Assessment of translocation of Blanchard's Cricket frog (Acris crepitans blanchardi) in Southeast Michigan.

Abstract

An entire population of Blanchard's cricket frogs (Acris crepitans blanchardi) threatened by construction, was translocated to three restored wetlands within the historic range of the species in the summer of 2004 and 2005. Working with the National Amphibian Conservation Center at the Detroit Zoo, state natural agencies and the developer, we moved about 1060 Blanchard's cricket frogs, a Michigan Species of Special Concern, from Lakewood Farms before housing construction began. This case study represents the first effort to track the effectiveness of translocations as a method of conserving cricket frogs in Michigan. I collected data on population structure and breeding success of the translocated populations of cricket frogs. I monitored nearby wild populations of cricket frogs to get baseline comparison data for the translocated frogs. Data on population size and breeding success were used to develop recommendations on amphibian translocation. Although initial breeding attempts were observed at all three release sites, and over 240 juvenile cricket frogs were seen at one of the translocation sites in August 2005, all translocated populations had declined rapidly by October 2005. The translocations apparently did not result in viable, self-sustaining populations of Blanchard's cricket frogs at any of the release sites. I recommend that no more cricket frog translocations occur until the causes of the decline is known and effectively removed at release sites. Conservation dollars and research should focus on habitat preservation and determining the causes of declining numbers of cricket frogs in the Midwest.

Resumen

Una poblacion entera de Acris crepitans blanchardi amenazada pot el desarrollo fue trasladada a tres pantanos restaurados en el area historica de las especies durante los veranos de1 2004 y 2005. Trabajando con el centro nacional de conservacion de amfibios en el Zoologico de Detroit, agencias de naturaleza estatales y el desarrollador, nosostros mudamos 1,060 ranas Acris crepitans blanchardi, una especie de Michigan de atencion especial, de Lakewood Farms antes que la construccion de casas comenzara. Este estudio representa el primer esfuerzo de monitorear la eficacia de los traslados como un metodo de conservacion para estas ranas en Michigan. Se recolecto data sobre la estructura poblacional, exito reproductivo de las poblaciones trasladadas de estas ranas. Tambien se llevaron a cabo conteos de las poblaciones silvestres cercanas de esta rana para tenet una comparacion de base con las ranas trasladadas. Datos del tamano de la poblacion, y exito reproductivo fueron usados para desarrollar recomendaciones de traslado de amfibios. A pesar que se observaron intentos iniciales de reproduccion y se observaron mas de 240 juveniles en las areas de traslado en agosto del 2005, para octubre del 2005 todas las poblaciones trasladadas habian disminuido rapidamente. Los traslados aparentemente no resultaron en poblaciones viables auto-sustentables de la rana Blanchard en ninguna de las areas de traslado. Recomiendo que no se hagan mas traslados de la rana Blanchard hasta que las causas de la disminucion se conozcan y se remuevan de manera efectiva de las areas de traslado. El dinero e investigacion para conservacion debe enfocarse en la preservacion de habitat y la determinacion de las causas de la disminucion del numero de ranas en el medio-oeste de los EE.UU.

Introduction

Since the late 1980s, there has been a global decline in population sizes and geographical ranges of a number of amphibians (Blaustein and Wake 1990). Possible causes for amphibian declines include habitat destruction and alteration, introduction of nonnative predators, pathogens, competitors, overexploitation, pesticides, pollution, acid rain, global warming, and UV radiation (Blaustein and Wake 1990). The root causes of many declines are unknown. The Blanchard's cricket frog was listed as a Species of Special Concern in Michigan in 1986 (Lee 1998). Surveys conducted in 1997 found 47 extant sites, so the species is too numerous to meet the state's criteria for threatened status (Lee 1998). In an attempt to increase the number of extant populations of cricket frogs in southeast Michigan, the National Amphibian Conservation Center initiated a translocation project to try to establish a self-sustaining population of cricket frogs in a restored wetland at the Detroit Zoo.

Usefulness of translocations as a management tool

Habitat loss appears to be the most significant factor contributing to amphibian declines (Wake 1991). Preserving critical habitat for threatened and endangered species is probably the best method for conserving species. Habitat preservation is not an option, however, when wildlife regulations do not mandate protection of habitat and when these laws are not properly enforced. One proposed method for mitigating habitat destruction is translocation, which is defined as the "intentional release of animals to the wild in an attempt to establish, reestablish, or augment a population and may consist of more than one release." (Griffith et al. 1989). Translocations are often promoted as tools for conserving amphibians, yet there is no consensus--and few data on the effectiveness of translocations as an amphibian conservation strategy (Marsh and Trenham 2001; Seigel and Dodd 2002). There are no generally accepted or widely used criteria for assessing the success or failure of translocations (Fischer and Lindenmayer 2000). Some measures that might be used to assess translocation success include population growth, and evidence of successful breeding (Towns & Ferreira 2001).

Here I report on a translocation that was used as a last resort to try to save a population of cricket frogs by introducing individuals into other wetlands before their breeding pond was destroyed to construct condominiums and houses. On May 18, 2004, I visited sites in Ypsilanti, Michigan (Washtenaw County), where cricket frogs had been previously reported (Lehtinen 2002). I heard cricket frogs calling in three distinct areas. One location, Lakewood Farms, seemed to host the largest population of cricket frogs in the area. The developer of Lakewood Farms had plans to build condominiums and single-family homes on the property, and intended to fill in the cricket frog breeding ponds for the entrance driveway into the complex. After negotiations with the developer, the Detroit Zoo, working together with the Michigan Department of Environmental Quality (DEQ), arranged to remove the frogs from the property before development began.

Goals and questions

My main objective for this study was to determine the effectiveness of translocation as a management tool to conserve populations of the Blanchard's cricket frog. I hypothesized that populations of cricket frogs in their native wetlands will have greater breeding success than populations of cricket frogs that were recently translocated into created or restored wetlands. I attempted to assess the success of this ad hoc translocation by surveying natural and release sites.

Methods

Study areas

All study sites were located in southeast Michigan. They were divided into two groups: potential donor populations and translocation recipient sites. Only two large populations of Blanchard's cricket frogs remain in southeast Michigan (Lehtinen 2002). I surveyed these two sites, Ford Lake in Ypsilanti (hereafter referred to as city park wetland), and Ives Road Fen in Tecumseh (hereafter referred to as Nature Conservancy site), for consideration as donor populations. After meetings of Detroit Zoo and Michigan Department of Natural Resources scientists, three sites were selected as translocation recipient sites: (1) Port Huron State Game Area, Avoca (hereafter referred to as release site 1); (2) National Amphibian Conservation Center, Detroit Zoo, Royal Oak (release site 2); and (3) St. John's Wildlife Marsh Area, New Baltimore (release site 3); (Figure 1).

[FIGURE 1 OMITTED]

Release site 1 is a marsh complex. Formerly farmland; it was transformed into wetlands in 2003 as mitigation for the construction of a Meijers store in Marysville. Release site 2, a wetland adjacent to the National Amphibian Conservation Center (NACC) at the Detroit Zoo, was created in early 2000. A highway and suburbs border the zoo, therefore no natural areas provide upland habitat or migration corridors for the cricket frogs. Release site 3 extends over 2400 acres and has been intensively managed by the Michigan Department of Natural Resources for over 13 years. The Nature Conservancy site consists of two abandoned gravel pits. Large stands of Phragmites encircle these shallow groundwater-fed ponds, which contain no fish and are prone to drying out or freezing. The city park wetland is only about one acre in size; it is bordered by Ford Lake Park and residential development. Emergent vegetation covers most of the pool and shoreline vegetation circles the pond.

Survey Methods

I surveyed all study areas for cricket frogs from May 2004 to September 2005. I conducted three types of surveys: visual encounter, photographic "mark-recapture," and calling surveys. These surveys lasted between 2-4 hrs per site. I started each survey at a different location, and alternated walking clockwise and counterclockwise. I used a modified version of a visual encounter survey during day visits to locate and count frogs (Crump and Scott 1994). I walked along the shoreline of the ponds in each study site and counted cricket frogs observed within 1 m of transect path.

Translocation

Due to planned construction at the Lakewood Farms site in summer 2005, volunteers and staff from the Detroit Zoo removed 1060 cricket frogs in the fall of 2004 and early summer of 2005, and relocated the frogs to the translocation recipient sites. All three-release sites received juveniles in fall 2004, while only release site 2 received tadpoles. In summer 2005, we captured 57 adults (31 males, 22 females, and four unknown) and released them at the site with the most comparable cricket frog habitat (Release Site 1).

Analysis

Translocations are generally regarded as successful when a viable self-sustaining population is established (Johnson 1990). To assess the success of these translocations, I compared population size and breeding success of founder frogs to frogs found at source and other natural sites.

Results

The initial population surveys in 2004 and 2005 indicated that some released frogs survived at the release sites, but few animals were found in a fall 2005 survey. The first and second translocations apparently did not result in self-sustaining, viable populations at any of the release sites.

Release sites

Twenty-three days after the initial release of juvenile cricket frogs on September 14, 2004, I encountered an average of 8.5% (SD = 4.6) of the frogs at all three release sites (Table 1). Calling surveys and visual encounter surveys in May and August 2005 indicated that few individuals survived from the translocation of 2004; eight surveys resulted in only two frogs, which were heard calling at the release site 2. The 2005 translocation of adults was more successful, as these animals produced large numbers of juvenile cricket frogs seen during visual encounter surveys in 2005 (Table 2). Adults released at release site I in spring 2005 survived long enough to breed, and juvenile numbers at release site 1 were comparable to the natural sites from late July until early September 2005. The population, however, appeared to decline drastically in late September and early October, as few cricket frogs were found at the site by mid-October.

Natural Sites

I surveyed natural populations to provide baseline comparison data for translocated populations. I encountered between 52 to 351 juveniles, with an average of 183.2 juveniles (SD = 124.6, Table 2) at the Nature Conservancy site and between 43 to 96 juveniles in 2005, with an average of 69.5 juveniles (SD = 37.5) at the City park wetland (Table 2).

Comparison of translocation and natural sites

To assess the breeding success of translocated frogs, I compared juvenile cricket frog numbers from release site 1 to counts of juvenile cricket frogs from the natural sites. Surveys of translocation sites and natural sites were compared if they occurred within 7 days of each other (Table 2). The juvenile cricket frog number at the city park wetland was usually lower than the number seen at the other two sites; this is probably due to the smaller size of the city park wetland, which has a shoreline distance of 214m, while release site 1 and the Nature Conservancy site have shoreline distances of 762m and 703m, respectively.

Combining the counts from the two ponds at the Nature Conservancy site provides a fairer comparison between the Nature Conservancy site and release site 1 surveys, as the shoreline distance, and thus, total area of suitable habitat, are then similar in size. For most of the season, release site I juvenile cricket frog numbers were similar to those seen at the Nature Conservancy site. The population of juvenile cricket frogs appeared to decrease rapidly at release site 1 at the beginning of fall 2005, however. On October 14, 2005, only 8 juvenile cricket frogs were seen at release site 1, while a survey conducted the day before at the Nature Conservancy site recorded 70 cricket frogs.

Discussion

The goal of any translocation project is the establishment of a self-sustaining, viable population (Dodd and Seigel 1991). Translocation programs can be assessed at various points to determine progress (i.e., the establishment of translocated animals at release sites) (Tasse 1989). In this project, initial surveys at the three release sites in fall 2004 indicated some establishment of juvenile cricket frogs in their new habitat after the 2004 translocation of adults, juveniles, and tadpoles (Table 1). But by the following spring, no cricket frogs were seen or heard at any release site. The results of the repeated surveys at the release sites indicate that the 2004 translocations failed to establish breeding, self-sustaining populations at the translocation sites.

Initially, the 2005 translocations of adult cricket frogs to release site 1 seemed more successful: adults were seen during early summer surveys and these adults reproduced, as indicated by the high number of juveniles found later in the summer (Table 2). Juvenile recruitment numbers at release site were comparable to the number of juveniles seen at the Nature Conservancy site for most of the summer and fall, until mid-October, when release site 1 numbers dropped well below those at the Nature Conservancy site. While release site I should be surveyed again in spring 2006 to determine if any of the juvenile cricket frogs survived, it seems unlikely that our project succeeded in establishing viable, self-sustaining populations of cricket frogs at any of the release sites.

Release site 1 is (155 km) north of the Nature Conservancy site, and it is possible that cricket frogs in release site I shifted to hibernation earlier than Nature Conservancy cricket frogs, due to the temperature difference between the sites. The timing and weather conditions varied between the two survey dates; the Nature Conservancy survey occurred on a warmer day and later in the afternoon than the release site 1 survey. Nonetheless, it is unlikely that latitudinal and temperature differences among the sites account for the disparity in juvenile cricket frog numbers. The timing of the population reduction at both sites is comparable to the timing of population contractions for other cricket frog populations and suggests that the main contributor to the decreased survival of cricket frogs at release site 1 is predation, not winter conditions. Cricket frogs are most vulnerable to predation in the late summer and fall after metamorphosis (Gray and Brown 2005, and I did observe an adult green frog eating a juvenile cricket frog at release site 1).

The Blanchard's cricket frog translocation in the context of other amphibian translocations

Previous reviews have found low success rates for translocations and particularly low rates for amphibian translocation programs. Griffith et al. (1989) estimated that nearly 700 bird and mammal translocations occur each year; the overall success rate of these projects is 44%. A review of 120 re-introduction papers found a success rate of 26%, while the outcome of 47% of the projects was unknown at the time of publication (Fischer and Lindenmayer 2000). Fischer and Lindenmayer (2000) emphasized that the re-introduction success rate they found was probably an over-estimate, since authors are more likely to publish their results if their project is a success. Dodd and Seigel (1991) examined 25 relocations, repatriations, and translocations (RRT) programs for amphibians and reptiles and found that only five (19%) were considered successful. None of the amphibian RRTs (n = 5) could be definitively classified as successful (Dodd and Seigel 1991).

Although Dodd and Seigel's earlier review in 1991 noted few successful amphibian translocation projects, a number of later projects (and one project they might have overlooked) achieved the goal of a self-sustaining populations for relatively common species: gray tree frogs (Hyla versicolor), spring peepers (Pseudacris crucifer), spotted salamanders (Ambystoma maculatum), wood frogs (Rana sylvatica), common toads (Bufo bufo), and common frogs (Rana temporaria) (Cook 1989; Sexton et al. 1998; Cooke and Oldham 1995).

Only one translocation project involving a rare or threatened species (the natterjack toad, Bufo calamita), resulted in the establishment of several self-sustaining populations (Denton et al. 1997). The translocation of another threatened species, Hamilton's frog (Leiopelma hamiltoni) yielded a survival rate of 58.33% for adult frogs; however, breeding at the new site was not confirmed at the time of publication (Brown 1994). Other threatened species translocations have not been monitored long enough to determine success; these include the Wyoming toad and the Puerto Rican crested toad (AZA 1998; Johnson 1990). A translocation project involving the boreal toad (Bufo boreas), an endangered species in Colorado, failed; no tadpoles or adults were seen at the release sites during intensive monitoring surveys (Muths et al. 2001). Lastly, short distance translocations of mountain yellow-legged frogs (Rana muscosa) resulted in loss of body mass of displaced frogs (Matthews 2003). Matthews concluded that moving frogs may be stressful, and animals may lose valuable foraging or breeding time looking for their home site.

Various factors affect the likelihood of success for translocation projects: for example, type of animal released (wild vs. captive-bred, game vs. sensitive taxa), causes of decline, number of animals released, and location of release sites within the species range (Griffith et al. 1989). Translocations were more likely to succeed when the source population was wild rather than captive-bred (Griffith et al. 1989; Fischer and Lindenmayer 2000). All the cricket frogs released in our project were wild, although the animals from 2004 were held in captivity for varying lengths of time, ranging from a few days to six weeks. The time spent in quarantine and travel between sites might have heightened the stress levels of animals and increased possible disease transmission; both of these factors might have lowered the likelihood of success for our translocation experiment.

Translocations that involved native game species have a higher success rate than those that move sensitive species like the Blanchard's cricket frog: Griffith et al (1989) report an 86% success rate for these species compared to 46% for threatened, endangered, or sensitive species. In addition, if the original causes of decline are known and addressed, translocations are more likely to succeed (Fischer and Lindenmayer 2000). Unfortunately, because the reasons for the decline for cricket frogs in the Midwest are unknown, it is unlikely that any original cause of decline was removed at the release sites.

Translocations also tend to be more successful when a large number of animals (n > 100) are released (Fischer and Lindenmayer 2000). In this case, our translocation followed best practices: all our release sites received more than 190 cricket frogs in 2004, and, while only 57 adult cricket frogs were released in 2005, these cricket frogs bred and produced over 200 juvenile cricket frogs.

Translocations into the core of a species' historical range are more successful than those on the periphery or outside historical ranges (Griffith et al. 1989). Our release sites were on the northern extent of the range of Blanchard's cricket frog, which might have contributed to the low success rate of our project (Lehtinen 2002). Thus, our cricket frog translocation met only two of the five factors observed to increase the likelihood of success for translocation projects.

No consensus exists in the literature on the suitability of amphibians for translocations. Marsh and Trenham (2001) asserted that amphibians are well suited for translocations, since most amphibians lack parental care, and are thus good candidates for egg and larval translocations. They suggest that translocations may be "indispensable tools" for conserving amphibians in landscapes with multiple breeding ponds and may be necessary to promote regional population persistence when ponds are isolated. These statements contrast with the findings of published translocation studies that the effectiveness of amphibian translocations is unclear, many attempts have failed, and those that have succeeded usually involve non-threatened species (Seigel and Dodd 2002; Muths et al. 2001; Dodd 2005; Matthews 1993).

While some amphibians may be candidates for translocations and captive-breeding programs, most threatened species are not, due to life history traits such as low reproductive output, short life spans, and low natural population numbers or density (Dodd 2005). Translocation projects can also harm conservation efforts by siphoning off funds that could be used for habitat preservation or other research (Dodd 2005). Lastly, animals used in translocations can transmit pathogens and parasites to other release animals or resident animals of the same species, leading to unknown consequences for the translocated individuals, resident animals and the release ecosystem (Cunningham 1996). Dodd (2005) suggests that translocations should only be considered as a last resort for amphibians and Reinert (1991) argues that translocations should only be considered if other options, such as protecting extant populations and improving habitat, are not available, but Burke (1991) maintains that translocations should be considered in any species recovery program.

Motives for translocations

If translocations are considered risky, experimental techniques, why are they promoted as solutions to the problem of declining wildlife populations? Reasons commonly cited for the use of translocations include favorable press attention, public education, conservation potential, and mitigation of human-animal conflicts (Fischer and Lindenmayer 2000; Dodd and Seigel 1991). The main rationale for our translocation project was the impending destruction of a cricket frog breeding pond.

Translocation projects, particularly those that involve the "rescue" of animals from doomed sites to safer locations, can attract considerable favorable publicity (Fischer and Lindenmayer 2000). Articles about our cricket frog translocation project appeared in three local newspapers: the Ann Arbor News, the Livonia Observer & Eccentric, and the Oakland Press. All the newspaper articles praised the Detroit Zoo for the cricket frog "rescue" and included information about the status of cricket frogs in Michigan. Publicity about translocation projects can educate the public about threats to declining species and might generate funding for other conservation activities, such as research and land preservation (Dodd and Seigel 1991).

If press articles gloss over the difficulties of succeeding in translocations, they give a false impression of the ability of translocations to conserve wildlife species. Developers can argue that it is okay to destroy critical habitat as long as the threatened animals are moved to new locations. One Department of Environmental Quality official praised the developer of the cricket frog breeding pond, saying that the developer deserved a "pat on the back" for coming up with a solution (Kuban 2004). I tried to emphasize to the reporters who wrote about our project that we would need to monitor the release sites before we can claim success for the rescue effort, but only the Ann Arbor News included a quote stating that there was no guarantee of success for the translocation project. That same article implied that the cricket frogs would be safe in their new homes, where "the only danger is hungry bull frogs, not bulldozers" (Rueter 2004). Post-relocation results are rarely reported in the media (Dodd and Seigel 1991) and, because our translocation results were not reported in any articles, most readers probably assumed that the animals survived and thrived in the release sites. This assumption might damage efforts to preserve habitat, because translocations seem to solve the conflict between habitat destruction and threatened species protection.

Another motive for conducting a translocation is public education. Involving community members as volunteers in the relocation effort can cultivate interest in conservation issues and activities (Dodd and Seigel 1991). Many volunteers from diverse backgrounds assisted with our translocation; most had no previous training or experience with amphibians. Participants in the relocation project might have learned more about local amphibian species and the threats facing them in our own backyards.

Translocations are used to try to conserve threatened species. Our translocation project was an attempt to establish more cricket frog populations in southeast Michigan, because cricket frogs are declining or nearly extirpated (Lehtinen 2002). Translocation efforts might ultimately hinder preservation projects, however, by diverting funds that could be better used for other conservation purposes, and increasing the risk of disease transmission (Dodd 2005; Cunningham 1996). A preferable method to conserve threatened species is early identification of populations or habitats threatened by development (Griffith et al. 1989). In our case, we only discovered that the cricket frog breeding pond was threatened with development a few months before construction began, limiting options for protecting the property.

Translocations are often promoted as a win-win solution to human-animal conflicts. Developers are allowed to destroy habitat for sensitive species as long as they grant permission to conservation officials to move the animals before construction begins. Participants in relocation attempts are happy that they are "saving" the animals from bulldozers. As Edythe Sonntag, the Detroit Zoo keeper in charge of our relocation effort, told the Ann Arbor News: "It's a good feeling to know they're not going to be rolled over by a bulldozer" (Rueter 2004). Moving animals away from certain death seems to be a humane solution to habitat destruction (Dodd and Seigel 1991). But, there is no guarantee that the animals will survive at the new site, so the question of when the animals die becomes more important than if they die (Dodd and Seigel 1991). Although the cricket frogs we moved did not die immediately from bulldozers, it appears that we simply delayed their deaths.

One of the main threats to cricket frogs is widespread ignorance and apathy about its conservation status among state and federal government agencies (Gray and Brown 2005). The unsupportive responses of some local and state government agencies to our requests for assistance with protecting the cricket frog population reveals a lack of political will for protecting threatened non-game species. This problem is prevalent throughout the range of the cricket frog, and could be contributing to its decline. For example, one solution proposed to save the cricket frog breeding pond was to reroute the entrance driveway to the condo complex around the pond. The local roads commission would not allow this, however, because a local statute mandates that entrance driveways should come straight off of the nearest major intersection and not be displaced to the side of the intersection.

Recommendations for future translocation projects and research on Blanchard's cricket frog declines

Given the mixed results of amphibian translocation projects and the low success rates of threatened amphibian relocation programs, it is not surprising that our cricket frog translocation did not succeed in establishing viable, self-sustaining populations at the release sites. Amphibian translocations should only be attempted if no other management options are available. Protecting the species and its critical habitat is usually the best way to conserve threatened animal and plant species (Reinert 1991). We attempted translocations with cricket frogs because we were not able to stop development of the cricket frog breeding site.

Despite our failure to establish additional populations of cricket frogs, our experience provides lessons on improving the success rate of future translocations. First, the timing of translocations and life stage released affected survival rates at release sites. Juveniles released late in the fall did not survive very long (Table 1), whereas adults released early in the breeding season were able to establish breeding territories and breed successfully before dying or migrating away from the wetland. Dodd and Seigel (1991) cite 50-500 as the minimum number of individuals that should be released to sustain a viable breeding population. Releasing 57 adults at release site 1 appeared to result in successful breeding: high juvenile recruitment was observed later that summer (Table 2). Lastly, a plan and process for assessment needs to be put in place before starting a translocation project. Long-term intensive monitoring, such as shoreline and calling surveys, should be used to evaluate the progress of the project and determine what factors might influence the success or failure of the project. Project managers should select specific criteria to assess their project and try to publish the results, even if they are not successful (Fischer and Lindenmayer 2000).

The causes of the population declines of Blanchard's cricket frog are unknown: thus, advocating more translocations seems to be promoting a solution to a problem that has not been identified (i.e., why cricket frogs are declining). The best way to protect cricket frogs in Michigan at present is to preserve their habitat and provide more legal protection to the species. The Michigan Department of Natural Resources is considering upgrading the status of the Blanchard's cricket frog to threatened in 2006 (Lee, personal communication). This additional protection might prevent more cricket frog breeding ponds from being destroyed for subdivisions and urban sprawl.

Habitat destruction is still the greatest threat to the survival of most amphibian species (Dodd 2005). Translocations will not solve the problem of additional habitat loss for cricket frogs and research dollars should be directed at the causes of decline and other, more effective management options. Empirical evidence demonstrates that the initial cause of decline must be removed for a successful translocation (Fischer and Lindenmayer 2000). Otherwise, animals might be placed in unsuitable habitats where they will still be affected by the factors that caused their original decline (Dodd 2005). We will not succeed in conserving cricket frogs until we know more about their ecology and the causes of their decline.

Acknowledgements

Thanks to Emily Silverman and Bobbi Low for helpful comments on this manuscript. Thanks to Kevin Zippel for initiating the translocation project and bringing me on board. To Michael Lannoo, thanks for sharing your knowledge of cricket frogs and reviewing my research proposal. Thanks to Edi Sonntag for managing the cricket frog translocation, helping me out in the field, and providing data. We would not have been able to move the cricket frogs from Lakewood Farms before construction began without the assistance of James Sallee from the Michigan Department of Environmental Quality. I really appreciate Mr. Sallee taking our concerns seriously and negotiating with the developers to allow our translocation to occur. Thanks to Doug Pearsall of the Nature Conservancy and Ernie Kafcas at the Michigan Department of Natural Resources for access to research sites. This project would not have occurred without financial support from the Doris Duke Charitable Foundation, the Marshall Weinberg Fellowship, and Rackham Discretionary Funding. Lastly, thanks to all the volunteers who assisted with the translocation.

Literature Cited

AZA (American Zoo and Aquarium Association). 1998. Wyoming toad and 98 fact sheet. http://www.aza.org/programs/ssp/ssp.cfm

Blaustein, A., D.B. Wake. 1990. Declining Amphibian Populations: A Global Phenomenon? Trends in Ecology and Evolution 5:203-204.

Brown, D. 1994. Transfer of Hamilton's frog, Leiopelma hamiltoni, to a newly created habitat on Stephen's Island, New Zealand. New Zealand Journal of Zoology 21: 425-430.

Burke, R.L. 1991. Relocations, Repatriations, and Translocations of Amphibians and Reptiles: Taking a Broader View. Herpetologica 47:350-357.

Cook, R.P. 1989. And the voice of the grey tree frog was heard again in the land ... Park Science 9:6-7.

Cooke, A.S., R.S. Oldham. 1995. Establishment of populations of the common frog, Rana temporaria, and common toad, Bufo bufo, in a newly created reserve following translocation. Herpetological Journal 5: 173-180.

Crump, M.L., N.J. Scott, Fr. 1994. Visual Encounter Surveys. Pages 84-92 In W. R. Heyer, M. A. Donnelly, R. W. McDiarmid, L. C. Hayek, and M. S. Foster, editor. Measuring and Monitoring Biological Diversity: Standard Methods for Amphibians, Smithsonian Institution Press, Washington and London.

Cunningham, A.A. 1996. Disease risks of wildlife translocations. Conservation Biology 10:349-353.

Denton, J.S., S.P. Hitchings, T.J.C. Beebee, and A. Gent. 1997. A recovery program for the hatterjack toad (Bufo calamita) in Britain. Conservation Biology 11: 1329-1338.

Dodd, C.K. Jr. 2005. Population Manipulations. Pages 265-270 In M.L. Lannoo, editor. Amphibian Declines: The Conservation Status of United States Species, University of California Press, Berkeley.

Dodd, C.K. Jr., R.A. Seigel. 1991. Relocation, Repatriation, and Translocation of Amphibians and Reptiles: Are They Conservation Strategies That Work? Herpetologica 47:336-350.

Fischer, J., D.B. Lindenmayer. 2000. An assessment of the published results of animal relocations. Biological Conservation 96:1-11.

Gray, R.H., L.E. Brown. 2005. Decline of Northern Cricket Frogs (Acris crepitans). Pages 47-54 In M.L. Lannoo, editor. Amphibian Declines: The Conservation Status of United States Species, University of California Press, Berkeley.

Griffith, B., Scott, J.M. Carpenter, J.W., Reed, C. 1989. Translocations as a species conservation tool: status and strategy. Science 245:477-480.

Johnson, R.R. November 1990. Release and Translocation Strategies for the Puerto Rican Crested Toad, Peltophryne lemur. Endangered Species UPDATE 8:54-57.

Kuban, K. August 29, 2004. "Rescue effort saves tiny frogs from doomed wetland." Livonia Observer & Eccentric. Pg. A8

Lee, Y.M. 1998. Final report on Blanchard's cricket frog (Acris crepitans blanchardi) surveys in southern Michigan.

Lehtinen, R.M. 2002. A historical study of the distribution of Blanchard's Cricket Frog (Acris crepitans blanchardi) in southeastern Michigan. Herpetological Review 33:194-197.

Marsh, D.M., P.C. Trenham. February 2001. Metapopulation dynamics and amphibian conservation. Conservation Biology 15:40-49.

Matthews, K.R. 2003. Response of Mountain Yellow-Legged Frogs, Rana muscosa, to Short Distance Translocation. Journal of Herpetology 37 (3):621-626.

Muths, E., T.L. Johnson, P.S. Corn. 2001. Experimental repatriation of boreal toad (Bufo boreas) eggs, metamorphs, and adults in Rocky Mountain National Park. Southwestern Naturalist 46: 106-113.

Reinert, H.K. 1991. Translocation as a Conservation Strategy for Amphibians and Reptiles: Some Comments, Concerns, and Observations. Herpetologica 47:357-363.

Rueter, A. September 2, 2004. "Zoo extends safety net to tiny, and rare, frogs: Rescuers step in before condominium construction begins." Ann Arbor News, pg. E1 and E2.

Seigel, R.A. and J.C.K. Dodd. 2002. Translocations of Amphibians: Proven Management Method or Experimental Technique? Conservation Biology 16:552-554.

Sexton, O.J., C.A. Phillips, T.J. Bergman, E.B. Wattenberg, and R.E. Preston. 1998. Abandon Not Hope: Status of Repatriated Populations of Spotted Salamanders and Wood Frogs at the Tyson Research Center, St. Louis County, Missouri. Pages 340-344 In M. L. Lannoo, editor. Status and Conservation of Midwestern Amphibians, University of Iowa Press, Iowa City.

Tasse, J. 1989. Translocation as a strategy for preserving endangered species. Endangered Species UPDATE 6:6-6.

Towns, D.R., S.M. Ferreira. 2001. Conservation of New Zealand lizards (Lacertilia: Scincidae) by translocation of small populations. Biological Conservation 98:211-222.

Wake D.B. 1991. Declining Amphibian Populations. Science 253:860-860.

Ariana Rickard School of Natural Resources and Environment University of Michigan Ann Arbor 440 Church Street Ann Arbor, MI 48109

Table 1. Results of visual
encounter survey of release
sites, Oct. 7, 2004

                     Number of         Number of
                  frogs released     juvenile frogs   Encounter
                   in August and      encountered       rate
Site                Seat. 2004         during VES

Release site 1     189 juveniles           26            14%

Release site 2   347 juveniles and         20            6%
                   102 tadpoles

Release site 3     195 juveniles           12            6%

Table 2. Juvenile cricket frog numbers in 2005

* NSC = no survey conducted

                Release     Nature        Nature      City park
Date            site 1    Conservancy   Conservancy    wetland

  7/3 - 8/3       66         NSC *          52          NSC *
 8/17 - 8/23      238         71            128          43
 8/26 - 9/2       171         101           143          96
 9/7 - 9/11       216         225           126          NSC
10/13 - 10/14     L8          35            35           NSC