Migration brings hard-won wisdom of the dinosaurs to high country

I know because 15 minutes after I filled the hummingbird feeder, a dapper black chinned showed up for a drink.

I know because the birds at the feeder scattered and fell silent when the first shadow of the first migrating cooper’s hawk fell across the world.

I know because in the gloom the night before, I noticed my first pipistrelle bat, swooping over the stream in an optimistic search for insects.

All right. I’m kind of cheating on the pipistrelle. Who can tell what flitters like the ragged edge of a dream in the dusk? But they were acting like pipistrelles – and the timing fits.

The season trembles on the cusp of change. The jet stream has wandered. The blasts of snow have faded. The curtain rises on the next act – on spring. But I have not yet glimpsed the first swallow, returned from far places to their mud nests on the cliff face.

Still, I turn my eyes to the sky, thinking that if I peer hard enough, I can see the wavers of the Earth’s magnetic field. The birds can sense it. They fly by its beacon all through the night. Sometimes, it wavers too much, battered by the invisible charged particles gushing out of sun spots. Sometimes the variation in the magnetic field leads them to fly mistakenly to far places, where they starve or thrive.

At least, this is what researchers from the University of California concluded after comparing the measurements of 2.2 million banded birds representing 152 migratory species between 1960 and 2019. They correlated the paths of the birds a mile above the earth through the dark night with measured variations in the Earth’s magnetic field between 1960 and 2019. They found the magnetic field fluctuations at least partly accounts for “vagrancy” – which is when a bird shows up far from its normal path. March vagrants in Arizona include trumpeter swans, crested ducks, Eurasian wigeons – and yes, a greater scaup.

I lived most of my life without seasons, born and raised in California, 20 years in Phoenix. Looking back, my life was so impoverished, and I did not understand how the world works.

Now, living here in Arizona’s high country, I’m grasping the nature of things. The spin of the planet. The long annual trek around the sun. The distribution of continents. The mystery of the jet stream. The true stakes of our endearing curiosity and our baffling indifference.

In short, I have started paying much closer attention to birds – which flit like portents and puzzles through a vast and unexpectedly fragile world.

I like to look at the BirdCast website, which every night records the passage of millions of migrating birds, mostly making their way north in anticipation of the bounty of the spring in the so recently frozen north. Last night, the silent radar stations counted 13 million birds on their journey — the first trickle of what will become a torrent.

Some 10,000 bird species grace our far-flung planet, and about 2,000 of those species migrate. Some cover thousands of miles each spring, including the arctic tern that flies from pole to pole and back again. Some, like the painted bunting, fly from the American South to stopovers like Arizona, where they lose their worn feathers, grow new ones and then continue on down into the tropics.

The birds are the tiny heirs of the dinosaurs – survivors of the asteroid strike that wiped out their gargantuan relatives. The clues to their improbable ancestry remain in a hundred details, including their hollow bones, which increase their oxygen exchange. In birds, it provides the energy boost needed to fly half the world on a whim and a feather. In the giant dinosaurs, those same bones provided the extra oxygen necessary to support their great mass.

Turns out, we’re like another asteroid strike for these sturdy survivors. One recent study concluded that we’ve lost about 3 billion birds in North America in the past 50 years through a combination of habitat loss, climate shifts and other effects. The list of birds now at a “tipping point” for extinction grows every year. I was dismayed to find that the rufous hummingbird is now on that list. The longest-migrating hummingbird, these pugnacious, glowing golden sunstreaks take over my hummingbird feeders during the migration. They stop to stock up before continuing a migration that starts in the tropics and ends in the north of Canada.

The miraculous migration of the birds weaves a gleaming golden thread through the world, illuminating the persistence, creativity and fragility of life.

Just as climate change may have produced our wet winter by shifting the position of the jet stream, so the headwinds of climate change could have a big effect on bird migration, according to researchers from the Cornell Lab of Ornithology, published in the journal Global Change Biology.

The researchers used data from 143 radar stations to record the altitude, density of flocks and direction birds take in spring and autumn migrations over several years. They ran those measurements through 28 different climate-change predictions to ponder the possible effects of continued shifts on the birds.

Turns out, the birds will most likely face more headwinds when flying north in the spring. This could change the timing of the migration, and require much more energy for the birds heading north. On the other hand, the same trend could provide helpful tailwinds in the fall.

Will this mean the rufous hummingbird will disappear from my feeder? That the painted bunting not make it to the riparian sanctuaries of Rim Country and the White Mountains to molt and recharge? That the greater scaup will no longer appear expectedly to delight of geeky birders?

I don’t know. No one knows.

Certainly, the birds have completed their great journeys long before our ancestors made their way out of Africa and set about to remake the world.

But still, I watch the sky — though I have not the magnetic eyes of the robin, the sonar of the pipistrelle, nor the built-in polarizers of the bunting.

I can only sit and watch the feeders as the world flits past, bearing secrets learned from far places.

I can only hope the rufous hummingbird will return to deliver the hard-won wisdom of the dinosaurs, for one more turn of the seasons.