Category Archives: Animal Adaptability

Buzzards and Vultures

What a joy to publish a guest blog piece  from a friend and true expert on bird behavior. The honor is even greater and more personal as Dr. Rylander was one of my principal professors when I attended college and majored in Zoology. What a surprise when Dr. Rylander and I learned that following our retirements that we had both chosen Fredericksburg, Texas, as a place to live. He is the author of Behavior of Texas Birds, published by the University of Texas Press.

One of the nearly constant sights over our ranch is the presence of vultures languidly circling high above. Little did I understand the differences of the two types of vultures that we see, although always being amazed by their graceful flight and efficient clean up of roadkill along our rural roads. Dr. Rylander makes their presence more meaningful and enjoyable to view than I had ever considered. Enjoy!

 

Guest Blog Piece by Kent Rylander, Ph.D.

Growing up on a farm during the late 1940’s, my brother and I called them “buzzards” – those large, black, hawk-like birds that soar in circles high overhead, or that stand on the highway by a road kill and fly away lazily if cars approach too closely. Even today most farmers in Denton County call them buzzards, and some still shoot them because they think they’re hawks or that they transmit diseases.
Later, when our parents gave us a field guide, we learned the preferred name, “vulture,” a term ornithologists introduced to distinguish our vultures from the unrelated African buzzards. We also learned that two species occur in Texas, the Turkey Vulture and the Black Vulture.

Black Vulture on the left and Turkey vulture on the right


Overhead these two vultures might appear to be the same species because they are so similar in general appearance. However, a closer look reveals that the Turkey Vulture is very light on the wing and rocks gently back and forth as it effortlessly soars for hours; it rarely needs to flap its wings. In contrast, the Black Vulture’s body appears too heavy even for its broad wings. Indeed, Black Vultures must flap and glide just to stay aloft even at high altitudes where thermals are strong.


The “personalities” of these two species are related to their different body types. Both have keen eyesight and regularly search for carrion while they soar high above the ground, but they differ in an important way. The Turkey Vulture’s large wing to body ratio allows it to fly low over the ground and locate small animals such as snakes and rodents. It also has a sense of smell, which almost all birds, including the Black Vulture, lack because olfaction is useless for an animal that spends most of the time in the air.


More than a century ago Audubon claimed he demonstrated olfaction in Turkey Vultures by placing a dead animal under a sheet next to a realistic painting of a carcass. A vulture flew down to the painting but ignored it, then pulled the carcass out from under the sheet.


Although Black Vultures can’t locate small carcasses because they must fly high to stay aloft, they compensate for this limitation by watching Turkey Vultures forage low over the ground. When a Black Vulture sees a Turkey Vulture feeding on a small carcass, it drops down and drives the Turkey Vulture away. The Turkey Vulture seems to accept being bullied by its much heavier and stronger relative, even when both are at a large carcass.


Is the Black Vulture more aggressive because its size enables it to be a bully, or is it basically just a more aggressive animal?


The answer to this question lies with the young, fluffy white fledglings, which hatch and live in small caves in cliffs and rock formations. When a person approaches a Turkey Vulture fledgling, the young bird cowers and retreats to the back of the cave; but when a Black Vulture fledgling is approached, it hisses and lunges at the intruder.


So when we look up and see Turkey Vultures and Black Vultures soaring together, ostensibly cooperating while looking for a well-deserved meal to share, we know that, thanks to their genetics, they’re not foraging together because they’re friends.

Survivor Duck

Years ago my neighbor and I shared a brood of Rouen baby ducklings. They were delivered by mail, raised in cages, and eventually when ours were grown walked by Trudy down to our nearby stock tank. Actually to Trudy’s surprise the following day she found that they had walked back to our back fence, and she had to again walk them back down to the stock tank.

These Rouen ducklings became big breasted and flightless ducks. While they can manage to fly for very short distances and at a foot or two above the water, they essentially are flightless. What we had not counted on was that these flightless ducks became particularly vulnerable to varmints, such as raccoons and coyotes. Sure enough, one by one, the ducks disappeared without so much as a suspicious pile of feathers being left behind. That is, all of the ducks but one, this being a male Rouen duck.

This is not MY Rouen duck, as he is currently moulting and not very pretty. This picture of a male and a female Rouen duck is taken from the internet


I’ve named thislone lone duck, Survivor duck, for obvious reasons. But what wasn’t at all clear to me was how this duck managed to dodge the predators and live when all the others had been lost early on. He has now been without any of his fellow ducks for some three or more years. How in the world did he manage this feat of survival?

As is my routine very morning, I head to the stock tank and throw out feed for Survivor Duck and for the bass and other stocked fish in the tank. Almost every day Survivor Duck paddles over to me and enjoys his breakfast. His ability to pluck the pellets from the water always reminds of of a sewing machine. His head simply flies up and down so fast that it becomes blurred.

He has become so used to my presence that he is almost tame. He will waddle along the ground a step in front of me and eat the feed that I throw either on the ground or in the water. I doubt he would let me approach him close enough to pick him up, but it would be close.

On the days when Survivor Duck doesn’t appear, I always fear he has become the latest duck to meet with a grisly fate. But within a day or two, I see him churning through the water toward me, as I open the duck box and begin to throw out feed.

My answer to this nagging question of how he has survived came not long ago. As I approached the stock tank, I scanned the pond and did not see Survivor duck. But Suddenly my eyes were drawn upward to a flying duck at around fifty feet. I watched it fly the length of the stock tank. As it approached overhead the duck banked to the right and made a long lazy loop out over the edge of my property and my neighbor’s property only to complete the circle back over the stock tank.

The duck flew toward me, lost altitude, extended its feet like orange skids, and landed in the water not more than twenty feet away. To my amazement it was Survivor Duck. Our so-called flightless duck had become proficient at flying. No doubt this ability explains his remarkable ability to avoid any duck devouring predators. I can now attest that there is at least one Rouen duck in the world that is NOT flightless.

Perhaps this just goes to prove that when faced with special challenges, this duck learned to evolve and adapt. Hmmm, may be there is a lesson here.

 

The Nutria Are Coming, The Nutria Are Coming

Not long ago I spied a medium-sized brown animal swimming languidly in my pond. At first I thought the animal was a beaver. How wonderful, I thought, for our stock tank to be a home for a beaver. After all, who doesn’t love those industrious, furry little flat-tailed creatures?

On closer inspection I saw that while the head looked like that of a beaver, its tail was not flat nor paddle shaped but instead bore the look of a rat’s tail. With a little research, I learned the identity of the interloping animal- it was a nutria.

Brown furry nutria

I began to read about nutria. From my reading I sensed an existential dread associated with nutria. I learned it was an invasive species and fully worthy of eradication. For me, a man of peace, the thought of shooting or trapping nutria was hard to accept. After all, I had spent a professional lifetime trying to preserve life in my chosen profession of medicine, such that killing simply doesn’t come naturally for me. Trapping of the nutria also made no sense either, as once trapped what was I to do with the despised animals?

Little Jack does not share my concerns regarding the killing of varmints. He in fact specializes in squirrels and armadillos

Nutria are an invasive species brought to Louisiana from South America in the 1930s. Some 20 animals were transplanted to begin fur farms so that their pelts could be made into hats and muffs. After the craze for nutria fur subsided, however, and the fur mills disappeared, these semi-aquatic rodents scampered and swam into the Louisiana swamps where they bred like crazy. Their initial numbers increased dramatically, having up to three litters per year and up to 13 pups at a time. It is now estimated that in the U.S.A. some 20 million nutria exist and are spreading out from Louisiana in a rapidly expanding rodent infestation. Texas is affected, your state may also be impacted or else may be soon.

Already nutria have spread to the northwest portion of the U.S. and as far as California. In California the threat they pose to the wetlands is said to be equal of the threat that wildfires have for the State.

What makes nutria so feared is that they eat water plants, both root and stem. Nutria will completely destroy water plants , creating an ugly “eaten out” and useless body of water. They are destructive little beasts with voracious appetites.

One of the stranger features of nutria are their stubby orange hooked front teeth. The orangeness comes from the dental enamel that makes nutria easily recognizable. They look to have been drinking Tang. Anyone remember this drink?

Note the distinctive orange teeth.

The dramatic increase in the number of nutria along with their wholesale destruction of aquatic plants in the bayous and estuaries of Louisiana led in 1958 to a bounty being placed on thm. Louisiana paid $5 per tail for the nutria. Over time the bounty system led to a reduction in their numbers. Nevertheless, the remaining tail-less carcass often was often thrown into the water, reducing the water’s oxygen content and negatively affecting the fish. This consequence led folks to question whether the nutria’s lean protein source could be used in some other way, such as a source of food. Might some other practical use for nutria be found?

Admittedly, the idea of promoting and selling nutria as a meat source has proved challenging. The critters have mistakenly been called “river rats” rather than the rodents they truly are. Who would wish to eat a rat? Nutria actually are more like squirrels which in some parts of the country remains a food source. Various chefs have come up with dishes using nutria. Nutria spaghetti casserole has been suggested and nutria meat has been mixed with pork to make sausage. It also has been used in dog treats.

Despite the influx in recent years of nutria into the State of Texas, to my knowledge no bounty system has been established at least in our County, nor have I seen a nutria dish on the menu of any restaurant I frequent. If nutria are to be controlled either a bounty or some practical use will need to be found.

Not long ago I asked my lovely wife, Trudy, if I were to shoot a nutria if she would cook it? Her disgusted look spoke volumes. I didn’t even make it to the part in my spiel, saying how it was gluten-free and low in cholesterol. No, I can’t see nutria or even squirrel being served at the Hutton house any time soon.

A company in Louisiana has also tried to push the use of its fur again and calls its product “righteous fur.” It has lined mini-skirts and has been fashioned into neck wraps. The orange nutria teeth have also been utilized in jewelry making. I don’t know if any of these practical uses for nutria products will catch on but without some practical reason to hunt or trap this critter, I fear for my home State of Texas. I also worry as well for other States and worry for the rest of our country as to what is yet to come. Beware, the nutria are coming, the nutria are coming!

Do the readers of this blog have problems with nutria where they live?

Great Blue Herons Are Adaptable

I’ve written about Great Blue Herons in this blog previously and have been especially impressed with their legends and natural beauty. Pleasingly our ranch has again been graced by several Great Blue Herons that create in me a sense of awe both by their size and striking beauty.

Each morning I’ve spotted  a Great Blue Heron in the top of a tall tree on the other side of our stock tank, watching me. My procedure has been to throw out feed for the duck and  fish. I always throw some feed near the shore to attract fish for the heron that I know will soon arrive. The feed  attracts fish and the Great Blue Heron arrives as soon as my back is turned. I’ve written of this previously in a blog post “Chumming for Heron”.

A Great Blue Heron. Not my heron but representative

The heron’s technique in the past has been to make himself small by curling itself up, hiding in the weeds, and at the right instance, launching itself at an unsuspecting  fish. Lately the fish seem to have caught onto the heron’s fishing ways and avoid swimming close to the bank of the pond. Nevertheless, many fish surface for the food just out of the heron’s reach.

Successful fishing. This is not really my heron but a look alike. Mine is too camera shy to allow me to snap a good image of it.

I’ve witnessed the heron missing meals of late due to this adaptability by the fish. To my surprise and in response to the change in fish behavior, I’ve also noticed a change in the heron’s fishing tactics. The heron  has begun landing on the surface of the water and swimming around like a duck. Upon spotting a fish in the shallow water, the heron suddenly turns tail to heaven. Soon it surfaces with a fish in its beak.

Also I’ve witnessed a second change of tactics. The heron flies across the tank at low altitude obviously searching for fish and then suddenly plunges into the water head first. The heron submerges itself, but sure enough on regaining the surface it has a fish in its beak. It then swims to the bank where it  enjoys its breakfast.

Such adaptability in herons as well as fish, I find interesting and surprising. I assume  in the game of life for herons and fish, adaptability benefits both just as adaptability has great value for us humans.

I trust the heron will enjoy a nice meal for Thanksgiving, as I hope readers of this blog will as well. Happy Thanksgiving!