Monday, April 27, 2009

It's Getting Cuckoo

Forest tent caterpillar weave masses of white silk in deciduous trees. They shelter in the "tents" and emerge to eat the trees new leaves.

This is the time of year when the trees are leafing out—or trying to leaf out. If a tree is unlucky enough to be infested with forest tent caterpillars, it may have a hard time getting its first batch of leaves out before they are devoured by the tent caterpillars. The caterpillars favor broad-leaved deciduous trees, especially oaks, maples, aspens, and on our farm, ashes and cherries.

The first part of the life cycle of the forest tent caterpillar goes like this: tiny (1/8th of an inch) caterpillars hatch from eggs and begin feeding on newly emerged leaves. The caterpillars congregate into colonies on favorite food trees, which they find by following silken trails laid down by others of their kind that are searching for a new food source. The caterpillars go through five instars or molts before reaching their full-grown size of two inches. While molting or between bouts of feeding, the colonies of caterpillars form large silken mats on a tree, often at the junction of branches and the trunk.

The caterpillars can defoliate a tree in a matter of days. If you stand near a tree that is actively being fed upon by these hungry "cats" you can hear their frass (poop) dropping to the forest floor. Only rarely does the caterpillars' defoliating of a tree result in the tree's death, and then, only with trees that were already otherwise compromised.

The complete life cycle of the forest tent caterpillar, including the riveting portion of their lives when they spin a cocoon and emerge as a moth, can be found here.

These forest tent caterpillars are nearly full-sized.

For now, I'm sticking with the "tents" and the caterpillars that are in them. I know that when I see the white masses of silk, crawling with caterpillars, that it's almost time for the cuckoos to arrive in spring migration. Many's the time I've seen yellow-billed cuckoos chowing down on these hairy crawlies, but the ornithological literature and all the smart people that you find on The Google, indicate that as many as 60 bird species take advantage of forest tent caterpillars as a food source. The list of 60 bird species includes nuthatches, warblers, orioles, blackbirds, grosbeaks, jays, and waxwings. Many birds also steal the silk from the "tents" to use in nest building, including the blue-gray gnatcatcher, as seen here in a BOTB post from 2006.

Yellow-billed cuckoo, an avid eater of tent caterpillars.

For me, the appearance of the blobs of white silk and the dark caterpillars crawling all over the son-to-be-leafless trees, means only one thing: It's cuckoo time!

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Wednesday, March 25, 2009

Forest Birding Around Subic Bay

Coleto, a starling relative, is a common forest edge bird. Its head is covered in bare pink flesh.

On the afternoon of March 3 and the morning of March 4 our group looked for birds in the forested hills around Subic Bay. The birding was somewhat difficult for a few reasons: the birds were not present in large numbers or variety (though a different group visiting later in the week had great birding there), the forest was thick and dark, and the light, after sunrise, made any bird in the canopy appear in silhouette. It may have been a timing thing, or perhaps these trails had been recently hunted (subsistence hunting has a major impact on wildlife in the Philippines). But we saw just a few birds well, but many more birds fleetingly. And we heard far more than we saw.

Most of our group in the forest near Subic Bay, scanning the canopy for small birds.

The main trail we walked along on the morning of March 4 was perfect for group birding—safe footing, and wide enough for all to find a good vantage point. There would be times on this trip when we'd all miss birds along a narrow forest trail. There is a Zen to forest birding. Quiet bird watchers moving slowly always see the most birds.

The Subic forest trail.

A canopy of bamboo.

With few forest birds coming close enough to photograph, I decided to photograph the forest itself.

Some bamboo species are native to the Philippines, others are imported for cultivation.

Lest I give the impression that we saw nothing, let me say that nearly every single bird we encountered was a lifer for me. Not all of them gave me the kind of "bee-eater" looks I'd gotten earlier on March 3: great views, lots of photos taken. But, as is the habit of an addicted bird photographer, I did not let the improbability of capturing a decent image stop me from taking dozens of frames.

A soaring brahminy kite.

Silhouetted against the light: a female tarictic hornbill: the smallest hornbill in the Philippines.

Yellow-vented bulbuls were everywhere.

Slender-billed crow.

White-throated kingfisher.

Soon it was mid-day and we were on the move again to another island: Cebu, via the Manila airport. As we loaded into the mini-bus for the ride back to our hotel to pack up, the cool, air-conditioned comfort laid many of us low. We nodded off with dreams of the Cebu flowerpecker dancing in our heads.

Sleepy birders on the bus.

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Monday, February 25, 2008

Goodbye Privacy Tulip

The glorious Privacy Tulip on the last day of its long life.

Our house sits on a windswept ridge in southeastern Ohio. The woods are all around us, but they are recovering woodlands, with few tree more than 40 or so years old. Timber harvesting happens all around us every year. Somebody's woods will have finally grown old enough to be 'harvestable'. Not ours. Our woods will never get old enough. Because we don't plan to timber them.

Several times every year various fellows in flannel shirts, Carhartts, and muddy boots come to the door and politely introduce themselves asking if we realized that we were sitting on ready cash with all these trees on our land. We smile and tell them "No Thanks!"

Our neighbor to the north is having his acreage timbered. It's a selective cut as they say. This means that instead of cutting everything standing, only the trees of a certain size will be cut. For two months now we've listened to the clanking roar of the bulldozer as the timber man cuts a muddy swath up and down the hills of our neighbor's land to get at the prime trees. Everything over 18" in diameter is being cut—and that means a LOT of trees. The chainsaw has whined nearly every day it wasn't raining or snowing. We've heard dozens of loud, creaking crashes—the very last sounds made by dozens of oaks, maples, hickories, and tulip poplars.

It's our neighbor's right to harvest his timber. We've got no recourse, so we tell ourselves that while the destruction being wrought is bad news for wood thrushes, scarlet tanagers, ovenbirds, Cerulean warblers, and box turtles, it might be good news for yellow-breasted chats and indigo buntings, and Kentucky warblers, and hooded warblers—all species that prefer brushy woodlands over older growth forests.

The one tree on the neighbor's land that we've had a special bond with is a giant old tulip poplar we called the Privacy Tulip. It blocked the direct view of our house and birding tower from the country road a half-mile across the valley. We liked having the privacy from the Privacy Tulip. All winter its branches covered the view of our house. In summer, its leaves smothered the noise of the county road. We worried that it would get cut down with all the other trees. The more we thought about it the more unhappy we became.

Viewed from our birding tower, the Privacy Tulip stands above all others. It's value to us is not measured in board feet.

Julie even called our neighbor to try to buy the tree, but he was having none of it. He was perfectly nice in turning her away but turn her away he did. To him, once a tree falls down from old age or weather, it's no good to anyone. Better to cut it now and make something useful out of it. I would argue that a downed tree makes for a healthier forest in the long run, adding to the richness of the soil, providing food and shelter for thousands of organisms, opening up the forest canopy to let sun and rain reach smaller trees. But that's not how our neighbor sees it. And I have to respect his opinion at least as far as the boundaries of our adjoining properties go.

So it was with a heavy heart a few Saturdays ago that I called to Julie when I realized the timber cutter had rumbled his 'dozer right up under the Privacy Tulip. He was so close I could hear him spit as he got off the 'dozer. The chainsaw started and it was over in a matter of minutes. The Privacy Tulip's reign on the hillside below our house was over. How long had it been there? Certainly long before our house was built. One hundred years? One hundred and fifty?
Leaning away from the biting chainsaw, the Privacy Tulip is brought down once and for all.

Twenty minutes later, scalped of its branches and crown, the core log of the Privacy Tulip—more than 34 inches in diameter near its base, was being dragged downslope through the mud to await stacking on the log truck for transport to the mill.

I think back on the many birds I've seen in that tree: the bluebirds loved it as a lookout perch. The cedar waxwings, too. They'd swirl to a stop in its top before dropping down to eat our grapes and wild cherries. All of the woodpeckers used the tree as a stopping point between feeders and nest sites. The male scarlet tanager always seemed to make his first major singing appearance of the spring in the top of the Privacy Tulip. What stage will he sing from now?

I can't go visit the stump just yet. I'm still trying to adjust to the new clear view of the county road off to our northwest. There is an un-fillable void there. The headlights of passing cars now dance across our walls where once they were blocked by a forest giant.
A gaping hole in the woodland horizon where the Privacy Tulip once stood.

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