Researchers from the University of Copenhagen have developed an interestingly effective method for monitoring tropical mammal populations which would otherwise be costly and difficult to survey. Leeches can contain traces of DNA from blood meals more than four months old.
This new method was tested in a Vietnamese rainforest. Twenty-one of the twenty-five leeches collected by researchers during this time contained DNA traces identified as those of local mammal species, some of which were very rare. One species of rabbit had not been seen in that region since it was first discovered in 1996, but subsequent monitoring of the area produced confirmed video of the rabbit.