The Arctic Nearby

*(VIDEO)*

  

There is a conversion meteorologists use called the Adiabatic Lapse Rate. What it says is that for every thousand feet of gain in altitude the temperature drops three degrees Fahrenheit.  Biologists employ a corollary equating a thousand foot gain in altitude with 600 miles of latitude, meaning that going up a mountainside a thousand feet is the climatic equivalent of traveling 600 miles north. So if you are in Ohio or Virginia at an altitude of 700 feet above sea level and you drive to Cranberry Mountain in West Virginia -- at 3575 feet -- you barter a hundred-mile drive for a trip to the boreal forests of Canada, 1600 miles to the north. That's the theory and in practice it is probably not far off. 

One way to confirm the altitude-latitude conversion is to look at the range maps of some of the birds which journey from the tropics to breed in the boreal conifers. Many observe a breeding range across Canada from the approximate latitude of Hudson's Bay to the U.S. -Canada border, a clean and regular band -- except for a dangling appendix down the spine of the Appalachian Mountains. If we pick a couple of boreal breeders such as Northern Waterthrush and Mourning Warbler we see that their breeding ranges reflect this Appalachian peninsula. As a result, we in the eastern or mid-western U.S. can drive a relatively short distance into the Appalachian highlands and enjoy a fair chance of finding these two northerly warblers on their breeding grounds. Cranberry Glades 15 miles west of Marlinton, West Virginia is the place to do it.

Cranberry Glades are a relic of  the Wisconsin glaciation; they constitute a botanic community of reindeer moss and red spruce which developed when the wall of Wisconsin ice bulldozed northern Ohio and Pennsylvania, pushing an arctic climate into our now-balmy realm. The ice retreated but the altitude and boggy soils permit Cranberry Glades' boreal botany to persist in glorious isolation, ours to savor on a day's jaunt.

Of course, sorting through the birds' calls when we get there is another challenge. The attached video offers a comparison of the songs of Northern Waterthrush and Mourning Warbler filmed at the Glades this morning and to complete the confusion we add a shot of the Louisiana Waterthrush, a much more accessible bird breeding along wooded streams at the lower elevations most of us occupy. All three (they are all warblers) sing in a burst of whistles followed by a dropping inflection, and because we rarely get to see and hear the northern worthies, we might find it useful to make the comparison with our more familiar lowland waterthrush.

Caveat:  this video won't help a bit when you get to Cranberry Glades. If your experience is like mine the overlapping chorus of echos and harmonies will leave you befuddled. But go anyway to enjoy this tiny nugget of the north in our midst.

(* Video *)

River Beings

May 2, 2013, Middle River, Swoope, Virginia.

The Middle River runs through this cattle farm.  We are about twelve water miles downstream of the highest gathers, a series of springs on a farm at the hamlet of McKinley,  and the trickles and tributaries give the flow a thirty-foot channel through Wheatlands, as this farm has been called since 1813. Downstream, the River merges with the North and that combined flow takes on the South at Port Republic to laze and loop northward under the name of South Fork, Shenandoah River, merging with the North Fork at Front Royal to make the main stem of the Shenandoah for its 65-mile run to the grand conjoining with the Potomac at Harpers Ferry.  Much of the nation’s history, tranquil or tragic, is written in that storied drainage washing the feet of official Washington.  Here in the high headwaters, too, we see our share of the sinister.  

What began this morning as a hike to greet the River’s spring arrivals -- a Solitary Sandpiper, a Spotted Sandpiper skimming the flow on stiff wings, a Great Egret, two Black-crowned Night-Herons – took a cloak-and-dagger turn.  A muskrat crossed the river to vanish under the bank at my feet, peculiarly close to an obvious intruder it seemed.  Then came strange scuffling sounds and a red streak shot away across the river, the early sun a neon pulse in its fur.  It humped up the bank and the bushes shook with squalls of protest.  A desperate contest thrashed the grasses until a muskrat tumbled down the river’s bank and swam upstream, dragging (or driven by?) a snaking tail. A noisy melee continued in the brush for some seconds. Then quiet resumed, leaving only a string of unanswered questions, like a Congress adjourned.  Did the escaping muskrat fight off the mink? Or did it leave behind a sacrificed family member? What happened in the hole in the bank under my feet? And are minks really foxy red or was that just a tricky light?  The river beings guard silence.

A Profile in Courage

                                                                     * ( VIDEO ) *

                                      A Profile in Courage

The late sun finds a crack in the clouds to aim into a westbound windshield where the road cranks hard right at a hilltop. Last night at that curve an opossum (hereinafter possum) wandered into the road and today's  glare gives a glimpse of a large bird astride the remains.  An instinctive jerk of the wheel puts my car into the oncoming lane, at that moment vacant as I am able to report.  I pull off the road, needing a look at this strange, defiant chicken refusing to yield to traffic. 

I can tell you what I see, but I cannot describe the sadness.  The bird has a ragged wing, a crippled foot, and a tail the color of a faded fire truck. It struggles to hold down its meal with one functioning foot, to balance with one working wing as it tears at morsels of marsupial. A car climbs the hill. The driver reads the road and eases over.  Another, just behind, yanks her wheel at the last instant. The wrecked and famished hawk bends to the possum as if it has no choice, trusting somehow in a universal kindness, standing tall as cars pass but yielding not an inch. 

Car after truck passes the poignant scene. Drivers, bewildered and uncertain at the mayhem in the road, shake it off with quizzical shrugs, perhaps a frown of sympathy. But the outcome seems inevitable and I can not bear to be a witness.  I can't but recall that the last injured Red-tailed Hawk I tried to help treated me to a trip to the ER, blood spurting through a welding glove.   I have no glove today and hawk and possum could hardly have chosen a more parlous platform for their drama. There is no point in adding a human carcass.

So I leave, but the scene travels with me. No, the bird has no choice; a steep bank blocks its way off the road and it cannot fly.   No, I was right not to intervene because the bird’s chances, sparse on a hilltop curve, may be no better under the triage protocol of a resource-strapped raptor center.  And might it fly again, ever,  or soar only in Valhalla? 

Or can it fly? Desperation drove the lamed and gaunt raptor to the road kill, but the bird didn’t hitch hike to get there.  And there is a universal kindness that responds with an involuntary  wheel jerk to the courage and determination of another hunter badly behind in the race for life. In my hopes the bird drags its full crop and battered being to the low side of the road and launches, listing and lurching, for a perch to rest and digest.

Grasslands at the End of WInter

* (MOVIE) *

Undertaker-in-Chief

In the Grasslands of the southern Shenandoah Valley the end of winter brings a new crop of calves and a stand of grass weary of its winter burden, gnawed short and peppered with frozen Frisbees. The grasses will start to grow in a fortnight but for now the cows rely on hay unrolled in the pastures and the rodents skitter in scant cover. The calves begin to hit the ground and the raptors rake the rodents. It is a rhythm harkening to millennia of shaggier ungulates farmed with fire and eating native stands free of fescue, but otherwise not so different from the tempo of our time.  Of all the players, the raptors and rodents may have marked the changes least.

One constant is the first-calf heifers, bison then and cattle now, struggling with calves sometimes more developed than they can birth.  Without the herdsman’s vigilance the late-adolescent labor can claim both mother and young. A calf is head-locked and stillborn and the work of saving the heifer reveals that the calf would have passed the head constriction only to be hip-locked as well.  It is a life that does not happen.

Or perhaps it does.  Life throbs in the pastures of this mini-Serengheti  and little goes wasted.  Turkey Vultures cluster, solemn bishops bound by their protocol;  a pair of Common Ravens drives them off. A Bald Eagle bumps the Ravens, upending the carcass for the fresh underside, a Schwarzeneggerian dead lift of fifty pounds.  The over-boosted audio in the eagle video’s second scene includes the faint bark of a red fox.  Is it protesting the eagle? The great bird launches with a full crop and in its talons a goodly share for an incubating mate.

By day Red-Tailed Hawks pick off the exposed rodents, Harriers sweep the swales.  At dusk a roost of Short-eared Owls ghosts into the gloaming to mouse through the cows and the scampering calves that won the birthing lottery. 

* (MOVIE) *

 Late Winter -- Not the Best Time To Be a Pasture Rodent

*  (MOVIE) *

 

 A  Collusion of Harriers

The winter of 2012-2013 brings an unusual number of Northern Harriers to Virginia's Shenandoah Valley. We see them in strong numbers and in expeditions; not just individuals quartering separately but pairs and trios sectioning the fields at staggered altitudes and in close proximity. A juvenile Harrier crosses a pasture flying low, straight, as if to a destination. A second bird, an adult male, follows 100 feet behind and 100' above. They recede from view in that echelon formation. On a friend's farm two Harriers circle low over her stand of native warm-season grasses, again an adult and a hatch-year bird. They tangle and the adult drives the young bird into the tree line, but two more approach from different directions to hunt the 30-acre grass stand, and the gray bird gives up his swaggering. A minute later they all leave. Out my kitchen window a juvenile sits on  a fence post scanning the winter-brown berry patch. Egad, three posts away sits another!  Then a third juvenile makes a run up the row of raspberry canes and both the perched birds turn to watch.

The close proximity of these hounds of the grasslands is not likely the result of chance; there are hundreds -- OK, thousands -- of acres of pasture in the Shenandoah Valley near Buffalo Gap
and if the Harriers so desired each could have a private hunting reserve. Instead they sometimes cluster, to the extent that if you see one they have trained you to look for another nearby.

So what's going on here? You don't suppose this is... cooperative hunting? The two perched juveniles watching a third make a  pass nearby behave similarly to a squad of Harris' Hawks I saw in Cochise County, Arizona; some perching to watch as others maneuvered. Harris' Hawks are accomplished cooperators, purposefully chasing and flushing while teammates wait to strike. But perhaps there is also a less coordinated, if still intentional, mode of gang hunting. Short-eared Owls do it, wheel and scan for grassland rodents in grumpy proximity,  tangling when their circles overlap. But  chummy or not, they bark at one another and cluster-hunt and you have to suspect there is a net benefit. They could as easily hunt singly. Perhaps it's not essential that everybody agree on an attack plan to bring off an ambush -- something less elaborate than the old  "You wait here while I circle around and flush him your way" trick might work occasionally. It may be sufficient that the adult Harrier who was dogging the young bird in echelon will nab a rodent fleeing the lead bird but unaware of the second. It may be that adjacent-hunting raptors would just as soon make a meal of one another as snatch a vole, but the vole is an easier snack and likely more rattled by two Harriers than by one. It may be that experienced adults clepto-hunt by keeping an eye on juveniles. Other raptors and scavengers, too -- a Common Raven for example -- might be caught on camera confiscating a young Harrier's catch.

Or the explanation may be as simple as young Harriers in casual collusion as a means of making it through their first winter.

Update: Researcher Amy Johnson sends her photos of a pair and a trio of Harriers hunting together.

*(MOVIE)*

Buffalo Gap Dickcissels, 2012

Distinctive Calls of Male Dickcissels

If you have Dickcissels in your pastures or if you pass their field with your window down there will be little doubt of it, for the males take their bright colors and loud voices to their advertisement perches and sing and counter-sing, hardly taking a breath break.   They arrive as a group and seize the grassland acoustics. Breeding males are loud and obvious and they generate a territorial din. This year the Dickcissels arrived at Wheatlands Farm at Buffalo Gap in Virginia’s Shenandoah Valley on June 1  and for the next 66 days they dominated the rap.

In our last post we noted the connection Kenn Kaufman sees between recent eastern breeding appearances of the Dickcissel and the stresses from drought and fire the bird faces in its traditional prairie nesting range.  In 2011 drought choked the southern prairies, engulfing Texas plus a 200-mile margin, and arguably accounted for the Dickcissel irruption east of the Allegheny Mountains as the birds sought alternate breeding opportunities. This year the drought expanded northward, toasting crops and pastures across Nebraska, Iowa, and  Wisconsin and compromising grassland nesting over an enlarged dry zone.  And in 2012 the Dickcissel chorus at Buffalo Gap grew by many voices; upward of a dozen males sang on this farm of 160 acres of grassland, more than double the 2011 numbers. That level of Dickcissel breeding density is characteristic of the grassland sweet spots in Missouri and Kansas but is uncommon in the East. (Check Lang Elliot's comments and recordings at www.birdtunes.com)

The U.S. Drought Monitor, maintained at the University of Nebraska in association with NOAA and USDA, observes regarding the 2012 episode,

 " The drought has inflicted, and is expected to continue to inflict, catastrophic economic ramifications for the affected states." 

So, the drought sequence will likely continue, seemingly a component of global climate change.  If 2013 is comparably dry in the prairie states and if the  Dickcissels again seek nesting relief  in the East, there will be little doubt of the Kaufman correlation. Would a record search show that eastward Dickcissel irruptions in earlier years were also the result of western weather stresses? At this point we are on notice of a likelihood that the Dickcissel will be needing welcome in such grasslands as remain in the East (after the massive twentieth-century abandonment of eastern farmland). In seeking breeding refuge to the east of its principal historic range, is the Dickcissel an early indicator species of climate change?

The Dickcissel has problems in the east which it did not have in its pre-Colombian prairie range where the main perils to nesting were bison hooves and fires; worse, of course, in dry years. Arriving in Virginia's Shenandoah Valley on June 1st of this year, the Dickcissels set up shop a month or more behind the Bobolinks and Meadowlarks. Eastern farmers cut hay in late May and early June.  Hay made in early June on this farm this year would have contained Dickcissel nests; some other nests as well, but many of the other grassland obligates have brought off a brood by then and could better afford the loss than could the Dickcissels.

Most of the eastern grasslands available for breeding are those which farmers maintain for pasture or hay and the Dickcissels arrive at the wrong moment in the farming schedule. If they choose hay ground the nests go through the cutter. If they select lightly-grazed pasture, that is likely to be clipped for weed control in early July. A Dickcissel's best hope is to find a spot inaccessible to cutting equipment -- a wet or rocky place -- large enough to accommodate a territory.

That is another problem.  Grassland birds including Dickcissels and Bobolinks are, in the terms of researchers, "area sensitive"; they need tracts of suitable habitat large enough to accommodate not just one territory, but several, perhaps many.  You don't often find one pair of Dickcissels or Bobolinks (like many grassland birds, both are polygamous and sometimes polyandrous so the term "pair" applies loosely), you find a nesting cohort which requires a large tract of grassland; research suggests a minimum of 60 acres for Bobolinks. Dickcissels migrate together, claim adjacent territories, winter together, and perhaps know one another as individuals across their lives.  A migrating group in search of accommodations doesn't just shed one or two pairs at each promising weed patch; the entire group stops when it finds a tract suitable to the tribal need. When nesting is finished, they decamp for Venezuela en masse as abruptly as they arrived.  At Wheatlands Farm they departed on August 5th this year.

In 2012 this farm gave up a cutting of hay on 45 acres of alfalfa and orchard grass to accommodate the Dickcissels’ relaxed schedule.  By the coincidence of a mild previous winter there was enough hay left over for the coming winter, assuming average weather, meaning no back-to-back three-foot snows. Such hospitality would normally be beyond the means of many farms, this one included, even with all hearts in the right place and all awarenesses attuned. Few farms can offer the largesse Dickcissels require of the eastern yeoman -- on the order of ten large round bales of hay per nest. By that crude estimate, a farm would sacrifice 250 cow days of winter feed in hosting one Dickcissel nest. But -- you don't get one nest; you get some nests or none.

The Dickcissels at Buffalo Gap outline a conservation challenge. The bird is persecuted with surfactants and other chemicals on its wintering grounds in Venezuela where grain farmers consider it a pest, as we once viewed the Carolina Parakeet. The Dickcissel is under pressure from drought and fire on its traditional North American grassland breeding grounds. So, we surmise, it has turned eastward for a chance to recruit and to sustain viable numbers. Here it runs into an adverse farming schedule in its principal nesting habitat. We must think of a way to accommodate all parties.

Buffalo Gap's Dickcissels, 2012

If you have Dickcissels in your pastures or if you pass their field with your window down there will be little doubt of it, for the males take their bright colors and loud voices to their advertisement perches and sing and counter-sing, hardly taking a breath break.   They arrive as a group and seize the grassland acoustics. Breeding males are loud and obvious and they generate a territorial din. This year the Dickcissels arrived at Wheatlands Farm at Buffalo Gap in Virginia’s Shenandoah Valley on June 1  and for the next 66 days they dominated the rap.

In our last post we noted the connection Kenn Kaufman sees between recent eastern breeding appearances of the Dickcissel and the stresses from drought and fire the bird faces in its traditional prairie nesting range.  In 2011 drought choked the southern prairies, engulfing Texas plus a 200-mile margin, and arguably accounted for the Dickcissel irruption east of the Allegheny Mountains as the birds sought alternate breeding opportunities. This year the drought expanded northward, toasting crops and pastures across Nebraska, Iowa, and  Wisconsin and compromising grassland nesting over an enlarged dry zone.  And in 2012 the Dickcissel chorus at Buffalo Gap grew by many voices; upward of a dozen males sang on this farm of 160 acres of grassland, more than double the 2011 numbers. That level of Dickcissel breeding density is characteristic of the grassland sweet spots in Missouri and Kansas but is uncommon in the East. (Check Lang Elliot's comments and recordings at www.birdtunes.com)

The U.S. Drought Monitor, maintained at the University of Nebraska in association with NOAA and USDA, observes regarding the 2012 episode,

 " The drought has inflicted, and is expected to continue to inflict, catastrophic economic ramifications for the affected states." 

So, the drought sequence will likely continue, seemingly a component of global climate change.  If 2013 is comparably dry in the prairie states and if the  Dickcissels again seek nesting relief  in the East, there will be little doubt of the Kaufman correlation. Would a record search show that eastward Dickcissel irruptions in earlier years were also the result of western weather stresses? At this point we are on notice of a likelihood that the Dickcissel will be needing welcome in such grasslands as remain in the East (after the massive twentieth-century abandonment of eastern farmland). In seeking breeding refuge to the east of its principal historic range, is the Dickcissel an early indicator species of climate change?

The Dickcissel has problems in the east which it did not have in its pre-Colombian prairie range where the main perils to nesting were bison hooves and fires; worse, of course, in dry years. Arriving in Virginia's Shenandoah Valley on June 1st of this year, the Dickcissels set up shop a month or more behind the Bobolinks and Meadowlarks. Eastern farmers cut hay in late May and early June.  Hay made in early June on this farm this year would have contained Dickcissel nests; some other nests as well, but many of the other grassland obligates have brought off a brood by then and could better afford the loss than could the Dickcissels.

Most of the eastern grasslands available for breeding are those which farmers maintain for pasture or hay and the Dickcissels arrive at the wrong moment in the farming schedule. If they choose hay ground the nests go through the cutter. If they select lightly-grazed pasture, that is likely to be clipped for weed control in early July. A Dickcissel's best hope is to find a spot inaccessible to cutting equipment -- a wet or rocky place -- large enough to accommodate a territory.

That is another problem.  Grassland birds including Dickcissels and Bobolinks are, in the terms of researchers, "area sensitive"; they need tracts of suitable habitat large enough to accommodate not just one territory, but several, perhaps many.  You don't often find one pair of Dickcissels or Bobolinks (like many grassland birds, both are polygamous and sometimes polyandrous so the term "pair" applies loosely), you find a nesting cohort which requires a large tract of grassland; research suggests a minimum of 60 acres for Bobolinks. Dickcissels migrate together, claim adjacent territories, winter together, and perhaps know one another as individuals across their lives.  A migrating group in search of accommodations doesn't just shed one or two pairs at each promising weed patch; the entire group stops when it finds a tract suitable to the tribal need. When nesting is finished, they decamp for Venezuela en masse as abruptly as they arrived.  At Wheatlands Farm they departed on August 5th this year.

In 2012 this farm gave up a cutting of hay on 45 acres of alfalfa and orchard grass to accommodate the Dickcissels’ relaxed schedule.  By the coincidence of a mild previous winter there was enough hay left over for the coming winter, assuming average weather, meaning no back-to-back three-foot snows. Such hospitality would normally be beyond the means of many farms, this one included, even with all hearts in the right place and all awarenesses attuned. Few farms can offer the largesse Dickcissels require of the eastern yeoman -- on the order of ten large round bales of hay per nest. By that crude estimate, a farm would sacrifice 250 cow days of winter feed in hosting one Dickcissel nest. But -- you don't get one nest; you get some nests or none.

The Dickcissels at Buffalo Gap outline a conservation challenge. The bird is persecuted with surfactants and other chemicals on its wintering grounds in Venezuela where grain farmers consider it a pest, as we once viewed the Carolina Parakeet. The Dickcissel is under pressure from drought and fire on its traditional North American grassland breeding grounds. So, we surmise, it has turned eastward for a chance to recruit and to sustain viable numbers. Here it runs into an adverse farming schedule in its principle nesting habitat. We must think of a way to accommodate all parties.