Summer snowstorm devastating to migratory songbirds

Photos by John Rawinski A weakened and hungry Wilson’s Warbler

SAN LUIS VALLEY - While the late summer snowstorm was a welcome event for our water supplies, it was also a devastating storm for migrating songbirds. The storm resulted in possibly thousands of bird deaths in the San Luis Valley alone. This comes at a time when songbirds are already facing serious declines globally - down 3 billion birds since 1970.


The timing of the storm was especially unfortunate for migrating songbirds. Migrating birds expend tremendous energy during migration and rely on the autumn abundance of seeds, flowers and insects to restore energy. However, the 14 plus inches of snow the Valley received effectively cut off the food supply for these birds and left them wet, weakened, hungry and cold. Many birds died in the process or were seen to be near death. They were easily approached in their diminished conditions.


Local bird craftsman Tarry Maxson, who carves beautiful wooden bird figures, found six dead birds around his house near Monte Vista. He said if he found that many around his house, he wondered how many died everywhere else.


During the storm, an email message went out to the San Luis Valley Birder’s Network, a group of San Luis Valley bird enthusiasts, to help the birds in any way they could, and many responded. At the authors house, clearings were made and ground feeders like sparrows and towhees fed on millet seed. Sage Thrashers, Hermit Thrushes and Robins feasted on mealworms that were provided for them. At least two hummingbirds survived by using the feeder, their only source of sustenance. Sadly, for some birds like swallows who eat small insects, nothing could be done. That fact was later confirmed by a survey done at Monte Vista High School. Science teacher Loree Harvey had her freshmen students do a mortality survey of birds around the Delta Center. They found 33 total birds and the majority were swallows. There were 24 juvenile Violet-green swallows, 5 adult Violet-green swallows, 1 MacGillivray’s Warbler, 1 Wilson’s Warbler, 1 Pine Siskin and 1 juvenile Barn Swallow. That count is conservative as the janitors are reported to have removed a few more.


Automobiles took a significant toll on the birds as well. Birds were killed along roadsides by vehicular traffic. When storms like this hit, birds are drawn to the only cleared soil where they might find seed and that is along the plowed roadways. Birds that normally spread out in forested or grassy cover, found themselves desperately confined and searching for seeds or insects along those cleared roadways. Unfortunately, when a vehicle approaches, the birds flush and often become casualties. Over a 4 mile stretch along the “Gunbarrel,” the author counted carcasses of 3 American Robins, 3 Vesper Sparrows, 3 Hermit Thrushes, 2 Green-tailed Towhees, 3 Mountain Bluebirds, 1 Western Bluebird, 2 Starlings and 1 Wilson’s Warbler. If this is extrapolated to other county and state roads in our Valley, the mortality would have amounted to thousands of birds from highways alone.


There has been a significant bird die-off in New Mexico recently that has scientists unsure as to its cause. This was being documented before the snowstorm. However, scientists are seeking to gather citizen input on the degree of mortality throughout Colorado, New Mexico and other places in this region. If you observed bird mortality, please consider reporting it via the following website. If we all pitch in on this important citizen science effort, researchers will have a more comprehensive assessment of the widespread impact. You can contribute by visiting the website below.


https://www.inaturalist.org/projects/southwest-avian-mortality-project 

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