Hackberry in winter

Twiggy branches of a mature hackberry tree

Hackberry (Celtis occidentalis) is a tree that's quite easy to identify in winter. If you learn to recognize its amooth-but-warty bark and its extremely twiggy silhouette, you can name this tree with confidence.

Celtis occidentalis, the common hackberry, grows in most of the United States except for the states west of the Rocky Mountains  (Those states have other varieties of hackberry trees.) It produces small berries (actually, drupes) that are eaten by a wide variety of wildlife. Because of the sweetness of the berries, one of hackberry's common names is "sugarberry".

This tree grows on the grounds of St. Peter and Paul Catholic Church in Hopkinsville, Kentucky. It's a very large tree. I am fond of it.

Hackberry: A great wildlife tree

Celtis, celtis occidentalis

Leaves and fruit of common hackberry (celtis occidentalis). Berries are indicated with arrows. Image from Wikipedia.

The small berries of hackberry trees are relished by many songbirds in fall and winter, including the bluebird, cedar waxwing, yellow-bellied sapsucker, mockingbird and robin. The reference book, American Wildlife and Plants,* lists over 25 different songbirds who include hackberries in their diet.

The berries are also eaten by gamebirds such as wild turkey, quail, doves and pigeons. And as you might expect, squirrels eat the berries, and so do beaver, possum, raccoons, skunks, gray fox, wood rats, and (in Texas) the ring-tailed cat.

Some species of hackberry trees are called sugarberries or honeyberries which helps to explain why the berries were used by the Native Americans and why people still use hackberries for jelly and wine.

One or more of the eight species of hackberries are found in nearly every state from the Rocky Mountains east. In western Kentucky where I live, our hackberries are celtis occidentalis or common hackberry.

For us, common hackberry is usually a medium to large tree, but in less hospitable conditions, it may not attain such size. It's a versatile tree that tolerates many growing conditions from wet to dry, but it doesn't like permanently swampy areas and it doesn't like acidic soil.

Forestry guide Steve Nix at About.com cautions that common hackberry produces surface roots that can interfere with lawn mowing and raise sidewalks. Think carefully about where to plant the tree, but do consider it because of its great wildlife value.

Cultivars are available from nurseries, or you can transplant a seedling from the wild in early spring or late fall. Starting them from seed requires some patience -- if planted outside, the seeds germinate in 1 to 2 years.

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Related:
Hackberry information page in the USDA Plants Database
Hackberry Emperor butterfly

* American Wildlife and Plants by Alexander Martin, Herbert S. Zim, and Arnold L. Nelson, published by McGraw Hill Book Company in 1951. The book is out of print, but it's often available from used book dealers.

Common hackberry in summer, Hopkinsville, KY

Bark of the Common Hackberry

Celtis occidentalis, Sugarberry, Nettletree

This common hackberry tree grows in Hopkinsville, Kentucky, on the Catholic church property. Its bark is fairly smooth with occasional warty areas and raised creases.

All of the hackberry trees I've seen around here have bark similar to this. None of them have bark that would be described as ridged.

Thus, I was surprised to read this sentence about hackberries in The Trees of North America by Alan Mitchell: "In Central Park [New York City], the trees have smooth gray bark, but it is normally well covered in dark, abrupt, broken ridges 1 in. thick."

The Audubon field guide shows hackberry bark that is similar to that in the photo above, but Trees & Shrubs of Kentucky has a photo of a hackberry trunk with ridged bark. More research in other texts yields more conflicting descriptions of the bark's texture.

I did notice that the word "warty" appears in most of the descriptions. Even the ridges were described as warty.

Probably there are regional variations in the bark, but Carl Settergren and R.E. McDermott in Trees of Missouri suggest another explanation. "Bark: Grayish with warty projections, smoother on more vigorous trees."

Attracting bluebirds

Trees and plants for bluebirds, advice about bluebird house placement

Eastern bluebird - United States Geological Survey photo

If you want to attract bluebirds year after year, consider planting some of the fruit-bearing trees and other plants that they like. Fruits are an important part of their diet, though they eat insects, snails, and spiders as well. Here are some of their favorites:

Fruit-bearing trees for bluebirds: Dogwood Redcedar Wild cherry Serviceberry Sumac Bayberry Holly Hackberry

Other fruit-bearing plants for bluebirds: Pokeweed Virginia creeper Poison ivy Mistletoe Wild grape Blackberry Elderberry Bittersweet Blueberry

Where to place a bluebird nestbox:

In unspoiled nature, bluebirds nest in holes or cavities in dead trees. Obviously, dead trees don't have much foliage around the nest area -- just vines, at most. Bluebirds prefer their man-made houses to be placed in similarly open areas. They don't like a birdhouse that is hidden within a bushy clump of leaves and branches.

A steel fencepost in the longest size that you can find (7 ft. is generally available) makes a good, inexpensive pole for mounting a bluebird house. The steel post is difficult for animal predators to climb and if the box is mounted at the top of it, it is at an adequate height to satisfy bluebirds.

Bluebirds (and many other birds) prefer to nest near a source of water. If you don't have a stream or pond, provide a birdbath and be sure to tend to it.

Bluebirds are territorial. They are require at least a 100-yard circle of "private property". If you live in a neighborhood of closely-spaced houses and your next-door neighbor has a bluebird nest in his birdhouse you probably won't get a nesting pair in your yard. However, you'll still be able to enjoy the birds as they come to your yard to feed on the fruit you've provided for them!

Related post: Eastern redcedar: A tree that birds love