Posts Tagged ‘migration’

Journeys

March 20, 2011

It was March 3rd this year when the cranes began to move. They rose on thermals almost directly above the house, circling higher and higher until they were visible only when their wings reflected sunlight. Headed north, they were disembodied trumpets to someone stuck on the ground, straining to see them. Trumpets in the orchestra of evolution, Aldo Leopold called them.

It was a good day to die.

And, since dying is a journey we all must take, why not take it on a day the cranes are on the move? A friend and loved one made that choice this year and took her last earthly journey with cranes flying high overhead, calling, beckoning all who listen to return to wildness.

Godspeed.

 

 

Hummingbird Migration

October 12, 2010

Recently we advised you to leave your hummingbird feeders out for a couple of weeks after you’ve seen the last one. We’re at that stage now but a friend and neighbor was over Saturday and reported that she had seen one that morning. So, we’ll leave them out a bit longer even though it seems that we may have seen the last of them until the Northern Hemisphere tilts back toward the sun next spring.

As we noted in that last hummingbird post, they’ve been at this migration business a lot longer than humans have been around to watch. Here is D.H. Lawrence on the subject of hummingbirds:

Primeval-dumb, far back
In that most awful stillness, that only gasped and hummed,
Humming-birds raced down the avenues.
Before anything had a soul,
While life was a heave of Matter, half inanimate,
This little bit chipped off in brilliance
And went whizzing through the slow, vast, succulent stems.
I believe there were no flowers, then,
In the world where the humming-bird flashed ahead of creation.
I believe he pierced the slow vegetable veins with his long beak.
Probably he was big
As mosses, and little lizards, they say were once big.
Probably he was a jabbing, terrifying monster.
We look at him through the wrong end of the long telescope of Time,
Luckily for us.

Leave Your Hummingbird Feeders Up!

September 8, 2009

hummingbird-8The question arises in the United States and Canada each year about this time: Should we take down our hummingbird feeders so the hummingbirds won’t stay too long and get caught in the cold weather?

The answer is: Leave your feeders up!

The urge to migrate far, far outweighs a bottle full of sugar water. Your hummingbirds will leave when their biological clocks command them to leave, no matter how much food is still available for them. It is likely, in fact, that the hummingbirds at your feeders today are not the same ones that were there two weeks ago. Hummingbird migration has already started and the birds you see today are likely migrants passing through rather than the ones who spent the summer with you.

And, of course, their food supply is dwindling now. Colder nights and cooler, shorter days mean fewer bugs, their primary source of protein, and less nectar from flowers which they also eat in abundance even if human supplied sugar water is available.

But your sugar water is especially helpful to them as they migrate southward. They need immense amounts of energy to migrate successfully and they need to add to their body weight substantially. If you leave your feeders up until the last one has flown through, you will help them maintain that weight for as long as possible and help provide a needed energy boost for the next leg of the journey.

Hummingbird-4For those of our readers who live in the Gulf Coast region of the southern United States, you should leave your feeders out all winter: You may be treated to Ruby-throated Hummingbirds some of whom no longer migrate any further south than your region. Warmer winters and hummingbird feeders have lured some of that species to stay for the winter in your temperate region.

But for the rest of us, it is not yet time to take down our feeders. There are migrating hummingbirds who will thank you to leave them up, with fresh syrup, for a few weeks more.

When Spring Trips North Again This Year

February 23, 2009
Lago Desierto, Patagonia

Lago Desierto, Patagonia

In the far reaches of the southern hemisphere the days are perceptibly shorter now.  The oceans and lakes surrender some of the heat they’ve stored over the summer and the daily temperatures begin to drop.  Conversely, in the southern reaches of the Northern Hemisphere, the first signs of spring are upon us.  Daylight hours are sensibly longer, temperatures are beginning their annual climb and the earliest and hardiest of plants have sent out tentative green.

In billions of birds, these signs stir primeval urges.

For instance, today, just to the west and high above us, Sandhill Cranes, the trumpets in the orchestra of evolution Aldo Leopold called them, are rising on thermals, circling and calling, then stretching into their V formation and soaring north.

It seems too early, but January and February here have been among the warmest on record so the birds may know something we don’t.  Or maybe it has little or nothing to do with the air temperature; perhaps this instinct to move is triggered solely by the tilting of the earth’s axis toward the sun. Possibly it is some of both; ancient pathways laid down in their genetic code coupled with the short term knowledge that the earth is warming and it is therefore safe to leave earlier.

Sandhill Crane

Sandhill Crane

There are other signs that winter is losing its grip.  The male House Finches that spent the winter with us are growing their bright red “attract a female” plumage, our feeders are being drained of seed more rapidly, at our store hummingbird feeders are selling even though it will be more than a month until the hummingbirds begin to arrive, and we are writing about the spring migration and looking for the hay fever medications.

Billions of birds migrate twice a year, some from the far tips of the southern hemisphere to the far northern tips of the northern hemisphere.  Passerines fly in great flocks to the boreal forest of Canada to breed.  Hummingbirds by the millions make the hazardous journey from Central America to North America.  Raptors of all types climb into the skies and head north. They’ve been doing it since long before there were humans to observe it, even long before the continents assumed their current shapes and sizes.  (For perspective, the first true birds appeared about 145 million years ago.  Modern birds had evolved and most survived the great K-T extinction at the end of the Cretaceous which wiped out the dinosaurs.  That was about 65 million years ago.  Homo Sapiens have been here for only about 250,000 thousand years.)

The earth 50 million years ago

The earth 50 million years ago

Science is not certain exactly how they do it.  Some elegant experiments have tried.  Perhaps it has something to do with the position of the sun in the sky?  No.  Make the birds fly only at night and they unerringly find their way home.  Maybe they navigate by stars?  No.  Make them fly only during the day and home they go.  Subtle fluctuations in the earth’s magnetic field?  Possibly.  But put them in a screwed up magnetic field and they orient in the right direction to go where they are supposed to go.  Tiny maps in an onboard computer?  Could be. but scientists have played games with bird brains and still they go home.

Most likely it is a combination of all of the above.  They fly thousands of miles and return to the same square foot of earth they left months earlier.  Some can even do it even though they’ve never been there before.  Many bird species migrate without parents teaching their offspring where to go, yet the youngsters get there all the same.  They fly in such numbers that they are visible as huge clouds on radar screens.

Weather Radar Image of Migrating Birds

Weather Radar Image of Migrating Birds

Of course, birds are stellar navigators.  Raise homing pigeons in a mobile loft and send them off to forage one morning and then, while they are gone, move their home to the next county and they will show up at the relocated loft in time for dinner.  Nobody knows for sure how they do that either.  Not all of life’s questions have been answered.

Wonder is an underrated emotion and, as we’ve often said before, calling someone a “bird brain” is not an insult.

New Godwit Migration Record

October 28, 2008
Map of Godwit Migration 2008

Map of Godwit Migration 2008

We wrote in this space last year about Bar-tailed Godwit number E-7, a female godwit who, according to the satellite tracking the transponder fitted to one of her legs, had just completed a 7,155 non-stop migration from Alaska to New Zealand, but she outdid herself this year, beating her own world record for non-stop distance flying; this year, as you can see from the map, she flew 7,242miles in eight days, garnering not only the distance record but her own Washington Post editorial plus more updates on the USGS site which tracks E-7and 22 other godwits on their semi-annual migrations; migrations which average about 18,000 miles of flying a year and upwards of 250,000 miles over an average Godwit life span which is more mind-boggling than the fact that we just told you about her eight-day trip this year in a single sentence the reading of which may put you in mind of how tired she must have been at the end of the trip.

Nobody knows for sure where the name “Godwit” came from.  It may be theological in origin or it may derive from the anglo-Saxon word for “good” and “animal” or “bird” because it was once considered a delicacy.  Ben Johnson could buy one for supper for a half a crown.  Two centuries before Johnson a Godwit cost twice as much in London as a Snipe, so don’t say you never learn anything useless reading our blog.

Hummingbird Science, Part I

January 21, 2008

Last time we shared the counting methods of a true hummingbird expert, Sheri Williamson. Ms. Williamson is the author of the Peterson A Field Guide to Hummingbirds of North America which, at the risk of her accusing us of “absolutely gushing” — something we leave to artesian wells — is a fine book; full of useful information. Ms. Williamson has forgotten more about hummingbirds than we will ever know. She has blogs and a website which you can find here, here and here.

Still, we thought her post a bit haughty; written with a certainty and hubris scientists are well advised to avoid. In addition to calling Dan True’s book on hummingbirds “full of half-baked ideas, misinterpretations of other people’s work, and out-of-date information. . . .” she accuses us of misleading you into thinking that Ruby-throated Hummingbirds migrate over the Gulf of Mexico rather than taking the longer shoreline route. More about that in a minute.

First though, a word about science. Science is the best, most successful method of describing and explaining reality yet invented. But it is slow. It has to be. Hypotheses must be developed, data painstakingly accumulated, tested and peer reviewed. Even after a theory explaining all the known data is erected, wise scientists know the entire edifice can come crumbling down on their heads if a new pertinent, reliable piece of data is discovered which contradicts all that earlier work. We have a scientist friend who is delighted if he is right half the time.

More important, ignorance engulfs us. We must stand stupefied before all we do not know. Why was there a “Big Bang?” What does it mean to say that a black hole is a singularity? How do electrons act at a distance? How many dimensions exist? Are Boltzman Brains really possible? What is consciousness? Why is so much of the world explainable by mathematics? What cures the common cold? How can we stop cancer cells before they kill their hosts? How did Aspen trees learn to clone themselves? Why do some thunderstorms become super cells? How do birds navigate? What routes do Ruby-throated Hummingbirds follow on their migrations? How many are eating at your feeder?

Here is a scientist on the point:

As a human being, one has been endowed with just enough intelligence to be able to see how clearly, how utterly inadequate that intelligence is when confronted with what exists.
Albert Einstein.

734px-gulfofmexico3d.png

But to get back to Ms. Williamson’s complaint about our post. Here is what she said:

One additional nitpick about the TFFBBB entry: It assumes that Ruby-throated Hummingbirds migrate south across the Gulf of Mexico when the evidence strongly suggests that the majority take an overland route around the Gulf in fall migration.

First, we did assume that large numbers of Ruby-throats migrate south across the Gulf of Mexico. And, while we are not — and never claimed to be — scientists, we don’t just make stuff up. Our statement that Ruby-throats fly directly over the Gulf of Mexico in autumn had two scientific sources.

The first, which we utilize frequently, is Cornell University’s Birds of North America. (BNA) (Available online, subscription required) According to one ornithologist: (Sheri Williamson, actually)

The most valuable published resource on the biology and natural history of North America’s hummingbirds is the Birds of North America series. . . .

Here is what BNA has to say about Ruby-throat migration:

Despite their tiny size, many of these birds fly nonstop across the Gulf of Mexico during fall and spring migration, a round-trip of more than 1,600 km. To accomplish this, individuals often double their body mass by fattening on nectar and insects prior to departure. (Emphasis added)

There is one problem with BNA. It is not updated frequently. For instance, the article on Ruby-throated Hummingbirds was written in 1996. So we checked one other, newer source: The 2001 Peterson A Field Guide to Hummingbirds of North America by Sheri Williamson. (That name sounds familiar, where have we heard it before?) In that book, at page 188, we read:

To reach their eastern nesting grounds each spring, many individuals take a direct but hazardous route across the Gulf of Mexico, flying non-stop over [sic] more than 500 miles of open water.

But, you say, that is the northbound trip. Could the southbound trip be different? Possibly. And, Ms. Williamson may have newer data and we hope she will share it with our readers and hers.

But the range map on page 192 of Ms. Williamson’s book flatly states:

Both trans-Gulf and overland migration routes used in spring and fall. (Emphasis added)

To be fair, both BNA and Ms. Williamson hedge their bets. BNA says:

Many fly across Gulf of Mexico, but many also follow coastal route. Routes may differ for north- and southbound birds. . .In general, however, migratory routes of this species remain poorly documented, and some proportion of the population may follow a coastal route south during the fall.

Ms. Williamson, on page 29 of her book, states:

Ruby-throated hummingbirds wintering in Central America take the most direct route available in spring migration, up the Yucatan Peninsula and across the Gulf of Mexico. This route would be dangerous in reverse, with a significant chance of missing the peninsula which may be one reason many thousands of southbound Ruby-throats follow the Gulf Coast through Louisiana and Texas.

To us, that smacks of anthropomorphism. The Yucatan Peninsula is a pretty big place and just because a flying human might miss it, doesn’t mean that Ruby-throated Hummingbirds, whose ancestors have been finding it for hundreds of thousands of years, will. Besides, even if they somehow missed it, the odds are good that they would make land-fall in Central America or in South America; another, even bigger place. Only an east-bound bird, leaving from Florida, could miss land. That would only be possible if the prevailing winds were blowing east, but we know the Trade Winds over the Atlantic blow toward the Gulf so would not be likely to blow birds out to sea.

783px-central_america_cia.png

But that isn’t science. To know for sure we need a professional meteorologist to tell us about the prevailing wind and weather patterns of the Gulf of Mexico. Then we might know if there was any autumnal danger for Ruby-throated Hummingbirds “missing” the Yucatan Peninsula.

We could ask Dan True.

Deer, Sandhill Cranes and Snow Geese

November 11, 2007

bosque-november-2007-1.jpg

Yesterday, instead of writing some long, thoughtful blog entry to entertain you, we went birding at the Bosque.  The Bosque del Apache in New Mexico.  We did get some nice photos and here are two.  It isn’t every day that you see deer and Sandhills dining together.  And, as you can see, the Snow Geese are back in force for another winter.

bosque-november-2007-2.jpg

Migration, Part II

September 22, 2007

In the first post of this series on bird migrations we discussed some of the astounding feats of avian migration. In this post we’ll examine the question of why most birds migrate. After that, we’ll move on to the question of how they migrate.

After my son acquired his undergraduate degree, he moved back to our hometown to pursue his Master’s Degree at the local university. This he did primarily due to financial constraints. He rented an apartment less than one block from his Mother’s house which did surprise me a little. When I asked him why his response was simple, “Dad, mammals have to live close to their food sources.”

The same is true for birds, of course, which is why they migrate.

Imagine that you make your living eating insects. Imagine that you are a wood warbler or a vireo or a thrush or a flycatcher. You love to eat insects. You also know, even though you think without words, that the farther north you go in the summer the more and bigger insects you’ll find. For instance, moving north along the western spine of North America, the insects are smaller and fewer in the southern Rocky Mountains. By the time you get to Montana they are larger, more numerous and much more irritating to the humans you share the planet with than they are back toward Mexico. But even Montana is nothing compared to Alaska where they joke that their state bird is the mosquito. There is even a murder mystery, the name and author of which I disremember right now, where the victim is left outside and naked as a summer Alaskan night comes on and is killed by the mosquitoes.

But if you are a bird, you like mosquitoes; big juicy fat ones in staggering numbers and you’ll find them in the Arctic every summer. You may even find some with nectar clinging to it like this one. Another bonus of the Arctic summer, billions of flowers, full of nectar. And it is beautiful as well and you appreciate beauty.

You’ll also find many more hours of daylight to eat bugs and nectar. If you can get far enough north, you’ll have sunlight almost 24 hours a day. Which is why you’ll go there every June and July. Not only will you have all those calories to eat and all those daylight hours in which to eat them; you’ll also have more energy to reproduce and raise your new offspring. More than 160 species of birds migrate to and from just the Alaska National Wildlife Refuge. You can find the entire list here.

But you certainly won’t want to be there in December when the sun barely makes it above the horizon for a couple of hours each day and the temperature never reaches freezing and all the bugs are long since dead. You have to maintain your body temperature, which is somewhere between 104 to 111 degrees Fahrenheit, depending on which species of bird you belong to. This higher body temperature means that your nerve impulses travel faster and your muscle strength is greater. Unless you hibernate, and only one species is known to do that, you better not be in the Arctic after mid-September.

To maintain your body temperature you need to be somewhere where the sun shines and somewhere you can find lots of bug calories to eat. You aren’t stupid and neither were your ancient ancestors, some of which started living on the planet 150,000,000 years ago. So, you fly south for the winter.


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