Temporal Fluctuations in Abundances of Anuran Amphibians in a Seasonal Amazonian Rainforest
1995; The Society for the Study of Amphibians and Reptiles; Volume: 29; Issue: 1 Linguagem: Inglês
10.2307/1565080
ISSN1937-2418
Autores Tópico(s)Wildlife Ecology and Conservation
ResumoAnuran amphibians were sampled over a period of 6 yr at a site in seasonal lowland tropical rainforest in southern Amazonian Peru. Three sampling periods were at the beginning of the rainy seasons in 1986, 1989, and 1991; two were in the middle of the rainy seasons of 1986 and 1990, and one was in the dry season of 1989. Temperature and rainfall were recorded throughout all sampling periods. Sampling was done along a system of trails and in four series of quadrats. A total of 5236 individuals of 61 species of anurans was recorded during the sampling period. Analysis of the data on the 20 most abundant species reveals that anuran activity is closely correlated with the occurrence of peaks of heavy rainfall and not total rainfall during a sampling period. There is no compelling evidence for declines in anuran populations at this site. RESUMEN. -Se muestrearon los anfibios anuros en un sitio en el bosque lluvioso tropical estacional de tierras bajas en el sur del Peru amaz6nico a lo largo de un periodo de 6 afios. Tres periodos de muestreo fueron en los comienzos de las estaciones de lluvia en 1986, 1989, y 1991; dos a mediados de las estaciones de lluvia en 1986 y 1990, y uno en la estacion seca en 1989. Se registraron la temperatura y cantidad de Iluvia a lo largo de todos los periodos de muestreo El muestreo se realizo a lo largo de un sistema de trochas y en cuatro series de cuadrantes. Se registro un total de 5236 individuos de 61 especies de anuros durante el periodo de muestreado. El analisis de los datos de las 20 especies mas abundantes revela que la actividad de los anuros esta estrechamente correlacionada con la occurrencia de maximos de lluvia torrencial y no con la cantidad de lluvia durante un periodo de muestreo. No existe evidencia convincente de descensos en las poblaciones de anuros en este sitio. al of Herpetol gy, Vol. 29, No. 1, pp. 13-21, 1995 right 19 5 Society for the Study of Amphibians d Reptil s oral Fluctuations in Abundances of Anuran Amphibians in a The lowland tropical rainforest in the vast Amazon Basin is home to more than 217 species of frogs, of which nearly 60% are endemic to the region (Frost, 1985; Duellman, 1993). Intensive studies have focused on the anuran faunas lo land tropical rainforest in the vast zon Basin is home to more than 217 species ogs, of which nearly 60% are endemic to egion (Frost, 1985; Duellman, 1993). I tenat selected sites-Belem, Brazil (Crump, 1971), Manaus, Brazil (Zimmerman and Rodrigues, 1990), Santa Cecilia, Ecuador (Duellman, 1978), Panguana, Peru (Schliiter, 1984), and Cocha Cashu, Peru (Rodriguez, 1992). With the exception 13 This content downloaded from 157.55.39.177 on Fri, 18 Nov 2016 04:14:24 UTC All use subject to http://about.jstor.org/terms 1WILLIAM E. DUELLMAN FIG. 1. Map of southwestern part of the Reserva Cuzco Amaz6nico showing trails and study zones. of a few studies of plots of forest floor inhabitants (Scott, 1976; Allmon, 1991; Rodriguez, 1992), there have been no efforts to determine densities of anurans in the Amazon rainforest. Likewise, there are no available data on temporal fluctuations in abundances of Amazonian anurans. Intensive studies on the herpetofauna at Cuzco Amaz6nico in southern Amazonian Peru have provided data on the occurrence and abundance of many of the resident species. Sixty-four species of anurans are known from the site (Duellman and Salas, 1991). The purposes of this paper are to present data on abundances of species of anurans at this site for six sampling periods from 1986 through 1991, and to assess the data with respect to climatic differences during the sampling periods and the microhabitats and reproductive biology of the individual species. MATERIALS AND METHODS The study site, Reserva Cuzco Amaz6nico, is a privately maintained preserve of 10,000 ha on the north bank of the Rio Madre de Dios, about 15 km ENE of Puerto Maldonado, Departamento Madre de Dios. Peru. The southwestern corner of the preserve is at 12?35'S, 69?05'W, at an elevation of 200 m. Data from the nearest weather station (Puerto Maldonado) indicate that the annual rainfall is 2387 mm with a distinct dry season from May to October. The primarily evergreen forest is classified as humid tropical forest in the Holdridge system (Tosi, 1960). The terrain is nearly flat alluvial flood plain; lower areas are flooded by rainwater runoff during the rainy season. A detailed description of the site was provided by Duellman and Koechlin (1991). Anurans were sampled during six periods: (1) 8 January-1 March 1986 by six persons for 261 person-days; (2) 13-30 November 1986 by four persons for 66 person-days; (3) 8 June-19 July, 1989 by five persons for 168 person-days; (4) 11 November-10 December 1989 by two persons for 50 person-days; (5) 19 January-2 March 1990 by eight persons for 240 person-days; and (6) 18 November-29 December 1991 by three persons for 102 person-days. Periods 2, 4, and 6 were at the beginning of the rainy seasons; Periods 1 and 5 were in the middle of the rainy seasons, and Period 3 was in the dry season. Sampling was conducted both by day and 14 This content downloaded from 157.55.39.177 on Fri, 18 Nov 2016 04:14:24 UTC All use subject to http://about.jstor.org/terms ABUNDANCES OF ANURANS TABLE 1. Sampling periods, anuran abundance, and patterns of rainfall at Cuzco Amaz6nico, Peru. J-F N-D J-J N-D J-F N-D Parameter 1986 1986 1989 1989 199
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