Basis for Listing

The Blanchard's cricket frog is widespread throughout the central and southeastern United States. Three subspecies are recognized with the more northern and western subspecies, Acris crepitans blanchardi, being found in Minnesota (Gray et al. 2005). Populations have been reported from the extreme southwestern and southeastern corners of Minnesota, though the last record from the southwestern part of the state is from 1967. An outlying record in Chisago County marks the northern limit of this species in Minnesota.

Despite intensive survey efforts, very few Blanchard's cricket frogs have been reported in Minnesota since 1980. Currently, the only known existing populations in the state are located in Hennepin and Winona counties. Declining populations have also been reported in the northern tier of midwestern states (Lannoo 1998). The decline of Blanchard's cricket frogs may be attributed in part to the vulnerability of its preferred habitat to human disturbance, especially pollution of breeding areas by fertilizers and various agricultural chemicals. Other factors that are attributed to the species' decline include acidified ecosystems, disease, and droughts in combination with severely cold winters. Blanchard's cricket frogs were originally classified as a special concern species in Minnesota in 1984, but were reclassified as endangered in 1996.

  Description

This small member of the treefrog family is only 2.0-3.5 cm (0.79-1.38 in.) long (Oldfield and Moriarty 1994). Its body color is variable and can be brown, green, or tan with black, yellow, orange, or red markings. Blanchard's cricket frogs have numerous bumps on their back, a green or brown triangle between their eyes, and dark bands on their thighs. Their hind feet are webbed and have toe pads that are small terminal disks. The male's call is a rapid series of clicks, similar to the sound of metal balls or pebbles being hit together. Their call resembles those of some bird species which share their habitat, so positive visual identification of cricket frogs is essential. Blanchard's cricket frog tadpoles can be identified by their black-tipped tails.

  Habitat

Blanchard's cricket frogs inhabit shallow wetlands, lakes, streams, or rivers, and are rarely found in large lakes, wide rivers, or polluted sites (Gray et al. 2005). They typically occupy areas along the water's edge, and prefer open areas with muddy shorelines and abundant emergent vegetation (Oldfield and Moriarty 1994; Gray et al. 2005).

  Biology / Life History

Blanchard's cricket frogs are thought to hibernate in crayfish burrows and cracks in pond banks (Irwin et al. 1999). They emerge from winter dormancy in late April. Breeding is stimulated by rain, and occurs from late May to July (Burkett 1984). Females lay up to 400 eggs singly or in small clusters. The eggs are typically attached to aquatic vegetation near the edge of the wetland, but can either be floating on the surface, or lying on the bottom (Gray et al. 2005). The tadpoles metamorphose into adults in early August and enter winter dormancy in late September. Blanchard's cricket frogs remain near water during the summer, but may travel overland to find new habitat during dry spells. Although this member of the treefrog family is not an avid climber, it can jump surprisingly long distances to avoid predators. The life expectancy of Blanchard's cricket frogs is about four months, with only 5% of the population surviving the winter (Burkett 1984). Blanchard's cricket frogs feed on small invertebrates (Oldfield and Moriarty 1994).

  Conservation / Management

Declines in Blanchard's cricket frog populations have occurred throughout the northern portion of their range (Hay 1998; Lannoo 1998; Hammerson and Livo 1999). Blanchard's cricket frog habitat is extremely vulnerable to human disturbance, especially agricultural activities. Changes in water quality from pollution and chemical buildup, and alteration in habitat hydrology from channelization and drainage, may quickly eliminate populations by making habitat unsuitable for this species. Natural catastrophic events, such as drought and flooding, add to population stresses brought on by fragmentation and degradation of habitats. Given the short life span of this species, these stresses are likely to have severe impacts on Blanchard's cricket frog populations.

  Conservation Efforts in Minnesota

The DNR's Nongame Wildlife and Minnesota Biological Survey programs have funded and conducted several Blanchard's cricket frog surveys in southern Minnesota, and they continue to survey areas for new populations (Whitford 1991; Van Gorp and VanDeWalle 1995; Van Gorp 1996; Hall 1997). Most surveys have failed to locate Blanchard's cricket frog populations, even in areas of historical presence. However, in 1998 a local field technician documented Blanchard's cricket frogs in Hennepin County (Moriarty et al. 1998). The Nongame Wildlife Program has surveyed this area regularly since then, and has documented between one and 20 calling males. This population is genetically similar to Blanchard's cricket frog populations in neighboring states, but given the urban location of the site, it is possible that the frogs were introduced (Berendzen et al. 2003). In 2004, a volunteer for the Frog & Toad Calling Survey reported a new population of Blanchard's cricket frogs in Winona County. This population has been monitored ever since by biologists from the U.S. Geological Service and St. Mary's University. Multiple individuals at several locations 2.3 km (1.4 mi.) apart have been observed.

  References and Additional Information

Berendzen, P. B., T. Gamble, and A. M. Simons. 2003. The genetic status of Northern Cricket Frogs in Minnesota. Final report to the Minnesota Department of Natural Resources, Nongame Research Program. 43 pp.

Burkett, R. D. 1984. An ecological study of the Cricket Frog, Acris crepitans. Pages 89-102 in R. A. Seigel, L. E. Hunt, J. L. Knight, L. Malaret, and N .L. Zuschlag, editors. Vertebrate ecology and systematics: a tribute to Henry S. Fitch. Museum of Natural History, University of Kansas, Lawrence, Kansas.

Gray, R. H., L. E. Brown, and L. Blackburn. 2005. Acris crepitan, Northern Cricket Frog. Pages 441-443 in M. J. Lannoo, editor. Amphibian declines: the conservation status of United States species. University of California Press, Berkeley, California.

Hall, C. D. 1997. Minnesota County Biological Survey - amphibian and reptile results, 1988-1994. Pages 58-62 in J. J. Moriarty, and D. Jones, editors. Minnesota's amphibians and reptiles, their conservation and status: proceedings of a symposium. Serpent's Tale Natural History Book Distributors, Lanesboro, Minnesota.

Hammerson, G. A., and L. J. Livo. 1999. Conservation status of the Northern Cricket Frog (Acris crepitans) in Colorado and adjacent areas at the northwestern extent of the range. Herpetological Review 30:78-80.

Hay, R. 1998. Blanchard's Cricket Frogs in Wisconsin: a status report. Pages 79-82 in M. J. Lannoo, editor. Status and conservation of Midwestern amphibians. University of Iowa Press, Iowa City, Iowa.

Irwin, J. T., J. P. Costanzo, and R. E. Lee, Jr. 1999. Terrestrial hibernation in the Northern Cricket Frog, Acris crepitans. Canadian Journal of Zoology 77:1240-1246.

Lannoo, M. J. 1998. Amphibian conservation and wetland management in the upper Midwest: a catch-22 for the Cricket Frog? Pages 330-339 in M. J. Lanno, editor. Status and conservation of Midwestern amphibians. University of Iowa Press, Iowa City, Iowa.

Moriarty, J. J., A. Forbes, and D. Jones. 1998. Geographic distribution: Acris crepitans blanchardi. Herpetological Review 29(3):172.

Oldfield, B., and J. J. Moriarty. 1994. Amphibians and reptiles native to Minnesota. University of Minnesota Press, Minneapolis, Minnesota. 237 pp.

Van Gorp, C. D. 1996. Survey for Blanchard's Cricket Frog (Acris crepitans blanchardi) in southwestern Minnesota. Final report submitted to the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resources. 20 pp.

Van Gorp, C. D. and T. J. VanDeWalle. 1995. Survey for Blanchard's Cricket Frog (Acris crepitans blanchardi) in southeastern Minnesota. Report submitted to the Minnesota County Biological Survey, Minnesota Department of Natural Resources. 24 pp.

Whitford, P. C. 1991. Blanchard's Cricket Frog survey of southeastern Minnesota 1990-1991. Report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. Unpaged.