Size of nesting female Broad-snouted Caimans (Caiman latirostris Daudin 1802)

Abstract

The southern distribution of the Broad-snouted Caiman (Caiman latirostris Daudin 1802) in Argentina occurs in Santa Fe Province, where its population has been under management by "Proyecto Yacaré" since 1990. From 1997 to 2016, we captured 77 nesting female Broad-snouted Caimans in Santa Fe Province. Our results suggest that previously defined size classes for Broad-snouted Caiman do not adequately describe the reproductively mature female segment of the population. Here we propose to change size ranges for general size classes for Broad-snouted Caiman. In addition, we have observed that reintroduced reproductive females by Proyecto Yacaré represent about 32% of captured females. These results indicate that reintroduced females by the management program are surviving and reproducing in the wild at least up to 20 years.Keywords: management, size class, reproduction, sexual maturity. Tamanho de fêmeas nidificantes do jacaré-de-papo-amarelo (Caiman latirostris Daudin 1802)Resumo Na Argentina, a distribuição mais austral do jacaré-de-papo-amarelo (Caiman latirostris Daudin 1802) ocorre na Provincia de Santa Fe, sendo que suas populações são manejadas pelo "Proyecto Yacaré" desde 1990. Entre os anos de 1997 e 2016, nós capturamos 77 fêmeas nidificantes do jacaré-de-papo-amarelo em Santa Fe. Nossos resultados sugerem que as classes de tamanho definidas para o jacaré-de-papo-amarelo não representam a realidade dos animais capturados no presente estudo. Portanto, propõe-se uma alteração nas classes de tamanho para o jacaré-de-papo-amarelo. Nós também observamos que as fêmeas reintroduzidas pelo "Proyecto Yacaré" representaram 32% das fêmeas capturadas. Estes resultados indicam que fêmeas reintroduzidas pelo programa de manejo estão sobrevivendo e reproduzindo na natureza por, pelo menos, 20 anos.Palavras-chave: manejo, classe de tamanho, reprodução, maturidade sexual.

Growth Curves of Wild and Reintroduced Broad-Snouted Caimans (Caiman latirostris) and Their Management Implications

“…Long-term studies of this species have shown that the release of captive-bred caimans is also a feasible management, and there is evidence that it is beneficial for the population's recovery. For example, since this approach was implemented in Argentina, the number of nests has progressively increased Leiva et al, 2019). Results obtained in this study support the idea that this method of ranching benefits wild populations of caimans.…”

“…parison of the asymptotic value obtained in the Py model (α = 76.7 ± 1.5 cm) vs. that of wild reproductive females ( = 81.4 ± 11.8 cm, average calculated based on the years that only presented wildlife data reported by Leiva et al, 2019) suggests that the maximum size obtained by us with the Logistic model is similar to that of wild animals. Furthermore, the von Bertalanffy model reaches an asymptotic value of 94 ± 1.8 cm (Moulton et al, 1999) that is similar to what Bertalanffy predicts for Py (Table 1).…”

“…AICc: Akaike value; Δ AICc: difference of the respective AICc with the lowest AICc value; wi: normalized weight; α: asymptotic size (cm); β: inflexion point (years); k: rate constant (year⁻¹); and η: constant; ** Non-significant parameters. Leiva et al, 2019) would be achieved for both groups at similar ages (about 7.9 years old).…”

“…Filled black circles: adult females of known age were used for curve fitting in both groups. The horizontal dotted lines depict the limits of the age class sizes as stated by Leiva et al (2019).…”

Sexual Identification of Caiman latirostris Hatchlings by Cloacal Inspection

“…We collected 100 eggs of Caiman latirostris from three nests collected in the localities of Cacique Ariacaiquín, Espín, and Intiyaco, which are areas of the "Proyecto Yacaré," a sustainable use and conservation program (Leiva et al, 2019). Once the nests were collected and transferred to the laboratory, we determined the embryonic development time of the nest according to the criteria of Iungman et al (2008).…”