Roadkills as a Method to Monitor Raccoon Dog Populations

Abstract

The raccoon dog (Nyctereutes procyonoides) is one of the most frequently killed species on Lithuanian roads. As an invasive species, up-to-date knowledge of population size, trends and spatial distribution is critically important both for species assessment and for the planning of control measures. In Lithuania, however, raccoon dog surveys have not been carried out since 1997. We investigated, therefore, whether roadkill counts on predefined routes could be used as a proxy for a survey. Our dataset includes survey numbers for the period 1956–1997, hunting bag sizes for 1965–2020 (including the spatial distribution of the hunting bag in 2018–2020) and roadkill data relating to 1551 individuals between 2002–2020. At the most local scale, that of the hunting areas of hunting clubs, correlations between the numbers of hunted and roadkilled individuals were negative and insignificant or absent. At the country scale, however, we found significant correlation both between the numbers surveyed and hunted in 1965–1997 (r = 0.88), and between those hunted and the number of roadkills in 2002–2020 (r = 0.56–0.69). Therefore, we consider that roadkill counts on predefined and stable routes may be used as a proxy for a survey at the country scale. Practical implementation of the method is proposed.

How Many Mammals Are Killed on Brazilian Roads? Assessing Impacts and Conservation Implications

“…Taxonomic names used in this study followed the current IUCN taxonomy database [30]. For this analysis, the exotic species (European hare and wild boar) were considered in the general medium-large mammals' road-kill assessment due to their relevance in safety issues on Brazilian highways and importance for monitoring invasive species [11,37]. The conservation status of the common tapeti (Sylvilagus brasiliensis) was considered here in accordance with the IUCN classification before 2019.…”

Aliens on the Road: Surveying Wildlife Roadkill to Assess the Risk of Biological Invasion

“…Individual hobbyists and wildlife enthusiasts have greatly increased in the last 30 years, and the majority of them upload opportunistic records to online platforms [ 38 , 39 , 40 ], including projects on road mortality [ 35 , 41 , 42 ]. Similarly, the low cost of detecting and uploading roadkill to online databanks (e.g., iNaturalist, GBIF) has also been used to monitor biological invasions, particularly at early invasion stages [ 43 , 44 , 45 ]. Immediately after release or escape, invasive alien species are present in new areas at low densities, which may prevent their detection through standardised monitoring, therefore relying on accidental observations, such as roadkill as first detection [ 46 , 47 , 48 ].…”

The Distribution and Activity of the Invasive Raccoon Dog in Lithuania as Found with Country-Wide Camera Trapping

“…By 1960, they had already invaded Lithuania [12] and later spread to other parts of Europe [11]. Surveys on this species in Lithuania ceased before 2000 but based on the number roadkilled and hunted raccoon dogs, the current population in Lithuania is at least 10,000 [13].…”

“…Strong and significant correlations have been found at the national level, both between the number of animals surveyed and the number of animals hunted, and between the number of animals hunted and the number of roadkill. Therefore, the number of raccoon dog who are roadkill on stable predefined routes was tested as a survey proxy [13].…”