VIE Marking of Tadpoles

The latest update from EDGE Fellow Werner Conradie.

Hewitt’s Ghost Frog (Heleophryne hewitti) was considered critically endangered, with a declining population. This was due to the fact that big fires and floods caused many of the streams to silt up. Big floods in 2007 cleared the streams from al lot of these silt and improved the micro habitat. The fact that tadpoles are doing well and that a new population was discovered in Cockscomb (which is in a pristine area) led to downgrading its IUCN status to Endangered in 2010.

For the last 20 months I’ve been marking tadpoles with the Visual Implanted Elastomer (VIE) markers to record their numbers and breeding cycles. The transect consisted of a 30 meters, in which I collected all tadpole I could find and marked them. See the following video on how I go about marking tadpoles.

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In total I marked over 700 tadpoles, with 44 recaptures (see figure 1). Normally the tadpole numbers is below 50. In the month of September adults start calling, mating take place and around 100 eggs are laid. This explains the high numbers of tadpoles collected in January. In the month of February and March the bigger tadpoles of the previous season start metamorphosing, explaining the slow decrease in tadpole numbers by October. It is expected that with the next marking in December the tadpole numbers will increase again.

To support the work of EDGE Fellow’s such as Werner you can donate to EDGE here.


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  1. on May 27th, 2011 at 4:00 pm

    good job my class love doin this work im 47

  2. georgia said,

    on October 27th, 2012 at 3:17 pm

    also,is there any particular reason as to why the graph follows this parabolic shape?

  3. David said,

    on November 13th, 2012 at 11:05 am

    Hi, Im doing ap roject on the conservation of the Hewitt ghost frogs, and part of it is to evaluate a previous attempt to save the species, and so i was wondering how much money this costed for EDGE to fund such a project

  4. gabriella said,

    on December 7th, 2012 at 6:46 pm

    hi, i was wondering, once collecting this data, what is the next step for the hewitt ghost frog?how will they be protected and how will this procedure benefit them or the scientist? Also, does this process give us any ideas about the chytrid fungus ie: what month it affects the most ghost frogs?

  5. Hannah said,

    on February 20th, 2014 at 9:55 pm

    I was wondering what the chytrid fungus has to do with declining numbers? I noticed on the EDGE webpage for Hewitt ghost frogs it said the chytrid fungus is affecting the population of Hewitt ghost frogs, but is there any evidence to suggest it is affecting the frogs? and if the chytrid fungus is affecting the frogs how will this help them?


  6. Jack Stewart said,

    on February 21st, 2014 at 9:25 am

    Hi Hannah,

    Chytrid fungus is now one of the leading causes of global amphibian decline. It is a highly contagious fungus that can cause high mortality in populations of amphibians. This blog from 2011 should explain things a bit better

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