The relationship between nesting habitat and hatching success in Caiman latirostris (Crocodylia, Alligatoridae)

Abstract

The relationship between nesting habitat and hatching success in Caiman latirostris (Crocodylia, Alligatoridae). The Broad-snouted Caiman uses different habitats for nesting; it has temperature-dependent sex determination (TSD) and nesting habitat selection by females could affect sex and other hatchlings characteristics. Here we evaluated reproductive parameters in three nesting habitats: forest, savanna, and floating vegetation. We collected 154 caiman nests during the summer of 2001-2002. Since natural incubation could mask possible clutch-effects, eggs were collected soon after oviposition and artificially incubated. We found that eggs laid in the forest were wider than those laid in savanna, hatching success varied, decreasing from floating vegetation to forest. As egg width is positively correlated to female body size, the present results suggest that female body size could be related to nesting habitat use in Caiman latirostris. However, there were no differences in hatchling size among nesting habitats.

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

“…The climate of the region is temperate, with a mean minimum annual temperature of 14.9 °C and maximum of 25.6 °C and an annual rainfall of 1.380 mm (information available in the web site of National Meteorological Service (SMN, 2017). The main habitats and nesting environments of Broad-snouted Caiman in Argentina are characterized as forest, savanna, and floating vegetation (Montini et al, 2006).…”

Unanticipated effect of climate change on an aquatic top predator of the Atlantic rainforest

“…an increase in precipitation and flooding of marsh habitat. It is unlikely that the vacated niche would be filled by other crocodilian species, since the effect is through reduction of more open habitat suitable for nesting and thermoregulation, a habitat requirement common to all crocodilians (Montini et al, 2006;Platt et al, 2008;Charruau et al, 2010;Katdare et al, 2011;Ugarte et al, 2013).…”

“…This is not surprising, given the dependence on water and riparian habitats that crocodilians have for feeding and nesting. Heavy flooding is a known source of mortality for nests of many species of crocodilians (Montini et al, 2006;Platt et al, 2008;Charruau et al, 2010;Ugarte et al, 2013). For example, a population of the Morelet's crocodile, Crocodylus moreletii, in Belize has high nest losses both from high water levels that flood nests and low water levels that facilitate access to nests by terrestrial predators (Platt et al, 2008).…”

“…A less intuitive alternative hypothesis is that the newly-formed habitat, by being predominantly flooded forest, is of lower quality for broad-snouted caimans, since they need a more open habitat for nesting and thermoregulation (Platt et al, 2008;Charruau et al, 2010). Indeed, hatching success of broad-snouted caimans is lowest in nests built in forest areas, compared with savanna and floating vegetation areas (Montini et al, 2006).…”

<i>Caiman latirostris</i> (yacaré overo)

“…Aunque el yacaré overo prefiere habitar ambientes acuáticos fuertemente vegetados de difícil acceso para predadores y el mismo ser humano, los hábitats que utiliza para anidar en la naturaleza (Larriera 1995) se los encuentra en un amplio rango a lo largo de la cuenca de los ríos Paraná y Salado (Micucci y W aller 1995). De acuerdo a Montini et al (2006), los lugares de nidificación de C. latirostris cerca de Santa Fe pueden describirse como: Sabanas (lugares de baja pendiente, donde el estrato vegetativo predominante es el herbáceo), Esteros (ubicados en cuerpos de agua fuertemente vegetados;…”