The Phenomenal Speed of Bird Migration

by Dave Hanks

A big break-through in bird studies is the result of the invention of a tiny mechanism the size of a dime. The device is a light weight geolocator backpack that is attached at the base of a bird’s spine. This is a location that doesn’t off-set the bird’s balance.

This device surprised researchers by revealing that migration speed is three times faster than was previously believed. One example: an individual leaving Brazil on April 12th will arrive on its USA breeding grounds by the end of the month. It is interesting to note that the desire to reach the breeding area results in a faster spring migration than the fall movement to warmer sites for wintering.

Most species migrate on a strict schedule – often the same day each year, which is determined by the length of daylight. To conserve energy, birds will ride thermal currents. Soaring is much easier than flap-flying. After the initial round trip, an individual can find their way – even if blown or thrown off course. It is almost as if one has a set of maps.

The GOLDEN-CROWNED SPARROW (pictured) breeds in southern Alaska and the Yukon, and winters in California. The relative short flying distance is a survival advantage for this species.


At rest in a northern California shrub

Carryovers from an Ancient Past

by Dave Hanks

Most all of us have visited museums that feature the huge skeletons of dinosaurs in their many and interesting forms. Although they are now extinct, their remnants now abound in much smaller forms. These modern ones come in four classes: Crocodilians, turtles, lizards, and snakes.

Reptiles are vertebrates (backbone), which breathe air and are cold-blooded. Their bodies cannot regulate their body temperature – which must be done by either seeking the sunshine’s warmth or the shade’s coolness. They are not “slimy”, but have dry, tough, scaly skin. Their skin has a high level of keratin to protect their bodies and prevent water loss.

All have four legs, with the exception of snakes. However the big constrictors have vestiges of hind legs in the form of stumps that are hidden under the skin. It is interesting to know that these big snakes will use these stumps to caress their partner when mating. The young develop inside an amniotic membrane, inside an egg, laid on land. Most reptiles are poor mothers that lay their eggs and leave them to hatch and care for themselves. Crocs and alligators will watch the nest and tear it open when the babies hatch. The little ones cries alert mom, who then transports them, in her mouth, to safety. Some python will curl around their eggs and the big King Cobra makes a two chambered nest – one chamber for the eggs and the other for the mother, and woe unto any whom dare to disturb her.


American Alligator, Pond Slider Turtle, Desert Spiny Lizard, and Western Diamond-Backed Rattlesnake

The Sharpening of one’s Senses

by Dave Hanks

How many times have you been startled by a snake, that you didn’t know was there, but almost stepped on? Or been distressed by finding a tiny bug crawling on your clothing? There are so many small, quiet species (and even some large ones) that you could bypass and never know they are near. Big predators make a habit of silence to enable them to stalk their prey. What slips so quietly through the habitat as a Mountain Lion? Forest employees in fire lookout towers have reported watching grizzlies move off a trail as hikers pass by – oblivious to the bear’s presence. The bear then returns to the original spot and continues its foraging.

A small, quiet bird that most would never notice is the BROWN CREEPER. It is a well camouflaged bird of woodlands. Resembling a small nuthatch, it flies to the base of a tree and then moves up the trunk in a spiral movement picking off invertebrates as it goes. Its movement is the opposite of nuthatches, which move down the trunk headfirst.

Brown Creepers build a hammock-shaped nest behind peeling flakes of bark. This is a common species, but one would hardly guess it because they are so small and silent. They rarely call, but when they do, it is a piercing sound.

There are so many insects, reptiles, rodents, and birds that move so quietly – that the quantity and variety that is going unnoticed is surprising! Many folks are missing out on a world of intrigue, because they have yet to become aware of what’s underfoot or partially hidden in the vegetation.

The quiet things are all around – But we don’t notice, there’s so little sound.

But oh for him whose ears are keen – A rich reward, things seldom seen.

So when you’re about ‘mongst shrubs or wings – Take time to notice the quiet things!


A tiny Brown Creeper moving up the tree trunk

Arena Behavior

by Dave Hanks

A lek is a strutting ground. It’s a Dutch word that science has adopted. The lek is comparatively small when compared against the whole habitat living area. Species that engage in Arena behavior display no sex drive or fighting drive outside of the arena.

This may seem strange to us. Perhaps nature has evolved a method to keep tensions at a minimum and promote harmony. Animals that engage in Arena Behavior do all their courtship, fighting, and mating within the arena (or Lek). It’s like all the boys gathering at the gym to show off their prowess. The girls show up and select the male that appeals to them and then mate with him right there in the gym. It is interesting (from research) to see that the males in the center of the Lek – which is usually on ground slightly higher in elevation – are usually preferred more often. I wonder if the human drive to have their home in the higher areas of a city has any subconscious relationship to this.

I know, from being in athletics – that venting aggressions on the playing field made me, and others, very low keyed and easy going when away from competition. This is one of the benefits that is no longer available to me, since I am no longer participating.

A male SAGE GROUSE (pictured) with chest and tail feathers extended and his yellow air sacs puffed up to make a booming sound. This is an early spring ritual.


Strutting on the lek

The Bruce Effect

by Dave Hanks

The Bruce Effect is the result of sexual pheromones in rodents. It is the manipulation of pregnancy by pheromones. For instance, a female rat comes into estrus and mates. She is very familiar with her partner’s scent (pheromones), and will not tolerate a strange male. If another male appears, his odor will cause the female to abort her fetuses.

This pregnancy block effect was first noted in 1959 by Hilda M. Bruce – thus the name. Besides rats, the pheromone was observed in deer mice, meadow voles, and collared lemmings. The blockage has also been suggested, but not confirmed, in lions.

Rodents are the largest group in the mammal category. These species include mice, rats, hamsters, guinea pigs, beavers, muskrats, porcupines, prairiedogs, marmots, chinchillas, voles, and lemmings. Rabbits are sometimes (but not always) included. Over one quarter of all mammals are rodents and are found on all continents except Antarctica. The landmass with the most rodent diversity is South America.

The DESERT WOODRAT (pictured) is identified by its large ears, white feet, dark throat hairs, gray-brown back, and bi-colored tail. It is adept at moving among the spines of cacti without injuring itself. Cactus serves as food, along with yucca pods, Pinyon nuts, bark, berries, and any available green vegetation.


Caught in its act of midnight thievery

Great Gray Owl

by Dave Hanks

We were in Yellowstone Park approaching the Canyon intersection, when I said to my wife: “You know what would make this a really great trip? – finding a Great Gray Owl.” We turned south and had traveled less than a half mile when my eye caught what looked like a knob on the end of a stick. My heart leaped and I said: “There’s one!” Sure enough, it was an owl, not just one but two! I started taking pictures at a great distance by stalking – moving up six feet, stopping, shooting, and moving again. I took off each of my extension lens as I got closer and closer. I got quite close, and one seemed content to just sit and watch me. Luckily he was low down, on a bare branch in a Lodgepole Pine.

The GREAT GRAY OWL is not the heaviest owl, but it is the biggest in volume. Its head is smooth (lacking the ear tuffs that identify the Great Horned Owl) and it has huge, heavily ringed facial disks that make its eyes look smaller than they are. These disks are tremendous aids in channeling sounds to the ears. The ears are to the sides of the eyes and concealed by feathers. Its hearing is acute. A mouse or vole, running underneath the snow, can be heard and pinpointed at a surprising distance. With both excellent vision and hearing, this bird is adept at nighttime, dawn, or dusk hunting.

Boreal forests and wooded bogs of the far north are this species preferred habitats. Although not common further south, they may also be found in mountainous, coniferous forests where they hunt the forest clearings. Their call is a series of deep, resonant “whoo’s”.

Of all the raptors, owls stir my senses the most. The Great Gray Owl is not easy to come upon and an observation, especially a photographic session, is a very special event.


Watching me as well as scanning for voles

Eurasian Collared Dove – An Immigrant Comes to Burley

by Dave Hanks

A rare bird report has been on IBLE (Idaho birders website) all this spring (2007). This same bird was described to me, in a telephone conversation, by a resident of southeast Burley. But “lo and behold”, the species had appeared in our yard. In fact a pair of Collared Doves has favored us with their presence since early spring. I assume that they must have a nest here. We have many and a great variety of trees. This species likes yards and conifers to nest in.

It is 13 inches long with a sandy gray body. The name is the result of a distinctive half collar on the back of its neck. A bit of white can be seen in their tail when taking flight. They are somewhat bigger than the Mourning Dove (which it associates with in our yard) and looks similar to the Ringed Turtle Dove (which it will hybridize with). A growling three note “Koo-KOO-kook” call is made while in flight. Both sexes look alike, and they will try to breed throughout the entire year. The producing of several broods annually has led to their rapid increase.

It’s an old world species that originated in India, spread across Europe, and was introduced to the Bahamas in the 1970s. The USA population is mainly in Florida but spreading. This bird has been tamed, and our population is the result of caged birds being released into the wild. When first appearing in England in 1963, it was protected and a boy was fined for shooting one. Protection was later raised, as the bird was becoming a pest – much like the European Starling that haunts farm yards in our area.

We were most surprised to look out our front window and suddenly realize that a new species, and an uncommon one at that, was utilizing our yard.


A Eurasian Collared Dove making use of bird seed strewn on our lawn