It is Rocky Mountain Bird Observatory’s third winter studying survival and movement patterns of Baird’s and Grasshopper Sparrows on their wintering grounds in the Chihuahuan Desert grasslands. These diminutive birds spend the winter scurrying among clumps of brittle grasses seeking seeds and cover, all the while avoiding the ever-abundant predators that prowl the prairies, such as Northern Harriers, American Kestrels, Short-eared Owls and shrikes.
This season, winter 2014-15, with the aid of collaborators from Universidad Juárez del Estado de Durango and Universidad Autónoma de Nuevo León, we have expanded this research to include three field sites across northern Mexico. The principal site, monitored since winter 2012-13, is within the Reserva Ecológica El Uno near Janos, Chihuahua. In winter 2013-14, we added a field site at Rancho Santa Teresa in the Cuchillas de la Zarca Grassland Priority Conservation Area (GPCA) in northern Durango. This winter, we began monitoring in the Valle Columbia GPCA in Coahuila.
As of late February, across all three field sites this winter, we had captured, outfitted with transmitters and tracked 107 Baird’s Sparrows and 117 Grasshopper Sparrows using radio-telemetry. Baird’s Sparrows were absent last season at the Chihuahua site, but this species returned in good numbers this winter. We even had our first recovered Baird’s Sparrow, initially banded two winters ago! In addition to these sparrows, we had the unexpected fortune of capturing and radio-marking two Sprague’s Pipits on their wintering grounds. This species could be listed under the Endangered Species Act, and little information exists on its habits on the wintering grounds. Although one pipit became the victim of a Loggerhead Shrike, we are still tracking a pipit and gathering data on its habitat use and survival in Chihuahua.
We’ve had several special visitors to the Chihuahua field site. Film crews from PBS’ Windows to the Wild series, and the Prince William Network and U.S. Forest Service International Programs’ FSNatureLIVE distance learning adventure series, visited to capture our work on the ground. An especially esteemed visitor, The Consul General of the U.S. to Mexico, spent an afternoon and evening with the RMBO team. We hope our visitors help promote awareness of the plight of grassland birds to a broader audience.
There are only a few more weeks left in the field season to track birds and collect information on their grassland habitat. Soon, we’ll recapture birds to lighten their load … that is, remove their transmitters for the last time. The unrelenting desert winds have picked up, and flocks of Snow Geese and Tree Swallows are passing through on their way north and will be followed shortly by the sparrows and pipits we’ve tracked since December.
Thank you to Universidad Juárez del Estado de Durango, Universidad Autónoma de Nuevo Leon and The Nature Conservancy for partnering on this research, and the Canadian Wildlife Service, USFWS Neotropical Migratory Bird Conservation Act, USDA Forest Service International Program and WWF-Carlos Slim Foundation for funding.
As with the last two field seasons, this winter has been insightful and fascinating. Stay tuned for an end-of-season update!
~ Erin Strasser, Biologist