gnat	May, 2006 Issues of Woodland Walkers Guide These are stories of the walks our collie has enticed us into taking as published in "The Home News", Spring Green's local paper. .

May 30, 2006

Most of my plants have been very happy with the frequent rains that have occurred the past few weeks, but there is one creature that has also flourished and is proving to be a nuisance. The eye gnat is a small shiny black fly, about 1/6 inch in length that is strongly attracted to moisture around the eyes and nose. Yesterday while working in the garden, I even resorted to searching out the net hat I sometimes use over my head in order to keep them away from my face. They are extremely persistent, and although they are not particularly fast flyers, gnats are hard to kill and swatting at them seldom does much good.

I just read an internet article by a Jim Conrad who writes from the foothills of California's Sierra Nevada asserting that all you have to do (to rid yourself of the pests) is to sit down, stop moving, and they'll go away. He suggests that they are less attracted by carbon dioxide and heat than by slow movement and moisture, and thinks these flies are programmed to locate a slowly moving mammal, land on it, and climb upwards until they reach a moist eye, nose, mouth or ear. I don't know about those California eye gnats, but the Wisconsin species evidently haven't read that particular treatise. Nothing I could do discouraged them until I finally donned the netting.

Gnats are really flies but because of their small size, people don't generally think of them as such. They go by many names, including punkies, buffalo flies, eye gnats, black gnats, black flies, no-seeums or just plain old "nats". Many females bite, as some species need a blood meal in order to produce eggs, and although the non-biting and biting gnats are related, there are distinct differences in the two. The biting types have mouthparts that are made for piercing and sucking and often attack in swarms causing considerable discomfort to any victim. After mating, the female will look for a moist damp area in which to lay its eggs, each type having its own favorite spot such as a marsh, stream, animal dropping or rain ditch. Once the eggs hatch, larva will feed for 2-3 weeks and then undergo metamorphosis into a resting pupal stage. After hatching, the males immediately take to wing to find a female.

Midge is the common name for a large number of the small, non-biting gnats. They have feather-like antennae and are very small--none larger than 1/8-inch long. The adult midge may be any color from dark brown to green. Many species resemble small mosquitoes, and like them, their larval stages are aquatic. Adult females lay eggs in masses over open water or attached to aquatic vegetation. They hatch in several days and the young larvae drop to the bottom where they build tube like structures of debris held together by strands of silk, and feed on bottom debris. One interesting fact is that the blood of some midge larvae (called bloodworms) is red, due to the hemoglobin it contains which allows them to survive under stagnant, low oxygen conditions. The larvae grow about four weeks and then pupate for several days. Just before emergence, the pupa rises to the water surface, like a mosquito. Larval midges are very beneficial because they serve as food for many kinds of fish.

Swarms of adult gnats often appear about dusk and may occur for several days at a particular spot, especially after a warm wet period. Swarming is a mating strategy used by many kinds of insects and usually occurs over some kind of landmark, such as a patch of ground that is lighter or darker in color than its surroundings. Inside the swarm, the males tend to fly up and down while the females fly horizontally until paths cross and mating occurs. Swarming is usually triggered by several environmental clues such as temperature, wind speed, relative humidity and day length, and each particular species responds to a special combination of these clues thereby increasing the chance to encounter other members of the same species. Supposedly, this behavior helps deter predators, and since most insects that swarm are very short-lived, this seems like an efficient way to find a mate quickly.

It is fascinating to discover the numbers of different small fly and gnat species that exist. They can be separated into a surprising number of insect families based on the patterns of veins in their wings and the location and orientation of bristles on the fly's head and body, as well as geographical and ecological conditions under which they can be found. My eye gnats could have been any one of a number of tiny insects called frit flies, most of which live in moist grassy areas. These tiny flies do not feed and only live long enough to mate, lay eggs, and die. The life cycle usually takes about 4 to 5 weeks, and there may be several generations during the summer unless it becomes very dry.

Should you be interested in observing a swarm, chances are you won't have to look far, as one will quite probably find you if you are out-of-doors for any length of time. Otherwise, visit places that are near water, or with clumps of moist vegetation, and bring a good reference book. You are likely to see a variety of the tiny colorful flies, and with an eye loupe or small magnifier, you may be able to identify some of the hundreds of species that live around us.

May 23, 2006

Most of our birds eat a variety of foods, including great quantities of insects and other creatures such as worms and spiders, while a few even prey upon small mammals and other birds. But there is one large group that consumes only plant material, mainly seeds. These are the finches, and include such common birds as the cardinals, rose-breasted grosbeaks, buntings, goldfinches, house finches, and towhees, as well as the much-maligned English sparrow. One characteristic these birds have in common is a stout beak, capable of cracking open tough shells to get at the meat inside.

A bird's beak is used for many things, from a weapon, to grooming, to the feeding its young. Some are relatively small and triangular, such as those of the towhee, junco, and goldfinch, while others like the grosbeak and the cardinal have thick, rounded bills. It is covered with a lightweight sheath made of keratin, which is the same substance found in our fingernails, and, ike a fingernail, the beak is constantly growing. The part closest to the bird has a blood supply and a significant number of nerve endings, while the part toward the tip, like the end of a fingernail, has no feeling. There is great variation in the size, shape, and strength of beaks, and the type is usually related to the type of food the bird normally eats.

Raptors have sharp, curved beaks for tearing meat; nectar-eating birds, such as hummingbirds, have long, pointed beaks for reaching deep into a flower; woodpeckers have extremely strong, chisel-like beaks; water birds, such as cranes, often have long beaks for probing; ducks have flat beaks with special plates called lamellae which help filter food in the water and mud; insect-eaters, such as warblers, have short sharp beaks; and more substantial straight bills are perfect for seed-eaters such as the finches. Even the seedeaters usually feed their young, for a few days at least, on more easily digested insects. An exception is the goldfinch that delays nesting until the softer, pulpier new seeds are available for feeding their young. These are partially digested by the parent and then regurgitated into the baby's mouth.

Another trait that many finches share is bright coloring. Some are inconspicuously covered in dull grays and browns, it is true, but among others the male is often brilliantly feathered. The intense spring colors and vivid patterns give most bird species the unique appearance and identity that they need for finding mates and telling friend from foe. Most color comes from one or more pigments in the feathers, substances that absorb some wavelengths of light and reflect others. The absorbed color disappears, and the reflected color is what we see. Pigments in the feathers of a cardinal, for example, reflect red light, and absorb all the shorter non-red wavelengths.

The two most common pigments in bird feathers are melanins and carotenoids. Melanins are synthesized by the bird and laid down in granules, producing shades of brown, black, gray, and some yellows. In dark black birds, melanin is found in both the core and outside of the feather. When melanin occurs only in the outer parts, the feather is shades of brown or gray, depending upon its concentration. In the white-breasted nuthatch, for instance, there is lots of melanin in the black cap, less in the gray back and wings, and none in the white cheeks and throat.

Carotenoids are obtained entirely from the plants in a bird's diet and produce red, yellow, or orange feathers. They are generally fat-soluble substances like the vitamin A in carrots from which the carotenoids take their name. These are stored in the liver and then transported to the bloodstream for eventual deposit in growing feather follicles where they crystallize. Caged cardinals fed carotenoid-free seeds gradually lose their brilliant color with successive molts.

Yellow goldfinches, likewise, get their bright color exclusively from the seeds they eat. The inner core of a yellow feather has no pigment, so only the bright yellow of the carotenoid in the outer parts is visible. Male house finches display extreme color variations, ranging from pale yellow to bright red, depending upon the amount of carotenoid pigments in the bird's diet, particularly during the molting period. Studies show that females prefer the brightest and reddest males, and it is interesting to conjecture that the intensity of color might be an indication of the male's fitness. The painted bunting is an extreme example of color in a bird, as its feathers are a striking combination of red, blue, green, and yellow. Incidentally, most finches are also very musical, with songs that vary from soft twittering to an impressive warbling, and many authorities consider them the highest and latest development on the avian evolutionary ladder.

May 16, 2006

This has proved to be an unusually good year for finding morels, at least on our farm. At first the various members of the family vied for choice picking spots, but with bags of the mushrooms in the freezer, I am quite willing to let others scrounge among the blackberries and prickly ash for any remaining specimens. Getting something for nothing is always fun, however, and we always look forward to the search. The news that the going price at a Madison farmer's market is more than $30 a pound is also a stimulus.

To better understand morels, we need to understand a few facts about all fungi. It was long thought that they were members of the plant kingdom, but the invention of the microscope allowed scientists to see that they were quite different. First, the body of a fungus is not a organism composed of stem, roots, and leaves, but is a mass of fine, branching threads or tubes, called mycelium. Some species, like the recent reports of a honey mushroom in Michigan, have mycelia that stretch for miles underground. Fungi also lack chlorophyll, the substance used in photosynthesis to produce nutrients with the help of sunlight. Instead they feed themselves by releasing powerful enzymes that break down organic matter into simpler water-soluble compounds that are then absorbed into their cells. Another major difference is that the cell walls of a fungus are composed of chitin, the material that also forms the exoskeletons of insects and crustaceans, rather than cellulose as in plants.

The morel mushroom (more properly named Morchella) is a sponge-like lump, 1 to 6 inches tall. The stem is attached at the base of the cap and both the stem and cap are hollow. Morels are highly variable in size, shape and color, but cylindrical to cone shapes are perhaps the most common. Despite its looks, a morel is nothing like a sponge. It is rubbery and brittle-characteristics stemming from what scientists believe is its ongoing evolution from a simple yeast fungus that probably existed in trees, to a multicelled organism living in the soil. This opportunity to observe evolution in progress is unprecedented. The most significant evidence of the evolving morel can be seen in the laboratory. If spores are germinated on an agar medium, the result is a rudimentary mushroom appearing as a disc of felt-like mycelium, a form that was present earlier in its evolution. Scientists tell us that the ability to revert to an early evolutionary form indicates very recent transition and propose with a high degree of certainty that Morchella evolved from yeast, as they share many common characteristics.

Morchella are unique among most fungi in that they exhibit an additional growth stage. When conditions are right, tiny knots of fibers form in the mycelia that gradually develop into walnut-shaped objects called sclerotia. These can grow up to 2 inches in diameter and are composed of large cells with very thick walls that allow the fungus to survive the winter and other adverse natural conditions. In the spring, each sclerotium does one of two things: it grows on to form a new mycelium or it forms a fruiting body.

The morel mushroom is actually only the reproductive part of the fungus and is sometimes described as an "apple", as picking it has no more effect on its mycelium than plucking a fruit from a tree. For this reason, you need not fear that gathering too many will harm the organism in any way. Its wrinkled and pitted cap contains millions of tiny spore containers that physically eject the spores, shooting them out. Once a spore is launched into the air, it often travels long distances before eventually settling on the ground. Researchers have found that the spores germinate readily but unless conditions are just right, they seldom grow into mycelium. What, exactly, these "right" conditions might be is not completely clear.

There are reports of people who have had some success in introducing morels into their own backyards by simply throwing out the wash water from collected morels onto their compost piles or their lawn. Nevertheless, all attempts to control fruiting commercially were hit-and-miss until 1986 when Ronald Ower of San Francisco, in conjunction with a team at Michigan State University, received a patent which described a process for formation of sclerotia that frequently produced fruiting bodies. According to Ower's patent, there are two essential steps. First, "the environment of the fungus is altered from a nutrient-rich environment to a nutrient-poor environment"; second, the sclerotia must be exposed to "high quantities of water in the substratum in which the fungus is growing." Presumably, in the wild, the death of a host tree followed by ample spring rains meets these requirements.

However, even in the laboratory, I understand that results are often spotty, and very small variations seem to disrupt the process and cause a crop failure. These efforts at producing morels in quantity have little interest for me anyway, as I feel most of the enjoyment is obtained from exploring the spring woodlands and returning triumphant after a successful hunt.

May 9, 2006

The noisiest bird in the farmyard these days is a brown thrasher. We have seen this bird around the pond every year, but now a pair must have set up housekeeping in the bushes right next to it, for the male is singing constantly at the top of his voice. I understand the bird can be an aggressive defender of its nest and has been known to attack people and dogs even drawing blood, so we will be careful. It belongs to the same family as the mockingbird and catbird, but, unlike those species, is usually retiring and secretive although this particular bird doesn't match the norm.

A relatively large songbird, the brown thrasher is about 10 inches long, and has a bright rufous back, white bars on its wings, a brown-streaked white breast, and a prominent yellow eye. Its song is quite distinctive as it consists of an extended series of short phrases, each repeated at least once. It often inserts bits of the calls of other birds, as it is an accomplished mimic. It typically nests in a low shrub or on the ground in dense vegetation in a hedgerow, old field, or wood edge, where it sometimes is host to a cowbird egg.

We were pleased to hear another noisy bird last night-a whippoorwill! Thirty years ago when we bought the farm, the calls of these birds could be heard from dusk to dawn every year from May to September, and we never tired of them. The birds vied with each other, one singer setting off several others and we would sometimes count an individual's phrases reaching 100 or more. Through the years, however, their numbers have declined so that it has been at least five or six years since we have been sure there was a pair nesting nearby. I was pleased to read that there are many more of the birds farther south, and that although there is concern, they are not considered threatened.

The whippoorwill is a master at camouflage, spending the daylight hours among the dried leaves on the woodland floor and looking like just another pile of debris. I once came upon one along a trail and would have missed it were it not for the bright black eye looking at me. It had long wings and tail and mottled brown plumage with lighter beneath. I read that their feet are too weak for perching and they typically sit on the ground or lengthwise along a branch. Nighthawks, a close cousin, look much the same but have white bands across their wings and are often seen flying above illuminated parking lots, circling and swooping after insects also attracted by the lights. Whippoorwills prefer the edges of woods and thickets and spend the nighttime hours patrolling their territories and eating endless numbers of flying insects as they go. They also proclaim their proprietorship by endlessly calling their name to the world and to any other birds of their species that might blunder into their domains.

I watched the courtship of a pair of whippoorwills one evening right on the road in front of the house. The male pleaded his case with stiffened wings held out, mincing steps, and soft chirps of invitation. The female must have been impressed for after a bit they flew off together. She probably did not construct a nest but typically deposits her two speckled eggs right on bare ground. One would think the bird would at least pile a few leaves together, but she prefers the hard surface of a rocky area, a plowed field, or a gravel roof. The eggs will hatch in three weeks and in another three weeks, the chicks are able to fly.

It is a widely held belief that whippoorwills hibernate during the winter and I even found this "fact" stated in one of my encyclopedias, but the truth is they migrate to the Gulf coast and south into Central America like many other birds. They are members of the Nightjar family, a name that comes from the disturbance they cause, but their scientific name means "goatsucker", from the old superstition that the birds drank milk from goats. Folklore also has it that if you open and look into your purse when you hear the first whippoorwill of the year you will receive something good, usually money (this never seemed worked for me). Another belief was that making a wish when hearing the bird's first song of the spring will make it will come true, and that when you hear it you know you will be in the same place doing the same thing next year at the same time.

Many other migrants have returned, including, happily, the hummingbirds. I hear wood thrushes and grosbeaks in the woods, as well as others whose songs I seem to forget during the long winters. That always sends me to listen to my birdcall tapes, as in the woods I hear many more birds than I see and I'm eager to identify each arrival. Robins, bluebirds, and no doubt other songbirds already have eggs or chicks in their nests. And, most of the 64 whooping cranes in the new Eastern flock have returned to Wisconsin. It is reported that five pairs have attempted to nest, but the last I heard, only one pair was still incubating eggs, however, as the other nests were abandoned or destroyed by predators, presumably because of the inexperience of the parents. Still, each step in the process brings the reality of a permanent flock that much closer.

May 2, 2006

It is difficult to think of friendly chickadees, tiny inquisitive hummingbirds, stately cranes, and forbidding owls as members of the same class, but of course they are, as all are birds, our most specialized group of vertebrates. All walk on two legs, and have feathers, hollow bones, four-chambered hearts, and specially designed lungs. Most have streamlined bodies and extremely strong flight muscles and tendons.

Birds are thought to have evolved over 150 million years ago from a reptilian ancestor as they share many characteristics in their skeletal makeup, as well as reproducing with eggs. There are some 10,000 species worldwide, with about 400 in Wisconsin. They range in size from the Cuban bee hummingbird, which is little more than two inches from bill to tail and weighs about one ounce, to the ostrich, which may stand nine feet tall and weigh over 300 pounds. Their most remarkable common characteristic is growing feathers, specialized appendages whose contours and strength make flight possible while providing excellent insulation and physical protection. Their colors provide both concealment and a means to finding appropriate mates and identifying rivals.

Among these various birds, perhaps the least observed group is the owls, as most are seldom seen and until recently little effort has been made to determine how many are present around us. Due to their nocturnal behavior and time of breeding, owls often go undetected using traditional methods of monitoring bird populations such as the Breeding Bird Atlases and Christmas Bird Counts. Last year, a large scale, long-term survey to monitor owl populations was organized in Wisconsin and Minnesota using volunteers, hoping to provide valuable information about the region's owl populations. Participants will travel designated routes three times in March of each year, pausing briefly at specified points to listen, and recording any owl calls they hear. Species of special interest are the great horned owl, barred owl, N. saw-whet owl, long-eared owl, short-eared owl, great gray owl, boreal owl, E. screech owl, and N. hawk owl.

Owls have a very wide range of vocalizations, ranging from hoots to whistles, screeches, screams, purrs, snorts, and hisses. They also make clicking noises with their tongues, and clap their wings. In addition to these sounds, many species use much body language, bobbing and weaving their heads or ruffling their feathers. When protecting young or defending themselves, owls may assume threatening postures, with feathers ruffled, heads lowered, and wings spread out and pointing down. Some species become quite aggressive when nesting, and have been known to attack humans.

Owls are instantly recognizable because of their large, round heads and huge, forward-facing eyes, which give them binocular vision. Their eyes are ten times as light-sensitive as those of a human but are so large that they cannot be moved in their skulls as there is little room for muscles. Still, they have extremely flexible necks, allowing them to rotate their heads as much as 270 degrees to follow a moving object. Males and females are generally similar in appearance, although the female is the larger of the pair.

Owls have the best hearing of all birds. Their ears are located on the sides of their heads and are hidden by feathers. The so-called "ear-tufts" on the top of the head in some species aid in camouflage but have nothing to do with hearing. An owl's range of audible sounds is not unlike that of a human's, but its hearing is much more acute at certain frequencies allowing it to hear even the slightest movement of prey in leaves or undergrowth. Some species have very pronounced facial discs which guide sounds into the ear openings, and sometimes one ear higher than the other. When a noise is detected, the owl is able to tell its direction because of the minute time difference in which the sound is perceived in the left and right ear. The owl then turns its head so the sound arrives at both ears simultaneously, telling it that the prey is directly in front of it.

An owl's wide wings, lightweight body and unusually soft, fluffy feathers allow it to fly silently. It seizes its prey, usually a rodent or other small mammal, and kills it with its powerful talons. If the prey is small enough, it is swallowed whole; otherwise the food is torn apart by the owl's strong, hooked beak. Several hours after eating, the indigestible parts are compressed into a pellet in the gizzard where it will remain for up to 10 hours before being regurgitated. Because the stored pellet partially blocks the owl's digestive system, new prey cannot be swallowed until the pellet is ejected.

Owls do not construct their own nests but appropriate those constructed by other birds or in tree cavities. Incubation of the eggs usually begins when the first one is laid, resulting in chicks of varying sizes. The largest get the most food and often there are not sufficient rations for the smaller ones who then starve. Most owls reach sexual maturity and find a mate about a year after they hatch, although larger species may not begin breeding until their second or third year. We hear barred and great horned owls throughout the winter, and often screech owls and occasionally saw-whets on spring and summer evenings. Listen for these fascinating birds, and don't forget to stop by for the openhouse Saturday or Sunday this week if you missed last week's. We'd love to see you.