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DFW Herpetological Society - Herp of the Month
November 2003


The DFW Herpetological Society is a group with a mission - to promote understanding, appreciation and conservation of reptiles and amphibians, and to encourage respect for their habitats.

If you want to learn about native species and recognize venomous snakes, this is the group for you!  Interested in observing and photographing reptiles and amphibians in the wild?  DFW Herpetological Society members enjoy field trips to local destinations as well as weekend-long expeditions to locations such as the Hill Country and Trans Pecos.

Anyone interested in herps is welcome at their meetings!  Meetings are held the 3rd Saturday of the month at 7:00pm, in the UTA Life Sciences Building, Room 119.  Check out www.dfwherp.org to learn about this great group!


This article is reprinted with permission of the DFW Herpetological Society.
Author Michael Smith, Editor  Cross Timbers Herpetologist


Acris crepitans blanchardi

Blanchard's Cricket Frog

Steve Campbell tells a true story of a time we visited Mary’s Creek and were greeted by a homeless man living under the bridge where we accessed the creek. We were catching several cricket frogs when the man asked if we had heard that amphibians like those frogs were disappearing around the world. We knew then that amphibian declines were entering the public consciousness, when even if you lived under a bridge somewhere, you knew that frogs were in trouble. In fact, in its northern range the Blanchard’s cricket frog has largely disappeared from Ontario, most of Michigan, Minnesota, Wisconsin, Illinois, and Iowa.

However, the cricket frog found through most of Texas is doing well in the Lone Star State. Walking along creeks and ponds during the hot summer days, these little frogs start hopping for cover as you approach. Sometimes you see four or five or even more springing away all at once, so that it is hard to follow any one because of the distraction of the others. They are so small and fast that you may be uncertain whether a frog or a grasshopper has just taken flight, and when they land they are so well camouflaged that it seems they simply disappear. During the day and also at night at this time of year, you hear the calls like a chorus of marbles being dropped on a hard floor: click, click, click, accelerating as they get going.

These little frogs, so common around any permanent body of water, are easily taken for granted. However, they are an interesting species with great variety in their coloration.


Description
Adult cricket frogs are small – adults range from just over a half to one-and-a-half inches from snout to vent. They are somewhat warty, giving the frog a slightly bumpy appearance. Looking down at the top of the head, there is a small backward-pointing dark triangle between the eyes. If you gently extend a rear leg, there is a dark line along the back of the thigh, normally not visible while sitting. In our local subspecies, Blanchard’s cricket frog, that line is somewhat ragged-edged. The back feet are strongly webbed and the toes do not have toe-pads like the treefrogs (which are in the same family, Hylidae). The snout is somewhat broad and flat.

Most Blanchard’s cricket frogs have a grayish to slightly olive or even light charcoal ground color. Added to that, along the back, are markings that may involve darker mottling, a smudge of cinnamon-orange, or bright green. It has been my experience that cricket frogs living along limestone creeks have lighter ground colors to go with their lighter habitat, while those seen in bottomland woods with dark soils may have darker colors. The effect of their mottled patterns with the occasional streak of brown or green is that the frogs blend amazingly well with their surroundings.

Cricket frog tadpoles range up to 1.5 inches in total length, with mottled and slightly speckled tails ending in a dark tail tip.


Habitat
Blanchard’s cricket frog is found throughout most of Texas except for far west Texas and far east Texas (where it is replaced by the Northern and Coastal subspecies). Its range extends up through most of Oklahoma and Kansas to southern Minnesota and Michigan, and eastward into Ohio. They make use of creeks, ponds, streams, and lake shores, favoring shallow areas around the water’s edge. I have often found them under limestone rocks near the water’s edge, or sunning on mud at the margin of streams.


Food
The cricket frog’s habitat offers a wide range of invertebrate prey, with small insects and spiders that live at water’s edge. It is estimated that 100 cricket frogs living around a small pond in Wisconsin would consume 480,000 insects and other small invertebrates in one season (Wisconsin DNR website).


Activity
These frogs are active across a wide temperature range. I have seen them out basking on sunny winter days when the temperatures are in the 40s or 50s, and they seem to thrive in midsummer when everything else has dug in to escape the heat. A walk down a blisteringly hot creek bed will still turn up throngs of cricket frogs as long as water is present and some escape is available under rocks or other cover. For defense, Blanchard’s cricket frog relies on its long hops, sometimes in a bewildering pattern of different directions. Quite often they leap into the water, only to immediately change direction and swim back to shore, while the observer searches the spot where the frog entered the water. They are good swimmers and may lodge themselves between submerged rocks or moss and wait for danger to pass.


Abundance
In Texas, Blanchard’s cricket frog is an abundant species. In localized spots with the right habitat, the water’s edge may be “thick” with them. This can be true even near roads where runoff presumably may compromise the water quality. Their local abundance is all the more noteworthy when you consider the numbers of wading birds, ribbon snakes, water snakes, turtles, and other predator species found in shallow streams and ponds.


Reproduction
The cricket frogs’ peak breeding time is spring and summer. On recent night drives (early July) I can tell when I pass near a body of water because of the choruses of clicking, like tapping stones together. If you wade a stream among a group of these frogs calling at night, the sound can be quite loud, like metal clickers held near your ear. When you find the source in your flashlight beam, it is a tiny male whose throat pouch balloons out while calling to females. Walking into a group of cricket frogs often disturbs their calling, but if they quit, the males can be induced to resume calling if you click two stones together to simulate the call. Other similar noises tend to have the same effect – the males seem to be competitive in their chorusing.

An additional effect of the chorusing may be to get other frogs ready for breeding. In some frogs, chorusing may stimulate hormonal production in other males who may not fully be ready for breeding, as well as stimulating ovulation in females (discussed in Stebbins & Cohen, 1995).

When a female is found, the male grasps her in amplexus so that as eggs are laid, they may be fertilized by the male. Eggs are laid in clusters, attached to underwater plants; a complete clutch ranges from 100 to 200 eggs (Bartlett & Bartlett, 1999). Those eggs not eaten by predators hatch into small tadpoles, which may have a dark tail tip later in their development.

Cricket Frog Tadpole
Tadpoles breathe with gills, and may consume small particles of algae or protozoans or may bite or scrape material with their beaks. Legs begin to develop from limb buds – one pair at the base of the tail become the hind legs, and the front legs develop while covered with a flap of skin (the operculum). Many changes take place as the tadpoles metamorphose into frogs. Those changes include the replacement of tadpole mouth parts by jaws with teeth and a tongue, lungs develop, the coiled intestine of the herbivorous tadpole becomes the shorter gut of the carnivorous frog, the tail is absorbed, and front limbs break through the operculum.


Notes
In this case, it appears that small size is accompanied by short life: notes on the Wisconsin DNR webpage indicate that the average lifespan is 4 months.


References and Further Reading:



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