Tag Archives: wildlife

Flying High

6 Nov

Last night on the way back from town, I observed and drove along with a flock of ~250-300 sandhill cranes returning to the refuge from foraging north of here. (Couldn’t do an accurate flight count and drive at the same time.)

Observing the flight dynamics of this group was really quite interesting. Unlike Canada geese that typically form several dynamic ‘V’ patterns, this flock of cranes did not. Except for the front ‘V’ with a very truncated side ‘arm’ of five individual cranes, the rest of the flock was one long linear flock stretching for a few miles.

Typically with geese the front leading bird of the ‘V’ formation frequently changes, trading places with nearby individuals. This seems logical because energy is then conserved among the leading birds. Not so with this flock. The leading crane never left its position as lead and never ‘coasted’ in flight, aka never altering or ceasing wing-flap flight. I was impressed, but also suspected it was very energy consumptive. Additionally, the five cranes forming the truncated arm behind the leader never changed positions and also never faltered in consistent wing activity.

The cranes following in line behind the leader, on the other hand, often coasted with short periods of folding wings alongside their bodies. Whether this was to rest (energy conservation) or to retain their position in the long line, I cannot be sure. I did notice that some individuals did change positions when some birds slowed or fell slightly out of line. Consequently, the line was truly maintained as one long linear fight pattern! I also wondered how many of these birds were immature cranes who aren’t yet as strong as the older adults, or if they haven’t yet mastered the ‘protocol’ of flying in large flocks. I watched one crane fly under and ahead of five other cranes in front of its former position and fill in a gap in the line. It reminded me of how blackbirds and other flock songbirds change positions while roosting on utility lines, with some hop-scotching to keep a tight and consistent line formation.

I was fascinated by the flock and flying dynamics of these several hundred sandhill cranes! Very different from the geese. Although my original intent was just to monitor where this flock landed, I was treated to an entirely different perspective of flock flying dynamics.

Because questions of daily roosting versus feeding movements and populations of sandhill cranes arose during a meeting between state and federal managers this week, I thought watching where this flock was destined might be interesting. Only a small percentage of the total flock (~24) landed on the small ‘crane ponds’ (small shallow water impoundments just north of the main refuge where cranes often roost). I expected a higher sub-set of this flock to land there. I briefly watched these birds try to locate the members of their family units for roosting overnight, then I drove ahead to monitor the remainder of the flock.

As the larger sub-set of birds approached the center of the refuge where two large impoundments are shallowly flooded for roosting and feeding, the linearity of the flock dissolved as smaller flocks formed and dispersed. Approximately 50% of the flock settled on these impoundments, and the other 50% flew east to roost on the sandbars of the Rio Grande River.

New Mexico state biologists survey populations of waterfowl on the river via aerial surveillance once a month. This refuge conducts feeding surveys every week. We are discussing now whether to incorporate ground roosting surveys for geese and cranes once or twice/month to add to the total data on use of the resources and land in the mid-Rio Grande Valley, especially since most of the cranes now present here are flying north to feed during the day at state-managed refuges (~38 and ~60 miles north of here).

Estimating the light geese roosting population would be easier than that of the cranes because the former typically take flight in one large massive flock. Cranes, on the other hand, usually depart from their overnight roosting places in small family units of 2-4. However, cranes congregate in overnight roosting  flocks at only a few locations on the refuge. Counters posted at each of these locations can easily count the family units and obtain total numbers as they take flight. It might take longer, but it might also be more enjoyable.

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Feeding sandhill cranes at Bosque del Apache NWR

An encounter with a young hawk

29 Jul

I heard a nearby truncated shriek. A familiar sound, but lacking the usual power and strength. Scanning the area around me, I saw a silhouette that, again, was a familiar shape.

Underneath the wide umbrella canopy of an old tree, sheltered from the sun, sat the form of a raptor. My first thought was one of the four raven fledglings that constantly explore the air and ground around the refuge headquarters and resident area. But the shape of the head, attentive and looking around, was not that of a raven.

Most of the buteos have a sloped skull that flows into the downward slope of their hooked beak. The bony ridge over the eyes of a buteo gives the profile of their familiar hooded eyes, which can be piercing.

A raven’s skull is shorter and rounder than a buteo’s. Ravens also lack the boney ridge over their eyes, which are like round black buttons. The long and fat raven beak is the key difference. Thick and long, it might be compared to a tapered black banana.

When the bird awkwardly took flight from the ground, white feathers of the short leggings and underwings confirmed that the mystery bird was a buteo, or hawk. What also caught my eye was that its talons were taking a meal for a ride.

Red-tailed hawk

Red-tailed hawk

The hawk flew into a nearby large and ancient cottonwood tree, where it couldn’t seem to find its balance on a branch. As I walked closer, perhaps about a hundred and twenty-five feet away, the bird gave up flapping its wings in amongst the branches and finding a place to perch. It flew down to the ground.

Now quite curious, I retrieved my binoculars out of the travel trailer and walked back to where I was. Scanning the weedy grass and rabbit brush, I could not see any sign of the bird. But occasionally I would hear a sound like a short and high-pitched bark. An odd sound for a raptor!

Walking slowly and carefully through the dried weeds and grass, I chose a direct path towards the sound. After 20 feet of noise with every foot-fall, I stopped and returned to the chunky gravel and decided to try my luck along the edge of the gravel refuge road.

Recalling what I was taught decades ago when learning to track animals, every footstep was slow and light. Any audible sound of the gravel rearranging under my feet was muffled by the strong breeze and moving tree leaves. Keeping my upper body as motionless as possible, I slowly shifted my weight with every carefully-placed footstep. Moving sideways, without moving my head and arms independently was a bit tricky, trying to keep it all a fluid motion. I made a mental note that I needed to get back into Tai Chi to improve my balance and proprioception.

With the binoculars held up to my eyes, I spotted first the raptor head, then the neck. Moving closer, I could monitor the bird’s eyes through the binoculars. Whenever its head and eyes moved in my direction, I froze; sometimes with a foot suspended above the gravel while waiting for the head and eyes to turn away from my direction.

It seemed to take forever for me to approach near where the bird was on the ground. Perched on a large branch lying on the ground and in the shade of the tree was a young hawk. A few features informed me that it was immature. The color of the eyes (iris) were grayish with subtle yellow. Adult Red-tailed hawks have dark brown irises, which often blend in with their black pupils.

The white breast feathers were typical of a red-tailed hawk. However, its white patch was smaller than most others I have seen on juveniles of this species. Below this patch were soft, almost downy variegated feathers; white with wide bands of medium to light brown, and many of them blowing in the breezes sneaking under the canopy of the tree. It’s cere was large and bright yellow, the brightest coloration on this mostly dark bird. Little white showed on the top of the wings and head. Below its white softly feathered leggings betrayed the presence of knobby legs and gray-yellow talon. This bird had not gone through its first molt yet.

Now at about 25 feet from the bird, I didn’t need the binoculars anymore. I held them to my chin to avoid any exaggerated movement. Standing stock still, I studied this bird and wondered why it decided to perch on a grounded branch rather than up in the tree canopy.

Slowly shifting my body a few more feet to the right I was able to see more of the story. One set of talons grasped the wood, and the other…….   All I could see was the bottom of its leg and the upper toes disappearing in the gray-rusty colored fur. These talons were deep into the hindquarters of an unidentified furry mammal with soft gray and tan-orange fur. Below the heap of fur was the bottom of a leg with some white fur and a foot. A paw, to be more exact. With the binoculars, the shape of a paw with dark tan fur had me stumped. Then another feature grabbed my curiosity.

To the right of the hawk I noticed and oddly shaped reddish branch covered with yellowish knobs. It looked like a miniature bloody chainsaw! Not until the hawk picked up its buried talons and shook the heap of fur did I see this odd reddish bar shake as well. It was attached to the heap of fur!

I realized that the hawk was sitting on a hindquarter that was still attached to the bloody spine of a mammal. After shaking the heap of fur and the rib, the hawk looked down at his trapped talons. Apparently the youngster buried those talons into the scavenged meal and was unable to remove them. Shaking it a few times unsuccessfully released it. It finally took a break and glanced around, yawning. And I continued to watch.

After a furious attempt to shake the cumbersome attachment to its talons, it managed to jump up off the fur heap and branch, and turn around with a squeal. Possibly sitting on the rib and powerfully pushing off, its talons were finally dislodged from the fur. With great dexterity, this determined bird caught the entire carnage before it fell on the ground, parked it on the branch, itself carefully perched on the wood, and began to tear off tufts of gray and tan fur. A whitish tail surrounded by gray and tawny-orange fur leads me to guess that the unfortunate meal was a white-tailed jackrabbit, a large relative of the common black-tailed jackrabbit.

The beautiful black and brown banded tail feathers confirmed the age of this bird. Although fledged for a month or so now, it was learning to hunt and feed itself on its own. Finding a partially consumed meal might seem an easy meal for this youngster, but now it needs to learn constraint on digging its talons into prey. And I thanked it for letting me share its experience.

 We need another and a wiser and perhaps a more mystical concept of animals. Remote from universal nature, and living by complicated artifice, man in civilization surveys the creatures through the glass of his knowledge and sees thereby a feather magnified and the whole image in distortion. We patronize them for their incompleteness, for their tragic fate of haven taken form so far below ourselves. And therein we err and greatly err. For the animal shall not be measured by man. In a world older and more complete than ours they move finished and complete, gifted with extensions of the senses we have lost or never attained, living by voices we shall never hear. They are not brethren, they are not underlings; they are other nations, caught with ourselves in the net of life and time, fellow prisoners of the splendor and travail of the earth. –  by Henry Beston, excerpted from The Outermost House

Fuzzy owls day off!

8 Jun

“Some things you miss because they’re so tiny you overlook them. But some things you don’t see because they’re so huge.”
― Robert M. Pirsig, Zen and the Art of Motorcycle Maintenance

The four Great Horned owlets near the Refuge headquarters have fledged from their nest. I visited with the entire family for a few hours the other day as they roosted in two large cottonwood trees. I was privy to some interesting behavior and interactions.

At six to eight weeks old, Great horned owl nestlings will begin to venture from their nest. By climbing branches or other structures next to the nest, the  young begin to exercise and strengthen their leg muscles. They will also flap their wings for the same purpose, often jumping around in the nest while flapping. At this stage, these nestlings, and other large birds of prey, are referred to as ‘flappers’. They will then progress to taking flight for short distances.

The four owl siblings were often spotted flying around inside the fire tower structure, where they could safely exercise without falling to the ground. It was like a large playpen for these owl youngsters. We knew then that they would be fledging soon outside of the fire tower box and take wing.

Owl fledglings remain in close proximity for several weeks.  They will often roost together in the same tree or in neighboring trees. Adults generally roost away from the young, albeit nearby, and they will continue to feed their young with decreasing frequency throughout the summer.

I spotted three of the youngsters with the dad in one tree. The lone sibling was in a tree across the way with mom. I heard the adults communicating with each other shortly before I spotted them, which is how I identified the gender of the adults. A pair of nesting ravens (in a spruce tree ~400 yards from the cottonwoods) tried harassing the lone owlet. Mom had enough and chased them off.

I quietly chuckled while watching the group of three youngsters preen each other while perched on a large tree branch. When one tried preening the feathers on its sibling’s leg, it got a foot of talons in its face. So it stepped on its siblings foot and proceeded to continue preening its leg feathers, while the other tried in vain to pull its leg away. All the while, third sibling did it’s rolling and bobbing the head-thing while watching its two siblings argue about pedicures.

I returned later with the camera and found that the siblings had separated. Two were deep in the shade of the tree canopy, their heads pulled down into their shoulders and wings. They blended in quite well with the rough bark of the tree. One lone sibling was still awake, watching below and in plain view. I set up the tripod and zoomed in for a few portraits. These youngsters still have some downy feathers on their heads, which makes them look lighter than the adults.

As the day was getting warmer and brighter, this one eventually succumbed to nap time. It very slowly tilted to the side and laid prone on a branch next to it.

Unfortunately, a visitor appeared, yelling out, “Whatcha watching there?! Anything good?!” Because it was my day off, and I was not in anything associating me with refuge staff, I told him to be quiet!

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On Being an Osprey

15 May

My treat for the day was watching the osprey finally get a fish on its fourth dive into the pond.

I can see its eyes, its talons, it indecisiveness and aborting a dive. I can almost feel it spring out of the water, shaking that cold wetness from its feathered back and wings, climb back up in the air, and finding a thermal to coast, I could almost feel its exhaustion.

I stood there with my eyes projected through the binoculars, almost flying and diving with it, smiling and rooting for this osprey, calling it ‘Sweetheart’, and remembering why it was known as the ‘sea eagle’ where I grew up.

I love ospreys. If I can’t be an osprey, take me with you in flight and in dive.

Osprey at Yellowstone; photo by Jean Philippe Dugault, French nature photographer.

Osprey at Yellowstone; photo by Jean Philippe Dugault, French nature photographer.

A Bald eagle adapts to a handicap

16 Jan

A handicapped Bald eagle on the Bosque del Apache NWR has been reported by a few individuals the last three days. A visiting photographer*  shared with me his magnificent photographs and observations capturing how this bird has adapted to daily life. How the injury occurred and when is unknown to us. But the animal appears to have adapted quite well to flying, landing, perching and even obtaining its own food.

Our one-legged Bald eagle. Photo courtesy of Mike Endres.

How does this handicap affect an eagle’s ability to perform its life functions? As this individual demonstrates, missing half a leg and one taloned foot probably does not significantly impair its ability to fly, perch and eat. However, depending on its sex, could it affect its ability to reproduce? That is a good question, especially for a female. Although no obvious impairments might directly affect courtship and nesting, we won’t know conclusively unless the bird is observed during breeding, nesting and fledgling time.

All eagles are sexually monomorphic, which means both sexes look alike. Thus determining the gender of an individual Bald eagle is difficult. Although the female may sometimes be slightly larger than the male, this difference is often subtle and only determined if a pair are together, such as at a nest. The only other differentiating characteristics, measurements of the bill depth and length of the rear talon, can only be discerned with the birds ‘in hand’.

How can we know if the bird is a male or female? We won’t unless it is seen with its mate, if it is paired, to compare size. The only other recourse is using molecular biology. For this, biologists rely on blood samples, which is an invasive and stressful experience for animals, or collecting feathers, which is the preferred non-invasive approach.

Feathers are processed and analyzed by techniques that are sometimes referred to as ‘molecular sexing’. DNA is extracted from feather segments using a common laboratory kit. Small aliquots are then prepared and run through a polymerase chain reaction (PCR) with molecular primers that ‘bind’ to a specific portion of a gene that is associated with either the male or the female. The ‘bound’ segment(s) of DNA is then amplified many times. Aliquots of the amplified PCR products are then digested into smaller segments and run on an electrophoretic gel. The resultant banding patterns, which indicate the sizes of  all the products, are then matched with what is expected with the male or the female gene segment.

The entire process may take from 3-5 hours in a well-equipped lab. With many sexually monomorphic birds, this is often the only way to determine their gender, but it is non-invasive with little stress (if any) for the birds. When we banded American pelican juveniles (pre-fledge) last summer, the final step (after attaching two leg bands and weighing) was plucking a feather and putting it in a plastic bag with a corresponding code. The sex of each of the seventy-five birds was molecularly determined back in the lab at a later time.

What might be the prognosis for a normal life for this bird? Perhaps we may be bold enough to predict it will survive and live normally. Bald eagles tend to have nearly equal contribution to mated life. During courtship, they fly and lock talons together. Paired bald eagles share duties in nest building, incubating eggs, and providing food for the hatchlings. Consequently, the bird’s life as a mated pair may not be jeopardized. In fact, compared with other raptor species, Bald eagles share nesting duties between the sexes more than many other birds of prey.

However, as the number of hatchlings increase, the female’s role of providing food increases because the male tends to range further for food. Thus, if this bird is a female and her ability to catch and provide food for herself and a large brood is compromised, the probability of higher chick mortality may increase.

Another factor is defending the nest and caught food. The loss of one taloned foot might be decisive in a battle with another bird, especially if it is a large challenger such as a Great Horned owl. But as we have seen demonstrated by this bird here at the Refuge, it seems to have adapted well thus far.

Let’s hope his or her future is bright and fruitful.

The eagle has landed.  Photo courtesy of Mike Endres.

* I gratefully acknowledge and thank Mike Endres of Little Wing Photography  for sharing his photographs and observations of this eagle on the Refuge. I hope readers will visit his website (follow link above), and view his other excellent photographs. Thank you again, Mike. I enjoyed your visit and our chat.

Western Tanagers are here!

12 May

No strangers to the Big Bend area, tanagers are some of the most colorful birds in the spring and into late summer here. And one of the favorites for both color and song is the Western Tanager.

Western Tanager. Photo courtesy of Anne Theil.

Western Tanager. Photo courtesy of Anne Theil.

The breeding range of these birds extends from southeastern Alaska to south through the western states and West Texas. Most Western Tanagers arrive in the Trans-Pecos and High Plains regions during spring from early April to late May. They usually breed in Texas from late April to mid-August. In the fall, they migrate south to central Mexico for the winter.

Big Bend National Park is on the migratory flyway of several tanagers as they migrate north and south. Thus, several species of tanagers can be found, especially in the Chisos Mtns., but also in the neighboring area. I enjoyed watching and listening to these colorful birds last May around Cedar Springs area on Terlingua Ranch. A local resident recently photographed a Western Tanager hunting for insects in a clutch of creosote.

Most red birds owe their colors of red, yellow and green to a variety of plant pigments known as carotenoids, which are deposited in their feathers. The Western Tanager gets its scarlet head feathers from a rare pigment called rhodoxanthin. Unable to make this substance in their own bodies, Western Tanagers probably obtain it from their diet of insects that feed on conifer (pine, fir, yew, and cedar) needles, and small fruit (especially of the honeysuckle) which contain the pigment. These pigments are stored specifically in their crown feathers to give them their red appearance.

Another related species of interest is the Flame-colored Tanager. Historically common only to central Mexico, their range has increased north over the last decade. They have become more common in the Sky Islands of Arizona with a few documented sightings in the Chisos Mtns. of BBNP. Interestingly, because their DNA are closely matched, more than of other tanagers, the Western and Flame-colored Tanagers are quick to mate and hybridize. Increasing documented sightings of hybrid birds are reported in Arizona the last several years. It is not unusual for closely related species to hybridize when their border habitats overlap.

Photo courtesy of Anne Theil.

Photo courtesy of Anne Theil.

Donkey or Burro??

3 May

They are the same animal. The only difference is the time frame and location in which the two names came into usage. On the other hand, before either of these words were ascribed to this cousin of the horse, it was called an ‘ass’. And it still is in most countries. What’s the difference?

Asses, zebras, and horses are members of the genus, Equus, which is from Latin for ‘horse’. DNA recovered from a fossilized horse bone (700,000 years old) places their common ancestor to be between 4.0 and 4.3 million years ago. Although the domestic horse and the zebra species have gone through several intermediates on the evolution tree since then, the ass has not. So how did the ass become a donkey or burro?

The wild ancestor of the domesticated donkey was the African ass, Equus africanus, which lived in the deserts of northeastern Africa. Members of the latter were domesticated as work animals around 3,000 B.C. in Egypt and Mesopotamia. In the late 18th century, the English name ‘donkey’ came into use, probably formed from the word ‘dun’, referring to the dull gray-brown color of the animal, and the suffix ‘-key’ to rhyme with ‘monkey’. However, in other areas of the globe, the animals were still referred to as ‘asses’.

Because it can carry heavy loads and cope with hot and dry conditions, the donkey became one of the most important domesticated animals. They were also favored for their easy maintenance; they are very adept at foraging for their own food. These traits, along with their toughness and adaptability, able them to thrive in harsh arid surroundings. Consequently, the Spanish found them invaluable during their explorations and establishment of settlements and missions. And it was the Spanish that brought them to the American continents during the 1400 and 1500’s along with their cousin equines, the horse.

Spanish explorers introduced the donkey to the subtropical deserts and semi-deserts of northern Mexico and the American Southwest during the 1500’s. The animal began to be known in Mexico as ‘burro’ in the early 19th century. Burro probably derives from the Spanish ‘burrico’ and the Late Latin ‘burricus’, meaning “small, shaggy horse.” Consequently, the animal may be called ‘donkey’ or ‘burro’ depending on which side of the border you are on. And an ‘ass’ if you are on the other side of the ocean.

Regardless, all three – donkey, burro, and ass – are the same genus and species: Equus africanus. On the other hand, the International Commission on Zoological Nomenclature ruled in 2003 that the domesticated ass, aka the donkey/burro, may also be classified as E. africanus asinus, simply because the domesticated animal was classified and named before the wild ass. Consequently, one will find the donkey/burro with either scientific name, whereas the wild ass will be associated only with the one. Although the colors and a few other small appearance details may distinguish the wild and domesticated ass, they are genetically the same animal.

Burros in Big Bend

Myths and legends abound relating stories on how the burro came to the Big Bend area. Without doubt, the animals arrived by many means and over many centuries. With the Spanish explorers and conquerors, and Mexican settlers, came the burros into the American Southwest. They were tough as nails, adapted to the arid and undeveloped area, and needed little in the way of husbandry efforts. They were the perfect work beasts.

Burros in Big Bend (photo courtesy of Rick Ethan, Terlingua)

Burros in Big Bend (photo courtesy of Rick Ethan, Terlingua)

Later came the prospectors and miners of the 1800’s and early 1900’s with their burros. As in Mexico, they became the favored beast of burden and they could almost fend for themselves. The animals hauled wood for railroads and fuel, ore from the mines, and grain for their human masters. Burros were also bred with horses for their hardy offspring, mules. These animals were used to haul stagecoaches and serve as supply trains for the Army during the early 1900’s.

Historically, burros were not corralled or tethered in the same way horses were. The usual practice was to leave them to forage on their own and then they were rounded up when needed. However, some escaped or were never rounded up. Many outlived their owners. They eventually roamed on their own and became ‘feral.’

Newspaper reports of burros abandoned by farmers can be found in the last several years. The series of droughts throughout the Southwest have prompted farmers to drop off burros in roadside pastures or other rural areas. These and other feral burros form small herds or join other herds. Escaped burros from across the border often join these herds and their population increases quickly. Burros are not heavily preyed upon and can live up to 40 years, so their population can double in less than three years if conditions are good.

An adult burro averages about five feet tall at the shoulders and weights about 350 pounds. It eats about three tons of food a year: grasses, forbs, browse. Their foraging can greatly impact the ecosystem that evolved and came into balance long before this non-native animal was introduced. Because of their large size, number and adaptability, the burro can be a problem for land managers in arid and semi-arid areas. If their numbers remain unchecked, their impact destabilizes the ecosystems they inhabit. Additionally, accidents on the roads are becoming more common. Burros aren’t motivated to move out of the roads and drivers crashing into wild burros.

Most feral burros live on public lands, especially the vast stretches of BLM land, national parks and wildlife preserves. The animals are not native to Texas or to the Americas. Nor are they a threatened and endangered species, or even of ‘heritage’ herds. Most of the animals have been abandoned from nearby ranches, many crossing the border from Mexico, and their offspring increase their populations.

Several national parks, such as Big Bend and Grand Canyon National Parks, had an early policy of hunting and shooting feral horses and burros to restore the lands to pre-human ‘wildness.’ In response to public outcry of mass killings, most of the national parks arranged for the capture and relocation of feral burros from their landholdings. However, they seem to return or replenish their numbers from mysterious origins.

Burros, donkeys and asses are the same animal. But, as for how they got here, you can choose your favorite legend.

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