Experimental design and taxonomic scope of fragmentation studies on European mammals: current status and future priorities

Abstract

Habitat loss, habitat fragmentation and habitat degradation are the greatest threats to mammals in Europe and the rest of the world. Despite the fact that extensive literature exists, no comprehensive review or synthesis is available to date and this may slow down scientific progress and hamper conservation efforts. The goal of this study is to understand if and in what direction progress has been made in the study of the effects of habitat loss and fragmentation on the spatial distribution of European terrestrial mammals. Firstly, we carry out a general synthesis which is structured around 11 key points. The aim of this point-by-point analysis is to identify trends, knowledge gaps and any significant bias in the available literature, and to highlight strengths and shortfalls of the different approaches which have to date been applied. Secondly, we follow a species-specific systematic approach: for each species, we synthesise key results. Our results show how substantial progress has been hampered for several reasons including: a large predominance of small-scale field studies of short duration, and a generalised lack of control of: (i) confounding variables; (ii) spatial autocorrelation; and (iii) false absences. Also, despite the relatively high number of studies, few were theoretical studies and even fewer were meta-analyses. The lack of meta-analyses is likely to be due to the small amount of crucial details included in the publications, such as model parameters or information on the landscape context (such as the amount of residual forest cover). We synthesise the main results for 14 species. The level of progress is highly variable: for some species, such as the red squirrel Sciurus vulgaris, a series of long-term, large-scale process-oriented studies has allowed an in-depth understanding of its ecology in fragmented landscapes. On the other hand, with other species such as the bank vole Myodes glareolus, despite a relatively large number of field studies, little progress has been made

Population and individual‐scale responses to patch size, isolation and quality in the hazel dormouse

“…As we have mentioned in the methods section the hazel dormouse is a forest specialist that has similar responses to landscape change as several other vertebrate species (Bright and Morris 1996, Mortelliti et al 2010b, Mortelliti 2013 it is therefore likely that our conclusions may be applicable to a range of other species. The results of this study suggest that in the case of the hazel dormouse there is a need to manage the quality of habitat to ensure that colonization rates v www.esajournals.org counter local rates of extinction, thereby increasing the viability of the system.…”

“…We selected the hazel dormouse as our target species for four reasons: (1) it is well documented as being sensitive to habitat loss and to the disruption of connectivity (Bright et al 1994, Mortelliti et al 2008, 2010b, Keckel et al 2012, (2) it is a forest specialist that has similar responses to landscape change as several other vertebrate species (Bright and Morris 1996, Mortelliti et al 2010b, Mortelliti 2013, (3) its food resources (fruit and flowers of shrub species) are well known (Juškaitis 2008) and relatively easy to estimate, and (4) by using nest-boxes, it is possible to directly estimate litter size of females (Juškaitis 2008). These four key characteristics make the v www.esajournals.org hazel dormouse an ideal model species for evaluating the effects of patch variables on individuals and populations (Bright and Morris 1996).…”

After the Ice Age: The Impact of Post-Glacial Dispersal on the Phylogeography of a Small Mammal, Muscardinus avellanarius

“…As such, they are important as a bio indicator of ancient woodland health (Morris, 2003). Because of the empirical observation that dormice have a limited range associated with such habitat requirements, it is thought they have a relatively small ecological window for dispersal (Mortelliti et al, 2010). Therefore, the hazel dormouse is a compelling species to investigate the effects of the LGM on geographical expansion under a regime of climate change.…”

Hidden dispersal in an urban world: genetic analysis reveals occasional long-distance dispersal and limited spatial substructure among Dutch pine martens

“…Worldwide, fragmentation and loss of natural habitat forms the most important threat for wild species (Vitousek et al 1997). Effects on biodiversity may be especially severe in strongly urbanized areas like north-western Europe (Mortelliti et al 2010). Decreased size of forest patches may reduce habitat quality and maximum local population sizes of forest dwelling animals, which may increase extinction risks due to both demographic and genetic effects (Fahrig 2003).…”