Wheatlands Grassland Birds – 2013

Part One

In their 2013 breeding enterprise the grassland birds at Wheatlands Farm confounded and amazed. But as Flip Wilson used to say,

“ I’m going to tell you that story , but first I need to tell you this one so I can tell you that one.”

A discussion of grassland birds needs a sketch of grassland history and dynamics, which we cover in this first part; we’ll get to the 2013 adventures of the grassland birds in the next two episodes.

Wheatlands, a 165-acre beef cattle farm in the southern Shenandoah Valley, lies in the rain shadow of North Mountain, specifically to the immediate east of 4463’ Elliott Knob which lofts nearly 3000’ above the Valley floor.  In the lee of that prominence the annual rainfall averages 35 inches, ten inches less than the 45 inches lavished on the rest of Virginia. Thirty-five inches is a moisture regime favoring grasslands over deciduous forest and is only slightly more than the average for the tall-grass prairies that once carpeted Illinois and Missouri and Iowa – with a little help from the grazing ungulates and the peoples who invested in the “millennia of exuberant burning” chronicled by Charles C. Mann in 1491.(www.theatlantic.com/magazine/archive/2002/03/1491/302445)

It would be more accurate to say that at a location in temperate North America experiencing a 35-inch rainfall, woody plant succession is more easily arrested than at 45 inches. However, even at reduced moisture, plant succession is still as certain as gravity unless some force acts to suppress the trees and shrubs.  Humans, sponsoring a rich and mobile protein source in the form of grazing ungulates, have been that force since the Wisconsin ice receded 11,000 years ago. Perhaps for all of post-glacial history humans have managed the North American landscape to create grasslands where practicable, including much of the region east of the Allegheny Mountains and especially , I am inclined to believe, in the rain shadow of North Mountain.  That 20-square-mile enclave is beef cattle country today as it was bison country a thousand years ago. Buffalo Creek has cut a waterway through Little North Mountain creating Buffalo Gap which offered the bison summer grazing in the interior of the Alleghenies. Wheatlands Farm is at the center of North Mountain’s 35-inch rainfall arc.

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Wheatlands Herd Management

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I live at Wheatlands, so I muse upon the Buffalo Gap grasslands, their history and their legacy complement of grassland birds. I and a Border Collie named Benson tend a cow/calf herd of Charolais-Angus beef cattle 75 to 100 critters strong.  The Wheatlands cattle, like the bison, are grazers; they eat a mix of grass and forbs (non-grass herbs).  When they discover a woody sapling in a pasture they attack, chomping and stomping, horning and wallowing, ripping off branches and pawing the successional intruder into oblivion. I suspect the bison carried the same genetically-encoded chip on their wooly humps, the innate urge to destroy trees, perhaps sensing that trees are a threat to their grassland "salad bar" (a Joel Salatin term. Joel also lives and raises cattle in the North Mountain rain shadow).  The cattle may be desperate for shade but they will not suffer a sapling to grow in their pasture. Moreover, they eventually kill even the mature trees by clustering under them, rubbing off the bark, and compacting soil at the roots.

My interpretation is subjective, but the bovid inclination to work in concert with fire-wielding humans to create and maintain grasslands is clear enough.  I am comfortable with the conclusion that grasslands in temperate North America and other locations, modern and past, are typically the result of the ancient alliance of humans and bovid ungulates – cattle (genetically, auroches ) and bison. Remove the bovids from the equation and humans have no incentive to burn (or mow). Remove the humans and the bison (or cattle) eventually face reduced rations or at least a shift of diet to browsing, which requires a different gut chemistry than is typical of bovids. Remove both and the land reforests in half a human span (Godfrey, 1980).

From the standpoint of grassland birds, grazers are a blessing, if mixed. As they can stomp woody saplings they can also stomp on-ground nests. But as they munch along they tend to leave a grass/forb stand of varying heights which accommodates the birds’ foraging and nesting needs. Dr. Scott Pendleton, a veterinarian in Cadiz, Ohio, monitors Upland Sandpipers and Bobolinks on reclaimed mine land in Harrison County. He notes,

“All the successful Upland Sandpiper and Bobolink nests I have seen on these reclaimed mine lands are in sections which the mine owners lease to local farmers for grazing. The birds need stands of varying heights and densities which the cattle create. The challenge is to encourage farmers to delay mowing to let the birds complete nesting.”

Call the grasslands a stool, if you will, of the kind that furnishes seating and requires three legs – people, ungulates, and a group of birds which are obligate grassland breeders.  If the grasslands and the grassland ungulates knew a close ecological kinship with the humans of olden times so must the grassland birds. Over the millennia the Meadowlarks, the Grasshopper Sparrows, the Bobolinks, the Dickcissels must have been co-passengers with the bison on mankind’s grassland rollercoaster.  Management by birds of seed dispersal, insect pollinators, and food-source insects (grasshoppers et al) are surely vital functions in grassland economics, perhaps of importance equal to the contributions of people and bovids. The entire avian cohort must have learned to balance in the shifting winds of human-created grasslands in North America, riding waves of tribal warfare, weather events, climate shifts, and developments in food-production technology.  We must have in mind that pre-Columbian native populations in North America were large -- 20 to 40 million people at times (Mann, 1491)-- and the ability, the need, of those populations to manipulate the landscape carried massive ecological impact. Trackless virgin forests? Forget it. Even in the East. It is much more efficient to harvest bison in large herds on open grasslands than individual deer skulking in forests.

A hypothesis emerges; like the bison and the grasslands themselves, the grassland birds must operate in  a confederacy with mankind. Over time (people have been in North America for at least 16,000 years) the grassland birds have followed moccasin and hoof through wealth and want, shifting their ranges and schedules and diets with the fortunes of the grasslands of human creation. We see our birds, our surrounds generally, through a squinty lens of 500 post-Columbian years.  That is a very short slice (maybe 5% of the whole salami) of the era of people and their grasslands in North America. The dynamics have always shifted and calamity is likely no stranger, but it seems justifiable to see at least a blur of birds and bison on mankind’s grasslands over 500 or so human generations. 

A Krakatoan blast hit North America’s grasslands after 1492 in the form of diseases distributed by the Spanish.  Very quickly, most of the native human population was dead. There was no immunity to the new pathogens and there was little immunodiversity in the native genetic endowment because the natives of the Western Hemisphere were descendants of a small number of adventurers who crossed the Bering Land Bridge. In Guns, Germs, and Steel Jared Diamond reports,

"Throughout the Americas, diseases  introduced by Europeans spread from tribe to tribe far in    advance of the Europans themselves, killing an estimated 95% of the pre-Columbian  native American population. The most populous and highly organized native societies in North America,  the Mississipian chiefdoms, disaappeared in that way between 1492 and the late 1600s, even before Europeans themselves made their first settlement on the Mississippi River. "

The scheme which had created and maintained the grasslands must have collapsed abruptly. Much of the continent, especially the well-watered East, quickly reforested.  Some understand the volume of atmospheric carbon sequestered in this sudden reforestation to be sufficient to account for the 200-year global temperature drop beginning in 1650 known as the Little Ice Age. By the time the English took an interest in penetrating the continent’s interior in the early 1700s a newly established canopy covered dark corridors of forest that shrugged as if to ask “Grasslands? What Grasslands?”

In the 1700s the English, and others, cleared a lot of forest and created a lot of new grasslands.  By 1900, 75% of the Piedmont was under plow or pasture.  In the accounts of A.C. Bent, the grassland birds recovered somewhat.  But by 1980 only 25% of the Piedmont was cultivated – we, especially we southerners, abandoned our farms wholesale and put them in the hands of the wood products companies creating a desert of row-planted pines.  The grassland breeders vanished from those lands.  Bent refers to a reduction in the Dickcissel’s presence in the East beginning in 1900; the 1980 edition of Peterson’s Field Guide to the Birds notes “formerly bred along seaboard Mass to S.C.”  The Dickcissel, an obligate grassland breeder, has responded to the abandonment (and reforestation) of eastern farmland by vacating much of the East. Other grassland endemics, including Bobolinks, are reduced as well.

Another disruption now threatens the grassland birds – climate change.  Beginning in 2011 and through the 2013 nesting cycle, there has been chronic drought and fire in the Dickcissel’s core breeding range, the traditional prairie grasslands.    The results are apparent in one corner of one valley in Virginia and probably at other locations to the east of the Alleghenies. An informed argument (Kaufman, private correspondence, 2011) suggests that drought-associated pressure on the core breeding range in the Great Plains forced some of the birds eastward. For the first time since 2000, Wheatlands hosted Dickcissels in 2011, probably a half dozen, then more than two dozen singing males in 2012. Numbers were down in 2013 to the 2011 level as the drought shifted westward.

We can hope that the Dickcissels that fled the western droughts in 2011-2013 to nest in the southern Shenandoah Valley may rekindle an interest that will persist even when drought spares the West. That depends on the health of the eastern grasslands and on the compatibility of our farming methods with the birds' breeding needs – in other words, the Dickcissels not only need to nest in the East, they need to nest successfully to recruit a cadre committed to the East.  Because nearly all remaining eastern grasslands are on active farms under intensive production, many nests go through hay-making machinery.

   

In the next two parts of this post we will detail the 2013 nesting cycle of the Bobolinks and Dickcissels at Wheatlands. Their unexpected schedules and behaviors may add an increment to our understanding of these birds with an ancient link to man.

A New Lease on Life

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Upland Sandpipers, Harrison County, Ohio

“Natural Grade”.

It’s what the natives of Harrison County, Ohio, call the shape of the land left after epochs of erosion of the once mighty Appalachians. That shape is unusual now in parts of Harrison County because the coal interests have deep mined, and high-walled, and strip mined 80% of some townships. The recontoured lands – those mined after the law required smoothing and seeding -- show a bloated uniformity contrasting with the angular “natural grade” remnants, some forested. The recontoured lands grow grass tufted with the alien invasive, autumn olive.

The dozerscape does not affront the grassland birds of Harrison County. These synthetic hills offer safe breeding harbor to Grasshopper Sparrows; Savannah Sparrows; Henslow's Sparrows; Vesper Sparrows; Horned Larks; Eastern Meadowlarks with dialects suggesting Dickcissel’s introductory notes; Bobolinks; and, wailing out of the mists of myth, Upland Sandpipers! What this polyglot singing on the dozered slopes says is that whatever mix of plants the coal company planted for erosion control evidently is acceptable to the native grasshoppers and other insects, for these invertebrates feed a multitude. It is difficult to imagine a more vibrant community of grassland birds.

After the first round of strip mining, the company began liquidating the mined-out land in tracts ranging from 5 to 200 acres. Then two things happened; a new technology enabled the re-stripping of parts of the land for coal that once had been deemed inaccessible or inferior and the Marcellus Age dawned. The coal company lost all interest in selling and made plans to further work the holdings, happily stripping and fracking into the 21^st century. The upside, if there can be an upside to a land torn by extraction, is land stripped before the reclamation law and scarred by 80 foot highwalls will be reclaimed to something approximating natural grade and large tracts of open grassland will be formed or preserved. 

But what to do with the tracts of grassland while they are warehoused for future exploitation? Leasing them to cattle farmers seemed logical; that generates a little revenue and it puts someone on the land with a security interest.  Grazing the reworked lands with cattle in large boundaries also happens to mimic the imprint of bison on the land – enriching soils, diversifying the grass and forb stands and, most importantly for the grassland birds, creating grass stands of varying heights and densities. In the words of Dr. Scott Pendleton, an accomplished field naturalist and a veterinarian at Cadiz Animal Clinic, a large-and small-animal practice near the Cadiz, Ohio, airport:

“More than half our Henslow’s nests and all of the Upland Sandpiper nests are on coal company land that has been grazed. Also, the sandpipers and their hatchlings like to forage on the newly-cut hay ground. We are working with the leasing farmers to schedule cutting and grazing after June 20^th when the young Uppies are out foraging with the adults and most of the passerine birds have fledged.”

The take-home points from this expedition to Harrison County, Ohio, are that:

The only place in the county to host breeding Upland Sandpipers, an Ohio Endangered Species, is recontoured strip-mined land, and

On that recontoured land the Upland Sandpipers show a clear preference for grass stands that have been grazed by cattle, a preference they share with many other grassland birds.

Does Harrison County offer a template for an exciting conservation initiative? 

The Arctic Nearby

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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.

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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

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                                      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

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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. 

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

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 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.