The Carlisle Mosquito Online

Friday, June 10, 2005


Gray Tree Frog

(Photo by Kay Fairweather)
Name: The scientific name of the gray tree frog is a bit tricky. There is the greater gray, Hyla versicolor, and the lesser gray, Hyla chrysoscelis. They are identical in their external characteristics and are differentiated from one another in the lab by microscopic analysis of blood cells and by chromosome counts. The lesser gray is diploid and the greater gray is tetraploid. The common name is also a bit tricky because the gray tree frog is as likely to be green as it is to be gray. Newly metamorphosed frogs are bright green.

When and where seen: Neils and Doris Larsen of Concord Road found this gray tree frog sitting on a fence railing out in the full sun on the morning of June 2. It stayed in the same place for more than an hour. You might see a gray tree frog on a humid summer night clinging to a window pane if house lights have attracted a lot of insects.

Characteristics: The gray tree frog is a medium-sized frog about two inches long. They have gray or green backs sometimes decorated with markings, and they usually have a white spot or rectangular patch below the eye. They violate the old rule of thumb that frogs are smooth and toads are warty — they are very bumpy and warty. Like all species of tree frogs, they have large round pads on their toes which allow them to cling to vertical surfaces. The gray tree frog is a master of camouflage. This one at the Larsens' was perfectly matched to the gray color of the weathered railing. Tadpoles can be distinguished by their green body and orange-red tail.

Gray Tree frog, well camouflaged. (Photo by Kay Fairweather)

It's a's a frog: Their bird-like trill can be heard all around town these days. Even though the frogs emerge from their protective winter sites in April, they are not heard from for several weeks until the temperature at night is around 50 degrees Fahrenheit. The males sing day and night and especially during thunderstorms. At night they are likely to be singing from a more exposed location than in the day. You can try and spot them with a flashlight, which doesn't bother them, but they have the ability to throw the sound in a way that makes it hard to tell the direction.

References: The US Geological Survey provides national expertise not only in geography, geology, and hydrology, but also in biology. The Northern Prairie Wildlife Research Center (NPWRC) is part of their Biological Resources Discipline and it has a good web site. The gray tree frog page is at Additional source: Thomas F. Tyning, Stokes Nature Guides, Guide to Amphibians and Reptiles.

Other nature notes:

Fisher update: On January 23, 2004, the Biodiversity Corner featured the fisher. The sighting at that time, by Tom Wilson, was of tracks and scent markings in the woods. At the end of March 2005, Betty Meehan of Autumn Lane photographed a fisher on the deck of her house as it tried to get at suet in a basket below the grill. She described it as "a beautiful mahogany brown, very sleek looking with an ugly face." It reminded her of a large bushy-tailed mink. It is likely to have been a male since they tend to forage at ground level more often than the females who tend to stay in the trees. Betty found the following text in the 1938 edition of Wild Animals of North America: "This strong and swift animal confines itself to the Adirondacks in New York and the Green Mountains in Vermont. It is extremely rare and may disappear entirely, because it is hunted as a dangerous animal." Today, sightings in Carlisle, while not common, are not rare either, and Central Massachusetts is reputed to have one of the highest densities of fishers in the country.

Turtle watch: June is the month when lots of turtles are on the move looking for places to lay eggs. Watch out for them on the road.

2005 The Carlisle Mosquito