Fireflies
Summer and bugs are synonymous. You can’t have one without the other. While many insects such as the mosquito and tick can be a nascence, some insects are totally amazing. The firefly is one of those amazing insects. I mean, who hasn’t enjoyed seeing, chasing or catching these luminous insects on a warm summers evening? Fireflies or sometimes called lightning bugs are not flies nor are they bugs. In fact they are a type of beetle. Beetles are defined as any number of insects in the family Lampyridae, having biting mouth parts and modified front wings to form hard wing covers that overlie the membranous rear wings. In other words they eat other insects and have a hard shell over the hind portion of their body and their wings. Fireflies glow at all stages of life, including eggs, larva and adult. Thus, the ability to glow just as an adult is not a characteristic of this group of beetles. To confuse the situation even more, not all bioluminescent beetles are fireflies. But you should leave this fine distinction between beetles to the entomologist (one who studies insects). Fireflies start out as an egg which is usually laid in rotting wood or the leaf litter on the forest floor. After hatching the larva feed upon other insects and sometimes snails. They then pupate (rest) for up to several weeks before emerging as the flying adult beetle. Although fireflies are found around the world they are most common in the humid tropical areas of the world. However in North America very few if any fireflies are found west of the Mississippi River. There are many kinds of fireflies and each has its own special way of lighting up the night. Each species flashes its own coded signal. Some flash a single brief light while others have a series of flash. Some flash while perched in tall vegetation while others will flash while in flight. The results of these flying flashes are like sky-writing, with some species creating a “J” , “U” or other shapes in the night sky. So why would a tiny insect have such an elaborate bioluminescent body? To attract a mate of course. Typically males will fly about just after dark flashing their species specific flash pattern. Females perched on vegetation watch for the males flash. Studies show that females prefer males that flash longer and brighter. If the male catches the attention of a particular female, she will respond with her own flash. A short flash dialogue may ensue between the potential mates. The male then seeks out the female by following her flashing. After locating her they will mate and she will go off to lay her eggs and start the cycle over again. Fireflies produce light via a chemical reaction consisting of Luciferin (a substrate) combined with Luciferase (an enzyme), along with ATP (adenosine triphosphate) combined with oxygen. I won’t boar you with any more of the details. Obviously the fireflies can control when and how long they flash, but how they turn on and off the light is still unknown. Many theories abound. One thing that is known, the light these beetles produce is very efficient with very little heat being given off as wasted energy. Just about 100 percent of a firefly’s light is given off as light. By comparison, a normal electric light bulb gives off only 10 percent of its energy as light, while 90 percent is wasted as heat. I am sure we could learn a thing or two about energy efficiency from our friend firefly. So, this summer, why don’t you revisit your childhood by going out and enjoy the natural fireworks of the firefly. Until next time…
Deer Antlers
Autumn is a time when many of us turn our attention to White-tailed Deer. Man-kind has a long history of association with deer. We have depended upon its meat for food, its skin for clothing and its antlers for tools and decoration for thousands of years. A deer’s antlers seem to hold great attraction for people. However like many things in nature that we covet, there is also a lot of confusion about antlers. For example many don’t know the difference between antlers and horns. Horns are permanent and are retained for the life of the animal. They are made of keratin with a bony core. Keratin is a protein substance without a blood supply of which hooves, hair, claws and nails are composed. Horns are found on mammals such as Bison, and Bighorned Sheep. They tend to be relatively short and thick. The Pronghorn, sometimes called antelope, is unique to North America. It is an exception to the horn / antler rules. They have horns that have a bony core with an outer horn sheath, which is shed each year. Their horns are like a combination of horns and antlers. Both male and female Pronghorns have horns, although the males are much larger. Antlers are completely different from horns. Antlers are made of solid bone. Only members of the deer family, Cervidae, grown antlers. Except for Caribou and Reindeer, only the male deer have antlers, with the odd exception of a rare female with a hormonal imbalance which sometimes grows a set of small antlers. Antlers are the fastest growing bones in the natural world and depending upon the species can grow as large as four to five feet long and weigh several pounds. All antlers start from a small swelling on a male deer’s head called a pedicel or antler bud. These first appear as a tiny twist of hairs on a young male fawns head and are visible from nearly the time they are born. It is the pedicel that is the key to a large antler. For example young male deer with poor nutrition or are deficient in testosterone develop small pedicels and thus small antlers. I think most would agree that the size of a deer’s antlers depends upon age, nutrition and inherited traits. But what is not agreed upon is to what degree each of these factors play in the eventual size of the antlers. Antlers start to grow in early spring. The growth is triggered by the length of daylight. From the beginning the newly growing antlers are covered with a network of blood vessels and nerve endings that is known as “velvet” because it looks and feels like velvet or suede. The rapidly growing antlers receive blood through the outer velvety skin and also through an inner core vessel. The velvet is very fragile and tender. It bruises easily and bleeds if it is damaged and even suffers frostbite if frozen. So a buck must remain careful during the growth period. This means no sparring with other bucks or running into tree branches. If an anther is seriously injured during growth it will be deformed in the place of injury. What is really amazing are the antlers will also “remember” an injury and succeeding antlers will also be deformed as long as the buck lives. As amazing antlers are, what is more amazing is how the antler grows. Researchers have proven that a buck must borrow large amounts of calcium, the chief component of antlers, from the body. And the place where this calcium comes from is the ribs and sternum. So much calcium is taken from the ribs that they become very brittle and often break during the critical antler growing period. However the research also shows that a healthy buck takes this in stride and fractures heal smoothly and with minimal discomfort. More on deer antlers in the next Nature Smart column. Until next time…
Invasions
This past winter many parts of the northland saw a record breaking invasion of owls. Great Gray Owls, Northern Hawk Owls and Boreal Owls delighted local birders and drew birders from all over the country to witness the spectacle. How many owls were there? While the exact numbers are impossible to know, the best estimates are have been recently published by the Minnesota Ornithologist Union (MOU). In December volunteers were able to record over 250 owls. In January, volunteer owl watchers were able to find over 450 birds in one weekend. By the end of winter the MOU records Committee tallied reports exceeding 2500 Great Gray Owls, more than 300 Northern Hawk Owls and more than 400 Boreal Owls. Compare these numbers to the winter of 2004 which saw 35 Great Gray Owls, 6 Northern Hawk Owls and just one Boreal Owl and you can see this was one heck of a year. It is estimated that there are only 30,000 Great Gray Owls worldwide and that 80 percent of these occur in North America. Considering these numbers, it looks like we played host to nearly 10 percent of the worlds Great Gray Owl population last year. Now it appears we have another invasion on our hands. This spring and summer, birders from all over the region are reporting widespread distribution of several uncommon species of bird–the Dickcissel and the Henslow’s Sparrow. Neither of these birds is very common in any one given area. Like a wondering band of gypsies, they tend to move around from year to year, rarely inhabiting the same area. The Dickcissel is an extremely handsome bird which superficially resembles the Eastern Meadowlark. It has a warm chestnut colored shoulders with a yellow chest offset by a black V-shaped bib. As far as sparrows go, the Henslow’s Sparrow is a very attractive bird although rather non-descript. It also has a warm chestnut colored shoulders. The face and head are a very pale yellow with a distinct white eye-ring. Both of these birds are found in open fields, prairies and along weedy roadsides. While the Henslow’s is a very secretive the Dickcissel has nothing to hide. It will sing its loud and clear song from the top of any perch strong enough to hold them up. Once you become family with the repetitive song of the Dickcissel you will find it much easier to locate this bird. In fact, the way I find them is to drive down the road with my window open and listen when passing weedy fields. The Henslow’s Sparrow is everything the Dickcissel isn’t when it comes to singing. While it is hard to get the Dickcissel to shut-up, the Henslow’s Sparrow only gives a soft insect-like hiccup call. In addition they often remain hidden and give their call from deep within the tall grasses. Occasionally a male will sit up tall and climb to the top of a sturdy perch to sing but it’s not all that common. In addition they don’t particularly like people around making them a challenge to see. Both of these birds have a limited ranged in the eastern half of the U.S. and the Henslow’s is listed in several states as an endangered or threatened species. While neither of these birds is as captivating as the northern owls they are a great follow up act in this year of the invasion.
Hummingbirds
It shouldn’t come as any surprise that I am crazy about birds. I am fascinated by the shear variety and stunning beauty of our avian friends. And one of my most favorite birds is the hummingbirds. Of the nearly 9,000 species of birds in the world, about 320 are a kind of hummingbird. The majority of these hummers are found in the tropical regions of the world. In North America there are 17 species of hummers with the most of these found in southeastern Arizona. Sorry to say, we only have one species of hummer in the northland–the Ruby-throated Hummingbirds (Archilochus colubris). The ruby-throat is our smallest bird measuring only 3″ long (8 cm). Females are slightly larger than the males and have longer bill. An individual hummer weights only 2-3 grams; it takes 5 average-sized hummingbirds to equal the weight of a single Black-capped Chickadee. Ruby-throated Hummingbirds often appear to be gray in color when viewed in dim or low light but are bright green in seen in direct sunlight. They have highly specialized feathers that contain individual cells that will absorb the sunlight and reflect only the green spectrum of sunlight back, making them appear green. Males have a specialized throat patch called a gorget that appears black in color until he turns to face you. Then the gorget lights up in a brilliant ruby red color as if someone has flipped a switch on a neon red light. The bright ruby color is also a result of reflected sunlight. The gorget is used to attract females. The bigger and brighter the gorget the more the females are attracted. Hummingbirds received their name from the “humming” noise created as their wings whiz through the air. Hummingbird wings flap around 50-60 times per second during normal flight and can reach up to 200 beats per second during courtship flights. (Try doing anything 200 times per second.) They can fly up to 50 mph and usually fly no higher than 300 feet. Hummingbirds can hover, fly up and down, and are also the only birds that can fly backwards. To power all of that wing activity, the hummers have very large hearts that beat at an amazing 1,260 beats per minute compared to our own heart that beats about 70 – 90 beats per minute. Their heart is so large it comprises one quarter of a hummers total body weight. They fuel all of their muscle activity with oxygen by breathing at 250 times per minute compared to our own respiratory effort at 12-18 per minute. To keep these flying machines going, hummingbirds have a metabolism that is 40 times that of our own. They survive on top of the line fuel—fast acting sucrose obtained from flower nectar. They consume up to 50 % of their own weight in nectar daily. That would be the same as you or I drinking a bathtub of soda daily. Hummingbirds are one of the few birds that don’t sing a song. They communicate with a single “chip” note. Often they string a bunch of chip notes together to produce something that sounds like chattering. I guess if you look and fly as well as a hummingbird you don’t need to sing a beautiful song. Hummers feed about every 10 minutes throughout the day but flower nectar is not the only food on their menu. Tiny insects such as gnats and flees make up most of their non-nectar diet and provide them with the protein not found in a sugar water diet. Until next time…
Dragonfly
The sense of smell is a powerful one. A whiff of this or a whiff of that can send your mind tripping back to times gone-by. For me, the heavy musky smell of a summer evening catapults me back to the grassy fields of my youth. Fields filled with the sounds of crickets and the flash of fireflies. High over-head, Common Nighthawks would repeat their raspy call—peent, peent, peent. But mostly I remember the precision flights of dragonflies as they wing across the tops of the tall grasses in search of a meal. It wouldn’t be summer without dragonflies. These critters have been around for a long time. Their fossil record dates back 350 million years ago. That’s about 100 millions years before the dinosaurs. There are over 5,000 different species of dragonflies in the world. In North America there are about 400 species and a little over 100 species in the Northland. Like all insects, the dragonfly has three body parts—the head, thorax and abdomen. The head of the dragonfly has two huge eyes. The eyes are so big that in some species they actually merge together on top of the head. Each eye is made up of hundreds of individual eyes–called compound eyes. The head of a dragonfly swivels freely allowing the dragonfly extraordinary field of vision. The thorax is the small segment in the middle of the dragonfly. It’s where the four wings and six legs are attached. Lastly, the abdomen is what most people call the tail. It is long and thin and is often mistakenly thought to be a stinger. It is important to note that no dragonfly has the ability to sting. You can tell a dragonfly from the similar looking damselfly by looking at their wings. All dragonflies hold their wings flat or horizontal and out to their sides when at rest–like the wings of an airplane. The damselfly folds their wings neatly over their backs when at rest. Dragonflies have four wings, which allow them to fly forwards, backwards and hover. The top speed of a dragonfly is around 35 mph. A dragonfly’s life revolves around flying. They capture and eat their food while flying and they even mate while flying. Their diet is mainly small flying insects like mosquitoes. This is how they got the name “mosquito hawk”. They catch their lunch by holding their legs like a catcher’s mitt, and scoop the prey up while in flight. A typical dragonfly can eat hundreds of insects a day. This pernicious behavior goes a long way to help keep mosquito populations down. While eating during flying isn’t very hard, mating on the wing is a little tricky. The male searches out a receptive female and locks on to her just behind her head with a small pair of pincers located at the tip of his tail (abdomen). The female curls her tail up and receives a reproductive packet from the male. This position is called the wheel and is easily observed. Because females will mate with several males if allowed, the male tries to stay locked on to her while she lays her eggs to ensure he is the father of the offspring. The two will fly around together as she deposits hundreds of individual eggs underwater. The eggs hatch into tiny alligator looking insects with a voracious appetite. At this stage of life they are called a naiad. For the next two years the naiad aggressively seeks out and eats mosquito larva, small tadpoles and even small fish. After several molts it attains full size and crawls out of the water onto a rock or vegetation. The back of the naiad splits open and the adult dragonfly emerges. After several hours the dragonfly wings are dry and ready to fly off to eat more mosquitoes and mate, thus completing the dragonfly life cycle. Until next time…
Squirrels
I just love squirrels! You won’t hear many bird nuts like me professing a love for these four legged, bird food robbing bandits. But I am not afraid to admit it. I enjoy all squirrels but in particular I really enjoy the tree squirrels. All squirrels are broken into two groups—tree squirrels and ground squirrels. For example, the Eastern Gray Squirrel and Fox Squirrel are types of tree squirrels while Chipmunks and Woodchucks are types of ground squirrels. Tree squirrels are mammals that belong to the order Rodentia or more commonly known as the rodents. There are over 1,600 species in this group which constitutes one third of the 4,500 species of mammals living on earth today. In other words, one in three mammals walking this earth is a type of rodent. Looking at the fossil record, tree squirrels appear to have originated in North America and subsequently spread to Eurasia, Africa and South America. The morphology of squirrels hasn’t changed much over the past 5 million years. In fact, squirrels have changed so little over this time that most authorities refer to tree squirrels as living fossils. Currently there are 26 species of tree squirrels in the genus Sciurus, with 3 species found in Eurasia and the remainder found in North and South America. The reason for their success is their ability to eat energy rich seeds and nuts and live in trees where other mammalian predators find it hard to go. So what makes a rodent a rodent? Scientist look at the skull and teeth to classify mammals. Squirrels lack canine teeth. The canines are the sharp pointed teeth located between the incisors and the molars or cheek teeth. The incisors of a squirrel or any other rodent for that matter are strong prominent teeth with a chiseled edge on the inner surface that equips the animal with tremendous gnawing ability. Like other rodents the incisors of a squirrel are open rooted and grow continuously through its life. Gnawing on thick shelled nuts and other hard surfaces keep the incisors from growing too long. An incisor that grows unchecked, called a malocclusion, can eventually pierce the skull and kill the animal. The jaws of a squirrel are amazingly strong and powerful. Combine the jaw strength with razor sharp incisors and you have a nut cracking and seed eating machine that will stop at nothing feed itself. One of the things I find fascinating about tree squirrels is their inability to digest cellulose. Cellulose is the chief component of green plants. Cellulose is a polysaccharide comprising up to 90 percent of a plant. Most herbivores (animals that only eat plants) require symbiotic organisms (usually bacteria) to aid in the digestion of cellulose, whereas many other species, including squirrels, are unable to digest cellulose. In other words they cannot live on green plants and must restrict their diet to the energy rich seeds and nuts. Let me just stop right here for a moment and digress just a bit. Many people believe that if they see an animal such as a squirrel or deer eat something in the wild, it must be safe for people to eat. Nothing could be further from the truth. For example, both squirrels and deer have been known to eat deadly Amanita mushrooms without any ill effect. If you or I were to eat one of these mushrooms you would not survive. Simple as that. Now back to the squirrels. Tree squirrels are well adapted to a life in the trees. This is called an arboreal lifestyle. All tree squirrels have extremely strong legs and elongated toes or digits, each equipped with a very sharp recurved claw. In addition their hind legs and feet can rotate 180 degrees, allowing squirrels to scamper down trees headfirst and hang from limbs to reach nuts for food and leaves for their nests. By far the tail of a tree squirrel is its most distinguishing feature. It is a multi-functioning appendage that aids in balance when scampering and jumping around on thin branches in the tree tops while at the same time helps to regulate heat loss and is also used as a flag or signal when communicating with other squirrels. In general tree squirrels have excellent eyesight. Aside from the primates, such as apes and monkeys, tree squirrels are one of the few mammals that can see in color. The position of their eyes is also very important. Set wide apart on either side of the head, tree squirrels posse an extremely wide field of view. Anyone who has tried sneaking up on a squirrel knows what I mean. Although tree squirrels are mostly diurnal (active during the day) tree squirrels possess extra light gathering cells, called cones, in their eyes which allow them to see in very low light of dawn and dusk. Excellent eyesight allows them to keep watch for predators. Now can you see why I like squirrels so much? Until next time…
Sandhill Cranes
Birds are one of the most diverse groups of animals on the face of the earth. From the tiniest of all birds, the 3-inch long hummingbird, to the largest, the 6-foot tall Ostrich, birds are remarkably different. Think about it. There are over 9,000 different types of birds in the world and each is very unique. Even birds that are closely related to each other are often very different. In the Eastern half of North America, there are 17 species of gulls, but each gull is remarkably different from the next. And each of the 14 species of blackbirds is vastly different from each other. We have over 20 species of ducks and 6 different kinds of geese. And you guessed it; they are all very different from each other. Amongst all of this avian diversity stand the Cranes. There are 15 species of crane in the world but just two occur in North America—the Whooping Crane and the Sandhill Crane (Grus Canadensis). Sandhill Cranes are tall and stately birds, standing four feet tall and have wingspans of 6-7 feet. They are certainly the tallest birds in the northland. Males weight between 10 and 12 pounds while the females are 9-10 pounds. Sandhill Cranes are slate-gray with long legs and neck. In defiance of their dull gray color, they sport a bright crimson red cap punctuated with a piercing orange-yellow eye. In most areas Sandhills frequently preen with mud stained with iron oxide, consequently they appear reddish brown rather than gray. Sandhill Cranes are often confused with Great Blue Herons. While they may be of similar height, and color, there are a lot of differences between the birds. One easy way to differentiate between the heron and the cane is in the way they hold their necks. The Sandhill Crane holds their neck straight, especially in flight or while walking on land. The Great Blue Heron holds its neck in a tight “S” pattern, especially in flight. Cranes also have a distinctive rapid upstroke in flight compared to the herons slow and steady flapping. What really amazes me about the Sandhill Crane is not its size or coloration. No, I am amazed at how long the Sandhill Crane has been flying across North America. Sandhills are some of the oldest living birds in North America. Fossils of Sandhills date back 9 million years. That is several million years before people started to walk upright and long before many other birds. A bird with that kind of lineage would lead a naturalist to suspect it was a primitive or an outdated bird destine for extinction. But that is not the case with these birds. They have changed little over the past 9 million years, presumably because they are so well adapted for any change the world throws their way. If the sight of a Sandhill Crane doesn’t move you to absolute admiration, the call of the Sandhill will resound within you for a lifetime. Its distinctive trumpet-like call comes from deep within a curved windpipe, like the bent tubes of a trumpet. The call can be so loud that an individual bird can be heard up to 3 miles away making them heard well before they are seen. It is not uncommon for Sandhill Cranes to live up to 20 years. They don’t breed until 3 to 5 years of age. During the first few attempts of mating they may change partners until they get a good partner and a good territory. After that they will stay mated for the rest of their lives and occupy the same territory. Befitting their grace and beauty, the Sandhill Crane is a dazzling dancer. For courtship and for shear pleasure, the cranes will dance. Standing face to face, the pair will bow than with their wings spread and neck arched, they throw back their heads and trumpet a musical song just before they spring up into the air. Flapping their wings as if in slow motion they slowly return to earth. They than skip, hop and spin around like a ballerina and than spring back into the air. At times they pick up a small twig or bunch of grass and toss it about to break up the dance routine. It is a wonderful sight. Until next time…
Migration
The annual autumn migration is well under way all across this great big planet. From the mammoth Humpback Whale swimming along the Pacific Coast to the delicate and dainty Monarch Butterfly on its annual flight to Mexico. In Jackson Hole, Wyoming the Elk are moving down and out of the mountains to spend the winter at lower elevations to the march of the Emperor Penguins in Antarctic, this ancient need to migrate is well underway. All across the Northland many backyard bird watchers are noticing an increase presence of small woodland hawks in their yards. The annual migration of these birds brings hundreds of thousands of these diurnal raptors into backyards where they are looking for a quick bite to eat before returning to their migratory activity. The tall and stately Sandhill Crane is gathering right now in groups of up to several thousand birds before heading south for the winter. Unlike the hawks that don’t migrate in large flocks, Sandhill Cranes revel in their large numbers. During daylight hours, small groups of cranes fly out to plowed agricultural fields to forage for large insects and spilled grain or corn. Come evening thousands will gather, their trumpeting calls filling the air as it has for millions of years, in wet meadows or shallow ponds to spend the night. They depend upon the relative safety of the water and the huge number of eyes to watch for predators such as foxes and coyote. A few lucky people have some unusual visitors to their feeders right now during migration. Harris’s Sparrows are showing up under feeders scratching for seeds. These handsome brown and tan sparrows have a black crest, face, chin and upper chest. They nest in the far reaches of Canada and are heading for Texas for the winter. Those lucky enough to have them visit will only see them for a couple days before they continue on their way south. Some of our favorite backyard songbirds such as the Rose-breasted Grosbeak are long distance migratos. They leave our backyards and head for the tropical regions of Central and South America. Unlike the raptors these birds migrate at night. Just before sunset, the birds take flight and will fly all night using a combination of the stars, major land forms such as large rivers and the natural magnetic pull of the earth’s poles to guide these birds on their amazing journey. The champion of these tiny migrants is the Black-pole Warbler. They are a tiny warbler that look like a cross between a Black-capped chickadee and a Black-and-white Warbler. The Blackpoll nests in the northern conifer forests of Canada and Alaska. Each autumn it starts its famous long migration by heading eastward to the Atlantic coast between Nova Scotia and Virginia. From there they stage and begin to feed heavily to build fat reserves. Then when the weather conditions are just right they embark on a 1,600 mile non-stop flight to the West Indies while others fly 2,200 miles non-stop to parts of South America. Birds trapped for banding in the staging area just before heading out weight 9 grams (the weight of three pennies). Bird physiologists have determined that the 4.5 grams of extra fat on the Blackpoll is enough to fuel a non-stop flight to the West Indies or South America. They start their journey at sunset and fly all night when the upper level winds tend to be less turbulent. It will take them up to three days of non stop flying to reach their destination. Some birds will rest in Bermuda which is along the flight path while others may take a break on ships. Birds without enough fat presumably will run out of energy and fall into the ocean and die. And you thought your daily commute to work was tough. Come next spring they will return to start the cycle all over again. Until next time…
Deer Antlers Part 2
In my last Nature Smart column we looked at deer antlers. More specifically we examined the difference between horns and antlers. (Yes there is a difference.) We also learned that antlers are composed of calcium, just like bones. In fact antlers are the fastest growing bones in the mammalian world. Where all of this calcium came from to build the antlers was even more interesting. Bucks pull the extra calcium from their ribs and sternum, making the bones prone to rib fractures. In fact the mobilization of minerals from the skeleton to a White-tails antler’s is so remarkable it may someday give us an insight into the mysteries of osteosarcoma (bone cancer) and also osteoporosis (a serious bone disease of older women). There is much to learn from Mother Nature. I am always amazed at the different color of antlers. They can range from Ivory to dark mahogany. The coloration comes from staining due to rubbing the antlers on tree bark or from the stain of blood hemoglobin when the antler is still in velvet. I have also seen antlers with different colored moss and lichen growing on the antlers, particularly at the bases, which makes them look different colors. By the end of the mating season a bucks antlers can be nearly white. Rain and sun do much to bleach the antlers. And by the end of January and occasionally February, bucks will shed or discard their antlers. Casting or shedding of the antlers occurs with little to no pain and very little blood. In fact the attachment spot heals quickly, usually within a couple days and new antlers start to grow within weeks starting the process all over again. Discarded antlers just don’t lie around the forest floor forever. No they are chewed upon, presumably to gain the calcium, by a host of small mammals. In fact a friend of mine once drilled a hole through a deer antler and threaded a heavy gauge wire through it. He then secured the antler to the ground with the wire and took note how long it took for the antler to be eaten. In a short 8 weeks there wasn’t much left of the antler. As incredible as antlers are, what is even more incredible is why a deer has antlers in the first place. Think about it. Of what use are a buck’s antlers? If you examine a buck’s entire year you will find that antlers are more of a hindrance than help. Think of it, from the day the antlers start to grow a deer must take great care to not injury the delicate growing antlers. During spring and summer bucks act and move around like does rather than the usual wild-eye buck. During this time, any disagreements between bucks is handled doe-like, with much rearing on hind legs and flailing with their forefeet because they need to protect their growing antlers. During summer it is the females that are dominant, not the bucks. In fact there is good evidence that bucks live in summertime bachelor groups because the does have driven them into segregation. So why do bucks have antlers? A common theory is that bucks grow antlers to defend against natural enemies and other bucks. But if that was true, why don’t female white-tails have antlers as well? The does are preyed upon even more than the bucks. Also, why don’t the bucks retain their antlers (more horn-like) throughout the winter when the predation is the worst? Besides isn’t a white-tails best defense its ability to quickly run away. Every deer I have come across has responded to me by running away and not standing and fighting. A new and more intriguing theory as to why bucks have antlers is now coming out and there is some good evidence backing it up. We will take a look at this way of thinking about antlers and also look at a trip I took to Canada to photograph moose with a moose biologist who is studying the size of moose antlers and what they are used for. Until then …
Deer Antlers Part 3
In part II of my Nature Smart column on Deer Antlers, we looked at where all the calcium comes from to produce a antlers and the consequences of such massive calcium shift. We also looked at the different colors of antlers. I also discussed what happens to antler sheds each winter. And we learned that nothing goes to waste in nature. But more importantly, I asked the question; why do male deer have antlers in the first place and I promised that I would write about my time spent with a Canadian moose researcher. So here we go with part III of deer antlers. Most believe that antlers are used to defend against predators. But if that was true, why don’t female white-tails have antlers as well? Female deer are preyed upon even more than the bucks. Also, why don’t the bucks retain their antlers (more horn-like) throughout the winter when the predation is the worst? Besides isn’t a white-tails best defense its ability to quickly run away. Well, a more intriguing theory suggests that antlers are for attracting mates—to impress the girls. Kind of like a fancy car and nice clothing for people. It is widely accepted that a male cardinal’s bright colors is a signal to potential mates that he is a healthy male with a good territory that he has a good food supply available to him. Food sole component for brightly colored feathers. Female birds choose their mates based on how the male looks and how well he sings. Since deer don’t sing, it would appear that does look for bucks with the largest antlers for a mate. Therefore large antlers are indicting his good health, food supply and genetics. In part one of this series we talked about how a buck’s diet is a major factor in the growth of the antlers. The more nutritious the diet the larger and thicker the antlers will grow. That, along with good genetics, will produce bucks with an impressive rack. Not only do large antlers impress the girls, the size of a buck’s antlers establishes a place or ranking in white-tail hierarchy. Early in the season, bucks with the most massive antlers and swollen necks will spare with bucks that are approximately their own size to determine dominancy. Rarely are the large bucks challenged by smaller less dominant bucks. Once the strongest and most skilled of these bucks establishes their ranking they usually don’t have to fight again and all of their attention is focused on breeding. So really a White-tailed Deer’s antlers are a visible way to say, “Hey, I am a strong and healthy male that will produce strong and healthy offspring”, “consider me for breeding.” This brings me to a photography trip where I spent several days with a moose researcher in Canada’s Riding Mountain National Park in Manitoba. Researcher Vince Crichton, whom you may have seen on an Animal Planet channel special, uses a stuffed moose head with interchangeable antlers to interact with bull moose and observe their behavior. He would strap the moose head to his chest, kind of like a reverse backpack and using a moose call walk up to bull moose during the rut. The goal was to observe the reaction the bull moose would have to Vince’s antlers. My reaction was that he was nuts, but that is a different story. Vince has established that when he approached a moose with smaller antlers, presumably a less dominant moose, that moose would not challenge Vince and his large antlers. Bulls with equal or larger antlers would stand their ground and become agitated indicating their willingness to fight by rocking their heads back and forth to show off their antlers. For several days I followed Vince around the north woods of Riding Mountain National Park and observed the behavior of the moose and was amazed at how these bull moose didn’t see a man with a moose head strapped to his chest but rather they seemed to only see the antlers further indicating how important antlers are to the members of the deer family. Until next time…