Study: Migratory birds affected by changing onset of spring

Published 1:30 am Sunday, June 4, 2017

We are constantly making choices. Should I check my tires’ air pressure, clean the bird feeder, go to a Mariners game, start a diet, do an unexpected kindness, save or spend a windfall, or volunteer to make a difference?

Rachel Carson decided to make a difference. After seeing the link between DDT and declining migratory bird populations, she decided to write a book, “Silent Spring,” published in 1962.

Carson’s choice jump-started the creation of the Environmental Protection Agency and lead to the ban on the pesticide DDT. Her research and passion won the day, despite her scientific findings being attacked and being called “hysterical” (women being women, you know). Sound familiar?

(I’ll offer another choice at the end of the column.)

Today we have different challenges and choices to make, some still related to spring. Researchers recently published a study focusing on migratory birds in the spring (www.nature.com). Science proves that the start of spring is shifting in North America, and research links that fact to climate change.

If spring gradually starts earlier (or later), that can present problems for birds because they depend on a particular habitat that provides an abundance of food for themselves (and their future offspring) when they arrive.

In the East, arrival of eastern breeding species increasingly lagged the onset of spring (called the “green-up” and not the Solstice), whereas in the West, birds arrived increasingly earlier relative to green-up, according to the report.

Green-up is not a direct measure of food availability but a yardstick that relates to habitat, temperature and food sources, according to the study.

Researchers studied 48 songbird species’ arrival times from 2001-2012 across North America using satellite data and 400 million bird sightings registered with the website eBird. During that time, the average difference between the onset of spring and the birds’ arrival dates averaged a half-day difference per year, a significant amount.

Songbirds’ migration north is triggered by a physiological response to the photoperiod, a consistent factor, but the climate can vary. The larger the mismatch between green-up and arrival, the lower the chance of songbirds maximizing the plant-eating insect population.

Some species have been able to alter their arrival date, but whether they will be able to continue that adaptation is the question, particularly if the green-up continues at the current rapid pace for some species, far faster than evolutionary changes usually occur.

Researchers found that nine of the species fared the worst in terms of arrival date vs. the green-up. They included the blue-winged warblers, indigo buntings, rose-breasted grosbeaks, Townsend’s warblers and yellow-billed cuckoos.

According to the study, if migratory birds can’t keep pace with the climate-changing effects, then the likely result is reduced fitness for individuals, reduced population sizes, and possible extinction of the species that can’t adjust rapidly enough.

And so it goes, the life-and-death dance between arriving too early, or too late.

So I have a choice for you: Choose to do something about the climate change issue. Or not. Educate yourself via credible websites or books or TED Talks (ted.com). Or not.

I get it. Positive change is difficult. You’re only one person. So what? You can contribute an opinion based on facts. Use a focused paragraph (no need to write a 1,000-word essay; they won’t read it) on your concern and send it to as many elected officials, corporations and bureaucrats as you can find.

You won’t lose your job, you won’t be fined, you won’t be jailed and your relatives won’t shun you.

There is a five-minute period between rising and falling into bed where you can send a message. Mine is right after breakfast before the day takes over. One a day; on a good day, a few more.

And don’t just choose – commit. Do it for the birds that can’t ask for help.

Columnist Sharon Wootton can be reached at 360-468-3964 or songandword@rockisland.com.