Tuesday, October 21, 2008

Young birders discover new birds and bent trees...

Eager young birders found life-list birds and oddly bent trees while exploring the growing trail system at newly opened Deer Haven Preserve, a new natural area restoration taking shape in old farm fields and wooded ravines near the Olentangy River, Preservation Parks of Delaware County, Ohio.

The Ohio Young Birders Club, Delaware affiliate, gathered with parents still young at heart and Education Coordinator for Preservation Parks of Delaware County, Jackie Bain with her geoecologically-bent husband (your blogger) to explore and learn new skills Saturday, October 18.

A name-sake tree along Bent Tree Trail.

Big birds like Great Blue Herons make big impressions for new young birders, but a star emerged from among mixed-species foraging flocks: Ruby-crowned Kinglets, little bundles of supercharged feathers wing-flicking and chasing through the shrubbery close-in along the new wetlands pathway. Jaws dropped behind awkwardly held binoculars trying to follow the busy kinglets.

A flurry of foraging Yellow-rumped Warblers made a great show, too. Curious minds are eager for new tidbits and tales so our small group learned to look past the birds to see much more and to question what they saw. "Why do they have yellow rumps?" "Why do different kinds of birds fly around together?" "How can you tell those black birds flying up there are Red-winged Blackbirds and Brown-headed Cowbirds?"

Cedar Waxwings whistled overhead in small flocks while we discussed invasive bush honeysuckle. It's bright red fleshy berries carry just enough sugars to keep the birds coming. Seeds are dispersed in bird droppings along fencerows and woodlands, everywhere. It's taking over!

Blue Jays congregated in American beech tree-tops scurrying for ripe sunshine-filled beechnuts and raining them to the ground around us while we discussed family chores and family economy long ago when abundant beechnuts were important food for American Indians and early settlers.

A Belted Kingfisher rattled from the pond nearby, a good beginner's song to get young birders thinking of bird listening, not just bird watching. "How do you know that was a kingfisher?"

Young birders found curious caddisfly larvae cases made of little bits of stone glued together on the undersides of dry streambed rocks as we discussed the erratic rounded rocks we overturned--those rocks and boulders so out of place on slopes and collecting in the streambed. "Where did they come from?"

The crystalline igneous rocks rode glacier ice all the way from Canada. Young birders turned their binoculars to see backward through objectives magnifying the interlocking crystals gleaming on a freshly chipped granite boulder. "How did they get here?"

We searched tree trucks for the diminutive Brown Creeper calling nearby but could not find the little camouflage expert as we talked about the anachronistic honey locust pods, scattered trees were drooping under their burden of long leguminous pods. Many pods already had accumulated on the ground under the trees and remained uneaten, though some were nibbled by seed predators that kill seeds rather than distribute them.

Mammoths and Megalonyx (the giant Jefferson's ground sloth, extinct) are no longer around to chew the sweet pods and swallow the small slippery seeds whole then distribute them in their dung*. Curious young minds devour tales of giant beasts of yore; just don't use words like, "anachronistic" and "leguminous" during the telling!

A Hermit Thrush scolded gently from the brush in the ravine where Eastern Towhees called repeatedly for tea, "Drink your tea!" American Robins "laughed," Downy Woodpeckers pecked, and huge Turkey Vultures raised from nearby roosts to ride early thermals just over the heads of young birders discovering bent trees.

Bent Tree Trail, a tree story...

A mangled tree along Bent Tree Trail, Deer Haven Preserve, Preservation Parks of Delaware County, Ohio. This old sugar maple is a survivor. The major limbs were broken-off close to the trunk during an extreme weather event. It survived by sending fast-growing leaders from the broken limb-tips toward the sunshine (candelabra shape).

Injured trees don't heal wounds, they wall them off to protect undamaged wood and bark near the wounds. Mangled trees retain the scars of their battles with weather and wildlife even when fully recovered.

Our recent hurricane Ike brought record winds to central Ohio and left behind a new pattern of damage to trees, extreme in places, light in others. Our young birders discovered Ike-damaged American beech trees among older fully recovered beech and sugar maple trees with severe damage from long ago, still obvious.

This huge American Beech along Bent Tree Trail lost its top forty-percent or so to Hurricane Ike. Several large trees nearby are severely damaged. Their location along a ridge slope leading toward the Olentangy River valley put them in harms way as high winds tore through the valley during the hurricane remnant's assault.

Badly mangled trees take on curious shapes inspiring wonder and begging explanation. Some large unique mangled trees inspire folklore tales. Surely they must have been manipulated by people. Didn't American Indians intentionally shape trees to signal the entrance to trails, or the direction of important pathways? No, says my professional archaeologist friend.

Nature has shaped wondrous trees in central Ohio with wind and ice many times since Pleistocene glaciers retreated and forests spread northward from southern refugia to raise their grand nearly continuous leafy canopies over the Midwest.

The old sugar maple pictured below is one of the bent trees that inspire wonder and it's one of the trees for which Bent Tree Trail is named. It was a young sapling before the oldest of the tree-watchers among us were born, but not by much. It certainly was not around when American Indians might have had reason to mark trails.

A closer look explains this tree's recovery. Look at the navel-like ring scars at the bends of large limbs, the successful leaders at the tips of limb stumps, and the failed leader close to the trunk on the large limb.

A careful look at this tree, and at damaged trees nearby, suggests a long ago severe weather event is the origin of the damage. The view pictured above is brightened and tightened from the first image to more easily see the scars holding the secret to this tree's recovery.

The close-in heavy branch pictured retains an obvious ring scar at the bend, as does the more distant limb. These scars closed-off damage around the breaks where limbs severed long ago. The nozzle-like protuberance leading to the ring scar is smaller in diameter and offers us a good clue to the size of the branch at the time it was broken-off.

Most of the large limbs of this tree show evidence of breaking-off at the same time and close to the trunk due to the same extreme weather event decades ago: Likely caused by very heavy ice-loading and high wind. I'll give odds it was an ice storm.

The major limbs were broken-off so close to the trunks of several damaged trees that all the determinate-growth bud sprouts (limited growth twig buds that produce annual growth in healthy trees) fell away with the limbs lost. The fast-growing tree-tip no doubt fell away, too. The living limb stumps sprouted indeterminate-growth leaders (fast and tall growing sprouts like the tips of fast-growing saplings, triggered by reduced hormones which normally suppress fast growth below the tips of trees). The leaders bolted upward to spread leaves in the sun.

Only the successful leaders remain these decades later, with one exception. Two indeterminate-growth leaders are visible on the large branch in the image above. A successful leader near the tip of the limb gives the tree its odd shape. An unsuccessful leader closer to the trunk was shaded-out after some years and remains in evidence because the dead stump has not yet fallen off the tree limb.

Horizontal limbs tell a tale of habitats. The unique tree pictured likely sprouted from its whirly-gig seed blown by the wind into a cut-over brushy habitat or a successional pasture with widely spaced larger trees very unlike the small tall-trunked trees of the young forest growing around it today. It's near-horizontal original limbs suggest that it bolted above surrounding competition to open a wide crown at moderate height with major branches reaching broadly outward from the trunk to capture sunlight above the brush and smaller trees surrounding it. Sugar maples are prone to crown low; given a chance they do so.

The combination of horizontally spread major limbs and vertical recovery leaders give this tree its unique appearance. Its bizarre shape will continue to inspire wonder and folklore tales for thousands of visitors for many years to come, along Bent Tree Trail.

When did a storm mangle the tree...

An increment borer drilled into the trunk of a tree can sample a pencil-thin core of tree rings for counting without stressing the tree very much. A core sample from our mangled tree would show an obvious series of very closely spaced rings for several seasons after the storm that mangled the tree, until it recovered its vigor. Undamaged older trees nearby would not exhibit the same cluster of closely spaced rings during the same interval.

American Beech trees recovered from historic damage.

Two American beech trees show damage and recovery that appears to date from the same historic severe weather event which mangled the bent sugar maples. The tree in the top image lost a major fork on its right side. A leader sprouting from near the old break has grown nearly equal in size to the undamaged fork, and has nearly obscured the old scar. The tree pictured below lost its top at the same time but retained a couple major limbs and was able to fill-in the crown with a cluster of awkward new limbs.

*Under the anachronism hypothesis, anachronistic fruits are those large fruits like honey locust pods, Kentucky coffee tree pods, and Osage orange "monkey brains" or "hedge apples" that are not wholly consumed by living large herbivores native to North America which swallow chunks of fruit with intact seeds, scarify (weaken the seed coat within the gut or between teeth) and distribute the seeds ready to germinate in scattered dung heaps away from the plant that provided the fruits consumed. Today, only horses and cattle (re-introduced with humans to North America) serve to distribute honey locust effectively (deer distribute the seeds somewhat poorly). The scattered honey locust trees we found during our walk are a clue to past land use in the area we visited. Anachronistic fruits evolved with an herbivore partner or partners which effectively distributed the species seeds, but now are extinct.
See: Barlow, C. 2000, The Ghosts of Evolution. Basic Books.

Sunday, October 12, 2008

Wind power: New wings join raptors over Allegheny Escarpment...

Wind power is taking flight on colossal white wings over the Allegheny Escarpment along Shaffer Mountain's skyline in western Pennsylvania. Photo by author 10/11/08.

Migrating raptors have owned the airspace over the Allegheny Escarpment for millions of years. Now, mega wind power is colliding with ancient raptor flight paths and with human sensibilities.

A world leader in wind power development is setting up housekeeping in PA. Giant Spanish turbine manufacturer and wind farm developer, Gamesa is bringing Union-friendly green collar jobs and wind-borne megawatts to PA. Not all citizens are pleased. Local roadside signs protest the wind farm project. One example found at the ends of dooryard drives beside both McCain--Palin and Obama--Biden signs reads, "Gamesa is harvesting subsidies, not green power."

Many two-megawatt turbines are spinning on towers already. One website claims forty are slated for erection along the escarpment to complete this pioneering project. Special agreements were written to allow launching the project. Regulations will be penned as experience with mega wind power demonstrates impacts. No legislation currently exists regulating numerical impacts on wildlife (birds and bats, mainly), or requiring remedies other than changing requirements for operation. Current agreements require monitoring and reporting.

Wind turbines along the southern Allegheny Front.

An aerial photo shows the close spacing of towers currently testing the winds and flight paths of birds and bats along linear Allegheny ridge tops. I drove by several similar clusters near Route 160 between Summerset and Center City, PA in early-October.

Both presidential candidates promise large investments in alternative energy development along with a slew of green-collar jobs. No doubt, wind turbines will become a common sight on windy landscapes throughout the United States. How will wind power development impact birds and bats? That depends on placement. The photograph of turbine assembly above was taken just a few miles from The Allegheny Front Hawk Watch...

Hawk counters with the Allegheny Front Hawk Watch search the sky for raptors from their Shaffer Mountain lookout.

More than twenty pairs of binoculars rose to observers' eyes in unison when someone first called out, "Heavy bird coming in over the notch." Excited hawk watchers found the large bird and followed its approach, waiting to see more as it grew larger in view with passing seconds. Someone braved a preliminary identification, "That's got to be an eagle." A murmur of agreement arose in the crowd of onlookers. Then, without bending a wing, the big bird tipped, exposing long white patches at the base of flight feathers of wings and tail. "It's a golden," voices called in unison. Soon its smallish head (compared to a Bald Eagle juvenile) and sunlit golden hackles on its nape became obvious to all. Someone called out, "It's a juvenile Golden Eagle," The official counter added a tic-mark to the list of birds seen this day. It was the third Golden Eagle for the day at the Shaffer Mountain lookout where the Allegheny Front Hawk Watch is supported and conducted by volunteers with the Allegheny Plateau Audubon Society and guests.

The Shaffer Mountain lookout is situated on a western bulge of Shaffer Mountain overlooking a vast valley 800 feet below. It's the leading edge of the Allegheny Escarpment, the eastern continental divide.

Migrating birds of many Families, particularly raptors, move eastward from as far west as Alaska before turning southward at the Appalachian Mountains. The Allegheny Escarpment and the knife-edge ridges of the Ridge and Valley Province, particularly the Kittatinny Ridge of eastern PA. These mountains greatly predate the Pleistocene glaciations and shaped the migratory movements of birds before multiple glacial advances reshaped North America and bird migration. The sinuous mountain chain leads birds to warmer climes on wind-assisted wings.

These ancient flight paths may be at risk. We don't have enough information today to guide choices beyond obvious avoidance of traditionally observed pathways. The vigilance of birders will help guide future placement of wind farms so we can reduce bird losses while gaining green jobs, and reducing carbon tonnage in the atmosphere.