Millions of birds migrate each year and many take a path that leads them through Utah. Because these cross-continental journeys take so much energy, challenges like extreme weather, food shortages, or light pollution, are often fatal for birds.
Just after Labor Day, a storm with hurricane-strength winds and extreme temperature drops hit Utah. Trees were ripped up across the state and many residents were without power for days. The storm came right in the middle of fall migration, which means visiting migratory birds were faced with a cold front they couldn’t escape.
Brian Maxfield is a Sensitive Species Biologist with the Utah Division of Wildlife Resources in the Uintah Basin and said during that second week of September in the Ashley National Forest, temperatures were in the 20s and snowfall was up to 14 inches.
“We started getting all sorts of calls from Dutch John and Dinosaur Monument of bluebirds, robins, and hermit thrushes just dropping dead,” Maxfield said.At first, Maxfield said they weren’t sure what was causing the deaths, but soon they learned it was not an isolated event.
“Folks kept bringing us birds from the same spots,” he said. “We were about to start testing them to figure out what was going on when reports started coming out of New Mexico."
Thousands of dead migratory birds were found across New Mexico right around the time that Utah’s DWR was recording local die-off events. Which had Brian thinking the event had to be bigger than a cold snap in the state.
Reports started coming in from Texas, Arizona, Colorado, and other areas of Utah. While the species varied across states, there was one thing in common. The majority of birds that were dying were insectivores, birds whose diet is composed almost entirely of insects.
While a cold event alone could be detrimental to migratory birds and increased snowfall could bury insects that insectivores rely on for food, a singular abnormal weather event is often fatal, especially not on this level.
But the extreme cold event in the fall had followed a particularly long and severe wildfire season in the West. Researchers looking at the mass avian deaths speculate it could have been the cumulative effect of a dry summer leaving thirsty birds, combined with wildfire smoke and a cold snap adding up to the “perfect storm” that migrants just could not endure.
“All the birds that we found were insectivores too, and they were just starting to migrate so they should have been at a good weight,” Maxfield said. “But the birds we found had no fat on them. The fat stores that they needed to fly were just gone.”
There are many anomalous weather events that can threaten birds when they occur during migration times. Just a few weeks ago, states in the Southeast were hit with a polar vortex bringing record low temperatures and below freezing events to states like Texas.
Birds migrate through Texas along the Central Flyway, which also passes through Utah. While peak spring migration won’t pick up until March and April, areas in the Southeast along the Gulf of Mexico are often overwintering areas for birds that breed in the northern United States and Canada.
Cooper Farr is the director of conservation at Tracy Aviary in Salt Lake City and said quite a few species, especially insectivores, experienced mortality events across Texas because of the storm.
“Those birds likely died because of a lack of food, since they were unable to access insect or plant materials under snow cover,” Farr said.
Even though the cold has subsided, there will be lasting effects from these storms that carry over into migration. Record low temperatures damaged plant species and insect populations in the Southeast. Most of March is when a lot of migratory birds coming from further south are flying over the Gulf of Mexico and are coming to land along the Gulf Coast.
“As they arrive, they are going to have to deal with lower food availability, lack of insects, damaged habitat, and more impacted by freezing weather,” Farr said.
So once again, birds who migrate through Utah will face additional challenges on their journey. As a major stopover point on the Central Flyway, Utahns provide support to birds who are flying through. Bird feeders are like rest stops on a migration route and Farr has a few suggestions.
“Putting out fresh water in your yard, putting out high protein bird food like mealworms for insect eaters, and suet cakes that birds can feed on as they move through,” Farr said. “Having a yard that has good cover and native vegetation always helps out our migratory and resident birds.”
And since a lack of food isn’t the only challenge birds will face, Farr said there are a few other measures people can take to increase avian safety.
“People can also help out by trying to decrease anything else that could impact migratory birds, in addition to what they’ve already dealt with,” Farr said. “We see a huge uptick in window collisions with migratory birds during these seasons. You can put decals on windows, or screens too, to keep birds safe from collisions. We can turn out lights at night to reduce light pollution and keep cats inside during migration times.”
