Waste Disposal Sites as All-You-Can Eat Buffets for Carrion Crows (Corvus corone)

Abstract

In cities and densely populated areas, several corvid species are considered nuisance animals. In Austria, particularly carrion (Corvus corone) and hooded crows (C. cornix) are regarded as pests by the general public that frequently cause damage to crops, feed on human waste, and thus spread trash. We conducted a detailed one-year field survey to estimate the abundance of carrion crows in relation to potential anthropogenic food sources and reference sites in the Austrian Rhine valley. Our results demonstrated that the number and proximity of waste management facilities, animal feeding areas, and agricultural areas, and the productive capacity of agricultural areas, predominantly influenced habitat choice and abundance of carrion crows. In the current study, the probability of observing more than two carrion crows at a survey site decreased with increasing human population density. Moreover, the abundance of crows increased despite a continuous increase in crow hunting kills registered during the past 25 years. Our study suggests a regionally comprehensive waste management plan could serve as a promising strategy to manage nuisance birds. A reduction in anthropogenic food supply through improved waste management practices is required for long-term, sustainable management to limit the abundance of crow populations in and close to urban environments.

Why do zoos attract crows? A comparative study from Europe and Asia

“…Although we cannot exclude the possibility that biogeographic differences such as lower crow abundance in the general Sapporo region than in the regions of the other zoos can explain this difference, our experience with Sapporo zoo suggests that the emergence of territoriality and aggression toward nonresident conspecifics induced by low food availability (see above) can at least partly explain the lower crow numbers. The limitation of anthropogenic food was suggested by Preininger et al () as a solution to reduce the number of crows at waste disposal sites. Finally, in cases when crows need to be captured for research or for translocation purposes, zoos may provide suitable places for trapping crows, taking into account any relevant national legislation regarding crow trapping (Kövér, Tóth, Lengyel, & Juhász, ).…”

“…Many species have adapted to human‐transformed landscapes and some have even become dependent on urban resources (Kark, Iwaniuk, Schalimtzek, & Banker, ; Marzluff et al, ; Preininger, Schoas, Kramer, & Boeckle, ; Vuorisalo, Talvitie, Kauhala, Bläuer, & Lahtinen, ). Cities are a special ecosystem for their abiotic and biotic characteristics and their unique species composition (Bezzel, ; Fey, Vuorisalo, Lehikoinen, & Selonen, ; Parlange, ).…”

“…An understanding of the relative importance of these factors, however, is difficult due to the variation in urban environments in terms of human population size, the built‐in and natural components of urban landscapes, and type and availability of food sources. A comparison of corvid use of urban landscapes that are similar in human population size, urban landscape composition, and food availability can thus provide insights into the relative importance of the factors suspected to explain corvid colonization of urban environments (Preininger et al, ).…”

“…Corvids are known for their behavioral plasticity and intelligence, which enable them to readily adapt to new environments, including artificial environments constructed by humans (Bird & Emery, 2009;Emery & Clayton, 2004;Hunt, 2014;Marzluff et al, 2008). Some crows are thus considered as "urban exploiters" (Japanese Ministry of Environment, 2001;Kark et al, 2007;Nishikawa, 2004) or even as nuisance or pest animals that feed on trash and spread diseases (Preininger et al, 2019).…”

“…A comparison of corvid use of urban landscapes that are similar in human population size, urban landscape composition, and food availability can thus provide insights into the relative importance of the factors suspected to explain corvid colonization of urban environments (Preininger et al, 2019).…”