The distribution and dispersion of herpetofauna in lowland farmland: with a focus on the common toad (Bufo bufo)

Thesis

Concern over unexplained population declines in the common toad (Bufo bufo) has led to it being recognised as a priority species for conservation research. The general consensus among herpetologists is that the most important cause of the declines seen as part of a global amphibian extinction crisis is habitat loss and degradation.

The aim of thesis is to investigate the effect of habitat availability and quality on common toad populations in the United Kingdom, with a particular emphasis on the effect of land under agricultural use. I use occupancy modelling, resource selection function modelling and genetic techniques to determine the effects of both terrestrial and aquatic habitat on common toads. Based on my findings, I consider the impacts of habitat at local, landscape and national scales.

My research revealed the importance of pond density and presence of woodland in increasing relative probability of toad occurrence in the terrestrial habitat (Chapters 2 and 3) and the importance of water quality, woodland coverage and available terrestrial habitat coverage in determining common toad presence in ponds. The isolating effect of urban areas is demonstrated in Chapter 4 where Isolation By Barriers (IBB) explains genetic distance between common toad breeding populations better than Isolation By Distance (IBD). In Chapter 5 I again use the resource selection function for terrestrial habitat use developed in Chapter 3, to investigate the importance of terrestrial habitat availability in determining pond use by common toads at a national scale.

In my concluding chapter, I make recommendations for management and further research including consideration of potential interactions between the effect of habitat loss, fragmentation and degradation with other potential causes of common toad decline.

Authors: Salazar, R; Rosie Salazar

• Publication date: 2014
• DOI: 10.5287/ora-kenxg5vz9
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: Oxford University, UK
• Language: English
• Keywords: agri-environment schemes; conservation; habitat; Bufo bufo; farmland
• Subjects: Ecology (zoology)