In the wild, birds mimic for a variety of reasons. Depending upon the circumstances, birds feigning the songs of other species can attract members of the opposite sex, fool predators into misidentifying the species of the singer, or ward off competitors for food or territory. Since humans are usually capable of differentiating between the song of a mimic from the song of the bird the mimic is imitating, it’s likely that the impersonation isn’t fooling other birds (whose hearing is much more sensitive than ours) either. But like humans, birds would rather avoid confrontation or competition than face it head on—mimicking clearly works.
Birds are flock creatures. Closeness within its species is crucial to a parrot’s survival in the world: While one parrot focuses on foraging, others look for predators. When taken out of the wild and into a household, birds will imprint with their human owners. Mimicking seems to be a way to foster closeness with their human “flock-mates.” As Todd Lee Etzel, an officer of The Society of Parrot Breeders and Exhibitors, wrote Imponderables:
The pet bird becomes imprinted with human vocalizations and hence mimicking takes place due to the bird’s desire to be part of the “flock,” even though it is not a natural one. Keep in mind that most species of parrots are highly social and the need for social interaction is so strong that innate behavior is modified to fit the situation.
If pet birds are motivated by social interaction, why do they tend to mimic at least as much when their owners leave the room? Animal behaviorist W. H. Thorpe offers a theory:
as they develop a social attachment to their human keepers, they learn that vocalizations on their part tend to retain and increase the attention they get, and as a result vocal production, and particularly vocal imitation, is quickly rewarded by social contact. This seems an obvious explanation of the fact that a parrot when learning will tend to talk more when its owner is out of the room or just after he has gone out—as if he is attempting, by his talking, to bring him back.
Thorpe’s theory advances the notion that bird psychology differs little from infant psychology, which isn’t farfetched in the least. Dr. Irene Pepperberg, a research scientist at MIT and a professor at Brandeis University, has studied and written about the abilities of African Gray parrots, particularly her oldest bird, Alex. Just as other scientists have proven that primates are capable of complex communication, so Pepperberg has shown that parrots can do far more than mimic. If shown two blocks that are identical except for their hue, and is asked what is different about them, Alex will answer “Color.” He has mastered numbers, and shapes, and locations, and the names of objects, and has learned to ask, or more accurately, demand them: “If he says that he wants a grape and you give him a banana, you are going to end up wearing the banana.” Pepperberg estimates that Alex’s cognitive ability is comparable to a four-to six-year-old child, with the emotional maturity of a two-year-old.
Pepperberg plays a version of the classic shell game with Alex and other parrots, hiding nuts below one of three cups. Alex usually succeeds at spotting the nut, except when the experimenter doesn’t play fair. Sometimes, the scientists will deceive the parrot by sneaking the nut under another cup while distracting him from the subterfuge:
So Alex goes over to where he expects the item to be, picks up the cup, and finds that the nut is not there; he starts banging his beak on the table and throwing the cups around. Such behavior shows that Alex knew that the object was supposed to be there, that it’s not, and he’s giving very clear evidence that he perceived something, and that his awareness and his expectations were violated.
In the wild, parrots use their wits to evade predators and find food and mates. The need to solve problems might be as innate in a parrot as its mimicking skills. If a parrot’s cognitive skills are as great as Alex has exhibited, Pepperberg implores pet owners to provide the proper stimulation:
I try to convince them that you can’t just lock it in a cage for eight hours a day without any kind of interaction. I don’t mean just interpersonal interaction, or having other birds around; parrots have to be intellectually challenged.
Etzel thinks that parrots and other birds mimic our language and other sounds in their environment “simply because they are able to do so. It might even be a form of entertainment for them.” Indeed, parrots might be musing about us while we are “training them”:
Doesn’t my owner look silly constantly repeating “Polly wanna cracker?” Oh well, might as well go through the drill if it’s going to end up with some tasty carbs down my gullet.
Submitted by Wayne Lipe of Long Beach, New York.
Why Are Portholes Round?
Windows have two main jobs: to let in light and fresh air. This doesn’t seem too much to ask of a sheet of glass surrounded by a base frame, but ships pose a few extra little problems. Obviously, portholes on ships need to contend with water (windows that don’t seal properly aren’t too popular on ships, especially windows that are underwater at times). But a more pernicious danger is the movement of the boat itself.
When most ships were made out of wood, portholes were usually rectangular. But once steel construction came into vogue, sharp corners morphed into arcs. Wood may not be as hard as steel, but it has one feature that makes it more porthole-friendly: Wood absorbs the stresses of the rocking of boats on the sea far better than metal. When steel hulls came into vogue in the late nineteenth century, sailors discovered quickly that stress fractures were endemic to rectangular portholes, starting at the corners. Round portholes, on the other hand, distribute the stress evenly, and naval architects figured out the spherical solution quickly.
Rectangular portholes are far from extinct, however. Some wooden ships still have them. And cruise liners often sport large rectangular windows on decks. But the more violent the weather a boat encounters, the rougher the seas it navigates, and the farther down in the boat it resides, the more likely the porthole is to be cornerless.
Submitted by Mike Roberti of Duarte, California. Thanks also to “Carol,” via the Internet.
Now We Know Why Ships’ Portholes Are Round. Why Are Airplane Windows in the Passenger Cabins Oval?
May we exert executive privilege and pose this Imponderable, which occurred to us after researching the last Imponderable? Surely, airplane windows are subject to extreme pressures in the air. Ken Giesbers, our mole at Boeing, confirmed it:
Rounded holes in the thin fuselage are structurally more sound, and much less prone to stress fractures. Stress fractures in a pressurized cabin can lead to explosive decompression and outright structural failure.
The seriousness of the issue was highlighted when the first commercial jet, the De Havilland Comet of Britain, was plagued with three crashes shortly after its introduction in 1952. Much to their shock, thorough investigations revealed that the main culprit in all three crashes was likely metal fatigue. And most of the deterioration started at the corners of the Comet’s large, rectangular windows. The Attorney General’s report concluded that
up to 70% of the aircraft’s ultimate stress under pressure was concentrated on the corners of the aircraft’s window.
The Comet was then redesigned with a stronger fuselage and round windows.
If round windows are best, why do Boeing and Airbus provide us with oval ones? According to Giesbers, they just aim to please:
Having round windows would necessarily mean more solid material in the gap between windows. By elongating the windows vertically, aircraft designers can provide more viewing area (more surface area devoted to windows) and also better accommodate passengers of differing heights.
Boeing is very proud of the large (19″ × 10.3″) windows its new 787 will have. The windows can be larger because the 787 will use more composite materials than before. Boeing makes no bones about the reason [for the big windows]: a better experience for the passengers.
Submitted by Dave Feldman, of Imponderables Central.
Why Don’t Trains Have Cabooses Anymore?
All but the youngest of Im
ponderables readers will remember the little caboose, the last car on every train. Such is the appeal of that humble car that most model sets, even of contemporary trains, still feature cabooses, even though they have mostly disappeared since the early 1990s. In their stead, the back of most trains feature a skeletal open car with a flashing light.
What purpose did cabooses serve in the first place? Up until the mid-1980s, the typical freight train used to have at least four crew members. An engineer and a brakeman sat at the front in the locomotive; the other brakeman and a conductor brought up the rear in the caboose. Before the advent of radio communications, the two men in the caboose were eyes and ears for the engineer, and vital communication was handled via hand and lantern signals. Many cabooses featured cupolas, which served as observatories for the crew, who were on the alert for any sign of smoke, fire, or dragging equipment. The caboose also housed much of the train’s valuable technology, including an emergency brake, gauges to measure brake pressure, and the tools needed to make repairs to the train.
The caboose also served as a combination bedroom, office, kitchen, and bathroom as well. Many were equipped with stoves for cooking, a desk for paperwork, a latrine, and bunks for the brakemen and conductor.
Radio communication and, later, sophisticated telemetry devices eventually rendered the caboose obsolete. Perhaps the most important development in the demise of the caboose was the invention of automatic rear-end devices (usually called “FREDs” (Flashing Rear End Devices)). FREDs allowed the engineer to determine the air brake pressure from gauges on his board in front, and often to apply brakes in the back of the train—duties heretofore performed by the brakeman in the caboose. These FREDs flash the red light you see in lieu of the caboose on most trains today.
Another technological breakthrough that replaced human expertise is the Hot Box Detector (HBD), which automatically checks for overheated wheel bearings or “hot boxes.” If there is a problem, the exact axle location is automatically signaled to the engineer.
Before sophisticated telemetry, a constant challenge was ironing out the slack on long trains. In the “old days,” the conductor in back would check for slack, but now the End of Train Device (ETD) lets the engineer in front know when the back is moving—a message display on the engineer’s board lets him know.
Most states had laws mandating cabooses on trains well into the 1980s, but these slowly fell by the wayside as the big railroads convinced the Federal Railroad Administration that brakemen, and thus cabooses, were no longer needed. The motive of the railroads, of course, was financial. As Jeff Moore, webmaster of the High Desert Rails Web site (http://www.trainweb.org/highdesertrails/) put it:
The elimination of cabooses saved railroads vast amounts of money. Supplying and maintaining cabooses cost a lot of money, as did having to switch them on and off trains and then storing and further switching them at terminals. Eliminating cabooses also meant that much less dead weight that the locomotives had to drive.
Alabama locomotive engineer Jerry DeBene told Imponderables that it costs about $2,500 a month to maintain a caboose: “Times that by a fleet of them and you can see why they were replaced.” Some estimates for the cost of cabooses run much higher, up to six figures a year.
Although they are endangered species, neither the brakeman nor the caboose is totally extinct. On some lines, brakemen have been renamed the more generic, “trainmen.” Charlie Tomlin notes that on the Burlington Northern and Santa Fe’s Chicago division, the collector positions on commuter trains are the responsibility of brakemen and those brakemen are responsible for much of the switching: “Believe me, from having worked all of those jobs as a brakeman, there is plenty of work to do for two.”
And Jeff Moore explains the main reason why some cabooses live on amidst today’s technology:
There are still a few applications where you will find cabooses in use today. These are primarily in situations where a train crew has to make a long reverse movement. Regulations require a train crew member to protect the movement by riding on the last car, which can be dangerous under any circumstances. In such situations, railroads will generally provide a caboose, although more often than not the caboose has been stripped of all hardware and crew amenities and is classified as a “shoving platform.”
Submitted By Douglas Watkins, Jr. of Hayward, California.
Do Birds Sweat?
Nope. Not even when they are nervous.
Birds don’t have sweat glands, so they can’t sweat. But they have plenty of methods to cool themselves off. Birds are warm-blooded, like we are, and their normal body temperature is actually a little higher than ours.
Although you may have never heard it, birds also pant, just like dogs, and can cool themselves off in this way. And when birds fluff up their feathers, it isn’t just to show off—fluffing allows air close to the skin so that even more evaporation occurs. These are the two most common ways that birds eliminate excess heat.
Birds are so active, and burn off so many calories while they fly about looking for food (including migrations that, for some birds, can require thousands of miles of flying), that it is a constant struggle for them to maintain the proper temperature. Hypothermia is a serious danger, so some species have developed specialized mechanisms to regulate their body temperature.
Have you ever seen the fleshy part of a bird’s bill vibrate? Herons do this most visibly, but many other species, such as boobies and roadrunners, regulate their temperatures by this “gular fluttering.” By vibrating the hyoid muscles and bones in their throat, gular fluttering achieves the same cooling effect as panting.
In Why Don’t Cats Like To Swim?, we discussed how penguins’ feet can withstand frigid conditions in Antarctica. But many other birds in warm climates use their feet to cool off. Martha Fischer, of Cornell Lab of Ornithology, explains:
Herons and gulls can also lose a large percentage of heat through their feet. The veins and arteries in birds’ legs and feet are intertwined and the blood flowing out to the extremities in arteries is cooled by blood flowing back to the body in veins. This is called countercurrent exchange (and is the reason ducks can stand on the ice without freezing their feet).
Fischer adds that birds are believed to have evolved from reptiles, which also do not sweat:
In their evolution to their present state, selection has favored physiological and morphological changes that enhance light-weightedness.
Dinosaurs would tend to agree.
Submitted by Lorelei Truchon, of Fairfax, California.
Why Is the Earth’s Core Still Hot?
We knew that the Earth’s core is hot, but not how hot. Actually, even geologists don’t know exactly what the temperature is, either, but they know it is almost as hot as the Sun. That’s hot.
Luckily for us, the surface of the Earth is considerably cooler. After all, the surface is losing heat by being in contact with cooler air. But the core is continually heated by the decay of radioactive elements. Scientists believe that the original heat from the formation of the Earth is still being played out in these transformations. The Sun is likely to expand and burn us before the core of our planet cools off.
The rule of thumb has traditionally been that for every sixty feet in depth, the temperature of the Earth increases by one degree Fahrenheit. But this old approximation was based on distances that scientists could measure by drillholes. If this ratio held true all the way to the core of the Earth, its temperature would be 180,000 degrees Fahrenheit. Most geologists agree that the actual temperature is closer to a still unfrosty 9,000 degrees Fahrenheit.
Why are we more worried about future global warming when our own core is so incendiary? The amount of heat that reaches the Earth’s surface is not enough to affect it drastically, and what heat there is quickly radiates to outer space. In their book, Physical Geology, Brian J. Skinner and Stephen C. Porter emphasize that the heat transfer is not uniform:
The heat loss is not constant everywhere. Just as the geother
mal gradient varies from place to place, so does the heat flow, which is greatest near young volcanoes and active hot springs, and least where the crust is oldest and least active.
Of course, the Earth’s crust helps insulate the core from losing more heat. These cracks in the crust, like volcanoes and springs, are the few venues that allow us to glimpse the heat trapped in the sizzling core below.
Over the past few years, scientists have developed the ability to measure radioactivity more precisely through measuring particles called “antineutrinos.” Scientists have long suspected that radioactivity might be responsible for all the heat generated at the Earth’s core, and geologists are optimistic that eventually they will be able to map exactly where the energy is being generated. Even more recently, two University of California, Berkeley, scientists discovered that potassium can form an alloy with the iron in the Earth’s core. Although Dr. Kanani Lee found that potassium might comprise only one-tenth of one percent of the Earth’s core, “it can be enough to provide one-fifth of the heat given off by the Earth.”
Why Do Pirates Love Parrots? Page 16