My research interests are around survey and monitoring protocols for biodiversity; improving the effectiveness of volunteer survey schemes; modelling of presence/absence, survival and detection rates in the British herpetofauna; conservation of reptiles and amphibians; and indicators of biodiversity.

Design of survey and monitoring programmes for amphibians and reptiles

Numerous survey methods exist for both amphibians and reptiles, but the effectiveness of these methods is not properly understood, nor are they consistent between surveyors. The effect of this may be to reduce our understanding of both population sizes and distributions of species. In 2007-2008 I examined amphibian survey programmes for the National Amphibian and Reptile recording Scheme (NARRS) in the UK. As a result of this research the timings, method and number of surveys required were all adjusted. In 2009-10 I repeated the process for reptile survey programmes.

Completing these surveys taught us much that is of interest to the wider community of ecological surveyors and I am currently (2011-2012) working on a programme to develop new surveying guidelines.

Modelling of presence/absence, survival and detection rates

If a species is seen on survey, it is certainly present. However, if it is not seen, it may either be absent, or present, but simply not detected. Occupancy modelling is a means of taking survey data and working out the estimated true occupancy rate of a number of habitat patches, along with the likelihood of detecting the species on survey. From this detection likelihood it is a simple step to work out the number of surveys required.

Occupancy modelling is concerned with the presence or absence of populations. Similar software systems can calculate the detection and survival rates of individuals. From these it is possible to calculate the size of individual populations, even when only a part of that population is captured in capture-mark-recapture studies.

 Amphibians as indicators of biodiversity

Although amphibians have been widely promoted as indicators of biodiversity and environmental change, rigorous tests have been lacking. For my PhD study I examined the extent to which the great crested newt (Triturus cristatus) met published criteria for indicator species.  Although I found a link between the presence of great crested newts and aquatic plant diversity, this was not repeated with the diversity of macroinvertebrates. Equally, many amphibians do not meet many of the published criteria of bioindicators. A whole suite of indicators, rather than just a single species, will usually be required.

Teaching

I will also be involved in the teaching on DI303: Survey and Monitoring for Biodiversity

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Publications

Griffiths, R., Sewell, D, McCrea, RS, (2010). Dynamics of a declining amphibian metapopulation: survival, dispersal and the impact of climate. Biological Conservation 143, 485-491.

Sewell, D, Griffiths, RA, (2009). Can a single amphibian species be a good biodiversity indicator? Diversity 1, 102-117.

Sewell, D, Beebee, TJC, Griffiths RA, (2010). Optimising the efficiency of biodiversity assessments by volunteers: the application of occupancy modelling to large-scale amphibian surveys. Biological Conservation 143, 2102-2110.

 

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