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06

May

Following the Long Distance Traveler of Isla Mocha

  • By eggedit

March 20, 2015

A Pink-footed Shearwater outfitted with a GPS tag to record the locations of its foraging trips. This data will be used to assess at-sea threats for the birds, such as bycatch in fisheries.Photo by: Jonathan Felis.

A Pink-footed Shearwater outfitted with a GPS tag to record the locations of its foraging trips. This data will be used to assess at-sea threats for the birds, such as bycatch in fisheries. Photo by: Jonathan Felis.

I check my watch once again. 5:15 AM. I stare into the pitch black, complete darkness of the forest and keep waiting. Only a few more hours until dawn, when we can wrap up for the night and head home. Suddenly, a crashing sound erupts from the trees above and in a barely controlled fall, a large, gray, long-winged seabird plops down, nearly hitting me in the head in the darkness. It’s a Pink-footed Shearwater—known locally as Fardela Blanca. A bird built for the sea, landing 1,000 ft. up a mountain in a dense forest on Isla Mocha, Chile.

When I click on my headlamp to check if the bird carries a small GPS recorder on its back, it stares at me in surprise for a second. No GPS. I click off my headlamp and it scuttles away in the dark and clambers down its nesting burrow, dug under a massive old-growth Olivillo tree.

Ryan Carle with some massive old growth Olivillo trees at the Pink-footed Shearwater colony on Isla Mocha.Photo by: Jonathan Felis.

Ryan Carle with some massive old growth Olivillo trees at the Pink-footed Shearwater colony on Isla Mocha. Photo by: Jonathan Felis.

More waiting. I keep staring into the dark, checking my watch every few minutes to see if it is time to check the Fardela nest burrows for birds with GPS’s. As it gets closer to dawn, there are more birds leaving the forest than arriving. It’s hard for them to take off out of the forest to return to sea—as a seabird, the Fardela Blanca flies extremely long distances (think thousands of miles), with minimal flapping, on long, graceful wings. But those long wings aren’t so graceful when they are trying to flap through bushes and dense foliage in the forest. Nor are they very good at walking on land on their long, webbed feet, as their entire body is built to be most efficient in the water and air.

To exit the forest, they perform amazing acts of climbing up the steep trunks of the huge trees that hang out over cliffs in the forest, scratching up with their sharp toenails, keeping up momentum by fluttering their wings, until they reach a high branch where they have a clear shot out of the forest. Then, a rustling sound and they’re gone. This is a wet, mossy forest, but on the trunks of their preferred climbing trees, the moss is scratched away in the paths of the fardelas—paths that have perhaps been used by generations of birds over centuries during the lifetimes of the massive trees.

A Pink-footed Shearwater climbing up an old-growth Olivillo tree in order to take off out of the forest and return to the ocean.Photo by: Jonathan Felis.

A Pink-footed Shearwater climbing up an old-growth Olivillo tree in order to take off out of the forest and return to the ocean. Photo by: Jonathan Felis.

We are here on Isla Mocha, located about 20 miles offshore from the continent of mainland Chile, to find out, using micro-GPS loggers, where these charming seabirds go to forage at sea during their breeding season.

Why is it important to know where these birds forage? The question has actually garnered quite a lot of international interest of late because the Fardela Blanca are listed as endangered in Chile and one of their greatest threats is bycatch in fisheries—bycatch is when a bird or other animal gets caught on a fishing hook or tangled in a fishing net, even though it wasn’t the target species of the fishery.

Often, if a bird gets hooked or netted, it ends up dying. We don’t yet know exact numbers of how many Fardela Blancas die this way, but the best estimate right now, and probably a minimum number, is 1,000 dead adults each year (Mangel el al. 2013). Therefore, it’s important to know where the birds are foraging so that we can better understand which fisheries they are interacting with, what threats exist in those areas, and hopefully, inform management action to reduce the risk of bycatch. There are estimated to be about 28,000 breeding pairs of Fardela Blancas in the world, so 1000 or more adults dying in bycatch each year is a serious issue.

A fluffy Pink-footed Shearwater chick awaits a meal in its nest burrow. Pink-footed Shearwater pairs raise only one chick per year.Photo by: Jonathan Felis.

A fluffy Pink-footed Shearwater chick awaits a meal in its nest burrow. Pink-footed Shearwater pairs raise only one chick per year. Photo by: Jonathan Felis.

I’m accompanied by colleagues Jonathan Felis of the United States Geological Survey (USGS) Western Ecological Research Center, and Veronica Lopez of Oikonos’ Chile program. We are pulling a week of all-nighters together to carry out this GPS tagging project. The procedure seems like it should be relatively simple—tape a small GPS recorder (about 20 grams in weight) to the back feathers of a Fardela Blanca ,wait a few days, take the GPS off, plug it into a computer, and see where the bird went. However, the reality is that capturing, and especially recapturing, a Fardela Blanca in the pitch-dark forest at night is a pretty good challenge. Which brings us back to me staring into the pitch black darkness on Isla Mocha.

Seventy percent of the Fardela Blancas in the world breed on Isla Mocha, so we’re targeting our tagging study here (the other 30% breed on the Juan Fernandez Islands (see previous Oikonos blog “Of Fences and Fardelas,” Feb 2015, for more info on the biology and conservation status of this seabird). After more hours of waiting and checking, waiting and checking, eventually, out of nowhere, the radio crackles and Jon’s voice tells me he’s captured a tagged bird.

I hustle through the forest to where I see the light of his headlamp, branches whipping me in the face. He hands me the fardela and begins to remove the GPS tag, which is attached to the bird’s back feathers with 4 strips of extra-special, extra-tough German-made tape. We record various data points, take some measurements to determine sex, and release the bird into its nest burrow. Moments later we hear its chick begging for food. Time for a meal of regurgitated anchovy paste and oil, mmmm…..

Ryan Carle of Oikonos and Jonathan Felis of USGS, preparing to climb the mountain to the Pink-footed Shearwater colony one more time.

Ryan Carle of Oikonos and Jonathan Felis of USGS, preparing to climb the mountain to the Pink-footed Shearwater colony one more time.

We stay up all night for eight nights straight and get back 18 GPS tags in total—about 2-3 tags per night, or 1 tag every six hours of waiting in the dark. This business takes perseverance. At 7 AM or so, with the sun just coming up over the water, we run down the steep trail back towards our cabin in town. After what seems like hours going down, down, down on the dark trail, we get to the bottom of the hill and climb onto mountain bikes we left at the park entrance gate and ride in the half light of dawn past cows and sheep and chickens until we get to our front door, exhausted. But of course, after all that, we can’t go to bed (and sleep till 3 PM), until we plug in the tags and see where the birds went.

Each morning, we plug in the tags and see the tracks in GoogleEarth—the 18 birds almost all go to two spots, one north of the island, one south. The spots appear to be foraging hotspots, at least during these last two weeks in March. Most of the birds stayed within about 20 kilometers of the coast. This is exciting—it means we now have a place to focus in on the bycatch issue—the birds have told us where they go!

GPS foraging tracks of 5 of the 18 Pink-footed Shearwaters  tagged by Ryan and Jon in March on Isla Mocha. Most of the birds stayed within 20 kilometers of the coast, and most foraging trips were around 3 to 5 days in length.  Note: These data/images are preliminary. Maps or data herein do not constitute publication and data remain copyright of the project partners.

GPS foraging tracks of 5 of the 18 Pink-footed Shearwaters tagged by Ryan and Jon in March on Isla Mocha. Most of the birds stayed within 20 kilometers of the coast, and most foraging trips were around 3 to 5 days in length. Note: These data/images are preliminary. Maps or data herein do not constitute publication and data remain copyright of the project partners.

 

One morning at the end of the project, Jon and I stay up on the mountain in a tent and get up around noon to meet a group of local schoolkids from Mocha (there is a small community of around 600 people on the island). Oikonos’ mission is not just to conduct science, but also to work with local communities to create lasting conservation solutions.

On Isla Mocha, this goal is realized in part by working with the local school to do environmental education and foster appreciation of the unique ecosystem of the island. This particular class is called the “Grupo Ecological,” and is composed of middle aged students who are learning about the environment, science, and conservation for a semester.

The students come up the trail with local Oikonos coordinator Tiare Varela and National Reserve park guard Francisco Astete Castillo to look at the Fardela Blanca chicks using a special infra-red burrow camera. As they look for the cute fluffy chicks, I show them our data on a smartphone, and by the end of the class, when I ask them where the Fardelas are feeding, the kids tell me “off Concepción and Valdivia!” the towns near where the birds we tracked went.

 A young Isla Mocha local uses an infra-red camera probe to check on a Pink-footed Shearwater chick, as part of an environmental education class run by Oikonos and the local school.

A young Isla Mocha local uses an infra-red camera probe to check on a Pink-footed Shearwater chick, as part of an environmental education class run by Oikonos and the local school.

What was a mystery to the world a week ago now is known by a gaggle of middle-schoolers from Isla Mocha. And with threats on all sides for Fardela Blancas, on breeding colonies and at sea, knowing where the Fardelas go is a very good thing. The kids soon need to go back down the hill, as Jon and I prepare for yet another long night of waiting for the Fardelas to come home.
Ryan Carle

Note: All data/maps shown here are preliminary. Maps or data herein do not constitute publication and data remain copyright of the project partners. This was a collaborative project of the United States Geological Survey-Western Ecological Research Center and Oikonos Ecosystem Knowledge. Funding for Pink-footed Shearwater conservation work on Isla Mocha is from the American Bird Conservancy and the National Fish and Wildlife Foundation.
Also, USGS/Oikonos also deployed 10 satellite tags to track the migration of the Shearwaters to the northern hemisphere this winter—you can watch their progress in real-time at this link!
http://www.seaturtle.org/tracking/index.shtml?project_id=1007

 

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