The northern leopard frog was once a very common species in North America. So common, that hundreds of thousands of students dissected the amphibian in high school biology class. The population of the frog has dropped 60 to 80 per cent in the last 30 years, and it is now considered threatened in Alberta. Zoo scientists working with other conservation organizations are conducting field research and developing a new sophisticated mathematical monitoring technique to better study the size and distribution of the population. Zoo veterinarians are also studying two pathogens that have been implicated in the decline of amphibians worldwide.