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

Abstract

Survival 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.

Population size and survival of the Brazilian Torrent Frog Hylodes heyeri (Anura, Hylodidae)

“…We captured frogs by visually searching the appropriate locations, and finding calling male frogs, occasionally using playbacks to stimulate response calls. At the time of capture, we uniquely marked all individuals with colour‐coded ‘belts’ (Hiert et al, 2012; Narvaes & Rodrigues, 2005, Figure 1). The belt comprised cotton thread with a unique combination of 2–3 coloured beads (2 mm diameter) that provided 275 permutations.…”

“…The belt comprised cotton thread with a unique combination of 2–3 coloured beads (2 mm diameter) that provided 275 permutations. Marking with belts is fast, efficient, minimizes handling and does not compromise frogs (Hiert et al, 2012; Narvaes & Rodrigues, 2005). This is further supported by a study that found no effects of a more intrusive marking method (Sapsford et al, 2014).…”

“…Frogs, with threatened populations around the world (Kilpatrick et al, 2009), are important examples of populations needing additional study. Frog population dynamics are poorly understood for most species, even though they are often amenable to capture, marking and recapture (Hiert et al, 2012).…”

One step forward: contrasting the effects of Toe clipping and PIT tagging on frog survival and recapture probability

“…With the current state of amphibian declines (Stuart et al 2004), quantitative links between vital rates and explanatory covariates are fundamental to understand the dynamics of and threats to populations (Biek et al 2002). The results obtained by marking individuals provide accurate information on population trends and demographic estimates (Manly et al 2005), especially when population dynamics are poorly understood, as in the Neotropics (Hiert et al 2012).…”

“… 2005 ), especially when population dynamics are poorly understood, as in the Neotropics (Hiert et al. 2012 ).…”