The longest calling period was in Central Ontario in 1995 when they were heard for 136 nights. The longest calling period occurred in Central Ontario in 1998 when they were heard on 137 nights. As the years go by, the importance of ongoing backyard monitoring throughout the calling period and performing road call counts during the correct dates and weather conditions becomes more and more obvious. As you can see, the calling periods can change a lot between years. It requires more than one year of data to confirm that each species still occurs at a location.
Pollution is a less visible and potentially insidious threat to amphibian survival.
Nitrate is an example of a pollutant which now occurs in many watercourses around the world at concentrations which can kill amphibians. Nitrate is a natural compound present in all ecosystems. It is one of the chemicals essential to plant life but too much can be a problem for plants and animals. It is also a component of chemical and manure based fertilizers. Nitrate can enter watercourses and ponds from sources such as areas of high fertilizer use, livestock feedlots and pastures, and sewage treatment areas.