Those brown, golf ball-sized growths on your oak tree are called oak apple galls. Oak apple galls are green at first and turn brown as they age. They are up to two inches wide, but are usually the size of a golf ball and have a thin paper-like covering and spongy interior.

The oak apple galls are created by Cynipid wasps which have an unusual life cycle. Winged adult wasps emerge from these galls sometime in June or July. They mate and then drop to the ground. There, the females burrow into the soil and inject eggs into the roots of the oak tree. Wasp larvae hatch and feed on the roots for about a year and then form a pupa. Only wingless female wasps emerge from the underground pupae and crawl out of the ground and up the tree trunk sometime in early spring. They inject one egg into the midrib of a leaf that is just starting to grow. The larvae hatch inside the leaf and release a chemical as they grow that causes the leaf to mutate into a round green ball around the larvae. There the larva feeds while protected from predators. As the larva grows, so does the gall. When the larva is done growing, it pupates and later emerges as an adult wasp by drilling a small hole in the gall, and the cycle starts again.

These wasps only lay their eggs in oak trees and are particularly fond of black oaks, red oaks and scarlet oaks. Their activities do not harm the tree but many of these wasps on one tree could cause the tree to lose their leaves early that fall.

Studies have shown that wild birds rely on many different sources of food for survival. Even birds that regularly visit feeders usually rely on them for less than 25% of their food supply, with wild food sources providing the rest. Wild birds have survived on this continent for millennia without people feeding them, and could do so again. People didn’t start feeding wild birds in North America until the late 1800s. Some people feel that human-caused habitat loss increases the need to provide food for our feathered friends. This is true, to some extent, in more urban areas. The flip-side to this is the millions of acres of habitat that were lost to grow the crops for the bird seed in the first place.

Feeding birds during cold winters in the Northern latitudes has been shown to increase the survival rate of chickadees. I’m sure that it isn’t nearly as important down here in the South because snow cover is what prevents them from finding food in northern states. Even when it gets cold here in Chattanooga, wild food sources are still available.

A Wisconsin study, conducted in the middle of winter, sheds some light on this problem. The conclusion was that birds who regularly visit feeders find wild food sources when their feeders are suddenly taken away, and they survive just as well as birds that depend entirely on wild sources. During a typical winter, wild food sources are enough to ensure the survival of wild bird populations.

So if for some reason you quit feeding the birds in your yard, they will find other sources of food to survive. Birds do tend to get into a routine of checking food sources. If you stop feeding them, it may take them awhile to come back to your feeders as part of their routine.

Feeding birds can be a tremendous benefit to people because in our increasingly urbanized world, feeding birds has become our primary interaction with wild animals.

Opossums are famous for “playing dead”. In fact the phrase “playing possum” has become part of our language, but it doesn’t happen like it’s often depicted in cartoons. Opossums aren’t making a choice to look dead until a potential predator goes away. They actually get so scared that they pass out. Laying on their sides in curled posture, their eyes glaze over, and they bare their teeth with tongues hanging out to the side. Their body temperature drops, their heart and breathing rate slows down so that they feel dead too. They also secrete a green liquid from glands under the base of their tail that smells putrid making them smell dead as well. They can remain in this state from a few minutes to over two hours or more. They are incapable of feeling anything, and poking or shaking will not revive them. They are somehow able to detect when the threat is gone and come out of their catatonic state.

This baby opossum isn't playing dead...

Another animal native to Tennessee that plays dead is the Eastern Hognosed Snake. These snakes roll over, open their mouths, hang their tongues out and secrete a foul-smelling liquid from their musk glands. Apparently they have conscious control of this behavior because if you turn them back on their bellies, they will roll upside down again. Hognosed snakes are toad predators. Toads are highly toxic and these snakes are one of the few predators that can eat them. Large adrenal glands in their brains neutralize the toxins. Most snakes in the world that specialize in eating toads also have large adrenal glands and play dead as a defense.

Other native Tennessee animals that have been reported to play dead as a defense include the Turkey vulture and the Blister beetle.
All of these animals play dead because most predators have to kill their prey before eating it and, in fact, their feeding stimulus is driven by the act of killing. Since most predators don’t wish to eat rotten meat, the foul smell usually associated with the “playing dead” behavior, deters eating the imposters.

Kyle Waggener