Monday, April 1, 2013

Up With Brush: The Benefits of Scrub Habitat

by Robert Evans

Habitat. No term in conservation carries as much importance as habitat. Protect habitat and you protect all of the plant and animal species that live there and ensure the survival of future generations. Most of us can easily list the types of habitat in our area: forest, grassland, wetland. But one type of habitat that is usually overlooked is scrub habitat. Scrub habitat plays a vital role for birds and other wildlife and it is becoming more scarce. But, fortunately, beneficial patches of this habitat can be created and maintained in your own backyard.

So what is scrub habitat? Most of us know that before European settlement, the northeastern United States was mostly made up of large forests. But as large trees fell from fire, floods, or even old age, sections of forest would open up and turn into grassy fields and meadows. But soon these grassy areas would become overgrown and small trees would start to grow. Eventually enough trees would grow that the field would turn back into forest. But the intermediate stage, too overgrown to be a meadow but not enough growth to be a forest, and characterized by low vegetation with bushes, vines, and a few small trees, is known as scrub.

The northeastern forests featured a continuing cycle of forest to field to scrub and then back to forest. But now that most of the forests have been cleared, most land, if not developed, is managed as either field or forest. Since scrub habitat is always temporary -- it will always eventually turn into forest -- it can be costly and time intensive to maintain. More permanent patches of scrub habitat were once commonly found in hedgerows around farms and homes or along the edges of roadsides and woodlots. But with changes in agriculture and the advent of large suburban subdivisions with meticulously maintained lawns and common grounds, scrub habitat is becoming more and more rare.

The Common Yellowthroat is one of many birds that prefer scrub habitat.

So why is scrub habitat important? Just as in other types of habitat, a number of species are particularly adapted towards living in scrub habitat. Spring migrants such as Brown Thrasher, Common Yellowthroat, and Prairie Warbler and winter visitors such as White-throated Sparrow and American Tree Sparrow are a few of the bird species that prefer scrub habitat. The Golden-winged Warbler breeds in scrub habitat and is in serious decline. Scrub habitat provides plenty of food for birds in the form of insects and the berries of low bushy plants. The thick vegetation also provides protection for birds and other small animals from predators. Scrub is also vital for the young of many bird species. The low, thick vegetation offers fledglings a safe place to learn and develop outside of the nest. 60% of baby birds don't make it past their first year. Without scrub habitat to provide a safe learning environment, many more are lost.

Scrub habitat deserves the same protections and attention given to forest and wetland. Valley Forge Audubon Society, along with Audubon Pennsylvania and Willistown Conservation Trust, has been awarded a Together Green grant to create demonstration areas of scrub habitat in three preserves in the Ridley/Crum Creek IBA: Ashbridge Preserve, Rushton Woods Preserve, and Ridley Creek State Park (you can read more about that here). As part of this effort, we are also trying to educate the community about the importance of scrub habitat and what homeowners can do to create and preserve it.

Very few of us are able to create a forest or a wetland in our backyards, but creating an area of scrub is well within many people's reach. Replace your fence with a hedgerow. Plant bushes or vines that provide birds and small animals food and shelter. Give up meticulous landscaping and let the vegetation grow thick and even a little messy in some areas. Do this and you are guaranteed to see an increase in the amount of birds and wildlife in your yard.

As always, use native plants. Our wildlife, especially insects, are specifically adapted to using native plants for food. Invasive plants are always problematic in scrub habitat. Too often, invasives are the first plants to colonize a field and they spread so rapidly that they leave no room for native plants to grow. The only maintenance a scrub area should regularly receive is the removal of invasive plants. However, if you are just starting out in the creation of a scrub area, don't remove invasive plants unless you plan on immediately replacing them with native ones. A scrub area dominated by invasives is still better for wildlife than an area with no vegetation or only turf grass. A list of suitable native plants can be found on the Backyards for Nature section of our website.

Besides creating areas of scrub in your yard, consider volunteering as we create the scrub habitat demonstration areas at Ridley Creek State Park and Ashbridge Preserve. On Monday April 8 we'll be holding a volunteer work day at Ridley Creek State Park from 4:30 to 6:30 p.m. Students from the Melton Center of West Chester will also be taking part in this work day. On Thursday, May 2, we'll be holding another volunteer work day at Ashbridge Preserve. If you're interested in volunteering on either day, please contact Blake Goll from the Willistown Conservation Trust at or 610-353-2565 ext, 20.

We'll also be holding bird walks at some of these areas where you can learn more about scrub habitat and see some of the birds and wildlife that live there. On Saturday, April 27 there will be a walk at Ridley Creek State Park and on Saturday, May 4 there will be a walk at Rushton Woods Preserve. Both walks start at 9 a.m. You can find more information on our Calendar of Events.

Hopefully the walks and volunteer work days will give you an appreciation of an overlooked type of habitat and inspire you to take the step toward creating some scrub areas in your own backyard. If more people consider their homes as part of a wider ecosystem, native plants, birds, and wildlife will all benefit, and you will be rewarded with wonderful views of the natural world right outside your own window.

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