Stutchbury Tracks Tiny Songbird Migration with Geolocator

Dr. Bridget Stutchbury, Ornithologist and author (Silence of the Songbirds) was one of the first scientists to use light logger geolocators to track tiny songbirds. Watch this exclusive SongbirdSOS video of Bridget retrieving a geolocator from a Hooded Warbler for the first time.

Bridget told us how it came about…

I started tracking migratory songbirds in 2007, after discovering that light-logger geolocators had been miniaturized to only 1.5g by the British Antarctic Survey.  For the first time ever it was possible to attach this device to songbirds and, if they returned the next year, re-construct their start-to-finish migration routes and timing.  At this size it was only safe to track relatively large songbirds that weighed over 50 grams but most songbirds weigh far less than 50 grams.  As with any technology, the geolocators were soon made even smaller, allowing researchers to track smaller songbirds.

In 2010 I had the good fortune to test the smallest tags at that existed at that time (0.6g). The tags were built by James Fox from the British Antarctic Survey. I wanted to know if it was possible to track warblers, which typically weigh less than 15g.  In the spring of 2010, after receiving permission from the US Banding Lab to do a pilot study, I caught five Hooded Warblers at my long-term study site in northwestern Pennsylvania. It was with some trepidation that I gave these little birds a relatively large piece of luggage to carry for the next year. I followed them carefully over the next months to make sure they were healthy.

Bridget and Student

You could not tell that a male Hooded Warbler was carrying a geolocator unless you happened to get a really good look at his back.  They sang vigorously, chased other males, mated with their females, and all five males successfully raised a family.  That August, just before they were about to depart for their winter-time migration, I recaptured three of the males and I was pleased to notice that their weight was healthy and that they were moulting their feathers normally.

Then came the long nine month wait.  The next year two of the five males returned to re-claim their territories in May and seemed no worse for the wear.  Amazingly, Director Su Rynard  and her SongbirdSOS documentary crew was there when we captured the first warbler ever tracked with a geolocator! After analyzing the light data I discovered that this bird, 2430-41205, had flown south to the Florida panhandle, across the Gulf of Mexico, and spent the winter in central Nicaragua.  In spring, he flew up to the Yucatan peninsula, across the Gulf of Mexico and up the Mississippi River valley back to his exact same 100m x 100m territory in Pennsylvania.  Even after tracking several hundred songbirds, I still find it amazing that such a small bird can travel so far and with pinpoint accuracy.

Banded Hooded Warbler

What become of this infamous bird? Bridget’s colleague Dr. Ron Mumme from nearby Allegheny College has been studying Hooded Warblers in her backyard forest ever since. He reports that this bird survived to make a second round-trip the next year and again nested successfully, although he has not been seen since.

The second Hooded Warbler Bridget tracked also wintered in Nicaragua and has nested on the same breeding territory every year since 2010. He was at least two years old when first banded, which means he’s flown the 7000 kilometre round-trip at least four times in his lifetime for a total of 28 000 kilometres!!  He wasn’t spotted in 2014, and a new male has laid claim to his territory.

Bridget reminds us that Aristotle believed that migratory swallows buried themselves in the mud over the winter like frogs.  In many ways that seems far more likely than a little 12 gram bird flying over half-way across the globe.

Geolocators Track Songbird Migration

In only the last few years, songbird migration research has taken a huge leap forward as ornithologists and bird researchers have been able to find out more about bird migration due to light logger geolocator technology.

Research teams can now equip the songbirds with tiny computer chip backpacks that record light levels and location information every two minutes. Within the device is a real time clock reference built in for each location measurement. The researchers who have successfully retrieved the geolocator devices from returning songbirds say that when they analyse data for even a small number of birds,  it is astonishing what they find out regarding flight, speed, distance, stop over sites and wintering-ground destinations.

Geolocator in hand

The tricky part about using this miniaturized technology is that the geolocators are not capable of transmitting live data, so in order for the researcher to get the data from the bird, the songbird  has to not only has to be strong enough to  carry a computer chip backpack for 9 or 10 months, it has to return to the same spot it was tagged to be recaptured the following spring.   Because of the perilous migration journeys  most songbirds face, researchers never recover all the birds they tag.

Tagged Purple Martin

For our documentary, one of the migratory research studies we are looking at is in the Purple Martin Conservation area of Presque Isle Park on the shores of Lake Erie.  Dr. Bridget Stutchbury, ornithologist and  York University Professor, is featured in the documentary as she captures and tags Purple Martins at this site.

Another participant in the film, Dr. Martin Wikelski from the Max Plank Institute of Ornithology in Germany,  was a catalyst for a very  exciting tracking project – Movebank, which compiles the animal and bird migration geolocator records from hundreds of  scientists worldwide.

Songbirds in Decline but Conservation Works!

State of the Birds ReportThe State of the Birds report is out.  The report tries to mitigate the drastic news about further declines and more ‘red listed’ species with Conservation success stories. What does this mean for Songbirds? The news is not great, for forest songbirds, nor for neotropical migrants.

“The eastern forests indicator for 26 obligate breeding birds shows an overall drop of 32%, with a continued steady decline since 2009. Species dependent on either young forests (such as Golden-winged Warbler and Eastern Towhee) or mature deciduous forest (such as Wood Thrush and Cerulean Warbler) are showing the steepest declines. Because 84% of eastern forests are privately owned, timber companies and other forest owners can greatly benefit bird populations by maintaining large forest blocks and participating in sustainable forestry initiatives.

The western forests indicator, based on 39 obligate breeding species, has declined nearly 20% and has continued to decline since 2009. More than half of western forests are on public lands. Species dependent on oak and pinyonjuniper woodlands (such as Oak Titmouse and Pinyon Jay) are showing the steepest declines. As in the East, both early successional species (such as Rufous Hummingbird and MacGillivray’s Warbler) and mature forest species (such as Vaux’s Swift and Cassin’s Finch) are declining.”

I feel very fortunate to have encountered two of the songbirds mentioned above on the SSOS filmmaking journey. We recorded a Golden-winged Warbler in Costa Rica with Alejandra-Martinez-Salinas and a Wood Thrush in Waterloo Ontario with Lyle Friesen. On the downside, filming a Cerulean Warbler was impossible, as their numbers are way down, and the State of the Birds report, like our film SongbirdSOS, helps us understand why this is so. 

“Thirty Watch List species are Neotropical migrant songbirds that breed in North America and winter south of U.S. borders.

Neotropical migrant conservation requires international cooperation to protect habitats throughout their ranges, on the premise that conservation in Latin America and the Caribbean will ensure these birds return to the U.S. in spring. Bicknell’s Thrush, a breeding bird of Northeastern mountains, needs immediate action to stop deforestation in Hispaniola. Virginia’s Warbler and Rufous Hummingbird both breed in the West and winter in Mexican pine-oak and thorn forests.

Cerulean and Golden-winged warblers breed in eastern forests and winter in the tropics. These fast-declining species have benefitted from collaborations by scientists, agencies, and businesses that created breeding habitat on U.S.timberlands and wintering habitat in Colombian coffee-growing landscapes. Such partnerships provide a model for voluntary, international habitat conservation for other Neotropical migrants.”

 

 

Bill Evans Unique Songbird Acoustic Monitoring

For nearly 30 years, Bill Evans has had his ear to the sky,  listening to the calls of songbirds as they travel through the night. The process is called acoustic monitoring and the data he collects provides valuable information on songbird migration and the health of their populations.

Bill’s journey as a renegade scientist began in 1985 after a long night of delivering pizzas. He was resting on a bluff in eastern Minnesota at two in the morning when he heard it: the sound of hundreds of unseen birds flying overhead in the dark spring sky. He was entranced by their calls. “It was just such an enthralling experience for me,” said Bill. “To hear those calls so clearly – I just happened to be in the right place at the right time.”

Bill Evans night sky

At that time Bill was a history of science student at the University of Minnesota. He didn’t know how, but that day he decided he would find a way to record those calls over the duration of an entire night and to archive the data for others. He’s been committed to this work ever since.

Bill’s process has evolved with technology. He recorded his first calls on hifi VCRs, playing back the tapes and noting the calls by hand. The advent of computers has sped up the process and he now uses software that can extract the calls automatically.

He left his academic path to pursue his passion full-time and now works from his make-shift laboratory at his home in Ithaca, New York. His methods are unorthodox.  He constructs his microphones with the cheapest materials he can find: buckets, rubber bands and plastic wrap. He publishes his songbird data and his do-it-yourself methods on his website, www.oldbird.org, in the hopes of empowering citizen scientists to participate in this ambitious and important long-term bird acoustic monitoring project.

Similar to the Breeding Bird Survey, bird acoustic monitoring employed by citizen scientists across the continent has the potential to become a valuable tool for ornithologists and conservationists. He wants his work to become an index for looking at change, not just for the birds, but for the health of the planet as well.

Mic and Observatory

“These birds are tied down to habitat,” said Bill. “If you’re monitoring the population of the species, especially those neotropical  migrant songbirds, you have a sort of pulse on the condition of central or southern America wherever those birds go. You have a way of tuning into the changes of the planet from your home.”

Bill’s innovative methods give scientists a new way to measure the population trends of migratory songbirds. He is still driven by the same passion from that awe-inspiring moment but now, considering the many threats faced by songbirds, with a greater sense of urgency.

The SongbirdSOS documentary crew filmed with Bill on a beautiful night near the Cornell Night Sky Observatory in Ithaca, New York. 

Are Pesticides Causing Problems for Tree Swallow Songbirds?

The call of the Tree Swallow is a familiar sound to anyone living in the fields and wetlands of rural North America. These songbirds winter farther north than any other American swallow and return to their nesting ground long before other swallows come back.

Distinguished by their deep-blue backs and pure, white fronts, Tree Swallows are known for their impressive flight acrobatics as they chase after insects.

This songbird species has historically thrived in agriculture areas and grasslands.  The species has traditionally fared well in grasslands but has quickly begun to lose ground in terms of its population stability.  Scientists are beginning to notice that aerial insectivores associated with farmland are now the steepest in decline.

The North American Breeding Bird Survey  reports that tree swallows in Canada have declined 62% since 1966.  This alarming pattern is also appearing in the USA and Europe.

“Their numbers are telling us something about the environment that they’re living in,” says Christy Morrissey, an eco-toxicologist at the University of Saskatchewan. “The common denominator there is that they are living in an area which is susceptible to pesticides.”

The tree swallow habit of nesting tree cavities and bird house/nestboxes means that scientists can study their breeding behaviour in great detail; they know more about Tree Swallows than any other aerial insectivore. Bob Clarke, a professor at the University Saskatchewan, has been studying them for over twenty years.  His research has provided the Morrissey with a strong foundation for continuing to study pesticides and their impact on the species.

Christy suspects the recent introduction of neonicotinoid pesticides could be affecting insect populations, which in turn impacts the Tree Swallow’s diet. “We are seeing very clear differences between sites that have more agricultural intensification than sites that are more natural,” she says. Let’s hope that Christy can find the answer. The Breeding Bird Survey reports that tree swallows in Canada have declined 62% since 1966.

 

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