What is it about?
Little is known about the native species, so much of the project focused on comparing the invasive and native species to evaluate the potential risk that H. frenatus poses to the local species. Dan caught a lot of animals of both species, measured and weighed each specimen, and marked it with a unique plastic tag. He also shone a lamp through the body to count the eggs (a clever little trick!). The unique plastic tag meant that he could recognise individuals and, through some clever statistics, work out how many animals were in the population. The results were interesting: the native species was larger and more common than the invasive (which runs counter to some other work on this species), but the invasive species had a greater number of eggs on average. This means that the native species may be holding its own for now, but might be vulnerable if the invasive species can out-breed it.
Why is it important?
There are so many species at risk that it is certain that some go extinct before we even recognise that there is a problem (sometimes we haven't even named the species before it is lost!). These kinds of studies on islands are valuable because they can provide insights into which native species are vulnerable to invasive species and which can hold their own.
The following have contributed to this page: Dr Christopher Hassall
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