Tag Archives: data logors

Baby hawksbills begin to come out

Happy New Year

We have good news here. The waiting period – approximately 60 days – is over and hatching of Hawksbill turtle eggs laid on the Cousin beach has began. Mary and Eric have had a busy time with turtle work. The work continues with the hatching. As reported earlier, apart from the regular monitoring program based on beach patrols carried out around the island to intercept and collect data on as many turtles as possible, Nature Seychelles – with technical assistance from Kelonia Marine Turtle Observatory in Reunion – this season introduced the use of data loggers to measure temperature in selected nests. Temperature inside the turtle nests is known to determine the sex ratio of hatchlings. Warmer temperatures produce more females and cooler temperatures give more males. This is an important area of study, as with rising global temperatures, it is important to understand the potential impacts of climate change on this critically endangered and thermally sensitive species.

When hatching occurs in the nests with data loggers (30 in total) Mary and Eric pick up and measure the weight and length of 30 of the hatchlings, as well as categorizing nest content to determine hatchling success.

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They are then put in basket such as the one below with a shadow to avoid dehydration.

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When the sample hatchlings have been measured  and weighed, they are released and head out to sea. The release is controlled to avoid the high level of predation by ghost crabs.

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It is impossible to tell the sex ratio of the hatchlings when they are this small. But from the data collected from the data loggers it is possible to determine the approximate sex ratio using existing and new temperature data. We will give you more information on how this pilot study evolves.

More on turtle work

Turtle laying her eggs

Hawksbill turtles go into some sort of trance when laying their eggs and mademoiselle here shows us how that looks like.

Eggs weighed and measured

While she is in this low state of awareness, her eggs are quickly counted and weighed.This is done by two people as it has to be done very quickly before she completes laying and starts covering the nest with sand. If she does complete her egg laying before the weighing and measuring is complete the eggs are quickly put back anyway.

data logger

This is the tail end of the data logger (and turtle :)) which is also currently being placed in the nest. Nature Seychelles is piloting this experiment with data loggers – with technical assistance from Kelonia – to gauge nest temperature. Data loggers record temperatures of nests throughout incubation. Sex determination in sea turtles is dependent on temperature, with a pivotal temperature in which equal numbers of males and females are produced. Temperatures above this pivotal number produce females and those below produce males. So data loggers help with sex ratio determination. The temperatures can also be used as indicators of the potential impact of  global warming on hawksbill turtles.