Ascension : Conservation Weekly
Submitted by The Islander (Conservation Office) 01.12.2011 (Article Archived on 15.12.2011)

Every year between the periods of the November to July male and female green turtles (Chelonia Mydas) make their way from Brazil to our tiny island in the South Atlantic Ocean,

Green Turtles on Ascension Island

 
Female Green Turtle (photo by Alan Marsh)

Every year between the periods of the November to July male and female green turtles (Chelonia Mydas) make their way from Brazil to our tiny island in the South Atlantic Ocean, a distance of over 2000km. The males mate with the females and then after a month of the mating trimester, the females come ashore and lay their eggs in the sand. How they find Ascension is not fully understood but it is possible it is through a combination of smell and magnetic orientation. It is estimated that 3000-5000 female green turtles nest on Ascension Island each year making it one of the largest rookeries in the Atlantic Ocean.

It is said that if it was not for the presence of the Green Turtle, Ascension may not be the place it is today. Historically, these herbivorous sea turtles were an important source of fresh meat for passing ships in the 1800s. When turtles came ashore to lay their eggs, they were captured and stored in the Turtles Ponds that can still be seen today in Georgetown. The turtles were kept alive on vessels returning to the United Kingdom as importance food source. Today it is forbidden by the local and international law to slaughter Green Turtles.

Green Turtles are found nesting in many tropical and sub-tropical beaches around the world; however the Green Turtles that nest on Ascension are the largest of their species. They reach maturity between 25 and 30 years and grow between 1.5m -1.75m in length and weigh up to 250kg. Their size allows them to cope with their arduous migration and the huge waves that crash onto the Island's shores. The turtles feed on seaweed and grasses of which there are little around Ascension.  It is therefore thought that neither the males nor the females feed during their migration and nesting season which is a period of 3-6 months between November and July. Most females will make the journey every 3-4 years.  Although it is not known exactly how long they live it is estimated to be in the region of 60-100 years.

Shortly after mating occurs the females undertake the nesting process as many as ten times at intervals of 2 weeks. When a female mates with multiple males she will store the different sperm and the eggs are fertilized when she lays. One clutch of eggs can be fertilised by multiple male Green Turtles.

Once the turtle has dug a large pit using all four flippers she digs a chamber with her hind flippers into which she lays between 120-150 eggs which look like ping-pong balls when seen in a 1m deep hole. When she has reached this stage she sits motionless. This is the only time when turtles should be closely observed. The whole nesting process can take a couple of hours.

Green Turtles in Water (Photo by Alan Marsh)

After 50-60 days of incubation in the sand the clutch of eggs hatches and the hatchlings climb up through the sand to make their way down to the sea.  The hatchlings have to escape predators on the beach, from the air and also in the near shore water around Ascension. The main threats are crabs and seabirds namely the Ascension Island endemic Frigate bird.  Predation, especially at sea is considerable and it is estimated that less that one hatchling in a thousand will survive to adulthood and return to complete the breeding cycle. 

During November the first process of the nesting season takes place.  This is the mating period. The best place to watch sea turtles during this time at Clarence Bay off Long Beach in Georgetown.

If you wish to see the Green Turtles nesting you should contact the Conservation Office. The peak season for nesting Green Turtles is in March when over 200 turtles can come ashore in one night. 

The peak season to see the hatchlings is between March to June. Hatchlings usually emerge at night and this can make it hard to see them. On a moonlit night, however, or early in the morning you can often see them rushing to the sea trying to escape the predators awaiting them.

Ascension Island is a globally important nesting site of the endangered Green Turtle. They are protected by local and international laws.

Please adhere to the following guidelines when turtle watching:

• Do not shine torches/flashlights on the beach
• Do not approach or photograph turtles when they are leaving or entering the sea
• Do not touch the turtles
• Do not make excessive noise or sudden movements
• Do not drive vehicles onto the beach
• Please park facing away form the beach
• Only approach a turtle when she has started to lay her eggs, try not to let her see you.
• Only use flash photography when a turtle is laying her eggs, and only from the rear or side to avoid blinding and disorientating her
• From December to August, at all times of the day, please keep dogs under control on beaches.

Watching turtles laying or hatching at night is a remarkable sight, please respect them.

COMING SOON - To see these beautiful creatures, tours are provided from the Conservation Office, £15 per person for tourist visitors, and £10 for local islanders aged 12yrs old and over.

BIRD SIGHTING

Photo taken by Angela Francis, Interserve Defence, Travellers Hill.

There has been a sighting of a bird seen around a few areas on Ascension it was last seen on Saturday 26 November by Interserve Staff

This bird visitor appears to be a Purple Heron. These birds have been seen on Ascension before, as well as Cattle Egrets and Storks. Should you have further sightings of this bird or other bird species, please contact the Conservation Office.

Thank you kindly.

Please be advised that due to on-going field work the Conservation Office will open from 7.30am -10am during week days. We open as normal on Saturdays, 10am-12noon, signs will be posted on the door when the office is closed.

Sorry for any inconvenience this may cause.

Volunteers welcome. Please contact Natasha Williams or Jolene Sim.  Ascension Island Conservation Department. Georgetown. Tel: 6359. Email:  natasha.williams@ascension.gov.ac  or assistant.conservationofficer@ascension.gov.ac