DOI: 10.5061/dryad.fxpnvx10b
title: Urban scavenging: Vertebrates display greater sensitivity to land-cover and garden vegetation cover than invertebrates

description: 1. Scavenging removes carrion or littered food waste from the environment,
 providing ecosystem services including nutrient cycling, reduced pathogen
 spread, and reduced waste management costs. These services are
 particularly important in urban environments, where high human population
 densities result in increased littered food waste. It is unclear how the
 magnitude of scavenging across urban-rural gradients is influenced by
 agent (vertebrates and invertebrates), land-cover type and patch size. 2.
 We investigated scavenging provision by vertebrates and invertebrates
 across a gradient of urbanisation in 37 woodlands and 35 domestic gardens
 across Liverpool, UK.  Sites were selected using random
 stratification across a gradient of urbanisation based on impervious
 surface cover. At each site, four different bait types were deployed
 either within vertebrate exclusion cages or exposed to vertebrates and
 invertebrates. The percentage dry weight loss of bait after 48 hours was
 used to quantify scavenging provision. 3. Data were analysed using general
 linear mixed effects models (Gaussian error distribution) and a full model
 approach to assess 1) the relative contributions of vertebrates and
 invertebrates across an urban-rural gradient; 2) variation in scavenging
 between woodlands and gardens; 3) the effects of semi-natural vegetation
 cover on scavenging provision. We also consider patch size as a
 preliminary assessment of how fragmentation influences scavenging. 4.
 Vertebrates contributed substantially more to scavenging provision than
 invertebrates across the urbanisation gradient. Vertebrate scavenging was
 substantially greater in woodlands than gardens, invertebrate scavenging
 was similar in both land-cover types. Scavenging increased with patch size
 in gardens, but not woodlands. Vertebrate scavenging increased with patch
 size, while invertebrate scavenging decreased. Within gardens, vertebrate
 scavenging increased with semi-natural vegetation cover. 5.
 Scavenging-mediated ecosystem services are important in urban areas where
 food littering is frequent, and efforts should be made to facilitate these
 services. Urban woodlands and gardens both make important contributions to
 scavenging-mediated ecosystem services in urban areas, but woodlands’
 contributions are much greater. There is a need to increase the cover of
 semi-natural vegetation in gardens to increase their contributions, and
 protect and expand woodlands, especially in areas with a high demand for
 ecosystem services reliant on scavenging.
description: # Urban scavenging: Vertebrates display greater sensitivity to land-cover
 and garden vegetation cover than invertebrates
 
 "urban.scavenging.csv" contains data regarding the percent dry
 weight loss of each bait type at each site, by vertebrates or
 invertebrates. Each site has a corresponding land-cover type, patch size,
 and the percentage impervious surface of the grid cell it occupies.
 Latitude and longitude have been provided for woodland sites, but not
 garden sites to protect the addresses of residents.
 "urban.scavenging_garden.features" contains data regarding the
 percentage cover of vegetation within each garden site. A semi-natural
 vegetation variable was created by summing the values for tree,
 wildflower, hedge, and shrub cover. "Lawn" refers to the
 percentage cover of mown amenity grass, "ornamentalflowers"
 refers to the percentage cover of ornamental flowering plants, which are
 typically selectively-bred varieties cultivated for display.