The Mobbing Crowd

It is not uncommon to see a group of crows or mockingbirds chasing a hawk or eagle, or a group of songbirds fluttering and calling around a perched owl. Such "mobbing" behavior is probably the most frequently observed overt antipredator strategy among birds. A predator may be mobbed regardless of whether it is in flight, on the ground or in vegetation. Birds attacking a perched or ground predator always give loud alarm calls and may make physical contact. Flying birds of prey are attacked by swooping down at a steep angle from above and behind, and emitting alarm calls. Sometimes contact is made with bill or feet. Nevertheless, the exact purpose of such noisy group demonstrations remains a matter of some debate.

Mobbing behavior has many functions. The most obvious would be to protect the young in the nest during the nesting season. Other times of the year smaller birds can simply move away from an invading predator, but in the spring, most birds have set up a territory and they are obliged to defend it.  Predators often rely on surprise to succeed. When a predator is discovered, birds will blow its cover by the loud alarm calls. This will alert other birds to the presence of a predator, and reduce its chances of success.

Careful experiments have shown that birds can learn from each other which predators to mob (indeed, one bird in an experiment was taught by another to "mob" a many-colored plastic bottle, although the mobbing was halfhearted). Therefore one function of mobbing may be educational -- to teach young birds the identity of the enemy. Another may be to alert other birds to the presence of the predator, either getting them to join in the mobbing or protecting them, since a predator is unlikely to be able to sneak up on an alert victim. The original mobber may benefit directly by the predator being moved along or indirectly if the protected birds are its kin.

It is not clear why predators don't simply turn on their tormentors and snatch up one or two of the mobbing birds. If they did, presumably mobbing would quickly disappear; that it persists suggests that surprise is an essential element in raptor hunting. One theory proposes that hawks become used to it and harassment simply becomes part of their life. It is going to happen no matter what, so they might as well try not to fight it. Also, there is little reason for the hawks to fly away because they are bound to end up in some other bird's territory and will have to listen to those new birds scream in their face. Large hawks are rarely quick enough to actually catch a small bird. Seldom do we see birds mobbing the smaller, quicker hawks. Small hawks can easily catch songbirds and would love to have the little birds visit them for lunch. So the small hawks are wisely avoided by most birds. The birds, instead, turn their attention to the less threatening larger hawks.

Last summer a Red-Tailed Hawk we called Adell was released at the Nature Preserve by Raptor Rehabilitation of Kentucky, Inc. As soon as she flew up into a tree, the mockingbirds immediately arrived loudly proclaiming the presence of a new predator. She was only a young hawk, and probably not a very good hunter at the time, but the mockingbirds didn't give her much of a chance.

The good news is that Adell is still at the Preserve. We have seen her flying around several times in the last few weeks. You can recognize her by the deep rusty color of her breast, which is rather unusual for Red-Tailed Hawks. Next time you see a hawk circling around or perched in a tree, look to see if it's Adell!

Sumac in the Fall

We all enjoy the bright colors of fall. Sometimes I can't find enough adjectives to describe the reds of maple trees and dogwoods. But the brightest red of all may be the sumac.  Sumac is a shrub or small tree, native to most of North America, although it is considered a nuisance in some places.

A variety known as Staghorn Sumac has smooth branches likened to the velvet on a deer's antlers - thus the name Staghorn. There are other varieties, which I couldn't pin down with much confidence. Look closely on the stems in this photo. See the small wings?  I think it may be the Winged Sumac.

The fruit grows in large clusters of red berries called "drupes".  (Where in the world do they get these names?) These acidic and tart berries can be eaten raw or dried, though they’re most popularly used in the form of a berry tea or beverage termed "sumac-ade," "Indian lemonade" or "rhus juice". This drink is made by soaking the drupes in cool water, rubbing them to extract the essence, straining the liquid through a cotton cloth and sweetening it. Native Americans also used the leaves and drupes of the Smooth and Staghorn Sumacs combined with tobacco in traditional smoking mixtures, and for many medicinal purposes. Sumac grows in other parts of the world as well. The fruits of the genus Rhus are ground into a deep-red or purple powder used as a spice in Middle Eastern cuisine to add a lemony taste to salads or meat. In Arab cuisine, it is used as a garnish on meze dishes such as hummus and is added to salads in the Levant. In Iranian (Persian and Kurdish) cuisine, sumac is added to rice or kebab.

Poison Sumac Berries

When most people hear the word sumac, they automatically think "poison sumac." Indeed one kind is related to poison ivy, and touching any part of it can induce a terrible rash. You can tell the good from the poison version by the berries. Poison sumac has white berries. Of course that doesn't help during the rest of the year, does it?

Ailanthus or Tree of Heaven

Sumac also bears a resemblance to the Ailanthus, or Tree of Heaven, which is definitely an invasive non-native plant. Both have compound leaves, but Ailanthus turns yellow and tan in the fall; staghorn sumac turns red, ranging into purples and oranges. The two plants have completely different fruit however. Both have greenish flowers at the branch tips. The Ailanthus’ come in whitish-green foamy plumes and the male flowers stink. The staghorn sumac’s flowers come in tight lime green pyramids. Ailanthus flowers mature, on the female plants only, into gold clusters of winged seeds tinged with rust (aging to light tan); staghorn sumac has fuzzy berries that go from lime to deep red.
  

Staghorn Sumac



Ailanthus

Believe it or not, comparing the leaf scars and buds points out the most interesting difference between these two trees and a few others. Ailanthus leaf scars are smile- or shield-shaped with the new bud at the top of the scar; staghorn sumac leaf scars are closer to heart-shaped and, amazingly, the new bud is right in the center of the old scar! The sumac buds are usually hairy if you look closely enough.

Enjoy all the reds of autumn at the Nature Preserve!

Naturally yours,

~denapple

Is It an Orange or Apple?

During these bright autumn days, you might notice a peculiar looking tree growing along the roadside. It looks like bright green oranges or softballs are hanging from its branches! Maclura pomifera, commonly called Osage-orange, hedge-apple, Horse-apple, Bois D'Arc, or Bodark (take your pick), is a small deciduous tree or large shrub, typically growing to 26–49 ft. tall. It is dioeceous, that is, having male and female flowers on different plants. The fruit, a multiple fruit, is roughly spherical, but bumpy and it is filled with a sticky white latex sap. In fall, its color turns a bright yellow-green and it has a faint odor similar to that of oranges. It is not closely related to the citrus fruit called an orange: Maclura belongs to the mulberry family, Moraceae, while oranges belong to the family Rutaceae.

The Osage-orange is native to a small area in eastern Texas, southeastern Oklahoma, and southwestern Arkansas. This region is the home of the Osage Indians which gives the tree its common name. Settlers found that the Osage-orange transplanted easily, tolerated poor soils, extreme heat, and strong winds and had no serious insect or disease problems. It was widely planted in the Midwest as a living fence because, when pruned into a hedge, it provided an impenetrable barrier to livestock. The development of barbed wire curtailed its widespread planting, but many Osage-orange trees can still be found in fence rows. The wood is extremely hard, heavy, durable and shrinks or swells little compared to the wood of other trees. The wood is used for fence posts, treenails, furniture, and archery bows. In fact, many archers consider the wood of the Osage-orange to be the world's finest wood for bows. Another common name for this tree, bodark, is from the French bios d'arc meaning "bow wood." This tree also produces a bright yellow dye which can be extracted from the wood.

The fruit of the Osage-orange is a nuisance in the home landscape and has little value. Hedge apples are not an important source of food for wildlife as most birds and animals find the fruit unpalatable. The thorny trees do provide nesting and cover for wildlife. The belief about the use of hedge apples for insect control is widespread and persistent. it is claimed that placing hedge apples around the foundation or inside the basement will repel or control insects. A few years ago, Iowa State University toxicologists extracted compounds from hedge apples. When concentrated, these compounds were found to repel insects. Scientists also found that natural concentrations of these compounds in the fruit were too low to be an effective repellent. So, don't be fooled into spending much to use hedge apples as an insect repellent. If you decide to pick hedge apples to check out the repellency yourself or to use the fruit as a fall decoration, it would be wise to wear gloves. The milky juice present in the stems and fruit of the Osage-orange can irritate the skin.

Is there any use for hedge apples, other than playing softball that is? Unfortunately, the seeds are a bit difficult to extract. This is why squirrels make such a huge mess in your yard while they are eating. To get the seeds, first wash your hedge apple. Next, cut your hedge apple into slices. Inside of the hedge apple, you will find stringy flesh that you cannot eat in the center. This flesh will be surrounded by hundreds of tiny seeds that look similar sesame seeds. The seeds will be trapped in a very sticky substance inside the husk. You need to remove the seeds from the fleshy part of the apple, then wash away all of the slime. Next, dry your seeds and remove them from their tiny husks. Your hedge apples can now be roasted, just like sesame seeds. You can roast them dry or toss them in some olive oil first. When this is done, you can use the hedge apple seeds in any recipe that calls for sesame seeds. They can be used to top rolls or breads, or spread over a salad if you want to give it a slight crunch. 
I think I would prefer softball. By the way, don't let one hit you in the head - it hurts!

Naturally yours,

~denapple