Conservation Strategies: Translocating an Entire Population of Blanchard's Cricket (Acris crepitans blanchardi) in Southeast Michigan

Ariana Rickard,1 Abstract Edi Sonntag,2 and The dramatic decline of amphibian populations worldwide is an urgent conserva- Kevin Zippel3 tion issue. The root causes underlying many amphibian declines are unknown. One Michigan of Special Concern, the Blanchard’s cricket frog (Acris crepitans 1School of Natural Resources blanchardi), is declining at an alarming rate in the northern portions of its range. In and Environment May 2004, the National Amphibian Conservation Center (NACC) at the Detroit University of Michigan, Zoo initiated a translocation project to reintroduce Blanchard’s cricket frog to three Ann Arbor manmade at the northern extent of its range. Calling surveys in south- 430 E. University east Michigan revealed several robust populations of cricket including one Ann Arbor, MI 48109 [email protected] site slated for development in the fall of 2004. Working with the developer and the Department of Environmental Quality, we successfully removed about 1,050 frogs 2National Amphibian and tadpoles from the threatened breeding ponds. The were released into Conservation Center two Michigan Department of Natural Resource restored lake plain prairie com- Detroit Zoological Institute plexes with features, and into a restored wetland near the NACC in fall of 8450 West Ten Mile Rd. 2004. These translocated populations will be monitored in subsequent breeding Royal Oak, MI 48068-0039 seasons to assess the success of the translocation project.

3 25 Spring Street Resumen Union Springs, NY 13160 La drástica disminución de poblaciones de ranas alrededor del mundo es un problema de conservación urgente. Las causas fundamentales de muchas de estas disminuciones son desconocidas. Una especie de preocupación especial en Michi- gan, el Blanchard’s cricket frog (Acris crepitans blanchardi), esta decayendo a una velocidad alarmante en el parte norte de su cobertura. En mayo de 2004, el Centro Nacional de Conservación Anfibio (NACC) en el zoo de Detroit empezó un proyecto de traslocación para re-introducir la rana Blanchards en tres humedales artificiales en la parte norte de su cobertura. Estudios de las llamadas en el suroeste de Michi- gan ha revelado algunas poblaciones robustas de las ranas, incluyendo un sitio planeado para la construcción de casas en el otoño de 2004. En colaboración con el diseñador y el Departamento de Calidad Ambiental, hemos retirado con buen éxito 1,500 ranas y renacuajos de los estanques amenazados. Los animales fueron liberados en dos lagos restaurados del Departamento de Recursos Naturales con características de humedales, y en un humedal restaurado cerca de NACC en el otoño de 2004. Estas poblaciones translocadas serán vigiladas en las etapas siguientes de cría para evaluar el éxito del proyecto de traslocación.

128 Endangered Species UPDATE Vol. 21 No. 4 2004 According to a recent global sur- populations of Blanchard’s cricket vey of all 5,743 known amphibian frog have declined drastically in the species, almost a third (1,856 spe- northern portions of its range cies) are threatened with extinction (Harding 2000). These declines (IUCN, CI, and NatureServe 2004). have been documented in Ontario, An additional 1,300 other species Iowa, Wisconsin, Indiana, Illinois, are probably also threatened, but Michigan, Ohio, and Minnesota. scientists did not have sufficient While the species has been extir- data to assess their status (Ibid.). pated from some areas, such as Amphibian populations are declin- Ontario and most of southeast ing more rapidly than either Michigan, the cricket frog remains or mammals (Ibid.). While many common in the southern and west- Figure 1. Acris crepitans blanchardi amphibian declines can be attrib- ern parts of its range. Potential uted to habitat loss and causes for this decline include con- overexploitation, the root causes of tamination of wetlands and water- other species declines are un- ways by pesticides or other pollut- known. The Blanchard’s cricket ants, successional changes in habi- frog (Acris crepitans blanchardi), a tat characteristics, climatic fluctua- Michigan species of Special Con- tions, competition and predation cern, is declining in some areas of from other frog species (e.g., bull- the Midwest, and scientists have frogs and green frogs), drought, not been able to determine why the acid rain, and habitat loss and frag- species is threatened in the north- mentation (Lehtinen 2004, Harding ern extent of its range. 2000). Some life history character- Blanchard’s cricket frog is a istics of this frog, such as a short life small (0.6 to 1.5 in), warty-skinned span and limited dispersal, might frog with long hind limbs and is re- make it especially vulnerable to pe- lated to tree frogs, but lacks toe pads riodic extinctions at the periphery on its feet and does not climb. They of its range. To test the hypothesis usually inhabit the more open that cricket frogs are declining in edges of permanent ponds, bogs, southeast Michigan due to the loss lakes, and slow-moving streams or of migration corridors, which allow rivers (Harding 2000). Blanchard’s for recolonization in new areas, cricket frog is one of three subspe- Kevin Zippel, former curator of the cies of the northern cricket frog National Amphibian Conservation (Acris crepitans) and ranges from Center (NACC), initiated a translo- southern Michigan, Wisconsin, and cation project to try to establish a southeastern South Dakota south self-sustaining population of cricket through , west to northern frogs in a restored wetland at the Mexico, and east to northern Ten- Detroit Zoo. nessee. The call of this cricket frog Ariana Rickard, a summer in- resembles a series of metallic clicks, tern at NACC, conducted the ini- similar to the sound made when tial population surveys to identify two pebbles are tapped together viable local populations that could (Harding 2000). Blanchard’s cricket be used as source animals for the frog was named in 1947 after dis- translocation project. Rickard fol- tinguished University of Michigan lowed up on population surveys herpetologist Frank Nelson done by Richard Lehtinen on the Blanchard. distribution of Blanchard’s cricket Since the late 1970s and 1980s, frog in southeastern Michigan

Vol. 21 No. 4 2004 Endangered Species UPDATE 129 (Lehtinen 2002). Between May 18 cricket frogs and two threatened and July 9, 2001, Lehtinen surveyed plant species. After ASTI concluded 60 sites that historically hosted that there were no cricket frogs on cricket frog populations. Only two the property, the developer stated of these sites in southeast Michigan, that it didn’t “make sense” for them Ypsilanti and Tecumseh, had cricket to give NACC permission to relo- frogs and full choruses of males. cate the frogs. Lehtinen concluded, “Blanchard’s ASTI surveyed the site three cricket frogs are not only declining, times in April and May 2004 and but are nearly extirpated from concluded, “the site does not con- southeast Michigan.” On May 18, tain the preferred habitat for the 2004, Rickard visited the same site subject species . . . . None of the sub- Lehtinen surveyed in Ypsilanti and ject species were encountered dur- heard cricket frogs calling from ing the assessment” (ASTI Threat- three different sites near Ford Lake. ened and Endangered Species Sur- One property, Lakewood Farms, vey 2004). However the consult- seemed to host the largest popula- ants’ survey was performed with- tion of cricket frogs in the area. out proper consideration for the an- After Rickard located the nual cycle of the cricket frogs, and cricket frog populations from the surveys were conducted when nighttime calling surveys near Ford the Blanchard’s cricket frogs were Lake, she identified the owners and unlikely to be found during visual development plans for the breed- encounter surveys. Calling surveys ing ponds. The developer of Lake- conducted during this frog’s breed- wood Farms had plans to build con- ing season would have provided a dominiums and single-family more reliable assessment of the size homes on the property, and in- of the cricket frog population at tended to fill in the cricket frog Lakewood Farms. breeding ponds for the entrance Zoo staff contacted the Depart- driveway into the complex. The ment of Environmental Quality company had hired a consultant, (DEQ) and a DEQ representative, Applied Science and Technology, James Sallee, served as a liaison be- Inc. (ASTI), to survey the site for tween NACC and the developer. Lakewood Farms rescue site. Sallee convinced the developer to allow NACC to remove the frogs from the property before develop- ment began. Representatives of all parties involved surveyed the site in July 2004 and confirmed a sig- nificant numbers of cricket frogs. With this information, the DEQ mandated that Edi Sonntag, Senior Zookeeper at NACC, must approve plans for the required mitigation site. Sonntag is researching the habitat requirements of this species and was surveying the extant south- east Michigan populations. This survey information was then ap- plied to the design of the mitigation

130 Endangered Species UPDATE Vol. 21 No. 4 2004 site to assure replacement of appro- Literature Cited priate cricket frog habitat. Applied Science and Technology, Inc. Threat- Sonntag also began recruiting ened and Endangered Species Survey: Lake- volunteers for the frog rescue effort. wood Farms Property. May 28, 2004. After the Department of Natural Harding, J.H. 2000. and Reptiles of Resources (DNR) approved emer- the Great Lakes Region. Ann Arbor: Univer- sity of Michigan Press. 378 pp. gency collection permits for the IUCN, Conservation International, and cricket frogs and the Zoo’s veteri- NatureServe. 2004. Global Amphibian Assess- nary staff completed health assess- ment. . Down- ments on the Lakewood Farms loaded on 17 November 2004. frogs to verify that there were no Lehtinen, R.M. 2002. A historical study of the distribution of Blanchard’s cricket frog (Acris contagious diseases present in the crepitans blanchardi) in southeastern Michi- population, groups of volunteers gan. Herpetol. Rev. 33(3):194-197. led by Sonntag began collecting Lehtinen R. M. March 6, 2004. The status of frogs 2–3 times a week in August Blanchard’s cricket frog populations in south- ern Michigan: implications for declines in Ohio. through October 2004. About Ohio Declining Amphibians Population Task 1,050 frogs and tadpoles were re- Force Meeting. Columbus, Ohio. moved and released into two DNR parks and the wetland near the NACC in September 2004. These sites were selected after careful con- sideration of habitat qualities, such as shoreline vegetation and water quality, and after health assessments of resident amphibian populations revealed no problematic diseases or parasites. Sonntag, Zippel, and Rickard visited the three introduction sites approximately one month after the frogs were released and found nu- merous cricket frogs basking or moving through their new homes. About 10% of the released frogs were seen at all the introduction sites, an encounter rate similar to what we have observed at Lake- wood Farms. From our population surveys at Lakewood Farms, we know that the number of individu- als seen at any one time is about 10% of the total population. Sonntag and Rickard plan to con- tinue to monitor the translocated populations in the spring of 2005. Hopefully, the cricket frogs will thrive in their new homes, and we will hear strong choruses at all three of the introduction sites next May.

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