Of Earth, Wind, and Birds
With a changing climate come changing winds, and implications for feathered riders of the breeze
At the end of a third day of seemingly ceaseless high winds in the portion of western Colorado that I live in, I watched a tired and subdued Steller’s jay trying to take a little shelter from the seemingly unending spring tempest. A normally energetic species, this fellow had plainly had enough. The Steller’s jay is common to Colorado, but not at lower elevations nor in the sere adobe hills of my neighborhood. The mature, if non-native, trees here often provide an artificial bird oasis. My yard had plainly appealed to this fellow as a welcome respite.
Photo by Eric Ellingson
As I watched his listless attempts to forage on the lawn, and slightly more animated attempts to avoid the irritated doves nesting in the willows nearby, I pondered his situation from the protected stillness of my living room. I recalled a light-hearted but compelling article from Forbes in the autumn of 2017 entitled “Where do birds go in a hurricane” by a writer identified only a “GrrlScientist.” I was captivated by the photo of a wounded hawk, named Harvey by the driver of the taxi in which he was seeking shelter during Hurricane Harvey. It was an interesting question, and one I felt had greater implications for bird populations in general. I hadn’t truly considered it further until the exhausted jay reminded me.
Climate change is responsible for many new and difficult conditions for both man and beast, but wind is one of the most overlooked of those elements. Farmers and outdoor buffs get it, but an increase in the force of spring winds is not yet the stuff of earnest discussion among the majority of folks in North America. Some folks wonder if it’s all in their imagination. It’s not.
Take this recent excerpt from the Washington Post: “In March, 17 of 31 days featured gusts of at least 30 mph, and three days had gusts exceeding 40 mph. In April, so far, we’ve had gusts over 30 mph on 10 of 19 days, and also three days with gusts exceeding 40 mph. Winds have gusted over 30 mph on seven of the past eight days in Washington.” The phrase ‘in like a lion, out like a lamb’ — which refers to the March transition from winter to spring in the Northern Hemisphere — no longer seems to apply. In like a lion sure, then out like a charging rhino is more the case.
Washington isn’t the only place experiencing higher winds. In 2008, most meteorologists were somewhat agreed on the likelihood of increasing future mean surface wind speed across much of Canada and the United States, with higher than normal winds sweeping across a broad swath from the Hudson Bay, through Texas, and as far south as the Yucatan peninsula. There was even greater agreement among these experts that the mountainous American West, the desert Southwest, and the Atlantic seaboard would receive the brunt of wind speed increases. That forecast was recently supported by a 2017 study by Spanish meteorologists at the University of Madrid reviewing wind speed trends. They found that boreal spring conditions in much of North America were indeed windier in the last 35 years. They also found that certain portions of Central and South America were even windier during March, April, and May. (There is still much uncertainty about exactly how and where climate change will impact wind speeds. Just as some places will experience more forceful gales, others will likely experience less wind.)
Increasingly severe linear and cyclonic wind events affect human health, safety, and economics, but what about the feathered riders of the wind? They are made for this stuff, right? The answer often is … sometimes. But increasingly, the answer is no.
Like most animals, birds are exquisitely sensitive to their environment. Their ability to successfully reproduce depends on it. For example, temperature signals many things to birds, such as when to begin a migration or when to nest. Globally, temperature increase is influencing nesting onset, such as in Great Britain, where bird-watchers noted that in the 1990s, of 120 species observed annually, over 40 percent seemed to be consistently laying earlier. And those findings were compiled more than 20 years ago. It seems reasonable to assume that many more British species are nesting early these days. This assumption is easily supported by research out of California, which revealed that all 224 species of birds nesting in the Sierra Nevada are laying up to 12 days sooner than they did a century ago.
Under some circumstances, in some places, for many bird species, early nesting is a great strategy. "By nesting a week or 10 days earlier, birds are avoiding some of the negative effects of climate warming," states American ornithologist Steve Beissinger. In fact, it can allow some birds to raise two broods in one year instead of just one. However, for some species, the phenological disjunction they experience that causes early nesting works against them.
Photo by Kevin Faccenda
Phenological disjunction happens when an animal misunderstands the cues present in their environment. Conditions in the Colorado Rockies provide an example of just such miscuing, where higher spring temperatures have led to the earlier arrival of American robins. Robins tend to begin nesting immediately upon arrival in the mountains. However, higher temperatures don’t always mean an earlier snowmelt date — increases in winter precipitation often accompany higher annual temperatures. According to David Inouye and other researchers at the Rocky Mountain Biological Laboratory in Gothic, Colorado, the interval between first nest attempt and bare ground has actually increased by 18 days, resulting in forage challenges for adult robins.
Add to this stronger and more sustained winds, and phenological disjunction is in full swing. For Rocky Mountain robins, this may result in reduced nesting success many years, especially in windy La Nina-El Nino conditions. Mortality will tend to vary both from year to year and bird to bird. For example, some robins will nest in evergreens for their first clutch, a good windiness beating strategy. But even so, most robin nests are loosely constructed and not well maintained, wherever they are built. Therefore, choice of nesting site would be more critical some years than others. Some well-placed nests may withstand several blasts, but in the face of winds of the type that created dust visible from space in March 2018 over eastern Colorado, even the most wisely placed nests may be ripped from their moorings, or the eggs quickly become so chilled from the winds that they become non-viable. Although more research on robin early nesting success is needed, ornithologists studying tree swallows in Alaska were surprised to find that between temperature, precipitation, and wind speed effects on nesting success, wind speed was most significantly correlated with nesting date and clutch success.
The energy expenditure of an early failed nest due to phenological disjunction between favorable temperatures and unfavorable winds can reduce an adult’s fitness for successful reproduction later in the year. Warmer temperatures may or may not favor reproductive success for robins and other tree nesting birds — the science is still out on that. Winds do not, and these days many parts of the globe are most certainly windier.
Though tree nesting birds may struggle, many ground nesting birds will be less affected by increased linear winds, at least when it comes to the safety of their nests. Even in the absence of a parent shielding the eggs from a windy blast, the eggs are still insulated from excessive heat or cold on one side, and can’t fall to the ground since they are already there.
Photo by Ed Dunens
Still, they may face other challenges. Despite the advantages of ground nesting, shorebirds and seabirds may have to cope with ever higher ocean winds, presenting unique reproductive challenges not faced by most terrestrial birds. Winds and albatrosses are an interesting case in point. High winds can be beneficial to free-wheeling individuals not in the family way. Depending on fish locations and head-winds versus tail-winds, non-breeding albatross seem to generally thrive in windier conditions. Not so for breeding birds. The need to tend to nestlings frequently limits the amount of time they can spend away from the nest. Strong and unseasonable headwinds that blast between nesting areas and fish populations can impact the adult’s abilities to return with a full meal to share with their young in a timely manner. An uncomfortable balance must be calculated between “increased energetic costs of reaching distant foraging grounds” and the needs of the nestlings, according to a collaboration of marine vertebrate researchers from New York to Monterey, California.
Concerning a different marine bird, French researchers have discovered that little penguins, found off the coast of Victoria, Australia, experience reduced reproductive success during episodes of high winds during the chick guarding portion of their reproductive cycle (until the chicks are about 75 days old). Unlike albatrosses, little penguin adults choose to maintain their own weight, while providing smaller meals to chicks during windy episodes. This means chicks don’t always get enough food, and chick survival is lower as a result. Although many seabirds will be capable of adopting high wind coping strategies, there does seem to be evidence that many populations will decline.
It remains to be seen which avian species will thrive and which will diminish in a windier world. But what seems certain is that changing wind patterns present yet one more challenge to birds attempting to adapt in a climate-changing world.
Correction: A previous version of this story incorrectly referred to David Inouye as Daniel Inouye.