Your Land & Water for August 2025

What's in this issue? The wonderful trill of a small but mighty treefrog is a common sound in the Southern New Jersey area. While they can be hard to find they are most certainly a delight to have around and are a special sight to see. Read below to learn more about this fantastic amphibian!

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GRAY TREEFROGS

By Suzanne McCarthy

One of the animals that may live near your house is the Gray Treefrog. You can recognize them if you hear their trilling calls from trees bordering your property or in nearby woods. The calls are often mistaken for bird sounds at first. The fact that the calls are very repetitive and are heard at twilight helps to identify the trills as coming from frogs. They can be heard from May through October. These little frogs get especially loud before thunderstorms and when it rains. To hear these frogs singing, go to: https://www.youtube.com/watch?v=9bzotS1ow0Q

There are two different species of Gray Treefrog, the Northern Gray Treefrog (Hyla versicolor) and the Southern Gray Treefrog (Hyla chrysoscelis), also known as Cope’s Gray Treefrog. The Northern species is found throughout the entire state of New Jersey but the Southern Gray Treefrog is at its uppermost limit in range and is found only in Cape May, Cumberland, Ocean, and Atlantic Counties. So, although abundant in the southern U.S. and parts of the Mid-west, it is listed as threatened in New Jersey. The two species are identical except for their different calls. The Southern Gray Treefrog’s call is quicker, shorter, and higher pitched, while the northern treefrog has a slower trill. Gray Treefrogs slow their calls when the weather is cool. During that time, observers can only tell the difference between the species when the calls are recorded and then digitally slowed.

Eastern Gray Treefrogs Photos by Wayne Fidler https://www.paherps.com/herps/frogs-toads

Although the ground color in the adult treefrog is gray, the Gray Treefrog's color changes in response to its environment and activities and can range from green to gray or brown.

The upper surface of the body has a blotchy pattern that resembles lichen, and they are warty looking, like toads. The inner surface of the hind legs is yellow or orange. They grow to be one to 2.5 inches in size. Young versions are bright green in color. The enlarged tip of each digit, which is very large in the Gray Treefrog compared to other treefrogs, produces an adhesive fluid. This, in combination with the large toepads, allows this species to better grip trees and to climb vertically.

Eastern Gray Treefrogs Photos by Wayne Fidler https://www.paherps.com/herps/frogs-toads

Their primary habitat is deciduous or mixed deciduous/evergreen woodlands, but adults often can be found near suburban homes where they feed on insects attracted to lights at night. Access to trees and a water source (even a puddle) is common to all habitats it occupies. When a Gray Treefrog is young and newly metamorphosed, it usually remains near the forest floor. As it ages, it may shift to living in the forest canopy.

High humidity and nights warming to 60ºF initiate breeding activity. Males usually maintain a distance of at least 30 inches from other males. They are very territorial and will fight other males to defend their area. Fights may last 30 to 90 seconds and consist of wrestling, shoving, kicking and head butting until the subordinate male retreats. Females instigate mating by approaching a calling male and touching him before rotating 90 degrees. Eggs are laid from late April through August. Transformation into a terrestrial frog occurs after one to two months.

Two gray treefrogs. www.wildlifeofct.com

Gray Treefrogs spend the winter beneath leaf litter, rocks, or in underground crevices. They have the remarkable ability to withstand freezing temperatures. Adults can survive for several days, partially frozen, at up to 20 below zero (Fahrenheit). They do so by developing large amounts of glycerol in their blood. Juveniles use both glycerol and glucose for antifreeze. In the experiments that determined this, over 40% of the frog’s total body water was frozen.

It is very difficult to see Gray Treefrogs in the daytime, even if they are calling. However, at night, they crawl onto tree trunks, branches, and fallen limbs and sing in full view. Use a flashlight to search calling sites. Horizontal branches over water, with little or no leaves, and along stone walls, wooden fences, building eaves, and around swimming pools and ponds are the most probable spots. If you find one treefrog, it will likely be there in the same location for more than one sighting, as they remain in their home range.

Sources:

“Signs of the Season Factsheet” https://extension.umaine.edu/signs-of-the-seasons/indicator-species/gray-treefrog-fact-sheet/

Kenney, Leo P. and Matthew R. Burne, with modifications and adaptations for New Jersey by Jason Tesauro, Kris Schantz, and Melissa Craddock. c.2001. Salamanders, Frogs, and Turtles of New Jersey's Vernal Pools: a Field Guide. NJDEP, Division of Fish and Wildlife,

Endangered and Nongame Species Program.

Pennsylvania Herps. https://www.paherps.com/herps/frogs-toads/copes_gray_treefrog/

Smithsonian’s National Zoo & Conservation Biology Institute Factsheet: nationalzoo.si.edu/animals/gray-tree-frog

Tyning Thomas F. Guide to Amphibians and Reptiles. 1990. Edited by Donald W. Stokes & Lillian Q. Stokes. Little, Brown and Co., Boston, NY, London. 1990.