Science for a Blue Planet

Science for a Blue Planet

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New Technology Uncovers New Connections for Conservation

By | September 23, 2016

Light-level geolocator tags provide songbird location data within 100 miles.

co-authored by: Ryan Burnett, Renee Cormier, Tom Gardali, and Diana Humple

edited by: Lishka Arata

When we try to pick out anything by itself, we find it hitched to everything else in the Universe. – John Muir

As scientists, we work to discover how the world works and as conservationists, we work to make the world better.  Along the way we see that the connections we make with each other help us do both, better.  In 2010 biologists at Point Blue’s Palomarin Field Station began using small geolocator tags to track songbird migration. In 2015, Point Blue’s Sierra Nevada Group Director, Ryan Burnett, deployed geolocator tags on Swainson’s Thrushes breeding in Sierra Nevada mountain meadows as part of a collaborative study.  The results are uncovering a story of connectivity between birds and the places they depend on, as well the people who study and care about them.

A Sierra Mystery

Unlike in coastal California, where Swainson’s Thrushes are widespread and abundant, in the Sierra Nevada today they are rare. The cause of these dramatically different population trajectories between coastal California and the Sierra is not well understood; some have hypothesized that it is the result of changes in the Sierra Nevada, while others believe it is the result of changes on the tropical wintering grounds.

“After interning at the Palomarin Field Station in 1997, I migrated up to the Sierra Nevada to take on our fledgling Northern Sierra program”, explains Burnett. “When I first visited Warner Valley my first summer in the Sierra I was astonished to find the meadow filled with Willow Flycatchers, Swainson’s Thrushes, and a high diversity and abundance of other meadow-associated birds. In the last 17 years I have visited hundreds of meadows across the Sierra and I have yet to find one that is more important to meadow bird conservation in California.”

Lush meadow habitat in Warner Valley.

Lush meadow habitat in Warner Valley.

Through a collaborative geolocator study with Will Richardson of the Tahoe Institute for Natural Science – a 1994 Palomarin intern and former Point Blue biologist himself! – we aim to shed light on whether Sierra Nevada Swainson’s Thrushes are limited on their breeding or wintering grounds.

New information

Swainson's Thrush with a GPS geolocator tag, help by Point Blue staff member in the Sierra Nevada.

A Swainson’s Thrush with a GPS geolocator tag, held safely in the “bander’s grip” by a Point Blue staff member in the Sierra Nevada.

Geolocator studies to determine migratory connectivity have become a standard part of the research and intern training program at Palomarin. In the summer of 2015, Diana Humple, Palomarin Field Station program leader, helped Ryan deploy two kinds of geolocator technology (11 light-level and 10 GPS tags) onto Swainson’s Thrushes breeding along the streams in Warner and Humbug Valleys in the upper Feather River watershed of the northern Sierra Nevada.

“From our earlier work tagging Swainson’s Thrushes at the Palomarin Field Station, we knew that this species was a good candidate for these trackers due to their strong migratory connectivity” explains Humple. “The light-level geolocators give us daily estimates of the bird’s location, but they are only accurate to within ~100 miles; in contrast, the GPS geolocators give us location estimates that are accurate to within meters, but they only record a handful of locations. Data from both types of tags, put on different individuals, are really important in giving us a picture of where exactly birds are going [GPS] and when they depart and arrive on their breeding and wintering grounds [light-level].”

But, there is a catch: to learn where the birds go after leaving their breeding grounds in California and migrating south, it is necessary to recapture the bird and remove the tag when it returns the following spring.

This past summer, Point Blue ecologists Renée Cormier, Tom Gardali, and Nat Seavy spent a long weekend in late June helping Burnett recapture Swainson’s Thrushes in the northern Sierra Nevada as part of the first effort to recover these geolocator tags. After 4 long days trudging through alder thickets following paths created by black bears, they had resighted 9 of the 21 tagged birds, and had recovered two tags. Immediate analysis of one of the tags revealed that it went to the Pacific slope of western Panama.

“We were surprised,” said Burnett. “Tags deployed in 2014 – just 100 miles south near Lake Tahoe –   by our collaborators at Tahoe Institute for Natural Science showed a consistent pattern of birds wintering in Colombia, so we weren’t expecting them to be in western Panama.”

More surprises

Because of the accuracy of the GPS technology worn by this individual bird, Renée Cormier was able to pinpoint almost the exact location of the Panama bird during the winter.

“One of the next things I did was to go onto the eBird website, where you can look to see how many birders have reported Swainson’s Thrushes near this location,” explains Cormier.

At the Palomarin Field Station, all of the interns use the eBird website as part of their internship, and one of their tasks is to enter the daily journal’s bird list onto the site. Many of the interns are new to eBird and continue to use the site to record their bird observations after they leave the field station.

Darién Montañez teaching students about bird ecology in Marin County, CA as an Education Intern out of Point Blue's Palomarin Field Station in 2006 through the NPS Park Flight program.

Darién Montañez teaching students about bird ecology in Marin County, CA as an Education Intern out of Point Blue’s Palomarin Field Station in 2006 through the NPS Park Flight program.

By looking up nearby records on eBird, Renée hoped to learn more about the habitat and bird communities in the region, and perhaps even identify a local birder that she could contact for more information. But Renée had no idea how easy that would be. The closest report of a Swainson’s Thrush was just 16 km from the GPS coordinates of the tagged bird. When Renée clicked on the observation to read more of the details, she was excited to discover that the record had been submitted by Darién Montañez.

“I was thrilled”, exclaims Renée. “I immediately recognized the name. Darién was an international intern from Panama at the Palomarin Field Station in 2006, where he was the education and outreach intern, living and working here during the fall season.”

Since leaving Palomarin, Darién served the Panama Audubon Society on their board for approximately 8 years (including as past president), and currently is on their Bird Records Committee. He is the Coordinator of Interpretation and Public Programs at the Biomuseo, a relatively new museum in Panama City dedicated to the natural history of the Isthmus of Panama, where he works with exhibit content and design, sets up programs for school groups and visitors, and helps manage the surrounding botanical park. He not only continues to use eBird today, but is regional eBird editor!

After learning of this bird, and the proximity to his own observation of a Swainson’s Thrush, he told Diana that they are “really, really common winter residents in the western lowlands” of Panama.  So it was not surprising that one ended up on his bird list when birding there, but it was a nice surprise that this individual bird reconnected him to the organization and people from his time in California a decade earlier.

Making connections

As the Swainson’s Thrushes we study are now on their way back to their wintering grounds, the Point Blue team is analyzing the data from the rest of the tags recovered this season to determine where the Swainson’s Thrushes went.  And the interns at the Palomarin Field Station continue their long-term monitoring: banding and entering daily bird lists recorded in the field station daily journal into eBird.

Darién in the kitchen at our Palomarin Field Station in 2006 toasting to a great season of education and science with fellow interns and staff, building connections for conservation that last lifetimes.

Darién in the kitchen at our Palomarin Field Station in 2006 toasting to a great season of education and science with fellow interns and staff, building impactful connections for conservation that last lifetimes.

“We often talk about the importance of migratory connectivity,” explains Diana Humple, “the patterns of connections between wintering and breeding locations of birds. But sometimes we are reminded that the work we do – and conservation in general – is also very much about building connections between people and places. I love how this story, and the individual bird at its very center who travels between the Sierra Nevada and Panama, so perfectly exemplifies all of these connections that were to some degree made at Point Blue’s Palomarin Field Station.”

With connections between people like this, it will be a lot less challenging to investigate and identify what limits the Swainson’s Thrush abundance in the Sierra, and then address it together.

 

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2 Comments

  1. Nancy Knudsen

    September 29, 2016 at 8:57 am

    Thank you so much for sharing this adventure with us.
    I am amazed to learn about this beautiful bird and the amazing work you are all doing. Such important work done with great effort, compashion, and sharing.
    Thank you all for what you do.
    Sincerely, Nancy K

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