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Early warnings of amphibian declines have been realized as species have vanished, or disappeared from large portions of their ranges (Blaustein et al., 1994a; Pechmann and Wilbur, 1994; Lannoo, 1998b,c). These declines have alerted biologists and conservation agencies to the need to combine proactive evaluation of status and trends with retroactive research on causes of disappearances (Heyer et al., 1994; Fellers and Freel, 1995; Green, 1997b; Lannoo, 1998a). An initial step in detecting population declines in seemingly stable species can be accomplished by comparing current population levels with historical data. However, detecting shallow declines is difficult in the absence of replicable baseline data for most amphibian species (see also Green, this volume). A number of programs have been initiated to gather baseline data on amphibian status (e.g., Wisconsin’s Frog and Toad Survey [Mossman et al., 1998]), with various state and federal monitoring programs based on this approach (Johnson, 1998b; Hemesath, 1998; Droege and Eagle, this volume; Weir and Mossman, this volume ). However, trends in the data generated by these programs may not be discernible for a decade or more (Mossman et al., 1998; Droege and Eagle, this volume). Because of this absence of baseline data, researchers must often rely on anecdotal data—as one venerable Louisiana herpetologist said, “You don’t see them like you used to.” An abundance of baseline data exists in the form of museum voucher specimens. Far from being just specimen “libraries ” for systematists, museum vouchers offer a wide range of natural history data for a number of biological disciplines (Greene and Losos, 1988; Winker, 1996; Resetar, 1998; Ferner et al., this volume). Under some circumstances (long-term, generalized acquisition of specimens from a specific region), museum specimens offer verifiable historical records that can be used in trend analyses (Jennings and Hayes, 1994; Burgman et al., 1995; Fisher and Shaffer, 1996). Under the assumption of equal collection effort per species per time period, collection trends for amphibians can be assessed by comparing percentage of recent captures to historical captures. To determine the utility of this method in identifying amphibian population trends, I analyzed data from four Louisiana museums that focused collection efforts on Louisiana’s Florida parishes. Because actual collecting activity may vary over time, and because interspecific differences exist in the ability of animals to be captured (Hyde and Simons, this volume), data are evaluated by interspecific comparisons of trends in capture percentages. An assumption of this analysis is that the variability in collection efforts by different individuals and institutions is reduced by combining results over periods of one or two decades. Materials and Methods I recorded the locality, year of capture, and number of specimens per accession for each of the 44 amphibian species occurring in the Florida parishes (Table 43-1) from the following collections: Louisiana State University (LSUMZ; n  9,170), Southeastern Louisiana University (SLU; n  1,088), Tulane University (TU; n  11,504), and the University of Southwestern Louisiana (USL; n  1,540). Each locality, when possible, was given latitude-longitude coordinates to the nearest minute, which assigned localities to approximate one-square mile blocks (hereafter locality). Localities, all species collected at a locality, and the year of most recent collection were assembled in a LOTUS® spreadsheet. Numbers of specimens for each species were summed in five-year periods beginning with 1945–49, with an additional block for pre-1945 counts. Trend data for each species were determined by (1) comparing percentage of specimens collected in recent years (1980–99) to previous years, and (2) by comparing percentage of localities from which each was collected in recent years. I examined possible causes for observed trends by regressing recent specimen and locality percentages against the following parameters and their respective coded values: Duration of larval stage: (1) 60 days, (2) 60–200 days, (3) 200 days Breeding site: (1) terrestrial, (2) permanent aquatic, (3) ephemeral aquatic Non-breeding site: (1) terrestrial, (2) facultative aquatic, (3) obligate lacustrine, (4) obligate riverine Geographic distribution: (1) 5 localities, (2) 50% of total land area of Florida parishes (except for species coded 1), (3) 50% of total area Habitat: (1) lowland, (2) upland, (3) both 295 FO RTY-TH R E E Museum Collections Can Assess Population Trends JEFF BOUNDY Trophic level: (1) microinvertebrates, (2) macroinvertebrates , (3) vertebrates and macroinvertebrates Movements: (1) small home territory including breeding site, (2) some seasonal movements, or relatively large territory, (3) mass migrations to and from breeding sites Commercial use: (1) none, (2) some, (3) extensive Clutch...

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