ALBERT

Description: Amphibian declines and extinctions have been documented around the world, often in protectednatural areas. Concern for this alarming trend has focused attention on the need to document all species ofamphibians that occur within U.S. National Parks and to search for any signs that amphibians may bedeclining. This study, an inventory of amphibian species in Virgin Islands National Park, was conductedfrom 2001 to 2003. The goals of the project were to create a georeferenced inventory of amphibianspecies, use new analytical techniques to estimate proportion of sites occupied by each species, look forany signs of amphibian decline (missing species, disease, die-offs, etc.), and to establish a protocol thatcould be used for future monitoring efforts.Several sampling methods were used to accomplish these goals. Visual encounter surveys andanuran vocalization surveys were conducted in all habitats throughout the park to estimate the proportionof sites or proportion of area occupied (PAO) by amphibian species in each habitat. Line transect methodswere used to estimate density of some amphibian species and double observer analysis was used to refinecounts based on detection probabilities. Opportunistic collections were used to augment the visualencounter methods for rare species. Data were collected during four sampling periods and every majortrail system throughout the park was surveyed.All of the amphibian species believed to occur on St. John were detected during these surveys.One species not previously reported, the Cuban treefrog (Osteopilus septentrionalis), was also added tothe species list. That species and two others (Eleutherodactylus coqui and Eleutherodactylus lentus) bringthe total number of introduced amphibians on St. John to three. We detected most of the reptile speciesthought to occur on St. John, but our methods were less suitable for reptiles compared to amphibians.No amphibian species appear to be in decline at this time. We found no evidence of disease or ofmalformations. Our surveys provide a snapshot picture of the status of the amphibian species, socontinued monitoring would be necessary to determine long-term trends, but several potential threats toamphibians were identified. Invasive species, especially the Cuban treefrog, have the potential to decreasepopulations of native amphibians. Introduced mammalian predators are also a potential threat, especiallyto the reptiles of St. John, and mammalian grazers might have indirect effects on amphibians and reptilesthrough habitat modification. Finally, loss of habitat to development outside the park boundary couldharm some important populations of amphibians and reptiles on the island.

Description: This document was submitted by the Florida Cooperative Fish and Wildlife Research Unit. Revised and reprinted 2005

Description: Amphibian declines and extinctions have been documented around the world, often in protectednatural areas. Concern for this trend has prompted the U.S. Geological Survey and the National ParkService to document all species of amphibians that occur within U.S. National Parks and to search for anysigns that amphibians may be declining. This study, an inventory of amphibian species in Big CypressNational Preserve, was conducted from 2002 to 2003. The goals of the project were to create ageoreferenced inventory of amphibian species, use new analytical techniques to estimate proportion ofsites occupied by each species, look for any signs of amphibian decline (missing species, disease, die-offs,and so forth.), and to establish a protocol that could be used for future monitoring efforts.Several sampling methods were used to accomplish these goals. Visual encounter surveys andanuran vocalization surveys were conducted in all habitats throughout the park to estimate the proportionof sites or proportion of area occupied (PAO) by each amphibian species in each habitat. Opportunisticcollections, as well as limited drift fence data, were used to augment the visual encounter methods forhighly aquatic or cryptic species. A total of 545 visits to 104 sites were conducted for standard samplingalone, and 2,358 individual amphibians and 374 reptiles were encountered. Data analysis was conductedin program PRESENCE to provide PAO estimates for each of the anuran species.All of the amphibian species historically found in Big Cypress National Preserve were detectedduring this project. At least one individual of each of the four salamander species was captured duringsampling. Each of the anuran species in the preserve was adequately sampled using standardherpetological sampling methods, and PAO estimates were produced for each species of anuran by habitat.This information serves as an indicator of habitat associations of the species and relative abundance ofsites occupied, but it will also be useful as a comparative baseline for future monitoring efforts.In addition to sampling for amphibians, all encounters with reptiles were documented. Thesampling methods used for detecting amphibians are also appropriate for many reptile species. Thesereptile locations are included in this report, but the number of reptile observations was not sufficient toestimate PAO for reptile species. We encountered 35 of the 46 species of reptiles believed to be present inBig Cypress National Preserve during this study, and evidence exists of the presence of four other reptilespecies in the Preserve.This study found no evidence of amphibian decline in Big Cypress National Preserve. Although noevidence of decline was observed, several threats to amphibians were identified. Introduced species,especially the Cuban treefrog (Osteopilus septentrionalis), are predators and competitors with severalnative frog species. The recreational use of off-road vehicles has the potential to affect some amphibianpopulations, and a study on those potential impacts is currently underway. Also, interference by humanswith the natural hydrologic cycle of south Florida has the potential to alter the amphibian community.Continued monitoring of the amphibian species in Big Cypress National Preserve is recommended.The methods used in this study were adequate to produce reliable estimates of the proportion of sitesoccupied by most anuran species, and are a cost-effective means of determining the status of theirpopulations.

Description: ISSN: 0196-1497; This document was submitted by the Florida Cooperative Fish and Wildlife Research Unit.