Monday, September 10, 2012

Podcnemis unifilis on Manzanilla Beach

The following story is from Newsday - September 10, 2012

Beach goers at Manzanilla Beach were called into action last week, when they came across several turtles coming out of the water. At first glance, believing them to be the young of the sea turtles that nest on this beach from March to August, they attempted unsuccessfully to carry them back out to sea, only to realise that the turtles struggled to come back to shore.

On closer inspection though, the turtles seemed different, with a closer resemblance to the land tortoises. Not being able to identify the particular turtle, contact was made with employees of the nearby Nariva Estate for assistance. According to Michael James, Manager of the Estate and member of the Manatee Conservation Trust, this is not an isolated incident since every three to four years, turtles and other reptiles that are not indigenous to Trinidad, have been migrating to the coastline travelling on mats of water lilies or water hyacinth and large debris - like clumps of trees or uprooted whole trees.

President of the Zoological Society of Trinidad and Tobago, Gupte Lutchmedial who coincidentally was on site confirmed that this seemed to be an alien species and advised that it would be imprudent to release the surviving turtles into the Nariva Swamp, which may not be this turtle’s natural habitat. The live turtles were subsequently sent to the Emperor Valley Zoo for positive identification, and over 30 carcasses discovered among the beach debris were buried.

Nirmal Biptah, Curator of the Emperor Valley Zoo, recognised the turtles as Podocnemis unifilis, commonly known as yellow headed sidenecks, one of four existing South American species. The turtles found were full-grown adults and are fresh water, land-based species. As these fresh water turtles cannot survive in sea water, this would have accounted for the high level of mortality observed. Lutchmedial added, “Another cause of mortality to these turtles may be predation by the stray dogs that dwell on the beach front. While some were lucky to survive the journey atop the flotilla of vegetation and debris, others could not get past this danger.”

There is a debate on whether or not these species are indigenous to Trinidad. According to a local journal, Kearney (1972) states that they occur in Trinidad but are "confined to a small colony in Nariva Swamp." However, according to Hans Boos, the former curator of the Emperor Valley Zoo, and expert on Trinidad and Tobago’s reptiles species, he disputed this statement saying, "This species is not indigenous to Trinidad and there is a possibility that these species are from our neighbour, Venezuela."

A couple years ago, there was the arrival of some juvenile anacondas on “rafts” of water hyacinths at Icacos beach, around the same period. These rafts were propelled from the Orinoco River and its tributaries because of the heavy rainfall there.

There are reported instances of other reptiles and even mammals making landfall, including the capybara, giant otter and the Brazilian tapir. In this instance where the rafts reached all the way up to Manzanilla, Lutchmedial explained, “The debris may have been because of the dredging activities for gold along the Orinoco River where heavy rains and flooding caused the bank flora to collapse.”

One of the surviving turtles is on display at the Emperor Valley Zoo and is attracting the attention of patrons.

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