Skip to main content

Tracking Curlews Across the Continent

By Stephanie Coates

Imagine your body feeling restless, pulled toward a distant expanse, and famished. It’s tradition, or more accurately your photoperiod-driven hormones, that will coerce your stores of fat to thicken and kindle your urge to skip town. You’re about to travel 500 miles, maybe triple that, all completely self-powered. You’ll probably make most of the journey under the cover of darkness. You’ll probably go to a place you were before. Twice a year, this is the life of a Long-billed Curlew.

Curlews will often form small flocks prior to migration. Photo by Liz Urban

The migratory flows of curlews are wedged apart by mountain ranges and guided by the edge of the continent. Knowing where curlews go, what routes they take, places they stop along the way, and how they move through habitat is critical. Linked to all these things, scientists need to know how distinct the connections are between breeding and non-breeding populations, or “migratory connectivity”. If a population of curlews is crashing, how else can we grasp the full reasons why?

At present, these curlew secrets are best revealed with transmitters.

Almost five years of curlew migration fly by at a rate of 20 days per second in this animated view of all the curlews IBO has tracked since May of 2015. Data animation by Stephanie Coates

That’s why each spring since 2013, IBO has deployed satellite transmitters on curlews. The device is lightweight − about 1 or 2% of a curlew’s body weight. Though transmitters are an extra burden for individuals, what we learn has implications for the conservation of the species across their North American range. For example, we’ve already found curlews who breed in western Idaho will most likely migrate to either the Central or Imperial Valleys of California. There they will spend nearly nine months in agricultural fields, probing soil with their long bills and gleaning their favorite meaty prey (curlews are carnivores) from the foliage of crops.

Once you reach breeding areas farther east, the Rocky Mountains deflect migrating curlews to a stopover zone stretching across parts of the Texas panhandle and eastern New Mexico, a mix of agriculture and grasslands dotted with energy extraction sites. Curlews may stay here for days or weeks before continuing south to Mexico or the Gulf Coast of Texas. Among many things, these journeys tell us we need to be thinking about the types of agricultural crops and land management practices that could benefit curlews, and which curlew populations would be most impacted by development in a specific area.

A Long-billed Curlew with a transmitter in flight. Photo by Stephanie Coates

Now, we’re racing to answer questions on our map of migratory connectivity, and we’re not alone.

During the breeding season in 2019, Jay lent a hand and expertise to help deploy transmitters on curlews in northern New Mexico and near Prince George in British Columbia, Canada. These birds represent populations at the extreme southern and northern ends of the breeding range and have never been tracked before. Without funding and vast collaborative efforts with agencies, non-government organizations, universities, private landowners, volunteers, and donors, none of this would be possible.

By the end of next year, we hope to start tracking curlews wintering on the coast of California, one of the only gaps remaining in the goal of range-wide tracking coverage. Collectively, we’re on the verge of completing the map of migratory connectivity, of illuminating the path for future conservation, and of glimpsing into the world of curlews as they travel across the continent.

Check out these links for more information about IBO’s curlew project, live-stream satellite tracking map, or how to donate.

IBO continues to flesh out the map of migratory connectivity with the addition of transmitter deployments on curlews breeding in New Mexico in 2019. Map by Stephanie Coates

This article is part of our 2019 end of the year newsletter! View the full newsletter here, or click “older posts” below to read the next article.