Constant breeding and low survival rates in the subtropical Striped Frog in southern Brazil

Abstract

AbstractSurvival and consequent implications for population dynamics in the subtropical Striped Frog Hypsiboas leptolineatus was studied for 1 year in the southern Brazilian state of Paraná. By means of capture‐marking‐recapture, we estimated survival and capture probabilities in an open population. A total of 583 captures of 374 individuals, comprising 96% male (n = 353) and 4% females (n = 21), resulted in daily survival estimates ranging from 0.808 to 0.998 day−1. The number of individuals captured per capture session varied from 8 to 37 (mean = 21) and was correlated with night length, after a two session lag time (r = 0.78). Males were found vocalizing throughout the year, while females were less common and gravid females were only found in November, March and June. Recapture probability was relatively constant at 25% for males, 24% for females and, overall, 29% of males were recaptured at least once. Young individuals were encountered in all months but one and, being extremely small, were impossible to quantify. Thus, the Striped Frog is active and breeding year‐round as indicated by the constant singing of adult males, the few gravid females found at different times and the frequent encounters of young frogs at all times of year. While survival and captures varied throughout the year, the only seasonality was in the number of captures that increased during longer nights. Nonetheless, recapture probability was constant. These dynamics contrast strongly with most anuran species and especially subtropical and temperate species in other places. This first detailed study of population parameters of a subtropical species with its unusual dynamics may suggest that once studied, other species of anurans may also have surprising population dynamics.