NATURALLY TEXAS: Golden-fronted woodpecker a good size

Many of my graduate students (and by mine, I mean those who worked on thesis research problems under my direction) studied behavioral ecology of woodpeckers. Behavioral ecology is a discipline that examines variation in animal behavior associated with different environments or different seasons. But perhaps the larger question is why study woodpeckers rather than, say, quail or other birds for which more people care? There actually is a good reason aside from the fact that I just like woodpeckers.

Many birds live their lives in a manner and in settings that make them difficult to observe well enough to tell what they are doing from moment to moment. Small birds can be difficult to see in dense foliage, especially sparrows that forage for seeds on the ground out of sight in grass.

Large birds may cover many square miles in a day, making them impossible to keep up with as they cross multiple properties controlled by multiple owners.

Most of these problems are not problems with woodpeckers, so woodpeckers make good species to train students in field techniques. They’re large enough to be seen well from a distance that doesn’t disturb them, and they often spend 20 minutes or more foraging in a single tree, giving the researcher time to observe their activities.

Your usual expectation is that woodpeckers find their insect food by excavating holes in wood, but that most often is misleading. Student Kathleen Kujawa studied foraging behavior in probably the most common of local woodpeckers, the golden-fronted woodpecker (Melanerpes aurifrons). She found that this woodpecker acquires most of its food by gleaning off the surfaces of wood, leaves or ground. And the food it eats will surprise you also: nuts, acorns and hackberry fruit (also soapberry fruit, prickly pear cactus, algerita, western soapberry, wolfberry and more) as well as the expected beetles, moths, ants, cicadas and grasshoppers. They also probe with the bill into natural cavities and fly out to catch insects in flight.

Student Mike Husak found that this woodpecker is an aggressive defender of a breeding territory from about February through June — the breeding season. Such territorial defense is intraspecific, meaning that they defend it only against other individuals of their own species. They couldn't care less what cardinals, mockingbirds or cuckoos are doing. The territory is large, averaging a whopping 43 acres, implying that resources are scarce enough to require a large territory if young are going to be raised successfully. They typically do not defend a territory from late summer through winter.

We have recorded 10 species of woodpeckers in the Concho Valley. The golden-fronted woodpecker is easily the most common residential (non-migratory) species here. Most of that species live in mesquite brushland, so you can expect that they have increased in local abundance over the past 125 years as mesquite density has exploded. The ones close enough to rivers often move into pecan groves in the fall as nuts mature.

Oddly, from my experience, golden-fronteds are decidedly uncommon in our wooded urban yards. By contrast, the smaller ladder-backed woodpecker finds our urban pecans and live oaks perfectly acceptable.

One interesting question about this or any other woodpecker species is how rapidly it can dig a nest hole in a tree trunk or utility pole. The average recorded depth of the nest hole for this species is about a foot, and it takes about 13 days for each member of the mated pair to cooperate in its excavation.

The nest cavity is not necessarily the safest place for infant birds. Adults guard the nest for much of the nestling period, but that does not always work. Mike walked up to an active nest cavity but could not hear the usually vocal infants so he tried to look into the hole when a sizeable rat snake came out right into his face. It’s a harmless snake, but still. The life of a naturalist has its memorable moments.

Terry Maxwell, Ph.D., is a retired professor of biology at Angelo State University. He can be reached at terry.maxwell@angelo.edu.