Sparrow Paparazzi
Following grassland birds from the Chihuahuan Desert to the Northern Great Plains provides us a peek into their lives and an understanding of the factors that impact their survival.
By Erin Strasser, International Biologist, Bird Conservancy of the Rockies
The story of grassland birds isn’t an easy one to hear. Native grasslands are being torn up for agriculture, overgrazed, suffering drought, taken over by invasive species, and experiencing shrub encroachment — leaving many bird species with a mere 10% of their populations remaining.
This year, Bird Conservancy of the Rockies and its partners from the Universidad Autónoma de Nuevo León, Universidad Juárez del Estado de Durango, and Sul Ross State University’s Borderlands Research Institute finished another winter of grassland bird monitoring in the Chihuahuan Desert. The project, which began in 2012, uses radio-telemetry to provide insights into factors that impact winter survival of Baird’s and Grasshopper Sparrows.
Basically, we capture birds, tag them with radio transmitters and follow them to get an insider view into their lives. In truth, sometimes we feel a little bit like sparrow paparazzi.
The species that winter in the Chihuahuan Desert eke out a fragile existence. This desert is harsh and during the winter, contrary to the breeding season when the sparrows focus on defending territories and raising young, the majority of a bird’s energy is invested in survival. Without dense grass needed for cover from predators and insulation from the cold, as well as a decent food supply of grass seeds, these little birds can easily perish to cold or predators. Those that do survive may not have the energy reserves to return north to the breeding grounds or do arrive but fail to raise nestlings.
Fortunately, in comparison with previous field seasons this winter has treated the birds well. As of late February, only 29 of the 298 sparrows are confirmed to have perished to predators such as Loggerhead Shrikes and Northern Harriers. In sharp contrast, by this time in winter 2015–16, almost 48% of the 260 tagged birds had died!
Better grassland conditions at many of the sites and milder temperatures have likely helped the birds survive the season.
Especially exciting for this year is that we’ve documented a few birds returning to their winter homes. One Grasshopper Sparrow was originally banded in December 2013. A Baird’s Sparrow which we tagged and tracked from December 2015-March 2016 returned to his same small territory located in prime grassland real estate. He is currently wearing his fourth radio-transmitter! Both will be tracked until mid-March when they will be captured prior to migration.
What’s Next?
From here, Bird Conservancy will shift its efforts to these species’ breeding grounds in the Northern Great Plains. We will monitor nests, fledglings, and breeding adults in Montana, North Dakota, and Alberta, Canada. This project is really one of a kind; we monitor these drastically declining and understudied species through their full life cycle at a tri-national level! With this data we hope to figure out the best way to conserve these species and their grassland habitat.
With this winter’s higher winter survival rates, we can only hope that more Baird’s and Grasshopper Sparrows will return to the breeding grounds. This would be especially valuable if birds tagged with geolocators (devices that allow us to determine their migration routes and wintering sites) return. We’ll find out this June when Bird Conservancy and partners from Audubon, Oklahoma State University, University of Manitoba and Canadian Wildlife Service travel to the Northern Great Plains to recapture these tagged birds.
Capturing Birds
This amazing video footage demonstrates how we capture birds and then track them with antennas to understand their lives on the wintering grounds. Teams move in a line, flushing birds out of hiding spaces and into the waiting nets. Birds are carefully retrieved, and the teams capture data about them including weight, general health and appearance, sex, etc. Some birds are fitted with tiny radio tags which are used to track their movements on the grasslands.
About the Author
Erin’s passion for research and avian conservation has led her to study birds in several Western states, as well as Belize and Honduras. She is interested in how anthropogenic change impacts breeding bird behavior and physiology, and the overwintering ecology of migratory birds. This is her 6th year studying overwintering survival and habitat use of Baird’s and Grasshopper Sparrows in the Chihuahuan Desert grasslands of Mexico. During the winter months, look for Erin and her puppy pal, Merlin, south of the border — then returning to the north during summer to study the same birds on the breeding grounds!
Bird Conservancy of the Rockies
Bird Conservancy of the Rockies, a member of the Playa Lakes Joint Venture management board, works to conserve birds and their habitats through an integrated approach of science, education and land stewardship. Their mission is advanced through sound science, achieved through empowering people, realized through stewardship, and sustained through partnerships.
