The Varied Thrush – The Northern Robin

by Dave Hanks

If you are in “wild” country, and will but stop to listen, there is a whole cornucopia of sounds. Some sounds, like Elk bugling or geese honking overhead, are very intriguing. One such sound haunted my wife and I over and over again whenever we were in northern Canada. It was a bird call. We could never pin-point the location from which it came and, because it was a call we were not familiar with, could not identify the species. One evening, southward bound out of the Yukon into northern British Columbia, we were resting our bodies by lying in an open-air hot pool at Liard Hot Springs, B.C. We heard that haunting call again, very close this time. It was coming from a branch just above our pool. It was a Varied Thrush, and it was very mesmerizing to be soaking in hot water, out of doors, and having that bird serenade us!

This Thrush is slightly smaller than the American Robin, but it also has a reddish-orange breast. The breast, however, has a bluish stripe across it. The face also has a stripe across the eye, and the male’s back and crown are a bluish tint. This summer resident of the far north migrates to the Washington, Oregon, and California coasts for the winter months. We have even been lucky enough to have had one of them in our yard one spring – a rare southern Idaho occurrence.

Varied Thrushes like to nest in mature, coniferous woodlands that are dense and moist. If you have been in the far north, you will realize that there are lots of insects. These birds like to spend much time in the trees feeding upon them and will defend their feeding territory from intruders. They do this by first turning their back and giving a tail-up display. If that doesn’t work, the male will then turn to face the problem and extend his wings to display the colors on his under-wings, plus the white tips on his tail. The tail is then extended over his head.

The logging of mature forests has caused a reduction of breeding populations of this species. My wife has a love affair with this beautiful bird, and we would feel sad if we could no longer hear its eerie song.

Along the Oregon coast in February

Mysterious Interloper

by Dave Hanks

In 2003 and 2004 I was called upon to identify a mysterious bird seen in the tall trees in the south-west section of Burley. I say mysterious because the species involved managed to stay hidden most of the time, or at least when I was called to observe it. After much searching and discussion of behavior, an unlikely visitor was identified. Unlikely because this bird is closely associated with marshes, where it nests. Because the river is within easy flying distance is the only reason that seems logical for this large wading species to be where it was sighted.

The AMERICAN BITTERN is 28 inches long with a voice that sounds like water gurgling. When alarmed it will stand in the sedges with neck stretched skyward, looking much like the reeds that surround it.

Immature Night Herons are also streaked and could possibly be confused with the bittern.

It is a hard species to approach and to get photographs requires a bit of luck.

Deferred Maturity

by Dave Hanks

Young song birds hatch, fledge, and are ready for migration. The young birds usually resemble the female parent. However, by the following spring the males acquire their adult breeding plumage and assume parenthood. Their development is relative simple and quick. However, most raptors and gulls go through several stages before reaching sexual maturity. Large birds like eagles or buzzards have 4 to 5 stages of development. Hawks usually have two stages to go through over a two year period to reach maturity.

Buteos are large hawks with broad wings. The FERRUGINOUS HAWK (pictured) is the largest American Buteo. Only the Bald Eagle, Golden Eagle, and female Snowy Owl weigh more than this hawk. Ferruginous Hawks go through three stages after the nestling stage: juvenile, sub-adult, and finally adult – three years from hatching to adulthood. This species has been known to live for 20 years (determined by re-catching banded birds), although the majority die within a 5 year period –which allows a five year old bird two opportunities to nest.

Ferruginous Hawk’s first year mortality is estimated at around 66% and adult mortality at about 25% per year thereafter. This ground nesting bird is preyed upon by Coyotes, Golden eagles, and Great horned Owls. Jackrabbits rank high on this species food list. When prey sources are at a low, many hatchlings will die of starvation. Illegal shooting of adult birds has also caused a problem to this not-so-common species.

This magnificent hawk has been used as a falconry bird in its native range.


A young Ferruginous in the sub-adult phase


Christmas all year!

by Dave Hanks

I can’t wait for the dawn when the sun lights the sky, To photograph beast or bird as each passes by!

I’m like a Christmas Eve kid thrashing in bed sleeplessly, Anxious to open those presents that are under the tree.

But I don’t seek presents wrapped with tinsel or bow. Nevertheless they are gifts that “set me aglow”.

There are never enough minutes in each safari day, To “shoot” all the species that come our way.

But those that I capture in each camera frame, Excite me like Christmas! It’s all just the same.

I can’t wait for the dawn when the sun lights the sky, To photograph beast or bird as each passes by!

SCOTT’S ORIOLE is a special gift. It is a southwestern species that combines yellow with the oriole black, instead of the usual orange. It’s a medium-sized oriole with a black hood that extends onto its breast and back. Its belly and rump are a bright yellow.

We have seen this species in the scrublands of southeastern Arizona, and in the juniper/scrub oak forests of Arizona’s Madera Canyon. Yucca is a plant with which it is closely associated. Yucca is used as both a nesting site and also its fibers and leaves as nesting material. This insectivore is one of the first birds to start singing each morning before sunrise, as well as throughout theday in summer – a real songster that will even sing in the winter.

Scott's Oriole Resting on a stump my wife provided for that purpose

Resting on a stump my wife provided for that purpose

Homeostasis and Waterfowl

by Dave Hanks

The bodies of all of us, both human and animal, have homeostatic mechanisms. These are both physiological and behavioral. Homeostasis means a state of constancy. The body must maintain its functions on a steady plain. If we’re too hot, we sweat; if we are too cold, we shiver; if we are sick to our stomach, we vomit. We could, also, turn on the air conditioner, or turn up the furnace, or take some Alka Seltzer. These are all examples of how we keep our bodies running on an even keel.

Waterfowl, with basically the same problems as ours, do basically the same things. “WATER RUNS OFF A DUCK’S BACK” is true, but only with a little homeostatic help – both physiological and behavioral. When trying to photograph waterfowl, it can be disconcerting when they won’t remain still – always fixing their feathers and probing at their tail. There is an oil gland at the base of the tail. The oil is the body’s answer for water proofing feathers, but can’t reach its destination without some help.

BARROW’S GOLDENEYE (pictured) is a northern species that graces our area’s open water during the winter months. By staying dry, their hollow, air trapping, feathers will protect them from the cold. To do this the feathers must repel the cold water. Hence, the duck rubs oil up and down each feather’s shaft. The feather filaments each have barbules which hook on to the adjoining filament. This forms a continuous covering to keep out the wet. When you observe the bird preening, they are doing two things. They are re-hooking the barbules and oiling their feathers. Also, without this constant oiling and barbule hooking, the bird would be unable to fly because the feathers would be waterlogged, and the unhooked feathers would be unable to trap air.

Comfortable swimming in an icy pool

Types of Migration

by Dave Hanks

When one thinks of migration, one usually thinks that animals go south in the autumn and go north in springtime. That is what is called COMPLETE MIGRATION, but it is an over simplification. Amount of daylight, weather conditions, or food supplies; are factors that influence the time or type of movement. Some species like Robins, Red-Tailed Hawks, and Towhees are PARTIAL MIGRATORS. Many of these species migrate but a portion stay around all year long – especially if food sources are adequate or to protect a territory and nesting site. Young birds are more apt to make the long trip because of a low social rank. Adult individuals force them to vacate the area.

DISPERSAL is the result of newly fledged birds moving to find space where they can establish their own territory. It is believed that this type of movement is the origin of complete south/north migratory patterns. Another type of migration is called DIFFERENTIAL. This type is influenced by existing conditions. Where nest cavities are in short supply, the American Kestrel may not move away from his established nest box. Water birds may move to the closest area that has open water. ALTITUDINAL MIGRATION is from High Mountain (where weather conditions mimic the more northern latitudes) down to lower elevations to spend the winter. Pine Grosbeaks and Juncos fit this type. Juncos that are abundant around bird feeders in winter are absent in summer.

IRRUPTIVE MIGRATION is very irregular. This is not necessarily a north/south trajectory, but often a lateral movement for better feeding conditions, and is not made every year. Years of severe weather can be a stimulus. A shortage of conifer cones makes Crossbills move to more productive forest areas. Abundance of small rodents (voles, mice, gophers, etc) affects predator movements. Owls especially are birds that are subject to these conditions.

Like all things in life, what appears simple on the surface is usually much more complicated.

A Great Gray Owl: An irruptive species

A Great Gray Owl: An irruptive species

Courtship Variety

by Dave Hanks

You are probably aware of some common bird courtship rituals – such as a male feeding a female, or the male and female preening each other; the cooing of doves, and the singing rituals of many other bird species. Grouse and turkeys display by strutting. Some mammals appear to be fighting, but it is only the male and female rough-housing – which gets their hormones flowing.

Other species have some unique courtship methods. Spiders are especially unique. The Australian Red-Back male is much smaller than the female. The female requires the male to do an elaborate dance for over an hour to two hours. During the dance, the male connects his web to her web. He then taps a drum-like rhythm on her abdomen. If he stops too soon, she will bite his head off – which she does anyway, after mating.

Rhino courtship is called “Bluff and Bluster”. When in estrus, the female urinates on dung piles to lure a male on. The male will scatter these piles in an attempt to keep other males away. The bull then snorts and swings his head side to side and runs from the female. Afterwards, the pair will then snort and spar, with the female working the male over vigorously. The couple will stay together for several days or up to several weeks.

The Leaf-Nosed Bat will find an opening in the rock of a cave that is narrow enough to only allow one other to enter, thus keeping other males out. He will call and flap his wings to entice any available female. If one enters his little abode, he wraps his wings around her and nuzzles her. If she doesn’t fly off, they will mate.

A favorite bird of mine is the COMMON SNIPE (pictured). I like him, not only for his looks, but for his “winnowing” display that can be heard on a spring morning over a meadow. He gains altitude and then descends in a spiral pattern. The air rushing through his wings makes sounds like the bleating of a goat. In many languages he is known as the flying goat. He will, also, make shallow dives to produce a “drumming” sound with his tail. Such a repertoire to go through in order to attract female attention!

Resting after the morning’s aerial displays

The Domestic Cat: A Miniature Tiger

The cat is a favorite household pet. Around 30 percent of American households have one as a pet. This animal has been a native historically world-wide, except in Australia and the oceanic islands. Their life span is 12 to 18 years.

Cats are famous for always landing on their feet. Try to throw them onto their backs – they will twist their bodies to face the ground. The vestibular apparatus of their inner ear orients their balance and sends a signal to their brain to rotate their head to an upright position – the body then follows suit. As a former wrestling coach of the Burley Bobcats, I stressed the fact that we were cats, and that therefore, we shouldn’t be turned on our backs. But back to ears, cats have phenomenal hearing. Large ears funnel sound waves to their inner ear, which is very sensitive to high-frequency sounds.

Cats have large eyes with binocular vision – a common predator trait. They can see as well as we can in the daylight, but up to six times better after dark. Images are intensified by a reflective layer outside of the retina (tapetum lucidum). Light passing through this layer is usually absorbed and is stimulating to nerve endings. If not immediately absorbed, it is reflected back, making cat eyes glow in the dark.

Your pet purring in your lap is a pleasant sensation. It is a method of communication that is felt as well as heard. Big cats have a hyoid bone in their larynx and this allows them to roar. Small cats, like Bobcats and Cougars, don’t have this bone. They all purr. Purring is associated with contentment, but, may be done under stress. It is a trait not well understood.

As “quick as a cat” is an apt description. This, along with a leaping ability that can extent up to seven feet high when properly motivated, makes this animal as frightening to other small mammals as a tiger would be to us.

Felis catus: A cuddly pet to us – a terror to rodents


Females: Larger than Males in many Species

by Dave Hanks

Predatory birds, many snakes, many fish, insects and spiders, the Blue Whale, and even the Spotted Hyena; are species where the female is the larger of the sexes. This is especially true with species that prey on vertebrates, or species that lay tremendous amounts of eggs. Obtaining food for herbivores is relatively easy, as long as the vegetation has not been denuded.

Natural selection has favored bigger females in many species, as it is a fecundity advantage. It takes more energy to produce eggs than to produce sperm. This requires the female to carry more weight, and the female must be larger to carry the extra weight that is required for that energy. Also, she is on the nest much of the time. Males are smaller because there is less demand on them to care for the young, and smaller sized males are more agile, and therefore more maneuverable when pursuing prey.

In predatory birds, such as hawks and eagles, the size difference reduces the competition for food between mated pairs. The bigger female will take bigger prey, which the male has trouble capturing. This division of what’s hunted puts less stress on the various prey species.

The NORTHERN GOSHAWK is a large falcon (21 to 26 inches) – larger than its cousins the Sharp-Shinned and Cooper’s hawks. It is a northern species that is not common. It mostly preys on larger birds (even ducks), but will take squirrels and hares. It is a resident of mixed coniferous woodlands, where it fiercely defends its territory and nest. This bird is a “home body” and rarely migrates, except from extremely cold regions.

We were most surprised to see one in our big maple tree. It had killed a Collared Dove. Feathers were floating down, as it plucked them out in preparation to eat its catch. We had only seen this bird (briefly) on two previous occasions.

The Finch Family: Diversity Personified

by Dave Hanks

Fringilladae is a large, world wide family. These are Passerine species – medium to small, perching, terrestrial birds. They are mostly migratory, have 3 toes opposing one, and are fine singers. Finches are seed eaters, and America has 14 species in this category. They range in diversity from Goldfinches, to Grosbeaks, to Crossbills, to Red Polls, to Bramblings, to Siskins; and finally to Purple, House, and Cassin’s Finches. The last three listed resemble each other, and are closely related.

The House Finch is the most familiar, as it is around the feeders in people’s yards most of the year. Purple finches are a dark purplish-red, but are more of an eastern bird. All three birds combine reds with their browns. The females of the threesome are sparrow-like in appearance. Cassin’s Finch is my favorite of this trio. Even though the Cassin’s looks much like a House Finch, when the two are together you will see a noticeable difference. CASSIN’S FINCH has a pinkish-red breast, and a dark red crown. The brightness of these two colors set it apart.

The male Cassin’s sings long, complex songs. He may even mimic other species. The female sings too. Her song is softer than her mate’s and only half the volume. A one year old male sings louder than either. He tones it down when he’s mature. Perhaps it’s to let any female know that he is now ready for mating. Interesting!

Some of the most positive things I did in my Biology classes were the field trips that we were fortunate to go on. We studied all aspects of whatever ecosystem we visited. On one such trip, two girls had situated themselves by a tiny creek. Birds were coming to the water. The girls were having a significant, eye opening experience. They didn’t want to leave the spot to do anything but watch the birds. A species that they were especially enamored with was the Cassin’ Finches that were coming in – their colors extra bright for the spring nesting season.