A prickly problem: developing a volunteer-friendly tool for monitoring populations of a terrestrial urban mammal, the West European hedgehog (Erinaceus europaeus)

Abstract

Across Europe, hedgehogs (Erinaceus europaeus) appear to be in decline in both urban and rural landscapes. Current methods used to monitor urban populations are, however, associated with several potential limitations. In this study, we conducted hedgehog footprint-tunnel surveys in 219 residential gardens across Reading, UK between May-September in 2013 and/or 2014; gardens were surveyed for five continuous days. Single-species occupancy models were used to investigate factors influencing hedgehog occupancy and two-species occupancy models were used to estimate a species interaction factor (SIF) between hedgehogs and (a) badgers (Meles meles), (b) foxes (Vulpes vulpes) and (c) dogs (Canis familiaris). The five-day survey protocol was associated with a falseabsence error rate of 0.1-0.4%, indicating that it was a reliable method for determining hedgehog presence; conversely, 34.7% of householders were not able to correctly predict hedgehog presence or absence. Hedgehogs were widely distributed across Reading, but detected in only 32-40% of gardens. None of the within-garden or outside-garden factors investigated significantly affected hedgehog occupancy in the single-species models, but the two-species models indicated that badgers (SIF = 0.471 ± 0.188), but not foxes (SIF = 0.954 ± 0.048) or dogs (SIF = 0.780 ± 0.228), negatively affected the presence of hedgehogs in gardens, although not significantly. Overall, footprint-tunnels represent a viable field method for monitoring urban hedgehog populations, however, other approaches are required to identify factors that make gardens Bhedgehog friendly^.

Should rehabilitated hedgehogs be released in winter? A comparison of survival, nest use and weight change in wild and rescued animals

“…This highlights the importance of suitable release sites for rehabilitated hedgehogs, with optimal release sites being those that are suburban and free of badgers. This is borne out by current research in the UK showing that hedgehog occupancy and abundance is low in rural landscapes (Hubert et al 2011;Yarnell et al 2014;Pettett et al 2017;Williams et al 2018;Williams et al 2018a), which suggests that these habitats are sub-optimal for hedgehogs and should not be used for rehabilitation release and that release into suburban areas without main roads and badgers should increase individual survival rates.…”

Patterns of Feeding by Householders Affect Activity of Hedgehogs (Erinaceus europaeus) during the Hibernation Period

“…Hedgehog presence/absence surveys were carried out in the back gardens of private households in the town of Reading, UK (51°, 27′ N and 0°, 58′ W; population >230,000; and area >60 km 2 ) and its outskirts from 18 November 2017–7 April 2018. Badgers and foxes ( Vulpes vulpes ) which are both potential predators of hedgehogs and competitors for hedgehog food, are present in Reading, although records of the former indicate that they are limited to the northern section of the town [ 54 ]. Domestic dogs ( Canis familiaris ) were present in some gardens surveyed, but these were typically confined to the owner’s garden from approximately 11 p.m., whereas hedgehogs could be active throughout the night; consequently, dogs have been shown to not affect patterns of hedgehog occupancy [ 54 ].…”

Decline in Distribution and Abundance: Urban Hedgehogs under Pressure

“…To assess the distribution of hedgehogs, we divided the urbanized area of the city of Zurich into km-squares, 46 of which were surveyed with footprint tunnels made from corrugated plastic (1200 mm × 210 mm × 180 mm) between May and October 2016 [31,40,41]. These 46 km-squares were chosen as they contained the most suitable hedgehog habitat (e.g., no lake and forest) and only areas with the chance of regular sightings by citizens (no peripheral agricultural areas).…”

“…We were able to build upon a city-wide call for hedgehog sightings in 1992, combined with a capture-mark-recapture study, which resulted in the creation of a distribution map, as well as an estimate of abundance numbers for a period in the past. In the recent comparative study, we used footprint tunnels [31,40,41], collected hedgehog observations, and employed a capture-mark-recapture approach in four urban districts with the help of citizen scientists to estimate current distribution and abundance measures for urban hedgehogs. The resulting indicators of hedgehog density and distribution were compared over the 25-year period.…”