The Value of Snags

One of the benefits of leaving large, dead trees standing is that they often become magnets for wildlife.  Their decaying bark and wood attract countless species of insects, which in turn become food for wild animals; they provide space for nesting and roosting; and hawks, owls, and flycatchers, among other species, use them as hunting perches.  I realize that sometimes these snags have to be removed, as they pose a danger to humans or to property, but if a dead tree stands in a place that isn’t inconvenient for people, I would argue that it’s better to leave it alone.  

Half-dead sugarberry tree

My observations of birds in and around snags in the neighborhood where I live bear this out.  Like most residential areas, my neighborhood has severely fragmented forest habitats, which aren’t ideal.  However, within those tiny woodlands, the ages of the trees vary widely, and there are some trees that have died.  Ecologically, this is a good thing!  If you have snags near your home, watch closely to see the variety of birds and other animals that use them.  For example, I often see a Mourning Dove perched atop one particularly large and prominent snag.  I don’t know whether this is always the same Mourning Dove, or whether several different individuals like to use this perch.  Woodpeckers, including the species Red-headed and Red-bellied, hammer on this tree, as well (juvenile Red-headed Woodpecker in the bottom photo).  

Mourning Dove

Red-headed Woodpecker

One rather exciting find for me this fall was a migrating Olive-sided Flycatcher foraging from this snag.  Although it isn’t exactly a rare bird, it is becoming scarcer, probably as a result of global climate change combined with habitat destruction on its wintering grounds in Central and South America.  Disturbingly, surveys show that populations have declined 79% since 1970.  

Olive-sided Flycatcher

The bird’s distinctive feeding style usually involves sitting at the top of a prominent perch and darting out to catch flying insects that pass by.  This neighborhood snag is tall enough to provide an excellent vantage point for flycatchers to survey a wide area, so while I was pleased to see an Olive-sided in it, I wasn’t really surprised.  The Olive-sided’s smaller and paler cousins, Eastern Wood-Pewees, also hunt from the snag—although less habitually.

Olive-sided Flycatcher (left) and Eastern Wood-Pewee (right)

The apex predators of the bird world, hawks and owls, use snags, as well.  Red-shouldered Hawks are the ones that I most commonly see around here, probably because of the creek that harbors the frogs, crayfish, and snakes that these lowland-loving hawks like to eat.  

Red-shouldered Hawk

Mississippi Kites left the neighborhood for their wintering territories in South America well over a month ago, but while they were here, they could be seen on occasion in the tops of the snags bordering the fields.  I sometimes see Red-tailed Hawks here, as well, and I am sure that Barred Owls and Great Horned Owls use these trees at night.

Mississippi Kite

Another of the dead or dying trees around here that I enjoy monitoring for wildlife is a moribund sugarberry.  It happens to be a prop for berry-producing vines, so wildlife can binge on those in addition to the sugarberries that grow on the living side of the tree.  I’ve seen many species of birds feeding on the fruit, including tanagers, orioles, bluebirds, mockingbirds, thrashers, vireos, and woodpeckers.  As you might guess, the tree also attracts lots of insects, so even non-frugivorous bird species—e.g., warblers and gnatcatchers—can find a buffet there.  And woodpeckers really seem to like its dead top branches for drumming and feeding.  Here’s a sampling of some of these birds:

Yellow-throated Vireo inspecting dead branches

American Goldfinch

Baltimore Oriole

Since we're in the thick of bird migration right now, taking another look at snags is well worth the effort!