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Vol. 54, 2015
Seasonality in
anuran activity and calling season in a Brazilian subtemperate wetland
Simone
da Silva Ximenez1 and Alexandro Marques Tozetti2*
1Instituto
de Ciências Biológicas, Universidade Federal do Rio Grande—FURG, Av.
Itália km 8, Rio Grande RS 96203-900, Brazil
2Laboratório de Ecologia de Vertebrados Terrestres,
Universidade do Vale do Rio dos Sinos—UNISINOS, São Leopoldo Av.
Unisinos, 950, Cristo Rei, São Leopoldo RS 93022-000, Brazil
Abstract
Background: Most tropical regions have a
climate characterized by marked seasonal rainfall patterns, and these
seasonal patterns of rainfall directly affect anuran activity. However,
in regions with temperate climates, the main aspect of climate related
to anuran activity is the thermal regime. Thus, transitional climate
regions represent good opportunities to study the effect of abiotic
factors on anuran activity. In this study, we present new data on the
activity pattern and calling season of Neotropical anurans in a
subtemperate climate. Anuran activity was assessed based on the rate of
capture of specimens in pitfall traps and calling surveys. The field
study was conducted between May 2010 and April 2011 in wetlands in
southernmost Brazil.
Results: An analysis based on directional
(circular) statistics showed that general activity in the studied
anurans was significantly seasonal. In addition, the general activity
pattern of most species was regulated by temperature, not by rainfall,
and approached that observed in regions with a temperate climate.
However, we did not record a well-defined peak in the number of species
displaying calling activity. This parameter did not exhibit any
influence of temperature
variations or rainfall.
Conclusions: The observed general
activity pattern is different from that expected for the majority of
anurans inhabiting eastern South America. The present study showed that
the general activity patterns of most anurans in the wetland region in
southernmost Brazil are regulated by temperature and not rainfall,
similar to the pattern of anuran assemblies from temperate climates.
However, the nonexistence of a significant relationship between calling
activity and any of the environmental variables tested suggests the
presence of a different environmental factor (e.g., photoperiod or the
length of the hydroperiod of the relevant water bodies) as a trigger
for the levels of general calling activity.
Key words: Anuran; Behavior; Calling;
Temperature; Wetlands.
*Correspondence: E-mail: alexandro.tozetti@gmail.com
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