Avian athletes

kw: book reviews, nonfiction, ornithology, migration, bird migration

Have you ever seen a blackpoll warbler? If you have, unless you are familiar with warblers, you may have mistaken it for a chickadee.

From this picture (from All About Birds), and the one below (same site, different page), you can see that they are similar. The warbler's body is strongly patterned, while the body of a black-capped chickadee is more uniform in color. We notice the black cap with a broad white lower face on both birds. They are so active, we seldom have time to see the differences.


But they don't sound the same. The chickadee is named for its call, which we often "spell" as "chick-a-dee-dee-dee-dee". The warbler's call is a series of very short, quick notes about an octave above the highest note on a piano.

Their migration habits differ dramatically. Chickadees don't migrate, except in the extreme north or south portions of their breeding range. Blackpoll warblers migrate 5,000 to 6,000 miles (8,000 to 10,000 km), each way, every year.

Both are endurance champions, just in quite different ways. Both are very small birds; a blackpoll warbler weighs 14-15 grams (~0.5 oz) most of the year and a black-capped chickadee weighs a little less at 11-12 grams (~0.4 oz). Except in the far northern reaches of its range, a chickadee stays year-round, braving winters that, in my experience living in Ohio, are about as miserable as I can imagine. The warbler, along with most warbler species, is a snowbird. I winters in the tropics and summers in or near the Arctic. Actually, our term ought to be "anti-snow bird"!

In Kenn Kaufman's new book A Season on the Wind: Inside the World of Spring Migration, he describes a blackpoll warbler's yearly trek at length. A condensed version:

The spring migration is less of an ultra-marathon and more a series of medium-length "hops". Beginning from a winter range in Venezuela or Brazil, a bird destined to nest near Denali or Nome, Alaska flies a few hundred miles to the northern coast of South America. There it rests a day or so and fattens up for a crossing of the Caribbean, which it crosses by island-hopping until it reaches Florida. The next hop may be to Georgia or thereabouts. Then it fattens up for a longer trek, nearly nonstop to western Alaska. The winter migration is a pair of ultra-marathons. The bird begins by crossing North America, which takes about three days of nonstop flying, until it reaches New England, perhaps Massachusetts. There, it eats until it weighs about a full ounce (28 grams or more). Then it flies south, out to sea, not to see land (except perhaps Bermuda in the distance) until it reaches the coast of Venezuela, weighing less than half what it did just four days earlier.

Every living blackpoll warbler is descended from ultramarathon champions! They are not the only ones. Hundreds of species of birds, many no larger than your thumb, yearly migrate hundreds to thousands of miles. Just in body-length terms, it would be like me (a six-footer) traveling halfway to the moon and back, every year…if there were somewhere halfway to the moon to stop for a few months.

One matter the author takes up in the book is the notion of "flyways". For ducks and other water birds, there do seem to be "highways in the sky" that they tend to follow. Not so for other birds. Recent technology shows this dramatically. Here is a national radar image from NEXRAD taken in May of 2016:

NEXRAD (Next generation radar) was developed to see rainfall. Birds are lots bigger than raindrops, so they are easily seen. As it happened, there were several large storm systems over the central and eastern U.S. that day. One stretches from southern Texas to eastern Nebraska, another just east of the Mississippi River into Indiana, and a smaller series of storms from Florida north to North Carolina. These all show up as green, yellow and red. The blue blotches with green centers show where the birds are during their spring migration. The black areas between blue blotches are areas not covered by the radar. The birds are spread out over the whole area; there are very few concentrations. One is visible at Lake Erie in northern Ohio. From about Cleveland, around the shore of Lake Erie to Toledo, birds that don't wish to cross the lake turn west and fly around it. If there are any "songbird flyways", this area is one of them. Its western portion is not covered by NEXRAD, so it isn't as prominent in this image as it ought to be.

A decade ago or so Mr. Kaufman moved from Arizona to Ohio, not far from the Magee Marsh refuge (and premier bird-watching boardwalk). The book focuses on events of a few springtime migration seasons. From the big eagles, vultures, and hawk, to blue jays, to little vireos and tiny warblers, hundreds of species of migrating birds fly through and stop over at or near Magee Marsh in the springtime. The author's lyric descriptions of these marvelous creatures and their travels are utterly captivating.

Here and there throughout the narrative, he tells the tale of a struggle he and his colleagues in northwest Ohio undertook to prevent the construction of an "experimental" wind turbine, right in the middle of the area, on a military reservation. It's worth considering just how dreadful big windmills can be for migrating birds.

A 2-megawatt turbine has a rotor about 90 m (~300 ft) in diameter, with three blades, atop a tower that places the top of the swept circle as high as 180 m (~600 ft). A stiff breeze of 20 m/s (~45 mph) is about midway in a turbine's power curve. When the wind is this speed aloft, it is about half that speed or less near the ground. In this breeze the blades rotate at 16 rpm, with a blade cutting through the air 48 times per minute, or about every 1¼ seconds. In that slice of time, a parcel of air 25 m long passes through the blades. For big birds like eagles soaring on this wind, there's one chance in 15 of getting hit by a blade. The speed of the blade tip is 75 m/s or 170 mph. They can't see it coming in time to react. For a duck-sized bird, the chance of getting hit are one in 35, and for a tiny warbler, "only" one in 165. But while only a few eagles pass along the Lake Erie shore daily, and a few dozen ducks, tens of thousands of warblers and other small songbirds do so, up to a few million each season. The daily "catch" of small birds can be hundreds. Not only so, one wind farm reported that more bats were being killed than birds. Think about this: every bat eats from 100 to 1,000 mosquitos and similar insects every day. How many can we afford to wipe out? There is one wind farm in California that is known to kill 100 golden eagles every year. Whatever happened to the Endangered Species Act? Big money, that's what.

Sadly, wind turbines aren't as eco-friendly as they are billed, and not just because they kill birds and bats. A big turbine contains a lot of metal, both steel and aluminum, which required a huge amount of energy to produce, and the coke (refined coal) needed to make the steel resulted in the release of a great amount of CO₂. What holds up a big turbine? Many tons of steel-reinforced concrete in a hole the size of a garage. How does the turbine get moved into location? Several trucks per turbine, driving hundreds of miles. Much of the energy needed to produce the metals, particularly the aluminum, comes from hydroelectric dams along the Columbia River. So I have called the wind turbine industry "a scheme for turning hydropower into aluminum and steel, moving it across the country, and turning the metals back into electricity…at a net loss." A turbine has a finite lifetime. I have yet to see a full econometric analysis of wind turbines that demonstrates how you get more out than you put in. If every bit of energy used for the mining, refining, manufacturing, transportation, erecting, and operating of every wind turbine was required to be derived exclusively from wind power, I think the whole enterprise would shrink away to nothing in pretty short order.

Just by the way, now that solar cells are routinely produced that exceed 15% efficiency, the industry is operating at a net energy gain. We ought to be pushing for more solar, and leaving the wind to the birds.

The turbine project on the military base that the author and others were working against was eventually cancelled. Good news, temporarily.

I lived in Sandusky, Ohio during my high school years. One spring morning I was up early, and I hung a microphone out the window to record the dawn chorus. I wish I still had the tape. It was amazing and glorious. At the time I knew nothing about bird migration. I had no idea that I was living right along a concentration of migrating birds like none other. I could recognize no more than five or six bird calls (robin, chickadee, crow, jay, and hawk, at least). But I could tell that the morning birdsong had at least fifty species of singers contributing. Even if I didn't know what they were, I could tell one from another.

I hope Mr. Kaufman's books reach a wide audience. The more of us who care about wildlife, including birds, the more likely that youngsters a generation or three in the future can wake up to a morning chorus as glorious as the one I remember.

The bird, the crab, the eggs, the blood, and the ends of the earth

kw: book reviews, nonfiction, natural history, horseshoe crabs, red knots, migration, ecology, environment

For anyone who lives along Delaware Bay or the Delaware River, there are two main choices for a day at the beach or shore. The local terms are "Delaware beach" and "Jersey shore". Having sampled both, I found I love the northern beaches of Delaware the best. Beach towns and parks from Rehoboth Beach down to Fenwick Island, and on to Ocean City, MD, are great fun, but we enjoy Cape Henlopen, Delaware's northernmost Atlantic beach, the most.

Those who visit the Cape in late Spring, near the full moon in May or earliest June, can witness an amazing spectacle right out of the geologic past: the spawning of the horseshoe crabs. These trilobite-like critters, bigger than dinner plates, and little changed in bodily form for 400 million years, crawl ashore by the thousands to mate and lay eggs in the sand. Right along with them, running among them, little sandpipers called Red Knots pick and probe in the sand for the nourishing eggs. Knots are not the only egg-eating shorebirds, but at times they are the most numerous, as this photo shows.

At both Cape Henlopen and Cape May, NJ, and at many sandy beaches that line Delaware Bay, crabs lay eggs and shorebirds feed frantically. The Knots are particularly frantic. They've just crossed the western Atlantic from northeastern South America, and they have several thousand more miles to go to their Arctic breeding grounds. They have an amazing weight-gain and muscle-building metabolism that allows them to eat half their weight daily, and to double their weight, mainly by adding flight muscle and a layer of fat, in just a couple of weeks. They will lose most of that added weight flying 3,000 or more miles north by mid-June.

The Western Atlantic Flyway for Red Knots begins at Tierra del Fuego, Chile, the "uttermost part of the Earth" at the southern tip of South America. It ends at the other "uttermost part of the Earth" in northern Canada. That is, in the March-to-July time frame. Six months later, it is the same route in reverse.

Think of it: little birds that weigh only a couple of ounces, fueled by a few ounces of shellfish (on South American coasts) and horseshoe crab eggs (on North American coasts), make a journey that we bulky humans find harrowing and quite expensive (at current Coach rates, flying from Punta Arenas, Chile to Iqaluit, Canada costs $2,625 one way, with four stops to change planes). The birds do this twice yearly.

Deborah Cramer, as she writes in The Narrow Edge: A Tiny Bird, an Ancient Crab, and an Epic Journey, made that trip just once, to see the Red Knot in all its habitats. The airline fares were the least of the expenses. There are no hotels near Bahia Lomas, and it takes almost as long to go that last 80 miles (130 km) from Punta Arenas by truck and boat, as it took to get to Punta Arenas from Massachusetts. She had to depend on an invitation from scientists who take advantage of an oil company's camp. Similar "camp-out" style dwellings awaited her on Southampton Island, in northern Hudson Bay, Canada. I presume she had hotels to stay in along the Delaware Bay and other mid-journey stopovers.

The book's entertaining travelogue provides one level of reading pleasure. But most importantly, it shows the interlocking lives of creatures of air and sea that actually affect human health throughout the world. Horseshoe crabs, it turns out, are a bountiful source of several benefits, and the most important is safeguarding our medicines.

Several generations ago, horseshoe crabs were harvested by the millions for bait and fertilizer. Better sources of fertilizer since the mid-1900's reduced the carnage somewhat, but by then their population was probably no more than 5% of what it had been. Their spawning runs were once legendary, with their little green eggs feeding tens to hundreds of millions of shorebirds, and still lying in heaps along the beaches. The shore birds now, seemingly abundant to our impoverished eyes, number less than a percent what they once did. Not only are there fewer crabs, they lay fewer eggs, ultimately because of a curious property of their blue blood.

Horseshoe crabs, and large arthropods in general, do not have as sophisticated an immune system as we and all mammals have. But horseshoe crabs in particular have a very sensitive clotting factor that engulfs certain bacteria, called gram negative bacilli, and deactivates the toxins they release. The metabolic products of gram negative bacteria are toxic to us, and cause fevers in even very small amounts. Their presence indicates bacterial contamination of medical products, so it is important that every IV kit, every serum, vaccine and other injectable medication be tested. Once there was a "rabbit test", but now the clotting factor in the blood of horseshoe crabs is used; it works ten times better.

Horseshoe crabs are captured, bled of about 1/3 of their blood, and returned to their native waters. A product called LAL is isolated from the blood, which is blue because rather than the iron in our kind of blood, theirs contains copper. Every time you've had a needle stuck in you for any reason, somewhere along the way the IV or hypo kit, and probably the medication also, were tested with LAL. Without it, about a third of the time the treatment itself would cause a fever lasting a day or two, and possibly a deadly reaction.

Female horseshoe crabs are bigger than their mates, so you can get more blood from them. But a crab that has been bled will be disoriented for days or weeks when she is returned to the sea, and will usually produce fewer eggs that year. A certain number are known to die before they are returned. Even more must be dying after return. A century ago, the usual sight was that each female crab was accompanied by one or sometimes two males as she came ashore to lay her eggs. Now it is common to see four to six males surrounding each female.

States such as North Carolina have banned the taking of horseshoe crabs for any reason other than this medical one. Nobody really needs them for bait any more, but some fishermen find it\\they are easier to gather than other bait fish, so there is legislative resistance to similar bans elsewhere. Researchers have devised several ways to use LAL that are from four to twenty times more efficient. But until the FDA (and similar bodies in other nations) rules upon the new tests, it is illegal to use them.

We soon may have no choice. Horseshoe crabs' numbers continue to decrease throughout the western Atlantic. A similar Asian crab species apparently cannot be used to produce LAL because of other toxins in its blood. And the birds? They are of no use to the crab. But they are of use to us. Their abundance, or scarcity, is a signal we had best not ignore. As the population of crabs declines, so does that of many species of shore bird, not just the Knots. And other populations are also affected. Large fish and seals that eat horseshoe crabs have turned in desperation to other prey, such as the famed Delaware Blue Crab. The price of Blue Crabs is increasing as a result. So it the price of your medicine, as it gets harder to gather enough crabs to meet an ever increasing demand for LAL, particularly as China Westernizes its economy and culture.

Doing something the cheapest way is not always, or even usually, the right way. Horseshoe crabs may be OK as a bait fish, but there are numerous alternatives. When the health of every human depends on them, is it permissible to use them for bait? Researchers find it hard to synthesize LAL, but it ought not be impossible. Sure, it'll cost a few millions to produce the first gram of synthetic LAL, but once the method is known, the price will drop and drop until it is cheaper than drawing blue blood from crabs. But will that price cutoff be reached because technology improves, or because crab capture and bleeding become so costly that natural LAL drives the cost of an IV kit to $1,000 and a flu shot is not $35 but $350?

And what of the birds? Will the loss of the Red Knot matter? Did the loss of the Passenger Pigeon matter? After 1914, when Martha the pigeon died, this marvelous bird species was lost forever. What else happened? At one time, they ate so many acorns and other forest nuts that there were fewer mice and other seed-eating small mammals. Now instead of millions of pigeons, we have billions more mice. One critter that inhabits mice is the "deer tick". So there are many, many more of them. Young ticks feast on mouse blood. Then they drop off and molt a time or two. Next they look for a larger host. They usually find deer, but a human will do. Then what happens? Lyme disease! Lyme disease was almost unknown before 1970. That shows that the burgeoning mouse numbers are only part of the equation. More and more suburbs being built into forests is another.

We don't know what other links are in the chain that includes Red Knots and Horseshoe Crabs. It is more of a mesh, anyway, like chain mail. Life is an unending Tetris game. Blocks drop and we fend them off. So does every other species. Eventually the stack fills the box and it is "Game Over". For many species, we are part of that Tetris game, not only adding extra falling blocks, but throwing them down faster and faster. Every species lost is irretrievable. You may not see the beauty in the horseshoe crab, but to the right kind of eye, the crab and the bird have equal beauty, and they are both of great value.

Gems traversing the sky

kw: book reviews, nonfiction, ornithology, migration, songbirds

Having lived for years in the Midwest and West, a favorite sight was the fall flocks of blackbirds. A grain field would seethe with small, black bodies, and suddenly the black mass would leap overhead, darkening the sky in what the Danes call Blacksun.

I knew that they would soon disappear, the next time a North wind arose, suddenly heading out at dusk toward Central or South America. Blackbirds are opportunists, and don't go farther than they must. Some stop in southern Texas, but in a dry year they'll all wend their way much farther, perhaps to Argentina.

The seemingly subtler migration of the more colorful, gemlike warblers and thrushes and finches often occurred without my notice, unless I happened to be out, perhaps walking after dark, or finding one more Messier object with my telescope.

On only one occasion while peering at the Moon did I see a barely-perceived, dark shape cross it. I realized later I'd seen a small bird, still small at 60x from two miles away, flicking across the quarter-degree-wide half-cookie of the moon in a second or less.

Mostly I just heard them; if I happened to listen stilly, I'd hear their faint twitters. It never occurred to me to try to record the sound. It has occured to others, and such recordings, computer-parsed and analyzed, are a powerful tool to discern songbird populations as they change from year to year. I like the idea. It's so much less intrusive than trapping a bird to glue a radio transmitter to the nape of the neck.

Miyoko Chu of the Cornell Lab of Ornithology writes of these and other methods for learning the hidden lives of migratory songbirds in Songbird Journeys: Four Seasons in the Lives of Migratory Birds. But even more, she writes of the birds. How tiny half-ounce chickadees or one-ounce warblers will fly a few hundred miles overnight, losing a quarter or more of their body weight along the way. No wonder they descend on the fields like a ravenous horde...they are ravenous!

I hadn't read, anywhere before, that all migratory birds nest in the North and, though it is Summer in the South while they are there, do not nest there, and that the birds that do nest there do not migrate. I wonder if this is a purely Americas phenomenon; the book focuses on American species. Perhaps South African birds that nest near the Cape migrate north to have a European non-nesting sojourn.

Each of the book's four sections has a descriptive, evocative portion, focusing alternately on specific species and on the larger phenomena of the season. Each also has a closing section on times and places at which one may see great concentrations of migrating birds (two seasons), nesting birds (Summer), and overwintering birds, plus tips for observing and recording bird behavior in your yard or neighborhood.

The most fruitful tip: few birds fly far on still days, very few when it is very windy, and the largest numbers on seasonably windy days. Particularly, wind on a cooling Fall day is spiraling from a high, which means winds out of the North if it to your West; on clear days in Fall, migrants take advantage of the tailwind. Wind on a rainy day in Spring is running ahead of a warm front, blowing out of the South as stormy weather approaches from the West. Spring migrants will risk the storm to get a good tailwind. A sudden shift in either kind of weather will yield a bird-fall with or ahead of the rainfall. Great days to see birds, but you must recognize that they are fleeing disaster, and probably exhausted.

One clear purpose of the book is to gain more eyes and ears, gathering some of the mountains of data needed by the rather small community of professional Ornithologists. This is one area in which the help of "amateurs" is vital. See eBird if you wish to participate.