acris crepitans

 

Northern Cricket Frog
Conservation status
Least Concern
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Amphibia Order: Anura Family: Hylidae Genus: Acris Species: A. crepitans
Binomial name
Acris crepitans Baird, 1854

The Northern Cricket Frog (Acris crepitans) is a species of small Hylid frog native to the United States and northeastern Mexico. Despite being members of the tree frog family, they are not arboreal. There are three recognized subspecies.

Description

The Northern Cricket Frogs is North America's smallest vertebrate, ranging from 0.75 to 1.5 inches (19–38 mm) long. Their dorsal coloration varies widely, and includes greys, greens, browns, often in irregular blotching patterns. One NY biologist has identified 6 distinct colour morphs and 4 pattern morphs, and several intrergrades between these.(Westerveld,1977). Typically there is dark banding on the legs and a white bar from the eye to base of foreleg. The skin has a bumpy texture. It is very similar to the Southern Cricket Frog, Acris gryllus, found in the US Southeastern Coastal Plain, though there is some overlap along the fall line. The Southern Cricket Frog has longer legs, with less webbing on the hind feet, and a more pointed snout, although some NY biologists have observed Northern Cricket Frogs with snouts indistinguishable from that of the Southern (Westerveld, 1998). The line on the back of its thigh is typically more sharply defined than that of the Northern Cricket Frog (Conant et al. 1998, Martof et al. 1980). NY biologists have recorded Northern Cricket Frogs with extremely sharp posterior leg stripes.

Behavior & diet

Northern cricket frogs are diurnal and generally active much of the year, except in mid-winter in northern areas when the water is frozen. Their primary diet is small insects, including mosquitos. They in turn are predated upon by a number of species, including birds, fish, and other frogs. To escape predators, they are capable of leaping more than three feet in a single jump and are excellent swimmers.

Reproduction

Breeding generally occurs from May through July. The males call from emergent vegetation with a high pitched, short, pebble-like call which is repeated at an increasing rate. the sound suggests pebbles being clicked together,much like a cricket, hence the name. One egg is laid at a time and generally attached to a piece of vegetation. The 0.5 inch (14 mm) tadpoles hatch in only a few days and undergo metamorphosis in early fall. Maturity is usually reached in less than a year.

Habitat

Cricket frogs prefer the edges of slow moving, permanent bodies of water. Large groups of them can often be found together along the muddy banks of shallow streams. The Northern cricket frog has been observed to hibernate upland, often at considerable distance form water.

Subspecies

• Blanchard's Cricket Frog, Acris crepitans blanchardi (Harper, 1947)
• Eastern Cricket Frog, Acris crepitans crepitans (Baird, 1854)
• Coastal Cricket Frog, Acris crepitans paludicola (Burger, Smith and Smith, 1949)

Geographic distribution

• A. c. crepitans - from New York, south to Florida and west along the gulf coast states to Texas.
• A. c. paludicola - southwestern Louisiana to eastern Texas.
• A. c. blanchardii - Michigan and Ohio, south through to most of Texas and Mexico. Has been recorded in Minnesota and Colorado.

Conservation status

Frogs like the cricket frog are very important to humans as an indicator of water and general environmental quality in the areas they inhabit. Since the 1970s, populations of all amphibians have been in decline, which is largely believed to be attributable to the increase in use of fertilizers and pesticides. A. c. blanchardi is listed as a species of concern in the state of Michigan. Acris crepitans is listed as an endangered species in New York. The last population of Northern Cricket Frogs in New York State survives at Orange County's Glenmere Lake. Biologists studying the Glenmere population are considering chytrid fungus, responsible for most worldwide amphibian extirpation, to be the cause of the frog's decline. One biologist studying the Cricket Frog population at Glenmere hypothesises that the bi-monthly treatment of Glenmere's water, (unique to this singular Cricket Frog habitat) with the fungicide copper sulfate has preserved this population from extirpation, while nearly all other NYS populations have vanished.

Effects of UV radiation

It has been shown that frog development is often impaired by exposure to ultraviolet radiation, particularly UV-B. Studies have shown that UV-B radiation may have a significant impact on cricket frog populations, theoretically causing local extirpations and a reduction in range of 70 miles from their previous northern extreme. Four factors are believed to contribute to the decline of cricket frogs due to UV-B radiation:

1. They are affected most by UV-B radiation in lab settings in comparison to other frog species.
2. They are less protected from UV-B than other frogs because their eggs are laid closer to the surface of the water (.75cm compared to 6cm)
3. Since they are not laid in large egg masses, they do not gain the benefit of the top eggs sheltering the lower eggs.
4. Eggs are laid later in the season, when days are longer, subjecting them to increased levels of UV-B.

Effects of Chytrid Fungal Infection

1. Despite the UV radiation theory, however, virtually all Northern Cricket Frog populations throughout New York State have suffered extirpation

save for the Glenmere lake population, which presents in a reservoir treated 6 times X year with the fungicide "Copper Sulfate". This factor leads biologists to theorize the Northern Cricket Frog's extirpation to be resultant of chytrid sp.' fungal infection.

References

• Hammerson et al (2004). Acris crepitans. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006. Database entry includes a range map and justification for why this species is of least concern

• Animal Diversity Web: Acris crepitans
• USGS: Northern Cricket Frog
• Frogs & Toads of Georgia: Acris crepitans crepitans
• Conant et al. (1998). A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Boston: Houghton Mifflin. ISBN 0-395-90452-8.
• Martof et al. (1980). Amphibians and Reptiles of the Carolinas and Virginia. Chapel Hill: University of North Carolina Press. ISBN 0-8078-4252-4.
• NYS DEC Northern Cricket Frog Fact Sheet
• New York State's last population of acris crepitans' and the positive effect of continued fungicide treatment of the lake *Westerveld Chytrid theory

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