Influence of emergence success on the annual reproductive output of leatherback turtles

Multidecadal trends in the nesting phenology of Pacific and Atlantic leatherback turtles are associated with population demography

“…In many birds, older individuals also tend to nest earlier in the year than younger individuals (Hipfner et al 2010). Similar trends have been ob served in leatherback turtles, as older and/or more experienced individuals tend to arrive earlier to nest and lay more clutches (Santidrián Tomillo et al 2009, Rafferty et al 2011. As a result, populations with an older mean age may have both earlier and longer lasting nesting seasons (Ezard et al 2007).…”

“…At both Playa Grande and Sandy Point, beach temperatures increase over the season (Santidrián Tomillo et al 2009;see Fig. S2 in the Supplement).…”

“…S2 in the Supplement). Consequently, nests laid later in the season are exposed to hotter and drier conditions and have lower hatching success and emergence rates (Santidrián Tomillo et al 2009). At Playa Grande, where the nesting season is shifting to later in the year, this means that an increasing portion of the population will experience fatally hot and dry conditions and hatchling output will decrease.…”

“…Consequently, determining the factors influencing leatherback nesting phenology likely requires the investigation of a broader range of oceanographic variables. Furthermore, even though local climate conditions directly affect hatching success (Santi drián Tomillo et al 2009, environmental conditions at the nesting beach are unlikely to govern when a turtle will arrive at the nesting beach, although they may do so over long time scales through natural selection (Berteaux et al 2004). This is because leatherback turtles conduct extensive reproductive migrations, and the distance between nesting grounds and foraging areas can extend across entire ocean basins (Benson et al 2011, Witt et al 2011.…”

Sex ratios of leatherback turtles: hatchery translocation decreases metabolic heating and female bias

“…February and March were beyond the in situ clutch incubation temperature monitoring period in 2 seasons, but the last monitored month (January or February) always exhibited sand and clutch incubation temperatures above the transitional range of temperatures and thus subsequent months could be considered 100% female. We assumed the potential contribution of clutches going through their middle third of incubation outside of October to March to be negligible (actually ~7% of annual nests, Reina et al 2002) because of sand temperatures approaching lower thermal limits on development at the very beginning of the season (25 to 27°C, Bustard 1972) and hatchling production decreasing to almost zero in nests that hatch in February and beyond (Santidrián Tomillo et al 2009). We corrected for differences in relative numbers of in situ versus hatchery clutches by weighting the mean sex ratio each month, in each location, by the number of clutches.…”