Red-tailed Hawk
Often it is the common critters that go unnoticed or at least unappreciated. After all, when was the last time you noticed a House Sparrow or Pigeon? How about an Eastern Chipmunk or Gray Squirrel? I’ve always maintained that we see woodpeckers do incredibly amazing things, such as landing on vertical surfaces without slipping, nearly every day but we don’t give it a second thought. It’s unbelievable that these woodpeckers fly up to a tree trunk and stick to it like Velcro. The woodpeckers act as if gravity doesn’t exist. All other birds are landing on horizontal branches. Recently while leading a birding trip to see migrating hawks in northern Minnesota, I got to thinking about all the Red-tailed Hawks we were seeing. This is one of those hawks that can be very common in both rural and urban environments and often goes unnoticed. I see Red-tailed Hawks sitting on highway light posts right in big cities and see many more along highways in the country. Red-tails are found breeding throughout most of North America, from Canada and Alaska all the way down to Panama and the West Indies. They are masters of adapting to different habitats. They are found from the mountains to the prairies. From the forests to the deserts. They also do well in edge habitats where forests met prairies or mountains met flatlands and they nest in large cities such as New York city. Sometimes called “Chickenhawks” they actually don’t hunt chickens but rather concentrate mainly on small mammals such as mice, voles and shrews. They will also hunt Cottontail Rabbits and ground squirrels. They hunt reptiles such as snakes and lizards and also chase down larger birds such as Pigeons for their next meal. They are opportunistic and seasonal feeders. Which means they will take advantage of any prey they find and follow whatever prey is seasonally abundant. They have been known to hunt and eat upwards of 500 different species. Small mammals make up 65% of their diet and 21% birds. Red-tails require about 7 to 10% percent of their body weight in food each day to survive which works out to about 3 mice per day or the equivalent weight in prey. Identifying Red-tailed Hawks can sometimes be challenging. Not because you don’t see many of them, but rather because they can be highly variable in color. There are 14 recognized subspecies of the Red-tailed Hawk. Within these, there are three distinct color morphs or phases of Red-tailed Hawks, light morph, intermediate and dark. The terminology is a little confusing here. When they are called morphs or phases it makes it sound like it’s a temporary condition or that they will change color. This is not correct. For example, a dark morph bird is born dark and will have dark feathers its entire life, or the light morph will stay light it’s entire life. The light morphs can be bright white while the dark morph is deep chocolate brown. In the light and intermediate morphs, you can clearly see the red tail but in the dark morph the red tail is much less obvious. Red-tails are a large hawk standing just over 2 feet tall. But for all their size they only weigh between 1.5 and 3.5 pounds. Adult females are about 20% larger than males. This is a noticeable difference. In biology, when one sex is larger than the other it’s called sexual dimorphism. Wing spans range from 3.5 feet to 4.5 feet from wing tip to wing tip. They use their big broad wings to fly and soar over open areas to hunt for prey. In many parts of the country Red-tailed Hawks will hunt for bats near sunset when the bats are emerging from sleeping all day. The hawks chase them down and snatch them right out of midair. Red-tails spend a lot of time just sitting and hanging out. Once a meal has been procured for the day they often will just hang out. So, it was a real pleasure that we got to see several Red-tails during the birding trip to Minnesota’s north shore along with other cool birds such as Northern Goshawks and Sharp-shinned Hawks. Until next time… Stan Tekiela is an author / naturalist and wildlife photographer who travel’s the U.S. to study and photograph wildlife. He can be followed at www.facebook.com or twitter.com. He can be contacted via his web page at www.naturesmart.com.
Bird Migration
I would love to write a nice little article about bird migration. Something short and snappy and to the point, but when I reflect about how I would do this, I shutter at the thought. You see, bird migration on the surface seems simple enough. Right? Birds fly south in winter and north in spring. But this is so overly simplistic and doesn’t even begin to encapsulate the grandeur and complexity of bird migration. Recently I’ve been out promoting my new book call Bird Migration, The Incredible Journeys of North American Birds by Adventure Publications. Almost always, someone asks, when did bird migration start or why did migration start? Of course, it is impossible to answer this question because birds have been migrating for millions of years, long before people came around. However, we do have some theories to answer these seemingly simple questions. So, let me try to capture some of the high points of bird migration. Why birds started to migrate all comes down to a simple cost-benefit ratio. You see, if the cost to the bird out-weight the benefit, migration wouldn’t exist. So, obviously the benefits of migration out-weight the cost. There are over 10,000 species of birds in the world and about 4,000 of them are migratory. That means about 40 percent of all the birds on the planet do some kind of migration. That should be enough to tell you that migration is a winning strategy for survival. Here in North America we have about 900 to 1,000 species of birds and about 350 species that migrate. Once again, this is almost half of all bird species in the Americas do some kind of migration. So clearly the benefits of migration are much greater than the cost. So, what are the benefits of migration? By answering this, perhaps it will help you understand why a bird migrates or why migration started. It is widely believed that migrating helps a bird find new open territories for breeding. Having a larger region in which to search and find a territory is very helpful. A larger area reduces the competition amongst the birds that are competing for a territory. Less competition means you have a better chance of finding a “good” territory. In most species, the males compete or physically flight for territories so having less competition means less fighting and less energy expenditures and more time available to attract a female. New territory also means more or higher quality food sources. Having a reliable and high-quality food source is the key for successful reproduction. A good food source means the male will grow bright attractive feathers. Studies show, in species that are brightly colored, females judge a male’s overall health and reproductive vigor by how bright and colorful his feathers. So, finding new territory with abundant food is the ultimate goal to have bright and colorful feathers. Nesting habitat is critical for many species. Most birds require or demand very specific habitat in order to nest and reproduce. Migrating allows these birds to move to regions that have just the right habitat in order to nest. For example, many warbler species migrate to the northern boreal forests. They don’t nest in deciduous forests and thus if they didn’t migrate, they wouldn’t reproduce and would die off. In addition, these birds feed on the abundant insects that are found in the northern boreal forests. If you have ever been in the northern forests during spring and summer, you will know what I mean. The insect populations are insane. The warblers take advantage of this overly abundant food to feed themselves and their nestlings. I am afraid that the answer of when did birds start to migrate is lost to history. We may never know when birds started migrating of if a few species started to migrate than others followed or it all happened at once. Most of our modern birds, the ones we see today, have been around for anywhere between 2 and 5 million years. I think it would be safe to say that birds have been migrating for millions of years. This would be long before any human walked the earth. So, you might be able to say that the reason birds migrate boils down to finding new food sources and finding territory for reproduction. Until next time… Stan Tekiela is an author / naturalist and wildlife photographer who travels the U.S. to study and photograph wildlife. He can be followed on www.facebook.com and twitter.com. He can be contacted via his web page at www.naturesmart.com
Eastern Gray Squirrel
I often enjoy the more common side of nature. The nature in our own backyards or neighborhood park. The nature that we see every day but seems to go unnoticed because it’s so common. For example, the Eastern Gray Squirrel (Sciurus carolinensis). Likely the most common squirrel species the United States and Canada. No matter if you live in the city, suburbs or out in the boondocks, chances are you have Gray Squirrels running around. There are many different kinds of squirrels in the United States and Canada. For example, we have 8 different species of “Tree” squirrel. As the name implies these squirrels live in trees and includes the Eastern Gray Squirrel. We have 56 species of “Ground” squirrel which include species such as chipmunks and prairie dogs. And we have 3 species of “Flying” squirrel. These are nocturnal species of squirrels that also lives in the trees but are obviously different from other squirrels with their ability to glide. The Eastern Gray Squirrel or just Gray Squirrel is the common backyard “tree” squirrel. I find these squirrels endlessly fascinating to watch and study. So, the other day when I was visiting my daughter in western central Wisconsin and saw there was a ton of Eastern Gray Squirrels that were very different looking because they are jet black, I thought this is something that I know a lot about, but most people don’t know exists. The Eastern Gray Squirrel has a dark side. There are scattered pockets of the Eastern Gray Squirrel that are not gray at all but rather totally black. This is a condition called melanistic. How dark the squirrel is depending upon how much melanin is present in the hair of the squirrel. Often these squirrels will have a black body and a rusty colored tail. Some will have patches of white on their bellies or tail. No matter these melanistic squirrels really stand out. To be clear, the melanistic or black squirrels are exactly the same species as the gray squirrels, but the black ones have a variant form of a specific gene which produces more dark pigment. In other words, they have a rogue gene that causes them to have black pigment in their hair. Recent research shows that we have more black morph squirrels now than in the past. Partially because people have trapped and moved the black morphs around the country. Several Universities trapped and moved the black morph squirrels to their campuses for research purposes. In addition, several cities in the south also imported the black morph squirrels. All of this has led to more black morph Gray Squirrels today than ever before, but they are still considered unusual or rare. Just how rare are these black squirrels? It is estimated that less than 1 percent of all the Eastern Gray Squirrels are melanistic or black. That translates to about one in every 10,000 gray squirrels is melanistic. So, it wouldn’t be a stretch to say they are not very common. However, in some pockets or regions the black morph squirrel is the dominant squirrel. The range of the Eastern Gray Squirrel stretches across the eastern half of the country extending well up into Canada. Typically, the melanistic squirrels are found in northern states and Canada. Several studies have shown that the dark morph squirrels had lower heat losses and lower basal metabolic rates compared to the regular gray morphs during winter. The dark morph squirrels have lower energy costs for living in cold and wintery conditions compared to the gray morphs. Therefore, melanistic squirrels are more common in the northern portions of the species range. Recent research has determined that the origins of the black morph Gray Squirrels has come from a close relative the Fox Squirrel (Sciurus niger). Also known as the Eastern Fox Squirrel or Bryant’s Fox Squirrel, it is the largest species of tree squirrel native to America. The Fox Squirrel comes in a wide variety of colors including black. It is believed that a black morph Fox Squirrel breed with an Eastern Gray Squirrel and passed along the variant gene that causes the dark fur. Studies show that the same exact gene in the Fox Squirrel that causes the dark fur is the same in the Gray Squirrel. From there natural selection took over and now we see the black morph Gray Squirrels all over the northern States. Until next time… Stan Tekiela is an author / naturalist and wildlife photographer who travels the U.S. to study and capture images of wildlife. He can be followed on www.facebook.com and twitter.com. He can be contacted via his web page at www.naturesmart.com.
American Crow
Continuing my look at some of the more common critters that we see everyday but rarely give them a second thought.