RESEARCH (as at 2009)
Conservation decisions for the Western Leopard Toad, like other animals and plants, need to be based on precise data obtained from objective research.
Research on most amphibians in South Africa has not concentrated on conservation issues and we often important conservation decisions must be based on very little data. For the Western Leopard Toad a provisional research agenda has been designed up to aid with immediate conservation planning needs. Some of the projects listed below are underway, and others have yet to start. As projects are completed we will add a link to a page with results and decisions. If you are interested in participating in Western Leopard Toad research, please contact the hotline.
Estimating the size of a Western Leopard Toad population
Every year we see Western Leopard Toads migrating to their breeding sites, and we see dead animals squashed on the roads. How many animals make it to breed every year? Do all animals go to breed every year? What proportion of the breeding population are killed?
Knowing how many animals make up a breeding population of Western Leopard Toads is of fundamental importance to almost every conservation decision. There is a tried and tested technique called “capture-mark-recapture” through which we can model population size. Happily, we don’t have to mark Western Leopard Toads as they – like Leopards - have their own individual markings on their backs – all we need is a clear photograph of the back, and some sophisticated computer ID recognition software, and we can estimate how many toads are in each population.
But we need YOUR HELP! We cannot photograph every toad that is out there as they all breed around the same time. To help you need a camera (your cell phone camera is suitable), a ruler or matchbox to allow us to measure the toad on the photograph, and you need to know where you area. We need you to photograph all the toads that you see and upload the images onto our website: UPLOAD YOUR TOAD
If we get enough pictures from ponds in your area, we can calculate how many adults live there, and even tell you where your toad was last seen!
Estimating current Area of Occurrence
Knowing how big an area animals occur in is crucial to estimating population sizes, numbers of populations and extent of any threats. This if often not as easy as it seems. Are we aware of the full extent of the distribution of the Western Leopard Toad?
In 2004, the Atlas and Red Data Book of the Frogs of South Africa (Minter et al., 2004) revised the IUCN red-listing of all the known frog species in the country. The Western Leopard Toad was recognised as being Endangered due to its small distribution and ongoing decline in the quality of habitat in the Western Cape. The atlas recorded the toad in 6 quarter degree squares (QDS, each equivalent to 25 km X 26 km2 around 650 km2), while it had previously been known from 7.
Very few breeding sites are known East of False Bay, and breeding activity in Betty's Bay and Kleinmond has not been recorded for over 20 years. Research is underway to discover exactly how many breeding sites occur on the Aghulus plain. If you live in this area and have Western Leopard Toads breeding on your property, please contact the webmaster or hotline.
This work is being sponsored by SANBI Threatened Species Programme.
Fine scale genetics of toads in the Cape Metropolitan Area
If Western Leopard Toads know where they are going and return to the same site every year, do they ever move between ponds? Or more technically: is there genetic structure within and between populations?
At some sites, Western Leopard Toads all breed at the same time, but at others they breed much later or earlier. Could this represent a temporal genetic isolation?
Western Leopard Toads have been found far from any known breeding ponds, do they disperse between ponds and is there a sex bias in those animals which disperse?
If Western Leopard Toads can move between ponds, can they also move over mountains?
Genetic studies can be of great help in making informed conservation decisions, as well as informed decisions during mitigation exercises. SANBI (ABR) molecular lab scientist, Lucas Chauke, created a microsatellite library for Western Leopard Toads in the Pritzker Laboratory in August and September, 2008. Microsatellites are polymorphic loci from DNA that generally exhibit a high level of variability. They have been successfully used to determine relationships within a species, both between populations and individuals.
This work is not currently being sponsored. Would you like to sponsor Western Leopard Toad research? Contact the webmaster or call the hotline.
Radio-tracking of Western Leopard Toad
Tracking movement of individual animals can give a generalised picture of which parts of a habitat is used. In the case of the Western Leopard Toads, we do not know whether the majority of toads move through the same areas (the highway theory), or if animals disperse randomly into the surrounding habitat (the scatter theory). Once individuals have finished their migration, the same equipment can be used to discover their home-range and preferred habitat type. Two approaches can be taken:
Attaching transmitters to toads in their foraging habitat just prior to breeding (i.e. during early August). The diurnal resting sites of many toads are known as they occur in gardens, parks and even on mountains in the Cape Peninsula. Locating and attaching transmitters to animals from ambiguous areas (those > 1km from any known breeding site) can be informative about which breeding sites these individuals use, the routes they chose to get there, and whether the same corridors are used by multiple individuals.
Attaching transmitters to toads immediately after breeding. It is easy to determine when females have finished breeding by their thin condition and movement away from a breeding site. At this time both males and females can have transmitters attached to discover the foraging area associated with a single breeding site.
Part of this project is going on in the southern-suburb of Kirstenhof by Farrah Feldmann for her MSc registered at Cape Peninsula University and Technikon. We are currently planning another radio-tracking study for Western Leopard Toads in the Gansbaai area.
This work is being sponsored by SANBI Threatened Species Programme.
Explaining the distribution of Western Leopard Toads
Western Leopard Toads have an odd distribution being found on the Cape Peninsula and part but not all of the Cape Flats. On the other side of False Bay they can be found in some ponds but not others. What factors determine the distribution of Western Leopard Toads?
In this study we are taking a modelling and measuring approach to the ponds where Western Leopard Toads occur and those where they don’t. If we can accurately describe the distribution of this species from knowledge of the conditions that they require, we can begin to decide how to create new habitats within their most threatened areas of occurrence.
Information compiled by John Measey, May 2009
Comments
Add a Comment