Bird Vision
I am often asked how birds find food. Or another great question is, if I put up a new birdfeeder, how will the birds know it’s there or find it. The answer is simple—eyesight. Eyesight is very important to birds. In fact, that might be understating the roll of vision in birds. It is darn right critical for survival. It is thought that the birds have the best vision among all animals. And not just some birds, nearly all birds have excellent eyesight. This excellent vision comes from large eyes. A bird’s eyes are so large that in some species the weight of their eyes is equal or more than the weight of its brain. In many species the eye accounts for about 15 percent of the mass of the birds entire head. Human eyes by comparison account for less than 2 percent of the head and weight a fraction of the brain. The largest eyes of any land animal are those of the Ostrich which are nearly two inches in diameter. All of this space allows for more photoreceptors called “rods and cones” in the back of the eye. The human eye contains about 10,000 cones per square millimeter while many of our songbirds have up to 12 times this amount or 120,000 cones per square millimeter (650 million per square inch) which gives them the sharpest vision in the animal kingdom. The Golden Eagle for example exceeds the visual acuity of humans by two or three times allowing them to see movement of small prey from more then a mile away. All of these extra receptors in a bird’s eye allow many species the ability to see in specific light frequencies, including ultraviolet that humans cannot see. Humans have three types of cones, each sensitive to different wavelengths of light or colors—red, green or blue. This is called trichromatic color vision. Birds have an extra cone for quadchromatic color vision (some have five cone types) that allows them to see the ultraviolet light frequencies. In addition bird eyes contain specialized oil droplets that act as filters, altering color sensitivity in the same manor as sunglasses. Human eyes don’t have these oil droplets. Seeing in ultraviolet light helps birds in all sorts of ways. Many birds have feathers that reflect ultraviolet light. It is thought this is used to communicate a bird’s species, gender or perhaps its social standing. Seeing in ultraviolet light allows some birds of prey to locate their food by looking for visual clues left behind such as mouse urine, which reflects a bright yellow when seen in UV light. The bird just follows the trail of urine to the mouse. Most birds can see well in low light conditions. We humans rely on photoreceptors called “rods” to help us see in low lighting. We have about 200,000 rods per square millimeter. Some birds such as owls have up to 1 million rods per square millimeter allowing them much greater vision in the dark. Rods don’t help in seeing colors but allow for amazing black and white vision after dark. Nearly all of the ten thousand species of birds in the world have in addition to the familiar upper and lower eyelids, a third eyelid called a nictitating membrane. It moves from side to side across the eye at right angles to the regular eyelids. This third eyelid cleans the eye’s surface and keeps it moist. In many aquatic birds such as the Common Loon, the nictitating membrane has a special window-like area in the center that presumably lets the membrane act like swim goggles to improve their underwater vision. The act of focusing on an object is termed accommodation. It is accomplished by muscles changing the curvature of the lens in your eyes. At the same time, the amount of light entering the eye is regulated by changing the size of the pupil. In birds both of these processes occur very quickly. Much faster than the human eye. This allows birds to quickly focus on objects near and far and to change from light to dark situations in the blink of an eye. A Peregrine Falcon diving (stooping) for example can keep focus on its prey even while traveling up to 200 mph and a songbird can see well enough ahead to avoid hitting tree branches while flying through a forest with pockets of light and dark. As you can see (pun intended) most bird species see in the full range of color like humans and much more. Birds see the world very differently than humans but not because of their excellent eyesight but because of the placement of their eyes in the head, and that is what I will talk about next time. Until then…
Bird Vision Continued
I was recently asked how birds find a new backyard birdfeeder. This simple question has a complex answer. So, this week we are continuing our look (pun intended) at bird vision. Because the answer to the question is vision. Indeed birds and other mammals see the world very differently than we humans. Some of this is due to the structures within a birds eye which allow them to see better, further, focus faster and see in a wider range of light conditions. Believe it or not, the position or location of a bird’s eye in its head is also a large factor in how well a bird sees. We humans have eyes positioned close together in the front of our heads. This gives us nearly equal field of view with both eyes allowing stereoscopic vision known as binocular vision. Many birds have eyes positioned on the sides of their heads leaving them with unequal field of view from both eyes. This is called monocular vision. At first you may think that having monocular vision is inferior to binocular vision and for the human species that may be true but if you are a small bird looking for tiny insects deep within cracks or crevices or watching out for aerial predators such as hawks and falcons it would be far superior to have eyes located on the sides of your head. Monocualar vision has many advantages because it results in a wide field of view, sometimes as much as 340 degrees which can allow a bird to see both in front and behind at the same time. This would be like having the proverbial “eyes in the back of your head”. Very handy when fast flying predators are in the neighborhood and they are looking for YOU! Some birds do have binocular vision. Owls for instance have large eyes close together in the front of their head. Both eyes see the same thing at the same time giving them binocular vision. Consequently they only have a field of view of up to 70 degrees (all in front of them). These birds don’t need to see behind them because generally they don’t have to worry about being someone’s lunch because they are the predator not the prey. In addition, birds such as snipe and woodcock not only have their eyes on the sides of their head, their eyes are placed near the top of their head giving them excellent vision above them without having to moving their head to see above. Remaining still is an import aspect since these birds relay on camouflage feathers to remain hidden from a predators view. If they had to move their head around to watch for predators the movement of their head would give away their location to a sharp-eyed hawk or falcon. Their eye placement also helps them watch for predators while probing in the mud with their long bills during feeding. Binocular vision is important not only for owls but also for many of the fast flying predators such as hawks and eagles. Binocular vision gives the bird good depth perception, thus determining distances and spatial relationship easily. This is very important when it comes to capturing prey while traveling at high rates of speed. For example a Cooper’s Hawk often ambushes small birds at a feeder by quickly darting out of the shadows of the woods. The hawk is traveling so fast that in an instance it needs to determine what bird it can catch without running into the birdfeeder, your house or a tree branch. Although monocular vision doesn’t allow for instant depth perception it doesn’t mean birds with monocular vision can’t judge distances very well. The head-bobbing and weaving movements of the Rock Pigeon or even a barnyard chicken allow the bird to get a series of different views or snapshots to help determine spatial relationships of objects on the ground. When the head moves rapidly forward, objects closer to the bird appear to move across the visual field faster than those at a distance giving them clues to the objects three-dimensional position. If you want to see monocular vision working you only need to watch an American Robin hunting for worms in your lawn. The bird rapidly runs forward, stops and cocks it head to one side or the other. Many people mistakenly believe the bird is listening for worms when in fact it is looking with one eye. The robin often cocks its head back and forth to gain a prospective on its food before quickly grabbing the worm. Until Next time…
Evening Grosbeaks
Nothing in nature ever stays the same. This is a fact that seems to be easily overlooked by the average wildlife watcher or hunter. We tend to look back at the “good old days” and remember how great things were and lament of how things are now. This innate human behavior manifests itself in unrealistic expectations in regards to wildlife populations. We want peak numbers of wildlife all the time. All the good and none of the bad. Nature is dynamic and is in a constant state of flux. It’s a good thing and more it importantly it is how nature works. Think of it as the ebb and flow of life. As one part of nature contracts or reduces there is always something else to expand and increase. Take the recent invasion of owls into some of our northern states. A change in the population of prey species (presumably the Red-backed Vole) has lead to a major movement of Great Gray Owls out of their normal range into areas where they have never been seen before. Due to the shortage of food and the rigors of winter some of the owls will die. A reduced number of owls relieve the hunting pressure on the voles allowing the remaining voles to quickly repopulate. Eventually the owls will return home to start the cycle all over again. That is how nature works. On the other hand there are some species that have increased or decreased without such a clear reason. The Red-bellied Woodpecker is a good example of a species that has really expanded. Twenty years ago this bird was not very common. Now it inhabits most backyards throughout the eastern half of America. Why that is, is hard to say. On the other side of the coin, the Red-headed Woodpecker (a very similar species) has declined dramatically in all regions. In fact in many parts of the country the red-head has completely disappeared—a term called extirpated. Areas where I use to see and photograph red-heads haven’t had a woodpecker in many years. Again, why this is, isn’t clear. You might be tempted to say it’s a loss of habitat, but how does that explain the ever increasing Red-bellied Woodpecker that lives in similar habitat. The reasons for a bird’s sudden decrease or increase are not a simple one. I don’t believe you can point to just one reason for the decline of a given species. We people are always looking for something or someone to blame. Rarely in nature does anything happen due to just ONE reason. Usually it’s a combination of many factors and when a certain unseen threshold is reached the trigger is tripped. One species of bird that has a well documented decline over the past 20 years is the Evening Grosbeak (Coccothraustes vespertinus). This bird use to be a common winter-time visitor to feeders throughout much of America. Now feeders that use to host hundreds of these birds now may see only a handful every couple of years or so. The decline of this finch has been well documented in the National Audubon Society’s 100-year-old Christmas Bird Count (CBC) results. See http://www.birdsource.org/Features/Evegro/index.html for more information. Here is a synopsis of the report on the decline of the Evening Grosbeak: The Evening Grosbeak nests in remote regions but spend the winter in areas that are more accessible. Since much of the breeding range of the Evening Grosbeak is inaccessible, winter surveys like the CBC provide the best indicator of the health of the species. Evening Grosbeak numbers were stable or increased until 1980 when their numbers began to decline significantly. The decline of Evening Grosbeak numbers between 1980 and 1998 was significant which indicates that there is less than one chance in one thousand that the decline in Evening Grosbeak numbers was due to random fluctuations in abundance. Also the rate of decline has increased between 1990 and 1998. Some states or province exhibited the most significant declines in Evening Grosbeak between 1980 and 1998. What is clear is that the Northeast and Great Lakes region show the steepest declines in Evening Grosbeak numbers. The cause of the decline in Evening Grosbeak numbers is unknown, but there are several possibilities. The most obvious is that Evening Grosbeaks may simply not be moving as far south during the winter due to the hemispheric trend in warmer winter temperatures. The declines might also be related to food availability. Hardwood tree seeds, a favorite natural source of food of Evening Grosbeaks, may be less common due to broad-scale changes in forestry practices in Canada. Finally, one thing is for sure, the decline of the Evening Grosbeak is something that many people have noticed simply by watching the birds in their backyards. Until next time…
Wood Ducks and Bluebirds
It’s that time of year again. Time to clean out your Wood Duck and Bluebird boxes. In just a few short weeks the first Wood Ducks and Bluebirds will be returning to the northland and right now is the time to get ready for their arrival. Cleaning out your nest boxes sounds easy enough but there are a few things to consider before jumping out of your Lazy Boy and running out to clean your boxes. You will need the following items before heading out. Gloves, ladder, plastic bag, dust (particulate) mask, and a 3 inch putty knife. I start by using my ladder to carefully climb up to the Wood Duck nest box. Most nest boxes are located over or near water, so getting to them now before the ice melts make it a lot easier. Always use a dust or particulate mask to avoid breathing in the dust when removing the contents of the nest box. Mice often use these boxes during winter and these four footed creatures can carry several airborne nasty diseases. Position yourself upwind so when you are pulling out the nest material any dust and debris blows away from you. Gloves serve well to keep your hands warm, clean and protected. I often find one or two infertile eggs remaining from last season. Be extra careful when removing these. If you’ve ever had one of these eggs break, you know what I mean. The smell of the rotten contents can be overwhelming. Handle these eggs with caution. This is where the plastic bag comes in handy. Remove and dispose of the eggs away from the nest box. You don’t want to attract raccoons and other predators with the rotten eggs. In addition to removing the infertile eggs, I always remove the soft downy feathers that line the nest box. The female woody will replace the feathers to cover her new clutch of eggs. If the woodchips at the bottom of the box are soiled, I often remove and discard the top layer. I have never found it necessary to remove all of the wood chips. Consider replacing all of the chips if they are wet or moldy. Before adding any addition wood chips I use my putty knife to scrape off any spider egg casings. The egg casings are the white fuzzy balls stuck to the inside corners of the box. Also make sure the wire that the young ducks use to climb out of the box is secured before adding the extra chips and closing up the box. Also, now is the time to make any necessary repairs to the box. Bluebird boxes tend to be a bit easier to clean out. First of all, you don’t need a ladder to reach the box and they rarely have any leftover smelly eggs to remove. However, if you left the Bluebird box closed all winter you might have to deal with mice. You’ll know if you have mice because you’ll find a large round ball of plant material for a nest and it will have a strong odor of urine. Don’t be surprised if a mouse jumps out at you either. All the same rules apply when cleaning out the Bluebird box as the Wood Duck. Wear a dust mask and gloves and stand up wind when removing the contents. I clean out all nesting material from my Bluebird boxes and the spider eggs. I also remove the nesting material from the area near the nest box. The discarded nest material can attract predators to your Bluebirds boxes. I have lost too many baby Bluebirds to domestic cats and raccoons to loose any more. If your bluebird box is urine soaked from mice, I recommend leaving the door open for a couple weeks to dry out before closing. Also, consider installing a predator guard at this time. You don’t want to install these wire guards after the birds have move in. Predator guards are always a good idea. Why not greet your favorite birds this spring with some brand new boxes or consider adding some additional boxes. Until next time…
House Finch
As a wildlife photographer I travel extensively throughout the United States. I consider it a major perk of the job. I am fortunate enough to see some of the most beautiful places at the best times of the year. For example, I am writing from Tucson Arizona right now. It’s a wonderful desert city surrounded by snow capped mountains reaching 9,000 feet elevation. Each region has it own unique mammals, wildflowers and birds. Some of the unique animals of this region are the Harris’ Antelope Squirrel and the Rock Squirrel. They would be similar to the Eastern Chipmunk and the Eastern Gray Squirrel. However there are some animals that are more familiar such as the Bobcat. Bobcats are very common in Southeastern Arizona. In fact, the other day at ten o’clock in the morning our small dog went to the back door and started to growl. Growling is something our little dog doesn’t do much so I went to investigate. I slide the screen door open and our dog ran out into the backyard. Right then a Bobcat sprang from a small bush and jumped up onto the wall surrounding the yard. It turned to look at my dog and me before fleeing into the desert beyond our yard. How exciting. I only wish I had my camera. One of the most common birds in the desert southwest is the House Finch (Carpodacus mexicanus). You may be familiar with this backyard bird in the northland, however it is not a native bird of the northern or eastern states. No, it is a relatively recent addition to our backyards. House Finches are sparrow-sized birds. The males are brown and white with a orange to red wash on its head, chest and rump. It has brown streaks on its white chest and flanks. The females are brown with a heavily streaked chest and sides. The historic range of the House Finch was the western half of the country. In the early 1900’s the birds were trapped and sold as a caged birds. The males beautiful red color and sweet warbling song made them highly desirable in the pet trade. Eventually laws were passed that made trapping and selling native wild birds illegal. Many birds were released on the east coast and a small population of House Finches became established on Long Island, New York in the 1940’s. It is believed that this population of birds is the origin of all the birds in the eastern half of the country today. By the 1970’s the House Finch invasion was well underway with populations extending across the Ohio Valley. By the 1980,s the westward march of the House Finch had reached Illinois. By the early 1990’s they had reached Minnesota and the Dakotas and started to meet up with the original western population. Currently, House Finches now extend all across the US. Clearly this is an example of a bird that has benefited greatly from human meddling. House finches tend to be early nesters, with nesting activity beginning in late March and early April in most of the country. Females nest more than once a year, some re-nest even before the first broods are fledged. The species uses a wide variety of nesting sites, but seems to prefer hanging flower planters for some crazy reason. However before the advent of hanging planters they used coniferous trees. If you do get a pair of House Finches nesting in your hanging flower basket, don’t worry. Just be sure not to soak the nest when you water your flowers and they will do just fine. Females do most of the nest building and all of the incubating, although the male does bring her food. If he does not bring enough food, the female may abandon the nest. The young develop rapidly and leave the nest after about two weeks. So there you have it. A little bit of the western states right in your own back yard. Until Next time…
Adventures in Southeastern US
My photographic adventures continue in southeastern Arizona. As you might remember, last time I wrote about an encounter with a bobcat in our backyard. Believe it or not, since then I have encountered several more bobcats which is more than I usually encounter. I have also seen several coyote, a dozen or so jack rabbits (which by the way are nearly as large at the coyote), a couple javelina (an animal that looks like a pig but is not related to pigs), a heard of about 35 mule deer and at least a billion desert cottontails. One morning I saw about 150 cottontails in just one group. Each encounter has been fun and exciting especially since these are animals that I usually don’t encounter in the Midwest. Spring is in full swing, here in the Sonoran Desert. The Sonoran Desert is an arid region covering 120,000 square miles in southern Arizona and southeastern California, as well as most of Baja California and the western half of the state of Sonora, Mexico. It is a wonderful place filled with all sorts of cactus and succulent plants. I think most people would think the desert is a barren region that is devoid of any wildlife. Nothing could be further from the truth. Each day I am impressed at the variety of birds and animals that call the Sonoran Desert home. One evening I was photographing a Western Screech Owl. Now normally that would be a very exciting event but as I stood there in the twilight a Great Horned Owl flew in and landed on a Saguaro Cactus just over my head. Three Elf Owls started to call about 50 feet away from where I was standing and a Barn Owl flew over to see what all the commotion was. That is four species of owl in just a few minutes and a hundred feet. I started feeding the birds in the backyard of our rental house and within a day or so I have had about 15 species of birds show up. In fact I am getting so many birds that they empty my 3 tube feeders and one tray feeder by 9 AM each morning. If I filled the feeders again they would have them empty again by noon. I am lucky if my feeders at home are empted every 3 weeks or so. The sheer volume of birds in the desert is nothing short of astounding. Even though this region is one of the hottest in North America, the nights still can get very cold. Average night-time temperatures during winter and early spring are in the 40’s. Many mornings when I go out the temps are in the high 30’s, but it doesn’t last long. By the time the sun comes up the temps shoot up to the mid 70’s and it seems like every day is a beautiful day. Many of the birds you see in the desert are very different from what you would see in the northland. One bird in particular looks similar to one of our common backyard birds. It is called the Pyrrhuloxia (Cardinalis sinuatus) pronounced Per-lux-e-a, and looks very similar to the Northern Cardinal. In fact they are so closely related that they are exactly the same size, shape and proportion. Both have a tall, pointed crest on top of their head and a large heavy bill for cracking open seeds. The male is over all gray with rosy-red highlights around its head, chest, tail and wings. It bill is yellow to tan, unlike the cardinal which has a bright red bill. The female Pyrrhuloxia is very similar to the female Northern Cardinal in all respects except for the color and size of the bill. The Pryyhuloxia’s bill is yellow and is shorter and not pointed. Even the song and call of these two birds are similar. I always have to stop and listen carefully to determine the differences. I find that I enjoy seeing the Pyrrhuloxia as much as I do the Northern Cardinal. Until next time…
Woodcock
Nearly 30 years ago, the legendary naturalist Kathy Heidel introduced me to a small plump bird named the timber doodle. Since that time I make a pilgrimage each spring to see one of my favorite rights of spring—the dance of the timber doodle. Better known at the American Woodcock (Scolopax minor) the timber doodle is a upland shorebird that is closely related to sandpipers but the woodcock lives far from the waters edge, instead preferring open or young woodlands and moist fields. Woodcock are an oddly shaped bird with a plump round body, short round wings and a stubby tail. Its long bill project from a tiny head that seems to be lacking a neck. The bill has a soft pliable tip that moves independently of the rest of the bill. This allows the woodcock to insert its long bill deep into the soft mud and still be able to open the tip and grasp a slippery worm before extracting them from the ground. Often confused with the Common Snipe (Gallinago gallinago) they are similar in size, shape and long bill. They are both tan to brown in color which allows them to blend into their leafy environment. One way to tell the difference between the two species is the pattern on their head. The Woodcock has stripping that extends from side to side while the Common Snipe has stripping that goes from front to back. Woodcocks are crepuscular, which means they are most active during the twilight hours just after sunset and to a lesser extent just before sunrise. Each spring near dusk, as it has done since before recorded history, the male woodcock performs one of the most elaborate courtship flights know in the bird world. As the female stands nearby on the edge of a small clearing, the male begins his mating dance with a loud call that sounds like he is saying “peent”. Suddenly and without warning the male woodcock launches himself into the evening sky. Peenting turns to a twittering noise as he ascends. The twittering noise is created mechanically by wind rushing through his outer primary fight feathers on each wing. Reaching an altitude of nearly 300 feet the timber doodle flies in circles high above the watching female. Round and round he goes uttering a canary-like song, until again without warning he drops from the sky like a rock. Near the ground he extends his wings and flutters to the ground. Landing nearly the same spot he launched from, the male woodcock begins the nasal peenting call again. He will continue this routine until after dark and sometimes all night if the moon is full. Even though the male and female woodcock look identical, only the male flings himself against the evening sky in his vertical-mating dance. Several males might display in a small woodland opening hoping to attract as many females and possible. A lucky male might mate with several females. After mating, a female will go off to scrape out a shallow depression in the ground and lines the nest with a few twigs and grass. She will lay 4 buff brown eggs and incubates them for 20-21 days. Most nests are located within 100-200 yards of the male’s display ground. After the young hatch, she alone raises the young. Each baby woodcock eats its own weight in earthworms every day. Their diet is supplemented with insects and seeds. To witness the splendid springtime goings-on of the woodcock, head out to your favorite clearing in the woods about 20 minutes after sunset and look and listen for the call and display flight of the timber doodle. Until next time…
Bluebirds
There are many signs of spring that I look forward to each year. I enjoy hearing the two note “spring-time” call of the Black-capped Chickadee. It’s hard to beat seeing a big old Tom turkey displaying for a hen. The emergence of the Eastern Chipmunk and Woodchuck is something I always look forward to. But it is hard to beat my favorite sign of spring—the return of the Eastern Bluebird.I am not the only one who has a soft spot in their heart for bluebirds. Throughout history the bluebird has played a large roll in stories, poems, art and even movies. In 1859, Henry David Thoreau wrote “His soft warble melts the ear, as the snow is melting in the valleys.” In 1909 Maurice Maeterlinck published his book, The Blue Bird, a fairy tale about the bluebird of happiness. The tenor, Jan Peerce made the song “Bluebird of Happiness” a nationwide hit in 1934. Shortly after that in 1939 the movie, The Wizard of Oz, staring Judy Garland sang “Somewhere over the rainbow, bluebirds fly……”. Frank Sinatra sang, “I wish you bluebirds in the spring…..” in his song I Wish You Love. The nineteenth-century American naturalist John Burroughs described a bluebird as having a “disembodied voice; a rumor in the air before it takes visible shape before you,”. He goes on to say about the bird blue plumage “one of the primary hues, and the divinest of them all.” Most certainly he was enamored with this bird as I am. The first settlers to America from England were greeted with a healthy population of Bluebirds. From the mid 1700 to mid 1800’s much of the eastern half of the country was extensively logged and farms replaced the forests. Despite a changing landscape Bluebird populations remained stable and in many cases thrived. In the days before pesticides farmers put up nest boxes for bluebirds to control insect pests since the main diet of these birds are insects. In 1825, Alexander Wilson’s American Ornithology noted “…few farmers neglect to provide for him, in some suitable place, a snug little summer house, ready fitted and rent free….And all that he asks is, in summer a shelter.” In 1842, the American naturalist Henry David Thoreau, wrote in his diary “Today… the bluebirds, old and young, have revisited their box, as if they would fain repeat the summer without intervention of winter, if nature would let them.” In 1884 the Peoples Cyclopedia of Universal Knowledge, noted that “Few American farmers fail to provide a box for the bluebird nest.” Staring in the early 1900’s several factors lead to the decline of the Bluebird. Introduction of the House Sparrow and European Starling which also uses cavities and nest boxes for nesting started to take a toll. Also at that time wooden fence posts that often had natural cavities for nesting were replaced with metal posts that offered no nesting. Field borders and fence rows which historically were used for Bluebird nesting were cleared to increase cropland acreage. During this time the chainsaw was invented which allowed farmers an easy and efficient way to clear dead trees and branches contributed greatly to the decline of nesting habitat. A dramatic increased in free roaming domestic cats also hit the Bluebirds hard. In the 1940’s and 50’s Bluebirds were delivered a final devastating blow. DDT an agricultural pesticide which was seen as a miracle chemical because of its amazing ability to kill huge amounts of insects was used in massive quantities by farmers across the United States. The chemicals effectiveness killed the Bluebirds main source of food and in addition poisoned the bluebirds reproductive tract. It didn’t take long. By the 1960’s and 70’s Bluebird populations were at an all time low and in some areas they had become extinct. In 1962, Rachel Carson’s book entitled Silent Spring was published. She said “Who has decided – who has the right to decide – for the countless regions of people who were not consulted that the supreme value is a world without insects, even though it be also a world ungraced by the curving wing of a bird in flight?” “Over increasingly large areas of the United States, spring now comes unheralded by the return of the birds, and the early mornings are strangely silent where once they were filled with the beauty of bird song.” It is believed that this book stimulated the modern environmental movement. In response, laws were passed to ban the use of DDT. Also, thousands of volunteers began working to bring back the Bluebird by putting up nest boxes. It took over 20 years but today the bluebird population is doing well but still recovering. To conclude, John Burroughs wrote, “With the earth tinge on his breast and the sky tinge on his back, it is surely enough attainable happiness for one small bird to deliver.” And it delivers that happiness to me each spring. I hope it can do the same for you. Until next time…
Cold Spring
This has been a bad spring for the birds. The extreme cold and several weeks of soaking rain is taking a major toll on many of our early nesting song birds such as the Eastern Bluebird and Black-capped Chickadee. Both of these birds lay eggs very early in spring and under normal weather conditions (if there is such a thing as normal weather) the young would have hatched and would be ready to leave the nest by now, but that is not what I am finding. I just got back from two days of photographing and while I was out I was checking on a dozen or so nests that I am scoped out this spring. Without actually counting the exact numbers, I would guess there has been about an 80 percent mortality rate. In other words, 8 out of 10 nests that I have been monitoring over the last couple weeks contained dead baby birds. In most cases, 4 out of 5 young were already dead. Now many things can contribute to the death of a young bird but I have my suspicions that the cold wet weather is the culprit. Cold wet weather affects the birds in several ways. First and the most obvious are the temperatures. Most baby song birds have no ability to regulate their body temperature for the first 3 to 5 days of life. This is a very vulnerable time of life. They are born naked and helpless. The only way they can keep warm is by snuggling with their nest mates and by the parents sitting on them in a process called brooding. Most song bird parents have a bare patch of skin on their bellies called a brood patch. The brood patch is covered by the long contour feathers of the body so you won’t see the brood patch by just casually looking at a bird. If you move the body feathers to the side you can see the patch. The brood patch becomes engorged with blood vessels just prior to incubation of the eggs to greater enable heat transfer from the parent to the eggs. After the eggs hatch the brood patch is used to keep the hatchlings warm, especially at night. Most young songbirds such as chickadees and bluebirds are fed only insects. This high protein diet allows the baby birds to grow amazingly fast. Now normally it’s not a problem for the parents to feed their young and keep them warm during a short cold snap but when the weather is cold and wet for nearly two weeks like it has been around the upper Midwest (about the length of time it takes for a baby chickadee to emerge from the egg and fledge) it’s a different story. Not only does the cold weather make it hard to keep the babies warm, but the insect population is nearly non-existent. As you know, most insects are not active during cold weather which means foraging parents must look longer and further away from the nest to find enough food to keep their babies alive. The more time it takes for the parents to find food the longer they are “off” their babies and the young birds start to slowly cool down. Once the body core temperature starts to cool down the digestive system starts to slow down. Once the digestive system slows down the vigor in which they feed is reduced so when the parents due come back to feed the young they are often too cold and weak to lift their heads and beg for food. It’s a tragic cycle. In addition the quality of food is poor when the weather is cold because the large juicy insects are no where to be found. The parents are forced to bring back smaller less substantial insects for their young. The wet weather also contributes to respiratory disorders in many bird species. The young developing lungs of a baby bird don’t handle the excess moisture in the air very well and the young die of respiratory complications such as pneumonia. So you may be asking yourself, what I can do to help my resident birds. Try offering them some meal worms. My bluebirds and chickadees love them and will eat as many as I put out for them. It is as simple as putting 20 or so meal worms in a slick sided plastic margarine tub so they can’t crawl out. Place the container with the meal worms near the nest site or near one of their favorite perches. Since both of these species are cavity nesters you can simply put the container with the meal worms directly on the bird’s house. You will be amazed how quickly they will find it and snatch up your offerings. Until next time…
Poison Ivy
If you like camping, hiking, biking or just about any other out-door activity, it’s time for you to learn a new word. Can you say Urushiol? Pronounced (u-roo-sha-ol) it is the name of the oil found in the poison ivy plant (Toxicodendron rydbergii). Poison ivy is a very common plant in the Northland. It is one of those plants that grows well just about anywhere. It enjoys direct sun but will grow in the shade. It also likes dry soil but will grow in moist soil. I find it mostly growing along paths or the edge of woodlands, fence rows, thickets, or if you’re really unlucky the edge of your backyard. There is a lot of confusion about poison ivy, poison oak and poison sumac, the toxic trio. Let’s start by clearing up a few misconceptions. We only have poison ivy and poison sumac in the northland, no poison oak. Poison sumac (Toxicodendron vernix), which is much more poisonous than poison ivy, grows deep within acid / tamarack bogs making this plant nearly impossible to come in contact with. So put any fears of poison sumac out of your mind, unless you are in the habit of wading through knee deep sphagnum moss. Poison ivy on the other hand is extremely common. There are some areas that are filled with the nasty devil. And the best way to avoid coming in contact with this scourge of the woods is to be able to correctly identify the plant and stay away. Poison ivy is a low growing plant or vine with a woody stalk that splits off into three branches. Each branch usually has three pointed oval shaped leaves that only somewhat resemble an “ivy” shaped leaf. Poison ivy is a master of disguise. Its leaves are usually shinny but can be dull. The edge of each leaf can be smooth or have large teeth. It grows on the ground but also vines high into trees. About the only consistent characteristic are its woody stem, yellow to green flowers that produce green to white berries after the plant is three years old, and a middle leaf stem, called a petiole, that is longer than the outer two. Lastly, it is one of the first plants to turn deep red each autumn. A good way to remember this plant is the old saying, “leaves of three, let it be.” Interestingly, it appears that only humans have troubles with poison ivy. Animals, birds and other wild critters have no troubles with this plant. Birds and bears eat the berries and lay amongst the leaves without any troubles. In fact many cases of poison ivy are transmitted from family pets like dogs and cats to their owners. The only way to get poison ivy is to come in contact with our friend urushiol. Urushiol oil is found in every part of the plant except the flowers. The oil, which causes the allergic reaction, has the consistency and color of 3-in-1 oil. Only when the plant is damaged in some fashion does the oil leak out. This is the point that the oil is transferred to you. When heated, the oil spatters like butter and will attach to smoke particles and can cause very serious rashes to anyone downwind. Nationally, only 10% of the human population is truly immune to its ill effects. So if you are one of those that say, they are immune to poison ivy, it may be that you have never come in contact with the plant. Urushiol can also lay in waiting for you on garden tools, clothing and even your pet for up to year. So let this be a warning to you about messing with poison ivy. If you think you have been exposed to this menace, the best treatment is water or alcohol and lots of it. Rinse the effected area with an alcohol and water mixture and wash all your clothing in hot soapy water. There are hundreds of “home remedies” most of which are not effective. Treatment of a minor case can be handled at home while a serious case of poison ivy should be handled by your doctor. There is a saying that goes: poison ivy that is left untreated will last about two weeks while a case that is treated will last only 14 days. So this summer make it your duty to learn just one plant, the amazing poison ivy and steer clear of this home wrecker of the woodland. Until next time…