It mystifies me that while I sleep, millions of birds pass silently overhead in a migratory flight that can – for some of them – be tens of thousands of miles.
I am fascinated by the instinct that drives them and the adaptation processes that prepare their seemingly fragile bodies to survive their arduous journeys. But I’m also frustrated that these finely tuned processes have been inadvertently circumvented by human invention, leading to one of the highest causes of mortality birds can face during migration.
The good news, however, is that it’s something we can fix.
As early as the 1800s, humans recognized the negative effects of artificial light on migratory birds. According to “A World on the Wing: A World Migratory Bird Odyssey” by Scott Weidensaul, lighthouse keepers reported a large number of casualties when migrating songbirds fought against the glass.
In recent years, with the advent of radar technology, scientists have continued to observe changes in behavior. For example, Weidensaul writes that in 2016 scientists noticed a trend in fall migrants on the East Coast. Forest-nesting songbirds were found in greater numbers in urban parks.
Eventually it became clear that city lights were reshaping migration, particularly in the fall when young birds in their first fights were attracted to artificial city light, which is “visible to a bird in flight from above.” as far as 190 miles”.
The problem is that many birds navigate by starlight, and with the increasing sprawl of city lights, birds become disoriented. Once removed from their migratory path, they become vulnerable to hazards, including collisions with windows, the second leading cause of bird mortality behind domestic cats (not counting general habitat loss). While it is true that these collisions occur year-round, the numbers increase during migration.
“Spring migration is intense,” said Krystal Anton of Johnson County Community College’s Center for Sustainability.
In 2018, concerned about the number of dead birds found on campus, Anton launched a study of bird-window collisions to understand the extent of the problem.
“That first year was overwhelming,” said Anton.
By the end of the study, the JCCC team had found 287 dead birds, 42 injured birds and 138 window prints, which they said were left by birds hitting a window but not dying on the spot.
To date, JCCC volunteers have found 94 different species of collision victims. The species with the highest mortality rate during spring migration is the Swainson’s Thrush. In autumn, it is the ruby-throated hummingbird.
After accumulating the results of his study, Anton researched methods to reduce bird mortality on campus, and in 2019 the JCCC team began installing vinyl dots on the most problematic windows, breaking their reflective surfaces to make them visible to birds.
“I tried different spacings, but placing dots every two inches was almost 100% effective in reducing collisions on windows that have them,” Anton said. “It varies from year to year, but we have about half as many collisions as before.”
These statistics are encouraging.
Nationwide, an estimated 600 million birds are killed each year by collisions. Fifty-six percent of these fatalities occur against low-rise buildings, 44% occur against residential windows, and 1% occur against tall buildings – although their bird-to-building ratio is the highest.
Often we look at issues that are close to our hearts and feel that we can’t do anything, that we are helpless. But in this case, individuals can make a difference.
Lights Out Heartland, a collaboration of organizations working to reduce light pollution during migration, offers a list of ways to make our homes bird-safe, some as simple as closing blinds or changing exterior light bulbs. . We can also encourage local businesses to get involved.
Using radar tracking, cities can be alerted when large flocks of migrating birds enter an area, allowing participating features to dim their lighting, allowing the flocks to pass safely.
“Reducing light pollution doesn’t mean it has to be completely dark outside your home or business,” Anton said. “It’s a dark sky, not a dark ground. Better lighting with shielded lights that only shine downwards or motion sensors will largely take care of that.
Migration begins as early as January for some species, but most will pass through Kansas between April and June, with May seeing peak migration. We can make a difference today.