Sunday, December 16, 2007


There are always at least two ways of looking at pretty much anything, including the weather.

Some years ago, I was in northwest Alabama, not far from Muscle Shoals, to speak at an ornithological conference. It was late January, but a huge cold front blustering through from Mississippi was spawning tornadoes left, right and sideways. And it was coming right at us.

The conference was in a state park resort, and as I was getting dressed for the opening reception, I kept a nervous eye on the local TV station, which was giving breathless updates. Just about the time the weather guy jabbed a finger at a huge blob of intense red on his radar screen and said, "If you are two or three miles northeast of Muscle Shoals, you should be taking shelter now," the sirens all went off outside.

I skedaddled for the main building as a sheriff's deputy drove past, his voice tinny over a loudspeaker, ordering everyone inside. All the conferees were already there, gathered in the only interior, basement room available – the men's restroom. It was a little tight, but we all had our "Hi I'm ---" name tags, and little paper cups of white wine.

"So you're from Pennsylvania!" one older woman said brightly, as the sirens continued to keen. "I could never live up there – y'all get such nasty ice storms."

I must have looked at her as though she were speaking Urdu. "At least," I said, my voice rising to a tense squeak, "at least an ice storm won't suck you up the chimney and smear you across the landscape in a million pieces!" Her smile froze, and she backed away. Slowly.

So here we are, with our second big ice storm in four days, and it's nasty, all right. But it could be worse. I just got off the phone with a good friend in Oklahoma, where the epic ice storms of the past week have left him without power for seven days and counting, and with all 14 trees on his property smashed and down. I told him my Alabama story and David said sure, he'd take tornadoes any time.

And there are two ways to look at this storm, too. The freezing rain stopped about 3 p.m., and I was crunching around the backyard, assessing how best to remove the big limbs that came down off one of the white pines and took out part of the back fence. Then the clouds parted and shafts of low, late-day sunlight illuminated the landscape. I've lived in this old farmhouse for more than 20 years, and I don't think I've ever seen our valley look as breathtaking.

The yard was swarming with birds, trying vainly to get purchase as they landed in the iced-up branches of the crabapple and birches. I heard a slightly strange note from the goldfinches on the thistle feeder, and realized that a couple of common redpolls had joined the flock, the first time in six years that I've seen this Arctic finch down here.

I was hurrying, trying to scrape clean the walkways while taking pictures as the light kept shifting; by now the whole sky was brilliant blue, the land glittering, the drip of meltwater off the trees a cascade that sparkled with backlighting. Yet still more changes were in the offing; the forecast was for 45 mph winds by nightfall, and already, the northwest horizon was gathering dark squall clouds. Once the wind starts to roar, I expect the power will fail as heavy-laden limbs crack and fall throughout the valley, and the ice sheathing the branches of the catalpa trees will shatter against the sides of the house like kids throwing gravel at the windows.

With my friend's experience fresh in my mind, it was an ominous thought. But then, a final band of light hit an isolated clump of trees in a neighbor's field, creating a halo of golden light against the blue-black of the approaching clouds. I grabbed the camera and squeezed off several frames in the second and a half just as the sun vanished and the light went out – and as my perspective changed, once again.

Thursday, December 13, 2007

And now to sleep...

We've wrapped up what can only be described as a remarkable season of saw-whet owl banding, and I suspect everyone on my crew is enjoying the chance to get caught up on their sleep. I know I am.

We’ve been banding migrant owls since 1997, and last year was one of the worst seasons on record – only 202 of the miniature owls, the product of two solid months of netting, every rainless night from dusk until midnight at three sites in central Pennsylvania.

This year was a stunning difference, though. As I've explained in earlier posts, this autumn marked the peak in a four-year cycle in saw-whet populations, and coincided with a crash in the number of small rodents in Canada. The result was an "irruption," a great wave of owls flooding south into the eastern U.S.

When we furled our nets for the last time a week ago, we'd netted 895 saw-whets – 393 of them at our Hidden Valley site in Schuylkill County, 284 at Small Valley in Dauphin County, and 218 at King's Gap in Cumberland County. Each owl was ringed with a lightweight, government-issued band stamped with a serial number, measured, and released.

Twenty-three of the owls we caught, though, were already banded, and these so-called foreign birds are always an exciting highlight. Thanks to a network of owl researchers called Project Owlnet, and the federal Banding Lab's online reporting system, we were able to quickly determine where most of these birds came from – and the results often surprised us.
Where our autumn 2007 owls came from.

Not surprisingly, many of the recoveries were of owls banded to our north, at places like Prince Edward Point Bird Observatory, on the north shore of Lake Ontario (seven owls) or Timiskaming and Hillardtown Marsh, near the Ontario/Quebec border (two owls). While many of the owls were banded earlier this fall, about half had been banded in previous years, including two banded in 2006 in the Shawangunk Mountains of southern New York, 2005 owls from Long Point, Ontario and Williamstown, Massachusetts, and a 2004 bird from Prince Edward Point.

The most remarkable foreign owl was the first of the season, netted Oct. 7 at Hidden Valley – a bird that had been banded at the end of July as a juvenile at Whitefish Point, on the upper peninsula of Michigan. It was one of more than 700 saw-whets the Whitefish Point Bird Observatory banded this summer, most of them in the "chocolate" juvenile plumage. Given that our site is almost 600 miles east/southeast of the UP of Michigan, it's an indication of how widely these birds wander.

Even though we've wrapped our nets for the season, the migration continues; Holiday Beach, Ontario, reports a few saw-whets still passing through, and I'll continue to net in the yard the rest of the month. And last week, my good friends and colleagues Bob and Martha Sargent netted a couple of saw-whets in north Alabama, where I suspect the big push has yet to arrive.

Thursday, November 22, 2007

Upcoming events

Shameless promotional message: I'm scheduled to appear Thursday, Nov. 29, on NPR's "On Point" program, from 11 a.m. to noon EDT. I'll be discussing my new book, Of a Feather, a history of birding and ornithology in America.

That weekend, I'll be giving the keynote for the Ohio Bird Conservation Symposium at Deer Creek Resort south of Columbus, and sponsored by the Ohio Ornithological Society and The Nature Conservancy. And on Tuesday, Dec. 4, I'll be addressing the Birmingham (Alabama) Audubon Society.

Hummingbirds in the snow

Hummingbirds in the snow…I'll admit, that seems like an avian non sequitur, since everyone knows that hummingbirds are the jewels of summer, little tropical hothouse birds that would faint at the first hint of cold weather, never mind an actual flake or two of snow.

Which is why I especially love days like this past Sunday, when I was driving over the Kittatinny Ridge in heavy snow showers. Down in the valley an hour south of my house it was slightly warmer, and the snow was coming down as rain, while I set up a cage trap on the porch of a lovely old 1800s farmhouse. A nectar feeder hung inside, and within minutes, I'd trapped an immature female Selasphorus hummingbird, which Deb and Jim, the homeowners, had spotted a couple of days earlier.

If that seems remarkable, it isn't; western hummingbirds have become commonplace in eastern states like Pennsylvania every fall and winter, often lingering until well past Christmas, and through nights when the temperature may dip below zero.

In fact, the only remarkable thing about this situation was that this was the second hummingbird to show up at Deb and Jim's home this month. A week earlier, my colleague Wayne Laubscher of Lock Haven (covering for me while I was out of town) had banded an immature male rufous hummingbird here, a sparkling bird the color of a new penny, with its fiery orange gorget almost completely molted in. The little guy was still hanging around on Sunday when I was there, and buzzed us a couple of times after we had the trap set up.

A rufous hummingbird, banded in late December 2004, Middletown, PA (©Tom Johnson)

Once I had caught the new hummer, it was a matter of about five or 10 minutes to band her, take a few measurements, some photographs, and then release her. The measurements allowed me to make a firm identification; female and immature hummingbirds of the genus Selasphorus are almost impossible to identify in the field, but by measuring the width of her outermost tail feathers, her wing and bill, and by looking for a distinctive notching in one of the central tail feathers, I confirmed that she was a rufous hummer, and not one of the look-alike Allen's or broad-taileds.

Wait a minute, though – what would any of those decidedly western species be doing in Pennsylvania, especially on a snowy, late-November day? The answer appears to be bound up with the rapid development of a new migratory route, and a glimpse of avian evolution in action.

Traditionally, all of these species – rufous, Allen's, calliope, black-chinned, broad-tailed and others – nested in the U.S. and Canada but wintered primarily in Mexico. To get there, they follow a genetically coded orientation that propels them south in fall – flying individually, not in flocks or with their parents, depending solely on the instinct inscribed in their DNA.

But DNA mutates, and when it does, sometimes you get birds that head in the wrong direction. That's probably what's happening with these hummingbirds; programmed to head east instead of south, they wind up in the mid-Atlantic states in autumn, then work their way down to the Gulf Coast, where thousands and thousands of them now pass the winter.

By catching and banding these birds, which may be recaptured miles or years later, we can document this evolution of a new migratory route and wintering ground. I'm one of a loose network of hummingbird banders in North America studying this phenomenon, and at this time of year, I'll drop everything to race out and band a newly reported hummingbird.

On Wednesday I drove to northern New Jersey to band what is only the fifth calliope hummingbird to be seen in the Garden State. This little immature female (calliopes, which weigh about 3 grams, are the smallest birds in North America) was snugged down in a small but lavishly landscaped backyard in Denville, where dozens of birders had been coming to see her.

She was a snap to capture, and calm in the hand as she got her own, custom-made band, a minute thing only 5.4mm long, hand-crafted into a neat circle and laser-printed with a serial number, N99797. The bands are so small it takes more than 5,500 of them to weigh an ounce, and are no hardship for the bird.

Within a few minutes of her release, she was feeding again at one of the feeders, her movements followed by several big telephoto lenses. At night, like all of these cold-hardy westerners, she'd be tucked in a dense thicket, where she'd turn down her internal thermostat from a daytime high of about 109F to about 50F, going into a profound, death-like torpor to save energy. (That's why these western hummingbird species, which can be found above 9,000 feet in the Rockies and as far north as the Kenai Peninsula in Alaska, are not bothered by sub-freezing temperatures in the East. If they're healthy, they can even tolerate lows below zero for a few nights.)

A couple of times she zipped out from her perch to snag a small, passing insect – even in cold weather, these birds are adept at finding invertebrates, often picking dormant bugs out of foliage and from the crevices in bark. Nectar, either natural or from a feeder, makes up less than half of their diet at all times of the year.

The calliope was in good shape, except for some missing throat and tail feathers, perhaps from a collision with a wire or twig, which she would soon replace. And I was just in time – she apparently left this morning, Thanksgiving, a lovely, mild day and a perfect one for heading south. She took with her a tiny band – and my thanks, naturally.

Wednesday, November 7, 2007

The Flood from the North

The boreal forest is emptying out – I can see it at our feeders, and every night we see it in our owl nets.

Last year, the forests of eastern Canada provided an incredible bounty of food, in the form of mast – the broad term for nuts, berries, pine and spruce seeds. Many trees "mast" unpredictably, as a strategy for thwarting seed predators like birds and mammals; some years they bear very little, keeping predator populations low, then they will flood the market, so to speak, with vast quantities of mast, so that at least some of the seeds will survive to germinate.

As it happens, 2006 was a year when most of the species in the eastern boreal forest heaped the table with a feast – mast in great abundance. Many species of seed-eating birds, like finches, nuthatches and chickadees, stayed north.

Because the mast provided food for huge numbers of mice and voles, many northern owls also stayed home last fall and winter, and those of us who band migrant saw-whet owls down here in the eastern United States had our worst season ever.

But my, how things have changed. This fall, the trees of eastern Canada shut off the spigot; the mast crop was meager to nonexistent in many areas. Faced with poor prospects, many northern birds have been flooding south in a phenomenon known as irruption (the term is the opposite of eruption – a rushing into, as opposed to an explosion out of, something).

Irruptive birds include purple finches, pine siskins, red and white-winged crossbills, common and hoary redpolls, red-breasted nuthatches and pine grosbeaks. They also include many northern raptors, among them northern shrikes and a variety of owls. Unlike most migrants, which travel predictable routes at predictable seasons, the irruptive species strike like lightning, appearing and disappearing as though on a whim.

(This has nothing to do with the severity of the coming winter, by the way. The last really good winter finch year we had down here, back in the late 1990s, was also one of the warmest on record. It's all about food, not temperature.)

But with the food growing scarce, the birds are getting out of Dodge. Night after night, my crew of owl banders have been catching record numbers of saw-whet owls, up to 75 in an evening. These birds have been in exceptionally good condition (we check their fat stores and muscle mass), but if they'd stayed north, chances are they might have starved.

Birders here in the mid-Atlantic states are also excited by the arrival of large numbers of northern finches and other seed-eating species. We noticed a huge influx of black-capped chickadees and white-breasted nuthatches starting in late August, and in recent weeks additional boreal species have been coming in; this morning, purple finches and a red-breasted nuthatch, both irruptive species, joined the melee at our feeders.

This past week, there have even been growing numbers of reports of evening grosbeaks across Pennsylvania, a stunning species that was unheard of in Pennsylvania prior to 1890, but which began to invade the state in winter more and more frequently, and in greater and greater numbers, in the early decades of the 20th century. Many of us remember fondly their biennial invasions in the 1960s and '70s, when they would crowd feeders, sometimes by the hundreds, consuming vast quantities of sunflower seed and earning the nickname "gross-pigs" from birders who got tired of shelling out for so much food.

Then, they were gone. Since the 1980s, evening grosbeaks have been almost completely absent from our region. In this case, though, there is more at work than simply the boom-and-bust cycle of northern mast production.

Evening grosbeaks nest across the boreal zone from Newfoundland to British Columbia, and south in high conifer forests into southern Mexico. Across much of their range, a favorite summer food is a moth larvae known as the spruce budworm, a cyclical species that can reach plague dimensions in spruce forests.

Many boreal songbirds depend upon spruce budworm, including Cape May and Tennessee warblers. Like the grosbeak, their populations rise and fall in lockstep with the fortunes of the budworm. The last time we had lots of grosbeaks coming south into the eastern U.S. was during a spike in the budworm cycle in the 1960s and '70s, when millions of acres of across Canada were defoliated. But since then the caterpillars have been on the wane, and the populations of many of these budworm specialists have been on the decline as well.

So while the lack of mast this year is obviously driving the grosbeaks south, they will probably not come in the great numbers I remember from my childhood, because there just aren't that many grosbeaks these days.

There may be more at work with the grosbeaks than simply the budworm cycle; while research in eastern Canada suggests evening grosbeaks are strongly linked to budworm numbers, that doesn't appear to be the case in part of the West. And in fact, there is evidence that at least some of the irruptive grosbeak flocks that reached the East in the good old days were actually from the West, crossing the Plains and eating the seeds of box-elders, planted in shelterbelts across the prairies.

There is still a lot to learn about this beautiful finch, but for now, I'm just keeping my fingers crossed, hoping that a few will show up at our feeders.

Monday, October 29, 2007

On Halloween winds

I'm odd in a lot of ways – just ask my long-suffering wife – but one of the oddest, perhaps, is that I love being in the woods at night.

Humans are diurnal creatures; darkness leaves us semi-blind, feeling vulnerable. But I revel in being outdoors after dark, since the woods that are so familiar by day seem new, charged with possibility, every sound and smell magnified.

Yet even I feel a twinge of – well, call it unease, as the sun goes down. It only lasts for a few minutes, but when the forest teeters at the dusky edge of night, as the last daylight is seeping away and the shadows are spilling out from beneath the hemlocks and below the fallen logs, something very deep and very primal in me squirms. Nighttime was the time of lions and hyenas, leopards and other big predators that saw early hominids as prey, and our genes have never forgotten it.

But once the darkness settles, that antediluvian twinge vanishes, and I'm free to enjoy the nocturnal forest.

It's something I do a lot of at this time of the year. Halloween is the midpoint in an eight-week research season that rolls around every fall, when I (along with my crew of 18 licensed banders and 85 volunteers) explore the nocturnal migration of the northern saw-whet owl, the smallest raptor in the East, and one of the least-known.

A saw-whet is the size of a man's fist, weighing about 90 grams (roughly the same as a robin), and cute as a button – unless you're a deer mouse or a red-backed vole, of course, in which case, this pint-sized hunter is your worst nightmare. They breed in forested regions across the northern United States and Canada, south in the southern Appalachians, and in the western mountains from Alaska deep into Mexico.

Until the 1960s, they were not considered to be regular migrants, and as recently as the early 1990s, few people suspected they migrate in large numbers down the ridges of the Appalachians, where I live. My friends Eric and Melonie Atkinson first started studying them in the Pennsylvania ridge country in 1996, and I began banding them the following year.

For the past 11 years, I've overseen a major saw-whet study through the Ned Smith Center for Nature and Art in Millersburg, PA, which tries to shed more light on this mysterious bird. Each October and November, at three sites in central Pennsylvania, my crew and I lure saw-whets out of the sky with a recording of the male's territorial call, a mechanical toot, and into our line of long, high mist nets, which hold them harmlessly.

We band the owls with a lightweight, numbered metal band supplied by the federal Bird Banding Lab, take a quick series of measurements, and send them on their way. (A few also receive a radio transmitter the size of a pencil easer, so we can track their movements; a few other sacrifice a few small feathers, so we can analyze their DNA.)

Last night was a perfect night for saw-whet migration. A cold front had roared through Saturday, and all day Sunday, the chill wind blew and the sky was full of puffy gray cumulus clouds. Then at sunset the wind died to flat calm, and the thermometer began sinking toward frost.

My crew of five volunteers and I opened the nets at sunset, and by the time we wrapped things up at 1:30 a.m., we had netted 36 saw-whets – our second-best night since we started doing this work more than a decade ago. One of the owls was already banded, an adult female originally caught in 2005 in Massachusetts; most years we catch several dozen such "foreign" owls, and an equal number of ours are reported by other banders.

Through such work do we learn where and when birds migrate, how long they live, whether they come back to the same breeding and wintering locations, and much more.

But it also allows me to connect with a part of the natural world about which most people are entirely ignorant – the wild, nocturnal part, when legions of little owls flood south across the continent, borne on Halloween winds.