How the most endangered sea turtle likes to travel

Kemp’s ridleys are the most endangered sea turtle species in the world.

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Before conservation efforts, Kemp’s ridleys nested mainly on one 16-mile stretch of beach near Rancho Nuevo, Mexico. A film taken there in the 1940s showed around 40,000 individuals of the species partaking in group nesting, called an “arribada.” Unfortunately, this important nesting beach became a target for massive over-harvesting of eggs and their numbers plummeted shortly after the 1940s film. While it may have seemed to the harvesters that the population was impossible to harm due to its considerable size, the ocean is a dangerous place for hatchlings and chances of survival are slim. It can take hundreds of eggs to produce only one nesting adult, so every egg counts.

The Mexican government attempted to battle the declines by protecting the nesting beach starting in the mid-1960s but the number of nesters continued to drop. Ground-breaking conservation efforts in the late 1970’s between Mexico and the U.S. were taken to try to prevent total extinction of the species – scientists transported eggs from Rancho Nuevo to a protected beach in Texas. At that point the population was reaching critically low levels and on the brink of extinction. Less than 800 nests a year were estimated in the 1980s, accounting for only about 300 nesting females.

Further conservation laws established in the 1990s required an escape route for turtles caught in trawling nets (named Turtle Exclusion Devices; TEDs) in both U.S. and Mexican waters. These devices prevented accidental deaths during fishery operations, although compliance has not been consistent in either country. All of these conservation efforts eventually paid off, and in recent years numbers of nesters began to recover in Mexico (around 13,000 nests counted in 2010) and increase in Texas (around 150 nests in 2010), resulting in over one million hatchlings in 2010.

However, there are other threats in the Gulf of Mexico and its nesting beaches, from too much beach lighting at night to the Deepwater Horizon oil spill in 2010. Whatever the cause, Kemp’s ridley nest numbers decreased during 2013 and 2014 to a 7–8 year low.

In addition to being the rarest, Kemp’s ridleys are also the smallest sea turtle. While the shell of the largest sea turtle species, the leatherback, can measure up to 8 feet in length (they can weight up to 2,000 pounds!), Kemp’s ridleys only reach a little over 2 feet long (and weigh more like 100 pounds).

In a previous paper we looked at the foraging areas that Kemp’s ridleys use in the Gulf of Mexico. Next, we were interested in the areas they migrate through. Migration corridors are important because turtles need to swim through these waters to get to food (foraging area) or nesting grounds. With so many threats in the Gulf of Mexico, we wanted to define these migration areas to help with conservation efforts for these small sea turtles.

Our paper was published in Biological Conservation and you can read it here.

The most interesting turtle in the world

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I have a special place in my heart for terrapins. There’s just something about their cute small faces and their sweet demeanor – it’s like they have yet to learn that humans are to be feared. True, once in a while they may try to bite a wayward finger if you aren’t paying attention. But you can’t really hold that against them – if you were temporarily snatched from home to be measured and tagged, you might think about doing the same.
 

Besides the occasional attempted bite, when we caught them they usually sought escape by ‘swimming’ through our hands with their cool webbed feet, their sharp nails digging into our skin with tenacity. And once in a great while, with the small prick of a needle in the behind, some males would have the opposite reaction: they would let out their flower-shaped penises from the safe hiding space in their tails to search for what they presumably thought must be some kind of mating attempt.

Terrapins are interesting in an ecological context, being the only turtle species in North America that lives exclusively in mangroves or coastal marshes. They are also interesting in a conservation context: they interact with crab fisheries along their range (they get too comfy in submerged crab traps and can’t find a way out, so they sadly drown) and also live on the coast, which means a lot of competition with us humans for that space – habitat loss or degradation is a principal concern for them.

 

One other interesting thing to me about terrapins is where I had to go to find them. I traveled deep into mangroves in Everglades National Park, where the edge of the Gulf of Mexico and the tip of the U.S. meet, so distant from major human influence that the lights of Miami were just a haze on the horizon amidst a Milky Way-filled sky. It was a place where the sea still shined with bioluminescence when our little skiff floated over its surface. A place where time took on a truly abstract meaning and our days were ruled by the height of the sun and the pull of the moon on the tides.

 

I went there, and I caught terrapins along with researchers who had been studying them for years. I wrote about the thrill of catching these small turtles, and about how terrapin blood holds one key to their conservation. Please read the article, published by Guru Magazine here: Hunting Terrapins.

Seeing over 200 North American bird species

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Verdin

Seeing 200 North American bird species is not much compared to the 749 species Neil Hayward saw to win the American Birding Association Big Year in 2013. (A Big Year is when a birder counts all the birds she sees or hears within a single year and geographical area – check out the 2011 movie with Jack Black and Steve Martin for a hilarious look at what they can be like.)

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Painted redstart

BUT, for me this moment is one I’m pretty proud of. It didn’t all happen in a year. I’ve been casually listing birds for quite a few years actually. As I crept closer to the 200 mark, I started to look for opportunities to break it. And today I did just that. I reached 201 bird species in my Sibley birding app.

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Roseate Spoonbill

It’s not really about the numbers though, even if that can be a fun part of it. Paying attention to the birds around me has given me some great moments to remember.

Like that time I saw a verdin flitting around and flourishing in a desolate, but beautiful desert. Or the roseate spoonbills, anhingas and purple gallinules I saw while kayaking through Florida mangroves. There was the American redstart bouncing quickly from trees to the cliff-faces I climbed in Arizona, all the while flashing its black and white wings and tail to startle insects.

Black Oystercatcher, Esquimalt Lagoon, Colwood, Near Victoria, British Columbia

Black Oystercatcher

There were the Brewer’s sparrow’s long, intricate, trilling songs cutting across the dawn air above sagebrush in Wyoming. Or the time my husband and I spotted brants, pigeon guillemots, harlequin ducks, glacous-winged gulls, bald eagles, black oystercatchers, rhinocerous auklets and surf scoters while floating on a tiny skiff in uncommonly peaceful waters off the northern coast of British Columbia, Canada. I saw a peregrine falcon ripping into a small mammal with its hooked bill and, nearby, critically endangered, dinosaur-sized California condors mating on top of a granite boulder in Pinnacles National Park.

So, thank you birds. You bring so much feathered beauty to this world (even you, condor).

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California Condor

Photos from wikimedia commons, except painted redstart which is from The Cornell Lab of Ornithology (http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=575116)

The Bahamas: a dreamy escape for sea turtles too

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The Bahamas. Photo from Wikimedia Commons

Who wouldn’t want to vacation in the Bahamas?

It turns out loggerhead sea turtles nesting in Dry Tortugas National Park (yep, the ones I was just talking about in my last post) swim an impressive distance to reach this desirable locale.

With satellite tags glued to their shelly backs, these turtles told us a story of where they like to live and eat when they aren’t busy laying eggs. We even found that, like a sort of homing pigeon of the sea, turtles tracked twice after different nesting seasons returned to their same Bahamas home waters. The journey from the Gulf of Mexico, across the Florida Straits and into the western tip of the Atlantic wasn’t enough to throw them. They found their stomping grounds again.

Read all about the science behind this story and some other interesting tidbits in our paper: “Bahamas connection: residence areas selected by breeding female loggerheads tagged in Dry Tortugas National Park, USA” published in Animal Biotelemetry in February this year.

Happy New Year to you and the loggerheads!

Dry Tortugas National Park was named after two things: 1) it was “dry”, which warned mariners of the lack of fresh water, and 2) the waters were full of “tortugas” (which is Spanish for turtles).

Dry Tortugas National Park is mostly water. Here though, you can see Fort Jefferson (complete with moat) surrounded by the water that makes the Park so beautiful.

Dry Tortugas National Park is about 70 miles west of Key West, FL and is mostly water with some tiny islands. In this picture, you can see Fort Jefferson (complete with moat) surrounded by that water that makes the Park so special and beautiful. Credit: Wikimedia Commons

While there were once many sea turtles swimming in the idyllic tropical waters, the Dry Tortugas subpopulation of loggerhead sea turtles is now one of the smallest of an already threatened species. Numbers are estimated between only 250-500 adult females nesting in this area.

In order to better understand how these female loggerheads – who nest on the beautiful white sandy beaches in the Park – use the habitats available in the water, we satellite-tagged them after they completed nesting. Essentially, this means we glued a small, temporary tag on their shells that transmitted coordinates when the turtles came to the surface.

Loggerhead tracks on the beach almost make  you think a heavy-duty tractor was there instead.

Loggerhead tracks on the beach almost make you think a heavy-duty tractor was there instead. Credit: Wikimedia Commons

We then matched up this location data to a habitat map of the seafloor in the Park. To accurately map this, we used a digital imaging system called ATRIS. We found that the loggerheads showed high “site-fidelity” (they stayed in a concentrated area for long periods of time) to areas near the nesting beaches with diverse habitat.

We published these results as a short communication in Oryx, a scientific journal with Cambridge University Press. It was just released online and, I think, comes as a nice way to start the New Year.

Credit: NOAA A loggerhead sea turtle nesting on the beach. Looks like she kicked up a lot of sand while digging her nest.

A loggerhead sea turtle nesting on the beach. Looks like she kicked up a lot of sand while digging her nest. Credit: NOAA

As we move forward into another year, it’s a great opportunity for us all to reflect on where are lives have been and where they are headed. I feel proud to start the year off with a published article that can help move the conservation of sea turtles and diverse oceanic habitats forward. I hope and plan to contribute to even more meaningful science this year.

No one person alone can ‘save the world’, but together, with each of us doing a small part, there’s always hope for more peace, more enlightenment and more wisdom. What are your plans for this year?

Happy New Year!

…and here’s a link to the article:

Breeding loggerhead marine turtles Caretta caretta in Dry Tortugas National Park, USA, show high fidelity to diverse habitats near nesting beaches
Kristen M. Hart,David G. Zawada,Autumn R. Sartain and Ikuko Fujisaki
Oryx,
FirstView Articles
http://journals.cambridge.org/action/displayAbstract?aid=9491669