Ecological role of vertebrate scavengers in urban ecosystems in the UK

Abstract

Recent research has demonstrated how scavenging, the act of consuming dead animals, plays a key role in ecosystem structure, functioning, and stability. A growing number of studies suggest that vertebrate scavengers also provide key ecosystem services, the benefits humans gain from the natural world, particularly in the removal of carcasses from the environment. An increasing proportion of the human population is now residing in cities and towns, many of which, despite being highly altered environments, contain significant wildlife populations, and so animal carcasses. Indeed, non‐predation fatalities may be higher within urban than natural environments. Despite this, the fate of carcasses in urban environments and the role vertebrate scavengers play in their removal have not been determined. In this study, we quantify the role of vertebrate scavengers in urban environments in three towns in the UK. Using experimentally deployed rat carcasses and rapid fire motion‐triggered cameras, we determined which species were scavenging and how removal of carcass biomass was partitioned between them. Of the 63 experimental carcasses deployed, vertebrate scavenger activity was detected at 67%. There was a significantly greater depletion in carcass biomass in the presence (mean loss of 194 g) than absence (mean loss of 14 g) of scavengers. Scavenger activity was restricted to three species, Carrion crows Corvus corone, Eurasian magpies Pica pica, and European red foxes Vulpes vulpes. From behavioral analysis, we estimated that a maximum of 73% of the carcass biomass was removed by vertebrate scavengers. Despite having low species richness, the urban scavenger community in our urban study system removed a similar proportion of carcasses to those reported in more pristine environments. Vertebrate scavengers are providing a key urban ecosystem service in terms of carcass removal. This service is, however, often overlooked, and the species that provide it are among some of the most disliked and persecuted.

Covariation in urban birds providing cultural services or disservices and people

“…This study was a part of a wider project investigating urban ecosystem services (e.g. see Cox & Gaston, ; Cox, Inger, Hancock, Anderson, & Gaston, ; Cox et al., ; Inger, Cox, Per, Norton, & Gaston, ), focused on the urban area of the “Cranfield triangle,” a region in southern England, UK (52°07′N, 0°61′W). This comprises the three adjacent towns of Milton Keynes, Luton and Bedford, which have a combined human population of c .…”

Habitat selection by an avian top predator in the tropical megacity of Delhi: human activities and socio-religious practices as prey-facilitating tools

“…Pickett et al 2001;McKinney 2010). Nevertheless, some animal species have managed to adapt and thrive under such conditions (Lepczyk et al 2017), some for example can take advantage of human waste and reach densities that are not otherwise encountered (Brook et al 2003;Gangoso et al 2013;Inger et al 2016). These urban exploiters are often alien invaders seen as 'nuisances to eradicate ' (e.g.…”

“…Third, many of them are facultative scavengers that subsist on animal carrion and human waste, thus providing fundamental ecosystem and sanitary services, as well demonstrated in urban and rural environments (e.g. Margalida and Colomer 2012;Gangoso et al 2013;Moleón et al 2014;Inger et al 2016). Fourth, they are often dominant components of the community, potentially limiting other species, and thus contributing to faunal homogenization (McKinney 2006;Shochat et al 2010;Carey et al 2012).…”

Ecological Potential for Rabies Virus Transmission via Scavenging of Dead Bats by Mesocarnivores

“…Two of these studies, in rural Indiana, found raccoons were the most important scavenger of rodent carcasses, followed by opossums (Didelphis virginianus) and gray foxes, with striped skunks taking rodent carcasses only once at each site (DeVault and Rhodes 2002;DeVault et al 2011), the opposite of the pattern we documented. Another study using rodent carcasses in the UK, found Common Crows (Corvus corax) and Eurasian Magpies (Pica pica) were important scavengers of mouse carcasses (Inger et al 2016). Although Ravens (Corvus corax) and American Crows (Corvus brachyrhynchos) are common in Flagstaff, we recorded a crow taking a bat only once.…”

“…Many scavenging studies done elsewhere (e.g., DeVault et al 2011;Inger et al 2016) relied on rodent carcasses because they are more readily available than bat carcasses, but whether mesocarnivores respond differently to bat versus rodent carcasses has not been tested. Within bats, species may also differ in relative attractiveness to mesocarnivores.…”