Northern Cricket Frog

Transcription

1 Northern Cricket Frog Acris crepitans Scientific Name Family Name Acris crepitans Baird, 1854 Hylidae New World Tree Frogs Did you know? A cricket frog can jump up to 5 feet--or 50 times its body length. Photo credits: Jack Hecht Summary Protection Endangered in New York State, not listed federally. Rarity G5, S1 This level of state protection means: A native species in imminent danger of extirpation or extinction in New York (includes any species listed as federally Endangered by the United States). It is illegal to take, import, transport, possess, or sell an animal listed as Endangered, or its parts, without a permit from NYSDEC. 1) Any native species in imminent danger of extirpation or extinction in New York. 2) Any species listed as endangered by the United States Department of the Interior. A global rarity rank of G5 means: Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery. A state rarity rank of S1 means: Typically 5 or fewer occurrences, very few remaining individuals, acres, or miles of stream, or some factor of its biology makes it especially vulnerable in New York State. Conservation Status in New York The cricket frog's range in New York has contracted significantly over the past century. Dozens of known populations have been extirpated, including all of those on Long Island and Staten Island, as well as several on protected State Parks in southeastern New York. Only a quarter of those that remain (11) are deemed to be of fair or better viability, and only five of those appear to be healthy. All but one of these occurs on private land, where ongoing and persistent threats continue to imperil this species. NYNHP Conservation Guide - Northern Cricket Frog (Acris crepitans)

2 Short-term Trends Populations from at least nine known sites have become extirpated since the late 1980s, although most were already quite small (<10 calling males). In addition, many of the extant populations have declined dramatically since the early to mid 1990s. Two new sites were discovered in Dutchess County in 1993, extending the range east of the Hudson River (Dickinson 1993). It is unclear whether this represented a range expansion or increased survey effort. Long-term Trends Historically this species was found on Long Island, Staten Island, and in the lower Hudson River valley. By 1930, Long Island populations had disappeared, as had those on Staten Island by the mid 1970s (Gibbs et al. 2007). Cricket frogs have become extirpated from no fewer than 20 historically occupied sites since about 1900, representing a significant range contraction within the state. Conservation and Management Threats Exact causes for the cricket frog's decline in New York are not certain, but it is clear that the species cannot tolerate urbanization above some threshold. The small body size, coupled with a vulnerable overwintering strategy and a short life span (average 4 months; max 4-5 years) makes (sub)populations highly extinction prone. Population size therefore fluctuates widely, and persistence at individual sites is highly variable from year to year. Gray and Brown (2005) outlined an extinction scenario that reflected a combination of 1) a brief adult life span; 2) small population size; 3) prolonged droughts; and 4) anthropogenic alterations of aquatic breeding habitats. Hecht et al. (1996) mentioned predation (by bullfrogs), overwintering mortality, landfill leachate, invasive plants, water level fluctuations, water quality, and pesticides as potential threats to viability. This last threat appears to be especially noteworthy since the sex ratios of cricket frogs in Illinois have been shown to be altered by several different organochlorine pesticides (Reeder et al. 1998), and sex ratios in the northern portion of the species' range appear to be male biased in comparison to those in the south. Furthermore, the commonly applied herbicide Atrazine has been implicated in sex ratio reversal in cricket frog populations (Reeder et al. 1998). Conservation Strategies and Management Practices The State Comprehensive Wildlife Strategy states that the development of a statewide recovery plan, as well as the restoration of populations from extirpated sites, should be management priorities. Since most of the extant populations occur on scattered waterbodies on private property, the implementation of any comprehensive management strategy will be difficult. Research Needs Life history, (meta)population dynamics and causes for decline all merit research focus in New York. Because of the wide geographic variability this species demonstrates, even within the northern portion of its range, studies specifically tailored to New York will need to be implemented. However, because of the very low population numbers and their NYNHP Conservation Guide - Northern Cricket Frog (Acris crepitans) 2

3 occurrence chiefly on private lands, any comprehensive research project on cricket frogs in southeastern New York will be challenging. Habitat This species inhabits the edges of sunny marshes, marshy ponds, impoundments, beaver wetland complexes, farm ponds and small slow-moving streams in open country; deep water is typically avoided. In New York, A. crepitans is a habitat specialist inhabiting only a few wetlands with floating mats of mosses, water lilies and other aquatic plants giving the appearance of sparsely vegetated mud flats (Gibbs et al. 2007). Reproductive success appears to be greatest in eutrophic ponds. Many of the inhabited ponds and lakes have recently been altered by Beaver activity with unknown consequences for cricket frog habitat suitability. Adults may periodically range into adjacent uplands in some regions. Associated Ecological Communities Bog Lake The aquatic community of a lake that typically occurs in a small, shallow basin (e.g., a kettehole) that is protected from wind and is poorly drained. These lakes occur in areas with non-calcareous bedrock or glacial till; many are fringed or surrounded by a floating mat of vegetation. Cultural Eutrophic Lake The aquatic community of a formerly eutrophic to mesotrophic lake that has received an increase in nutrients (especially phosphorus and nitrogen) from sewage effluent, agricultural runoff, and other pollutants. Eutrophic Pond The aquatic community of a small, shallow, nutrient-rich pond. The water is usually green with algae, and the bottom is mucky. Eutrophic ponds are too shallow to remain stratified throughout the summer; they are winter-stratified, monomictic ponds. Associated Species Spring Peeper (Pseudacris crucifer) Bullfrog (Rana catesbeiana) Green Frog (Rana clamitans) Pickerel Frog (Rana palustris) Identification Comments The Northern Cricket Frog is one of the smallest vertebrates in New York (~1"). They have small dorsal warts, a light belly, and a dark triangle pointing backward between the eyes. Most specimens have a brownish-greenish background color, but there is wide variation from subtle browns or grays to stripes of brilliant reds or greens. The male's throat patch is yellow during the breeding season. NYNHP Conservation Guide - Northern Cricket Frog (Acris crepitans) 3

4 Identifying Characteristics Females can produce eggs, but they are rarely seen because they are attached to vegetation and laid singly or in small clusters below the water surface. The tadpoles, which can be identified by a black tip on the tail, emerge from the eggs within a few days, and are generally bottom feeders. The call starts out as a slow "click, click, click" that is repeated more rapidly for a half minute or so, resembling an insect chorus, giving the frog its common name. The sound can be imitated by tapping two pebbles together (Gibbs et al. 2007) Characteristics Most Useful for Identification Tiny size (approx. 1"), dorsal warts, dark triangular-shaped spot behind eyes, a ragged, longitudinal stripe on the thigh, and extensive toe webbing. Best Life Stage for Identifying This Species Behavior Diet Adult. Males call from plants rooted in the floating mats, or from the surface of the water. Intense competitive interactions often occur between calling males. Although it is considered a treefrog, this species is a poor climber and is usually found within a few inches of the ground. Cricket frogs employ a unique overwintering mechanism by burrowing into preexisting shallow cracks or crayfish burrows in a band of moist soil near the edge of ponds and streams (Irwin 2005), possibly communally. It has also been suggested that they may overwinter terrestrially in forested uplands beyond 150 meters (Hecht et al. 2000), and possibly up to 450 meters (A. Breisch, personnal communication) from breeding ponds. When approached by a potential predator, cricket frogs make several quick zigzag leaps, diving beneath the water. Larvae feed on periphyton and phytoplankton. Adults are opportunistic feeders both day and night, eating various small invertebrates obtained in or near the water. Food items include insects, spiders, annelids, mollusks, and crustaceans (Gray et al. 2005) The Best Time to See The frogs emerge from hibernation in late March or early April and begin to forage for terrestrial arthropods. Chorusing finally begins in mid-may and lasts until mid-july and the strongest choruses are heard on warm, humid nights. These are the last frogs to breed in New York. The eggs hatch in a few days, and larvae metamorphose before mid-september when they are barely 1/2" long. Metamorphs and adults move toward overwintering sites during late September through October (Gibbs et al. 2007). NYNHP Conservation Guide - Northern Cricket Frog (Acris crepitans) 4

5 Present Active Reproducing Larvae present and activ Similar Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec The time of year you would expect to find Northern Cricket Frog in New York. Western Chorus Frog(Pseudacris triseriata): The range of these two species does not currently overlap in New York, and P. triseriata has three, often broken, dark brown longitudinal stripes on the dorsal surface. Spring Peeper(Pseudacris crucifer): Spring peepers breed much earlier in the season and have a distinctly different call from that of A. crepitans. The dorsal surface of a peeper has a well-defined "X" pattern and no warts. Taxonomy Kingdom Phylum Animalia Craniata Class Amphibians (Amphibia) Order Frogs and Toads (Anura) Family Hylidae (New World Tree Frogs) Additional Resources Links New York State Department of Environmental Conservation Google Images NatureServe Explorer NY Amphibian & Reptile Atlas Amphibiaweb References DeGraaf, R.M. and D.D. Rudis Forest habitat for reptiles and amphibians of the northeast. United States Department of Agriculture, Forest Service Eastern Region, Milwaukee, WI. 239 pp. Dickinson, Rosalind A Northern cricket frog (Acris crepitans) survey in Ulster County, New York, M.S. thesis, Bard College, Annandale-on-Hudson, New York. May pp. NYNHP Conservation Guide - Northern Cricket Frog (Acris crepitans) 5

6 Gibbs, J.P., A.R. Breisch, P.K. Ducey, G. Johnson, J.L. Behler, and R.C. Bothner The amphibians and reptiles of New York State. Oxford University Press, NY. Gray, R.H., L.E. Brown, and L. Blackburn Acris crepitans. Pages in M. Lanoo (ed.) Amphibian declines: The conservation status of United States species. University of California Press, Berkeley Gray, R.H., and L.E. Brown Decline of northern Cricket Frogs (Acris crepitans). Pages in M. Lanoo (ed.) Amphibian declines: The conservation status of United States species. University of California Press, Berkeley. Hecht, J.H, A.R. Breisch, and R.A. Dickinson Status and distribution of Northern Cricket Frogs in New York (abstract). The New York Natural History Conference, New York State Museum, Albany. Hecht, J.H., A.R. Breisch. and R. Dickinson Saesonal activity and upland movements of the northern Cricket Frog (abstract). The New York Natural History Conference, New York State Museum, Albany, NY. Irwin, J.T Overwintering in Northern Cricket Frogs (Acris crepitans). Pages in M. Lanoo (ed.) Amphibian declines: The conservation status of United States species. University of California Press, Berkeley. Johnson, Bruce K. and James L. Christiansen The food and food habits of Blanchard's cricket frog, Acris crepitans blanchardi (Amphibia, Anura, Hylidae), in Iowa. J. Herpetologica. 10(2): Keys, Jr.,J.; Carpenter, C.; Hooks, S.; Koenig, F.; McNab, W.H.; Russell, W.;Smith, M.L Ecological units of the eastern United States - first approximation (cd-rom), Atlanta, GA: U.S. Department of Agriculture, Forest Service. GIS coverage in ARCINFO format, selected imagery, and map unit tables. Mathewson, R.F Reptiles and amphibians of Staten Island. Proceedings of the Staten Island Institute of Arts and Sciences. 17(2): NatureServe NatureServe Central Databases. Arlington, Virginia. USA Reeder, A.L., G.L. Foley, D.K. Nichols, L.G. Hansen, B. Wikoff, S. Faeh, J. Eisold, M.B. Wheeler, R. Warner, J.E. Murphy, and V.R. Beasley Forms and prevalence of intersexuality and effects of environmental contaminants on sexuality in Cricket Frogs (Acris creptians). Environmental Health Perspectives 106: Schlauch, F.C Preliminary evaluation of the status of the northern cricket frog, Acris crepitans crepitans, in the state of New York. Report to Endangered Species Unit, New York State Department of Environmental Conservation. Delmar, NY. 14 pp. Wright, A.H Frogs and toads of New York. New York State Conservationist (August/September): New York Natural Heritage Program 625 Broadway, 5th Floor, Albany, NY Phone: (518) acris@nynhp.org This project is made possible with funding from: - New York State Department of Environmental Conservation Hudson River Estuary Program - Division of Lands & Forests, Department of Environmental Conservation - New York State Office of Parks, Recreation and Historic Preservation Information for this guide was last updated on Aug 04, 2017 This guide was authored by NYNHP Conservation Guide - Northern Cricket Frog (Acris crepitans) 6