization gradient [19][20][21][22][23].…”

Predation release of Texas horned lizards (Phrynosoma cornutum) living in small towns

“…Feral and pet cats and dogs are also common in town but do not occur on the ranch. Altered predator communities are a consistent result of urbanization (Fischer et al., 2012; Jokimäki et al., 2020; Prange & Gehrt, 2004) and relaxed predation pressure in town may be a contributing factor to the high density of Texas horned lizards in Kenedy and Karnes City (Ackel, 2015) and their dietary shift to consuming small prey items (Alenius, 2018).…”

“…The role that predation plays in structuring urban communities is not well understood but has been suggested to be similar to what is found in natural areas (Shochat et al., 2006). Increasing evidence, however, indicates that predation may act differently in urban environments, leading to what some authors have termed an urban predation paradox (Eötvös et al., 2018; Fischer et al., 2012; Jokimäki et al., 2020). Studies done largely on urban birds and mammals have shown that urban environments have high densities of mesopredators, but paradoxically lower rates of predation (Eötvös et al., 2018; Fischer et al., 2012).…”

Synergies or Trade-Offs? Optimizing a Virtual Urban Region to Foster Plant Species Richness, Climate Regulation, and Compactness Under Varying Landscape Composition

“…We focused on the species richness of vascular plants. While former urban studies assessed the effects of land sharing versus land sparing on the diversity of bats (Caryl et al, 2016), birds (Sushinsky et al, 2013) and their predators (Jokimäki et al, 2020), ground beetles and butterflies (Soga et al, 2014), vascular plants have been neglected in the debate. As primary producers, plants are the basis of food webs and they provide many ecosystem services such as carbon sequestration or local climate regulation.…”

“…Rather, depending on their functional traits, some taxa will decline and some will increase in richness with density, while others will peak in richness at intermediate density (McDonnell and Hahs, 2008). Accordingly, while several studies concluded that urban biodiversity responds less negatively to land sparing than land sharing, they indicate that this response will vary depending on species' habitat preferences (Soga et al, 2014;Jokimäki et al, 2020) and sensitivity to urbanization (Sushinsky et al, 2013). It needs to be emphasized that we did neither distinguish among groups of plant species (e.g., native versus non-native, rare versus common species or different functional groups) nor did we consider other taxa.…”