News about frogs with missing limbs and other abnormalities has regularly been featured in newspapers and on the evening news for the past four years, nationally and here in Vermont. Field surveys conducted at 20 sites within the Lake Champlain Basin between 1997 and 2000 found that of 7,227 young northern leopard frogs examined, 7 percent suffered from external malformations.

The U.S. Geological Survey National Wildlife Health Center performed external and internal examinations on normal and abnormal frogs collected in several states. Examinations performed by this lab support current theories that many of the abnormalities are caused by primary errors in development, rather than later physical damage.

The Agency of Natural Resources will conduct a federally-funded study in the spring of 2001 to learn more about the causes of these malformations in the Lake Champlain Basin. The study will include diagnostic examinations of northern leopard frogs, chemical characterization of water and sediment from sites, and other laboratory and field studies. To date, there are still numerous possible explanations for the frog abnormalities, and it's certainly possible that several factors may be acting together.