Calling Amphibian Monitoring Project (CAMP)

The Conserve Wildlife Foundation of NJ coordinates the statewide Calling Amphibian Monitoring Program (CAMP). The object of this program is to assess the distribution, abundance, and health of New Jersey’s amphibians. This is part of a larger initiative called the North American Amphibian Monitoring Program (NAAMP) and the data collected in New Jersey will be submitted into the National database.


Each of the 16 species of frogs and toads in New Jersey has a unique vocalization or “call” that can be heard during their mating season.

Here’s a list and call quiz of the Frogs in New Jersey:
Eastern Spadefoot (Scaphiopus holbrookii)
American Toad (Anaxyrus americanus)
Fowler’s Toad (Anaxyrus fowleri)
Northern Cricket Frog (Acris crepitans)
Pine Barrens Treefrog (Hyla andersonii)
Green Treefrog (Hyla cinerea)
Gray Treefrog (Hyla versicolor)
unknown gray treefrog species (Hyla chrysoscelis/versicolor)
Cope’s Gray Treefrog (Hyla chrysoscelis)
Spring Peeper (Pseudacris crucifer)
New Jersey Chorus Frog (Pseudacris kalmi)
American Bullfrog (Lithobates catesbeianus)
Carpenter Frog (Lithobates virgatipes)
Green Frog (Lithobates clamitans)
Wood Frog (Lithobates sylvaticus)
Southern Leopard Frog (Lithobates sphenocephalus)
Pickerel Frog (Lithobates palustris)

The Amphibians that are listed as Endangered or Threatened in New Jersey:

Endangered Amphibians
Salamander, blue-spotted – Ambystoma laterale
Salamander, eastern tiger – Ambystoma tigrinum
Treefrog, southern gray – Hyla chrysocelis

Threatened Amphibians
Salamander, eastern mud – Pseudotriton montanus
Salamander, long-tailed – Eurycea longicauda
Treefrog, pine barrens – Hyla andersonii

Volunteers participating in the CAMP project conduct roadside surveys (after dusk) for calling amphibians along designated routes throughout the state. Each 15-mile route is surveyed three times during the spring (March, April & June), during the given four week period. Each route has 10 stops, where you stop, listen and record for 5 minutes. A structured protocol is followed to determine which nights to survey, how long to survey, which species are calling, and how to estimate the total number of individuals calling at each site. All volunteers receive a Calls of NJ Frogs and Toads, CD with which to familiarize themselves with the calls.

The results of these surveys will provide ENSP (Endangered and Nongame Species Program) and the United States Geological Survey with valuable data on the calling amphibian populations in New Jersey. Because each route will be surveyed at the same time and for the same amount of time, routes can be directly compared within a given year and between years. This allows for trends in populations to be identified over time and if needed steps may be taken to protect these populations in the near future.

— Larissa Smith, Biologist/Volunteer Manager, Conserve Wildlife Foundation of NJ


Learning How Frogs See and Hear

Guest post by Wes Deyton

How Frogs See

Frogs, due to the positioning and design of their eyes have nearly a 360 degree view. This makes up for the fact that they are not able to turn their head and look behind them like other animals can. Frogs, with their nearly 360 degree of field of view, make it difficult for predators to sneak up on them. Frogs also are unable to move their eyes within their eye sockets like humans and other animals can. This causes a Frog to have to turn his head to line up with it’s prey.


Frogs cannot see while they are attacking prey, so they must have their prey lined up when they go in for the strike. They are unable see their prey while they are making a strike, because when their sticky tongue comes out to snatch up an insect, their eyes retract into the top of their head.

Frogs are near-sighted and they do not see very well at a distance. Their eyes are extremely sensitive to movement, so if a frog’s prey does not move, they will not detect it. They also have excellent night vision, due to a mirror like layer in the back of their eye called a Tapetum. The Tapetum helps frogs reflect and collect ambient light between the back of the eye and the frog’s cornea. Frogs also use their eyes in a rather interesting way. They are unable to swallow like humans and other animals, so they actually push their eyes down into their head to push their food into their stomach.

Frogs eyes come in all different colors, from copper to bronze, gold to silver, and orange to red, like the Red-Eyed Tree Frog. They have three different eye lids. The third eye lid is the most interesting which is a clear membrane, and is called a Nictitating membrane, and this eye lid helps the frog to see underwater as well as to hide from predators.

How Frogs Hear

If you have ever been outside on a warm night you know just how loud Frogs and Toads can be. Male Frogs and Toads call to attract females. Below is a video of an American Toad calling to attract a mate.

You can see in the video, a Toad’s eardrum is the circular indention behind their eyes. You can also tell from the video, this toad calls quite loudly. Frogs and Toads are able to call at upwards of 90 decibels. They have quite sensitive hearing, so the question is, how do they not damage their eardrums or deafen themselves with their loud calls?

Scientists have discovered that Frogs hear with both their ear drums and their lungs and a pressure system builds inside the Frog that minimizes vibrations from internal noises made by the frog.

To further elaborate on this, I need to talk about how a frogs ear drum works. A frog’s ear drum is called a Tympanum and works in very much the same way that our human ear drums work. A frog’s ear drum, just like a humans ear drum, is a membrane that is stretched across a ring of cartilage like a snare drum that vibrates. There is rod that is connected to the ear drum, which vibrates by sounds that come at the frog. That sound is just pressure waves. The rod sloshes around in the inner ear fluid, which causes microscopic hairs to move, which send signals to the frog’s brain for interception. A frog’s ear lungs also vibrate when sound waves come toward it, although they are less sensitive than the frogs ear drum.

Earth Day poster with frog photographer, Wes Deyton and designed by Susan Newman

Some frogs, like the Spring Peeper, pictured, have a call that is so loud, they can be heard up to one mile away. These creatures are so noisy, it is a wonder that they do not hurt their ears and deafen themselves with their own calls. Frogs have a very clever method of making sure that their own loud calls do not hurt their own hearing.

In 1988, Scientist Peter Narins, who is a professor at UCLA of Physiological Science, found that frogs have an internal pressure system, a closed air loop, that keeps the frog’s own ear drum from vibrating excessively from its own call. Scientists have found that pressure builds between their lungs and ear drum, which then equalizes the pressure between the inner and outer surfaces of the frogs ear drum, which greatly cuts down on the vibrations that a frog experiences, from their internal calls. It is also believed that another purpose of the closed loop pressure system, is so Frogs can detect the direction a sound is coming from with its lungs, that way they can escape danger while calling. Being in the vicinity of a frogs calling can subject a human to sounds so loud, that are upwards of 90 dB, which can cause discomfort and hearing loss for humans.

Sources: April Holladay: Frogs Can Hear Without Ears. 4/26/2001. Wes Deyton’s blog at Last Mile Photography


A – Z Frog Species: American Bullfrog (Rana catesbeiana)

american bullfrog
Is the most widely spread “true frog” of North America. Found in almost any body of water, they are aggressive predators, consuming everything from plants to small mammals. It is said that if the Bullfrog can shove it in its mouth… it will be eaten! Starting as eggs they go through metamorphosis in 3 months to 3 years depending on climate. Northern specimens taking longer than those in warm southern states. A frog jumping contest favorite, these amphibians can leap as far as 6 feet in a single bound!

Coyote Peterson with frog
New series by guest blogger, Coyote Peterson, Coyote Peterson Brands, LLC.


Bullfrogs and other Super Species – Will They Soon Dominate Our Planet?

Super species are the phenomenally successful invasive creatures—animals, plants, and microbes—that are dominating ecosystems around the globe. Feral pigs are relentlessly trampling across Europe, North America, and Australia. Jellyfish are dominating the world’s oceans, clogging fishing nets. Not to mention the invasive species that are in our own backyards:  house sparrows and eastern gray squirrels.

In Super Species: The Creatures That Will Dominate the Planet (Firefly Books, published October 2010) Garry Hamilton details the fascinating stories of the species that seem to have won the natural selection sweepstakes. Some of these super species include the European green crab, the giant African land snail, the Argentine ant, nutria, zebra mussels, the chytrid fungus, and killer algae.

One of the species he describes, the invasive American bullfrog, especially concerns us at Frogs Are Green. Hamilton contends that bullfrogs are more invasive than Australia’s notorious cane toads. The reasons are many—bullfrogs were shipped around the world for use as biological control agents, as pets, or for sport.

Frog farms have also led to their introduction to nonnative areas. In the late 1800s after gold miners out West ate their way through native frogs, entrepreneurs imported American bullfrogs from back East to satisfy the increasing demand. Eventually farming bullfrogs spread to other parts of the world as well.

As Hamilton describes it, bullfrog farming isn’t easy and many of the frogs in these “farms” were let loose. Most frogs wouldn’t have survived. But like many invasive species, bullfrogs are highly adaptable. Bullfrogs like deep, stable, non-moving aquatic habitats. This describes many human-modified environments: reservoirs, farm ponds, irrigation channels, and even garden water features.

Bullfrogs can survive through cold Ontario winters and the extreme heat of Southern U.S. summers. Female bullfrogs can produce between 6000 and 7000 eggs and as they mature, up to 25,000 eggs per clutch. As carnivorious amphibians, they prey on fish, water beetles, snails, turtles, bats, voles, ducklings, snakes, lizards, and salamanders.

Bullfrogs compete with and prey on native frogs. This is one of the contributing factors to the worldwide decline of amphibians. Bullfrogs may also be helping to spread the deadly chytrid fungus, which is devastating frog populations around the world.

Attempts to deal with invasive bullfrogs have been challenging. But scientists have found that their numbers are fewer in waterways that haven’t been altered by people. As Hamilton writes, “By changing the physical parameters of a freshwater wetland, humans also change the playing field for all life-forms in the ecosystem, and this results in a cascade of ecological readjustments.”

The answer, Hamilton contends, is not to use the old methods such as killing the frogs and draining ponds. Rather, he says that in order to save native frogs, we need to save their habitats. Altering habitats is conducive to an invasion of bullfrogs.

I had mixed feelings reading about invasive bullfrogs. I like coming across them in ponds in the woods of upstate New York (one of their original habitats), their eyes peering just above the water, as they croak a bass jug-a-rum sound. One of my favorite frog books, The Frog Book, written in 1906 by naturalist Mary Dickerson, describes the bullfrog:

If we go rowing on river, lake, pond or park lagoon,  some moonlit night late in late June, we are certain to hear the deep-toned call of the Bullfrog many times. Coming as it does at unexpected intervals  and from unexpected directions, it seems startlingly weird in the quiet of the night. For June nights are quiet. The insect orchestras are not in full swing and the frog choruses have disbanded.

During Dickerson’s time, bullfrogs were less common than other frogs. At that time, they had many natural predators to keep them in control: snakes, otters, hawks, owls, herons, and turtles, and frog farming was mainly in the future. But human intervention tipped the balance.

In Super Species, Hamilton documents the story of many species like bullfrogs in which human intervention and alterations of habitats led to an imbalance. But his tone isn’t hysterical. Some invasive species like the plant kudzu, he contends, don’t actually have much of an impact on local biodiversity despite alarmist news stories. These species may actually be creating a new biosphere from the “rubble of our own destruction.”

This review is part of Ecolibris’s  Green Books Campaign.  Today at 1:00 p.m. ET, 200 bloggers will take a stand to support books printed on recycled or FSC-certified paper by simultaneously publishing reviews of 200 such books. By turning a spotlight on books printed using environmentally-friendly paper, Ecolibris wants to raise the awareness of book buyers to this issue and to encourage them to take it into consideration when purchasing books.


Frog Call of the Week: Jeremiah the Bullfrog

Jeremiah (the American bullfrog) is our largest native frog, growing from 6 to 8 inches in length. Bullfrogs are found throughout most of North America. They like to hang out in large bodies of water like lakes, ponds, and slow-moving streams. Where bullfrogs have been introduced (for example, in the western U.S.), they have become pests because they eat anything smaller than themselves, including native frogs.

The bullfrogs call sounds like rumm….rumm…rumm….or a stuttering ru-u-u-umm…ru-u-u-umm (often written as jug-a-rum).*

I picked up a book recently called The Frog Book, written in 1906 by herpetologist Mary C. Dickerson. She wrote beautiful descriptions of the amphibians she studied. Here’s her description of the bullfrog call:

If we go rowing on river, lake, or park lagoon some moonlight night in late June [in the northeast], we are certain to hear the deep-tone call of the Bullfrog many times. Coming as it does at unexpected intervals and from unexpected directions, it seems startlingly weird in the quiet of night. For June nights are quiet. The insect orchestras are not in full swing, and the frog choruses have disbanded. The Bullfrog does not sing in chorus; the call is an isolated one. The notes are so low that we think of him as the bass viola among frogs. The call resembles, to a considerable degree, the roar of a distant bull..

Here’s a video of a bullfrog calling, created by Ravenswood Media. Enjoy!

Info from The Calls of Frogs and Toads by Lang Elliott and The Frogs and Toads of North America by Lang Elliott, Carl Gerhardt, and Carlos Davidson. Both books include CDs of frog calls.