ORDANO Mariano Andres
Scinax nasicus (NCN). Habitat.
MARIANO ORDANO; PABLO COLLINS; RAFAEL LAJMANOVICH
Society for the Study of Amphibians and Reptiles
Año: 2000 vol. 31 p. 171 - 171
A population of Scinax nasicus was studied in Sauce Viejo, Santa Fe town suburban area (Santa Fe, Argentina), from 10 February to 4 April 1996. Six hundred and ninety-seven observations of S. nasicus activity were recorded in houses and sorrounding habitats. Individual counts in three windows (1.2 x 1.6 m) with different light intensity (A:50 Ev [lux], B: 83.33 Ev, C: 166.66 Ev) were conducted each day (22-24 h). Climatic data were obtained from EEA-INTA Paraná Meteorological Station. The proportions of frogs from each different light intensity were tested with the Multiple Proportions Test (Zar 1996. Biostatistical Analysis. Prentice Hall. New Jersey. 662 pp.). The temporal distribution of the number of frogs in different windows was tested with the G test (Sokal and Rohlf 1979. Biometría. Blumé. Madrid. 830 pp.). Scinax nasicus activity relative to environmental variables was analyzed through the Conformity rate (h2). During the day, frogs were found in wet shelters near water sources (reservoirs, fountains tanks, bathrooms, closets, cocks, pipes, drains). At night, the frogs left these refuges and congregated at the windows where arthropods were attracted by the light. The numbers of frogs at the windows with the greatest light intensity was significant (c2 = 46.2; p<0.05). Temporal distribution of frogs showed significant differences between windows A and B (G: 0.89; p<0.05), A and C (G: 0.88; p<0.05), and B and C (G: 0.77; p<0.05). Frog activity increased when the temperature (h2: 0.87; p<0.05), relative humidity (h2: 0.71; p<0.05), and rainfall (h2: 0.60; p<0.05) increased. A clear trend to use the windows with the greatest intensity was observed. The waste-water drainage systems and the local distribution of human dwellings likely provides refuges for S. nasicus during periods of dry conditions. These observations may help explain the propensity of S. nasicus to colonize urban areas, as S. nasicus is one of the few frogs that cohabit with man in large neotropical areas.