Herons, Bald Eagles already nesting as weather warms around the area

Larger birds have started nesting around Western Colorado. Above, a Great Blue Heron touches down in a bare-boned cottonwood tree near the Colorado River east of Grand Junction. There are several heron rookeries in the area, and bird watchers can follow courtship and nest-building activities going on now.

A Bald Eagle peers from a nest west of Grand Junction. Both male and female eagles share nest-sitting responsibilities during the 35-day incubation period.

Tired of puffing into my cupped hands and trying to keep up with the leaky faucet that my nose had become, I turned my back to the blustery wind and headed upstream along the Gunnison River.

Spring is barely nascent in western Colorado and the stiff breeze tossing bare branches skyward along the jade-green river carried just enough cold and sand to remind me how uncomfortable early season birding can be.

It’s been an interesting late winter and early spring, particularly if one adheres to the adage, “May you live in interesting times.” After what was termed the “warmest February in history,” there was a return to winter and then another short spring and today the wind again is slamming battleship-gray clouds and curtains of snow against the side of Grand Mesa.

So why start now? Why lug out the long lenses, the field binoculars and enough guidebooks and plain-text notebooks to start my own field-journaling class?

Well, for one reason and one that’s not entirely flippant, because I could, since I had the day free to roam.

But also because I had noticed several large nests which I had been watching all winter were suddenly filled with feathers.

One was a Bald Eagle sitting on her nest hard by Interstate 70 west of Grand Junction. Another was a flock of Great Blue Herons tip-toeing among the skeletal tops of cottonwoods along the Colorado River bike path. Two more included a Cooper’s Hawk carrying branches to a nest downtown, and a pair of Golden Eagles returning for the third consecutive year to a nest along the back roads of Delta County.

And that doesn’t include the free-wheeling parade of ravens near Austin acting ostentatiously amorous or the appearance of a Great Horned Owl in a familiar nest or the House Sparrow with its beak splayed full of dried grasses, like it was carrying a long-legged crab.

Why now? With snow enough still on Grand Mesa to keep skiers happy at least until Easter, along with a runoff forecast sure to keep water managers busy until mid-summer, you’d think nesting was still a few weeks or a month away.

Not so for bigger birds.

According to the National Eagle Center in Wabasha, Minnesota, Bald Eagles may begin nest-building up to three months prior to breeding, early enough to have birds to watch during the annual eagle festival in early February at Barr Lake State Park near Denver.

That explains the white head poking from the top of that nest along I-70 in early February despite the promise of six more weeks of winter.

There is, not surprisingly, some indication that small songbirds are feeling the effects of climate change to where some — not all — have changed their nesting behavior.

A just-updated supplement to the Birds of Colorado hints at some migrational changes in Colorado and may even point to some birds no longer leaving Colorado. Have you seen how many Sandhill Cranes spend most of their year prancing and gleaning in the cornfields north of Delta? 

According to research by the University of East Anglia in Norwich, England, climate warming has been tied to earlier nesting and earlier hatching, which appears linked to earlier migration. That earlier migration seems limited so far to birds with shorter distances to travel, which isn’t yet fully understood.

Research by Allen Hurlbert at the University of North Carolina also has found correlations between warmer climate and early migration. According to the study, some birds have “shifted their migration on average nearly a day (early) for every degree Celsius the climate has warmed.”

But again, while some birds arrived on their summer grounds as many as six days early for each degree rise, other species ho-hummed their way north and stuck to what has been their historic timetable.

Hurlbert maintains that the timing of migration is critical to bird populations, as early birds may suffer from severe winter weather or arrive before insects have appeared.

Conversely, birds arriving too late may find themselves behind the competition to the earlier birds.

A lot of think about on a windy and leonine March day.


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