Assessment of Translocation of Blanchard's Cricket Frog (Acris Crepitans Blanchardi) in Southeast Michigan

Article excerpt

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). …