Why We Should Be Cutting More Trees

By Joe Smith for Cool Green Science

Throughout their lives and even within a single day, American Woodcock are citizens of many habitats.

By day they forage in forest, probing the soft soil with their bill in search of worms and insects.

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American woodcock./T. Flanigan

But every evening at sundown woodcock silhouettes appear in the sky as the birds commute from the forest to settle in fields and clearings where they spend each night.

One reason they may do this is to avoid predators. By measuring predator activity in both habitats, a recent study in Rhode Island found that predator abundance at night was far lower in open fields where woodcock roost compared to the forests where they spend the day.

In late winter and early spring, woodcock also use open fields as courtship grounds where they make their dramatic display flights. But taller woods need to be close by, because that is where the female will ultimately make her nest.

In addition to forest and fields, woodcock also use the shrubby, dense vegetation that fills a field when it is allowed to grow and become forest again. They use this young forest for feeding, nesting and raising chicks.

In a landscape now controlled by humans, the balance of habitat types can become skewed.

Up through the early part of the 20th century, mature forest was a scarce commodity.

Nearly every square inch of North America was systematically logged and logged again at a rapid clip. These were times when wood played a central role in nearly all human endeavors, as construction material and a source of warmth and energy.

Since then, land conservation, decreasing demand for forest products and globalization have relieved some of the logging pressure on eastern U.S. forests.

Now, especially in the Northeast, the challenge is to make sure that there is enough forest being cleared to supply the regenerating shrublands and young forest that many species (like woodcock) depend upon.

Adding to this challenge, the natural events that once cleared patches of forest to create a balance of habitats are no longer humming along.

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Beaver dams flood and kill trees. Once beavers exhaust the food resources at a site, they move on to the next one. The flooding then subsides and young forest begins to grow again./C. Fergus

Forest fires are less frequent and beaver populations remain at relatively low levels. Beaver were once incredibly abundant throughout North America.

As a result of the beaver’s nomadic patterns of building dams, flooding forest and moving on to new places when they use up the trees in an area, they busily maintained a vast mosaic of forest clearings and wetlands.

In the absence of natural processes that create openings, we have to do it the hard way: with people and machines.

When people take over management, things get complicated. They ask all kinds of questions that beavers never think to ask.

“What shall we manage for?”

“Does management for one species amount to management against another?”

The “umbrella species” concept in wildlife management is one way of grappling with the needs of many species occupying the same landscape. It asks the questions “can managing for a single species serve the needs of many?”

In this regard, the woodcock unites.

If you provide the broad palette of habitats that woodcock require, you are also likely meeting the needs of species that at least use some fraction of this palette.

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Golden-winged warblers site their nests in shrubby habitat./M. Cong

For example, recently cleared forest makes for good woodcock roosting and courtship habitat. At the same time, regenerating shrubs and saplings provide nesting habitat for a range of species such as golden-winged warbler, blue grosbeak and brown thrasher.

A whole different suite of bird species nest in mature forest where woodcock spend their days feeding, such as wood thrush, red-eyed vireo and black-throated blue warbler.

But there can be a management tension when a species of conservation concern uses only one habitat type.

If we want more golden-winged warblers, we need more shrubby fields.

On the other hand, if we want more wood thrush, we need more mature forest.

You might think.

But recent research is revealing that even those species we thought were specialists might also require a broader range of habitats to have a successful breeding season – much like the woodcock.

Several studies have surveyed forest birds in summer during the nesting season and after the young have fledged. They’ve found plenty of “mature forest” specialists in clearcuts.

Likewise, they’ve found “young forest specialists” such as golden-winged warbler in mature forest, sometimes even nesting.

While golden-winged warbler and wood thrush might nest most often in their “assigned” habitat, researchers who use radio telemetry to track their daily movements have noticed that the birds are using multiple habitats throughout the nesting season.

Using this technique, a study in Minnesota showed that during the nesting season, male golden-winged warblers spent the majority of their mornings in young forest habitat, but spent the majority of their afternoons in mature forest.

Multiple habitat use becomes really prominent during the period when the young fledge and the adults start to molt, just prior to migration.

It appears that many species, whether they are considered mature forest or young forest specialists may preferentially use dense vegetation that is characteristic of regenerating forest.

The dense vegetation may help protect fledglings and vulnerable molting adults from predation.

What’s emerging from this body of research is a more nuanced view of the habitat needs of songbirds.

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Wildlife biologists check out young forest habitat created for woodcock at Millington Wildlife Management Area in eastern Maryland./C. Fergus

Both wood thrush and a golden-winged warbler, each poster children for habitats at opposite ends of spectrum, likely require a full range of habitats to thrive – from scrubby young growth up to mature forest.

Just like the woodcock!

Can all forest species snuggle under the (management) umbrella of the timberdoodle?

As “umbrella species” go, the woodcock does a pretty good job.

Although we can’t expect all of the thousands of species in a forest to be perfectly served by managing for woodcock, creating a mosaic of diverse habitats that benefit woodcock will likewise benefit a broad range of other wildlife.

In truth, our umbrella species could be any animal that needs a broad range of habitats in order to thrive. A ruffed grouse could serve this purpose just as well, or even a golden-winged warbler.

The bottom line is that these species are emblematic of the shifting mosaic of habitats that is created and perpetuated by forest disturbances. Again, with less frequent natural disturbances, all that mosaic-making is now largely up to us.

With this responsibility, we proceed imperfectly, using the best information we have to make decisions about how much forest to cut, how often and where.

Along the way conflicts inevitably emerge as we debate these decisions.

Maybe, in the end, the best management question we can ask is “what would beavers do?”

ImageJoe Smith, PhD, explores the lives of the birds around us by sharing insights from scientific research. As an ecologist for a New Jersey-based conservation services company, he helps to restore coastal ecosystems and the migratory birds that depend on them. Joe lives in the birding hotspot of Cape May, N.J., and has done field research with birds throughout the U.S. and Latin America. He writes about nature in his backyard at www.smithjam.com.