By Kaitlyn Wilson, North Dakota Field Crew Leader
Bird Conservancy of the Rockies, working alongside partners including North Dakota Game and Fish Department, just completed a second summer season studying breeding season survival in adults and juveniles of nesting Baird’s and Grasshopper Sparrows in the Northern Great Plains of North Dakota and Montana.
When we first arrived at the beginning of the season, the species we were looking for had not yet returned from their wintering grounds in Mexico. Then, one morning, the musical trill of a Baird’s Sparrow broke through the wind of the prairie. It was followed by the insect-like trills of a Grasshopper Sparrow. The birds had found their way back once again, and the breeding season had begun!
The males are always eager to defend territory. We lured them into mist nets by playing a Baird’s Sparrow song, imitating a rival. Within a minute our first sparrow darted into the net in an attempt to run off the intruder. Each captured bird was fitted with a transmitter. We used radio telemetry to track their exact location every day, in an effort to determine survival rates and habitat use.
As we continued capturing males, the females began to sporadically arrive. The beginning of the nesting season for Grasshopper Sparrow becomes obvious as they start acting ‘nesty’—making chipping calls much different than their usual calls. Baird’s Sparrows are more elusive, only giving their nest away when flushed, or by flying circles overhead and chipping because we were getting too close to their nest.
We monitored nests for survival (fail or fledge), and also attached transmitters to nestlings to track their survival. Unfortunately, many of the nests did fail, often due to depredation. Predators include Northern Harriers, coyotes, ground squirrels, weasels, and snakes. Some nests were abandoned for unknown reasons. The failures, though disheartening, give insights into the challenges facing these birds.
Grassland songbirds are declining at a steeper rate than any other group of birds in North America. According to the State of North America’s Birds 2016 report, 27% of the 45 grassland species have lost, on average, almost 70% of their continental populations since 1970. A likely cause is habitat loss. We look forward to another season in 2017 with opportunities to learn more and hopefully shed light on what can be done to ensure their song continues to be heard across the wide open landscape.
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