Survey methods

Conservation measures intent on the preservation of wildlife and their habitats should be built upon sound scientific data.  These data typically include baseline information on the species found in an area, the habitats with which they are associated and measures of species abundance.

ZSL employs a suite of scientific techniques that can be used individually to answer specific questions, such as “which species are found in a certain area?”, or can be combined to address more complex issues, such as “what factors are contributing to a species’ decline?”

While much of the work is done in the field, increasingly conservationists employ Geographic Information Systems (GIS) and satellite imagery analysis to target survey effort and analyse results.  These tools provide an excellent means of conveying research findings through the production of high quality maps and landscape models.

Surveys conducted in discrete locations can often be combined to tackle far larger scale issues.  With the permission of the associated industrial partners, researchers can combine data from smaller scale surveys to investigate regional conservation questions, such as how many Sumatran tigers live outside protected areas?

Researchers apply different survey methods depending on the nature of the underlying question(s) and the constraints imposed by the local environment, logistics and finance. Current methods include:

  • Detection/Non-detection surveys

  • DNA sampling

  • Pitfall traps

  • Call surveying

  • Social surveys

Detection/Non-detection surveys

The area of interest is divided into different habitat types and a grid of smaller research sites is overlain. These sites or ‘cells’ are repeatedly surveyed. The species present are identified and recorded from their foot prints, faeces and from direct sightings.

This technique provides a list of species encountered and a measure of survey accuracy. Outputs include species distribution maps that can also include an indication of habitat condition and levels/types of human activity if required

Landscape surveys provide the data on which effective conservation measures depend. Flexible study design and innovative data analysis techniques are combined to address both the needs of our industrial partners and those of the wider conservation community.

DNA Sampling

Genetic material is often collected from animal’s faeces, hair or blood samples.  In a fieldsetting, extraction of DNA from faeces has proven an excellent means of monitoring black rhino. This method can identify individuals, age, sex and relatedness within a population.

Pitfall Traps

Pitfall traps are usually buckets dug in to ground level and lined with moistened sponging.  They are usually placed along solid fences or at the end of solid fencing (also known as “drift nets”). Animals move along fences at night and drop into the pitfalls, where researchers collect them from in the morning. Fence and pitfall arrays are often used at breeding ponds (in the case of amphibians), but can also work well with species that are strictly terrestrial, such as the long-eared jerboa.

Call Surveying

Call surveying involves walking through the target species’ habitat at night and listening for vocalisations. There are many limitations to call surveys, not the least of which it only samples animals that make calls

Social Surveys

Questionnaire surveys can be used to identify different socio-economics groups, their prevalence in a given area and their use of natural resources. They can be used to compile measures of human activity and the associated impact on wildlife or as indicators of land use patterns, for example the rate of agricultural land clearance.

As scientific information on a species’ life history, ecology, and community dynamics develops, so does the capability to action sound conservation practices.  However, current data for many species are sorely lacking. Target species may be secretive, nocturnal (night-active), diurnal (day-active), arboreal (tree-dwelling), aquatic (water-dwelling), fossorial (burrowing) and even switch between habitats at different stages of development (in the case of amphibians).  For these, and other, reasons, field techniques designed to reveal the ecology and habitat requirements of different species are myriad.

Good estimates of population dynamics require long-term data sets, which are unavailable for many poorly-known EDGE species.  To bypass this shortcoming, researchers are moving towards comparative studies with specific a priori hypotheses.  For instance, if deforestation is deemed to be a potential threat to a forest-dwelling frog with direct development (development that involves no free-living aquatic larval stage), a research team may decide to select a set of forest patches, half suffering from deforestation and half not.  Within these patches, they may erect fenced arrays with pitfall traps located at the ends of the arms of the arrays and at the fulcrum of each pair of arms. Because the species is a direct-developing one, there is no need to dip-net (link to relevant section in Amphibians Survey Methods) or seine water bodies for larvae, however, teams may perform time-constrained ground-searches for nests.

More recently, approaches are being used that bypass population size estimates entirely and instead focus on how the occupancy of habitat patches over broad geographic areas is correlated with presumed species threats.These site occupancy techniques enable smaller numbers of researchers to gather large amounts of reliable data and examine area occupancy in a comparative manner.