Why Did the Amphibian Cross the Road?

Eastern Tiger Salamander (endangered in NJ)

Not only can you ask "Why Did the Amphibian Cross the Road?" but why would it try to cross a Jersey road?

In the article "Death by Rubber" on ScienceLine, they look at global amphibian declines and the scientists and volunteers who are trying to preserve backyard biodiversity.

That article looks at some volunteers on a wooded road in northwestern New Jersey, last March who were looking for frogs and salamanders to count. They wait for the amphibians to cross the road on their way from the wooded uplands where they winter to the marshy lowlands and vernal pools where they will do their spring mating.

Their night wasn't very successful and it's interesting that even experts are unsure what exactly triggers the spring migration. It might be rising ground temperatures, dropping barometric pressure and even the sound of the raindrops since the amphibians need the rain to stay moist and will need the vernal pools when they cross the road. In that case, they were hoping to see at least wood frogs and blue-spotted salamanders (pdf) which are more common amphibians in northern New Jersey and not endangered.

The NJDEP, Division of Fish and Wildlife’s Endangered and Nongame Species Program, the Conserve Wildlife Foundation of NJ, and the NJ Audubon Society are partners on the Amphibian Crossing Survey Project(pdf). They use volunteers to help us monitor sites in Warren and Morris County and to identify additional crossings throughout the northern region of the state. Due to limited resources, they are currently focusing efforts on northern New Jersey.

Seven years ago, volunteers had reported over 400 amphibians crossing the road in one night. Of course, crossing an NJ road has got to be a bit more hazardous than some other places and traffic has only increased in those 7 years.

It is estimated that one third of the world’s amphibians are threatened with extinction, according to the International Union for the Conservation of Nature (IUCN).

One habitat in Morris County, has probably lost its local population of blue-spotted salamanders which are an endangered species in the state, probably because of road kill during these crossings.

But roads also cause problems because of car exhaust, road salt & chemicals that leach into neighboring waterways and damage amphibian eggs and tadpoles and the simple fact that roads break large amphibian breeding groups into small, fragmented populations.

And NJ is not immune to other factors besides loss of suitable habitat. Even in safe areas, droughts and drier conditions have made these vernal pools disappear, perhaps due to climate change.


NJ Online Field Guide for Reptiles and Amphibians