Nest relocation boosts hatching success

Ai Chelis Beach flooding

The sea turtle nesting beaches of Kefalonia are short in length and very narrow, often backed by clay cliffs. This limits the nesting space with optimal incubation conditions. Storms regularly transform the island’s nesting beaches during the final months of the season (September and October) further reducing incubation success. Loggerhead sea turtle nests which are laid on these narrow beaches have a high probability of failure due to elevated moisture levels within the nest, removal of sand from the top of the nest or washout caused during the storms.

When nests are flooded, the sand above the eggchamber becomes compact making it much more difficult for hatchlings to emerge. Eggs may also drown if the nest is repeatedly flooded as gas exchange is blocked, or eggs may be washed away in severe storms when wave damage causes serious erosion to the beach. Under these conditions, hatching success could be drastically reduced or the nest destroyed completely. It is possible to reduce this damage by relocating the nest within the first 24 hours to a safer incubation location on the beach.

Nest inundated on Ammes Beach

The goal of my research was to examine the difference in hatching and emergence success in nests which were left in situ versus nests which were relocated. We predicted that hatching and emergence success would be improved in nests which were relocated to a safer incubation locations compared to nests which were left in situ.

All 112 nests from the 2013 and 2014 nesting season were considered for relocation based on three criteria. If the distance to sea was too short (less than 10m), if the eggchamber was too deep or too shallow (deeper than 34cm or shallower than 17cm) or if the microenvironment conditions were not suitable (too much clay near the nest, too close to public walkways, limited sun exposure) then the nest was relocated to a safer location (33 nests in total). 

Emergency nest relocation post innundation

When each nest had finished hatching, an inventory was conducted to identify the number of eggs which had hatched and the number of hatchlings which had emerged from the eggchamber. Hatching success was defined as the number of hatched eggs divided by the total number of eggs. Emergence success was defined as the number of hatchlings that exited the eggchamber divided by the total number of eggs.

Our results revealed that both hatching and emergence success were higher in nests which had been relocated versus nests which were left in situ. Hatching success was 69.3% in relocated nests compared to 53.4% in in situ nests, and emergence success was 68.8% in relocated nests compared to 49.7% in in situ nests.

Jess Betts and her research poster presented at ISTS35

This has very important implications for the narrow and stormy nesting beaches of Kefalonia. Successful relocation criteria will enable nests at risk of flooding and inundations to be moved to a safer incubation location. This in turn will increase the overall success rates of all nesting beaches across the southern coast of Kefalonia and is therefore a very powerful conservation technique.

This research was recently presented at the International Sea Turtle Symposium in Dalaman, Turkey. This is the 35th year the conference has been held and it covers all aspects of sea turtle biology and conservation. Over 800 delegates attended from 80 different countries, each contributing new research to enable conservationists to reduce the declining numbers of sea turtle populations globally.

Check the International Sea Turtle Symposium Research Poster Here: http://wildlifesense.com/media/download/Betts-et-al.2015-Poster-ISTS-Turkey.pdf

Written by Jess Betts 

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Tags: Kefalonia, research, threats, sea turtle nest, nest relocation