Applying remotely sensed habitat descriptors to assist reintroduction programs: A case study in the hazel dormouse

Abstract

For reintroduction programs to succeed, it is vital to identify suitable release sites. This is especially true for low dispersing habitat specialists, which are at particular risk from habitat fragmentation. The habitat specialist Muscardinus avellanarius (hazel dormouse) is part of a large-scale reintroduction program in the UK. The program began in 1993 and has so far had varying levels of long-term success across 24 sites. Although the causes of population persistence at reintroduction sites are not well understood, continued habitat suitability is hypothesized to play an important role. Here, we establish broadscale habitat descriptors associated with the current distribution of natural hazel dormouse populations in England, using ecological niche factor analysis and remotely sensed, open-source maps. We also apply generalized linear mixed effects models to long-term monitoring data for reintroduced hazel dormouse populations, revealing that broad-scale habitat factors strongly influence the number of animals present in nest boxes. To aid conservation practitioners in future site selection, we illustrate the practical application of habitat suitability mapping to help prioritize the most appropriate woodlands for future hazel dormouse reintroductions, using the county of Cheshire as an example. Although demonstrated here for the hazel dormouse, this approach to reintroduction site selection could be beneficial to a broad range of species.

ENphylo: A new method to model the distribution of extremely rare species

“…Although more sophisticated algorithms progressively replaced ENFA in the mainstream of modelling studies (but see e.g. Andersen et al, 2021; Cartledge et al, 2021; Mugo et al, 2020; Sutton et al, 2021), this method has been used in >200 papers since its publication in 2002 (according to Scopus database in January 2022), and is still widely adopted to describe species habitat preferences, niche characteristics and vulnerability to global change (Cordier et al, 2021; Melchionna et al, 2018; Raia et al, 2020; Rinnan & Lawler, 2019). ENFA marginality and specialization can intuitively be translated into biologically meaningful concepts, as they represent the position and width of a species niche in the environmental space relative to the habitat conditions available to the species (Hirzel et al, 2002).…”

“…The method rationale is to calculate niche marginality and specialization factors, as routinely implemented under ENFA, for all the well-sampled species and then to rely on phylogenetic relatedness to derive marginality and specialization for the poorly sampled species. Although more sophisticated algorithms progressively replaced ENFA in the mainstream of modelling studies (but see e.g Andersen et al, 2021;Cartledge et al, 2021;Mugo et al, 2020;.…”

Hazel dormouse in managed woodland select for young, dense, and species-rich tree stands

“…A good range of woody species may also be related to a high diversity and abundance of invertebrates which is believed to be critical for the dormouse, especially when the production of flowers, fruits, and nuts is scarce in the spring (Chanin et al ., 2015). This supports other studies, indicating that the dormouse may not be such a selective feeder as thought in the past (Bright and Morris, 1996) but can occupy a wider variety of habitats (Trout et al ., 2012; Juškaitis and Baltrūnaitė, 2013; Cartledge et al ., 2021). This opportunistic adaptability to use food resources according to local species compositions may make it more robust to changes in species compositions caused by for example climate changes or changed forest management actions (Juškaitis et al ., 2016; Goodwin et al ., 2020).…”

“…data) and social organisation with overlapping home ranges (Bright and Morris, 1991; Juškaitis et al ., 2020), the habitats with the highest predicted occupancy (99%) must as minimum have sustained several individuals per hectare. This points directly to the targeted management of forest habitats as an potentially important management action to ensure viable dormouse populations in contiguous forest areas (Cartledge et al ., 2021). The hazel dormouse’s dependence on a wide range of woody plants can be regarded as a management bonus as forest management aimed on improving living conditions for dormice can be combined with biodiversity considerations in general.…”

“…In regions where forest is sparse, fragmented, and managed, silvicultural management practices may be of great importance for the density and ultimately viability of the remaining dormouse populations (Mortelliti et al ., 2011; Zapponi et al ., 2013; Mortelliti et al ., 2014; Dondina et al ., 2016). There is a need for improved evidence-based knowledge on the habitat requirements of the hazel dormouse in heavily managed woodlands to improve conservation and management options of potential dormouse forest habitats (Cartledge et al ., 2021). From a legal perspective, knowledge of optimal habitat features for dormice is of particular importance for national management authorities that are obliged to protect the species throughout the EU where the species is placed in the Annex IV of the EU Habitats Directive 92/43/EEC.…”