06/18/14

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.

Gray-Tree-Frog-by-M-Patterson

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

05/1/14

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.

American-Bullfrog-by-Wes-Deyton

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

04/22/13

A – Z Frog Species: Spring Peeper – Pseudacris crucifer

Spring Peeper

Spring Peeper (Pseudacris crucifer) is a tiny little chorus frog found across most of the eastern U.S. and Canada. Tan with a dark cross on its back they are often less than an inch in length. Making home to a number of wetland environments they prefer semi-wooded areas and must lay their eggs in an aquatic location. Feeding on a variety of invertebrates they can often be found near lights in warm summer months where all sorts of bugs gather. Capable of surviving temperatures as low as -8 dC they hibernate under logs or beneath lose bark. One of the greatest sounds of spring, their call, signals warm weather is here!

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