Did You Know This About Birds?
Bird Trivia by Dan Gleason?
#1 — Observed rate of flicker in birds
Birds have the ability to see higher flicker frequency rates or cycles per second. Imagine turning a light on an off. The faster you turn it on and off the higher the flicker frequency rate. A fluorescent lamp flickers at a rate of about 60 cycles per second (cps). The human eye is only capable of seeing a rate of 50-55cps, thus the fluorescent light looks continuous because it is flickering faster than we can detect (unless the light slows as it ages and we sometimes become aware of it). Some birds can see flicker rates of over 100cps. The faster we move, the more nearby objects, such as branches, become blurred. The could be a problem for fast-moving birds were it not for the faster flicker frequency rate. A Sharp-shinned Hawk, in quick pursuit of prey through dense woodlands can clearly see and avoid the branches in its path. Just one of the many ways birds’ vision is superior to that of humans.
#2 — Number of feathers on a bird
Over the years, naturalists and researchers have counted the total number of feathers on various species of birds, and the counts range from a low of 940 feathers on a Ruby-throated Hummingbird to a high of 25,216 on a Tundra Swan. Most songbirds have 1,500–4,000 feathers. The greatest concentration of feathers on most birds is around the head and neck, and, in most songbirds this amounts to 30–40% of the total number of its feathers.
#3 — The size of birds
The smallest bird in the world is the Bee Hummingbird, Mellisuga helenae, found only in Cuba. It weighs just 1.6 grams, about 3/4 the weight of a dime. The Anna’s Hummingbird that frequents our skies weighs about 2.75x more than the tiny Bee Hummingbird!
The largest living bird (by weight) capable of flight is the American White Pelican, Pelecanus erythrorhynchos, which has been recorded weighing up to 30 pounds. The Trumpeter Swan, Cygnus buccinator, is a close second with adult males weighing over 26 pounds.
The largest living flying bird (by wingspan) is the Wandering Albatross, Diomedea exulans, with a wingspan of about 12 feet and a weight that may reach 26 pounds, although 23-24 pounds is more typical.
You might already know that the largest living bird is the Common Ostrich, Struthio camelus, of Africa. Males can stand nearly 9 feet tall and weigh up to 320 pounds.
The largest bird that ever lived is the extinct Elephant Bird, Aepyornis maximus, of Madagascar. It stood over 10 feet high and weighed up to 1,600 pounds. Its egg was over 13 inches long and held about 2 gallons in volume. It became extinct about 1,000 years ago, probably because of human activity.
#4 The Bobolink — A long-distant Migrant
The Bobolink, a member of the Blackbird Family, is common in the grasslands of southern Canada and the northern United States. In Oregon, it is found at Malheur National Wildlife Refuge and a few other locations in eastern Oregon. It is a remarkable long-distant migrant, one of the longest migrations of any songbird. Each year it flies from its breeding grounds in North America to Bolivia and Argentina south of the equator—a distance of about 12,500 miles round-trip. Some birds have been known to live up to 10 years making their lifelong mileage over 125,000 miles per individual—a distance more than 5 times around the world at the equator! To navigate, they use the stars and cues from the Earth’s magnetic field.
#5 The Fastest Bird — Peregrine Falcon
The fastest bird in the world is the Peregrine Falcon. It has been clocked at a speed of 240mph in a power dive. The Golden Eagle is a close second with speeds of over 200mph in a dive. The fastest bird in direct powered flight is the White-throated Needletail, swift of SE Asia and Australia. It has been clocked at a speed of 105mph.
#6 Ducks — How They Find Food in Muddy Water
An unguis is a nail or claw. In ducks, it refers to the nail-like structure on the tip of the bill. This structure is densely packed with sensory cells for touch. These sensory cells are able to discriminate a far lighter touch than other birds or mammals can; a much lighter touch than humans can feel with our fingertips. This helps ducks find food items in muddy water by touch rather than relying on visual cues.
#7 — Pterylae
The feathers in birds grow in defined tracts on the skin over the body. These are called pterylae. There are 8-10 major tracts that can be further subdivided into smaller tracts. The bare regions between these tracts are called apteria. All birds have these tracts except penguins where the feathers are uniformly distributed over the body. There is actually evidence of feather tracts embryonically in penguins but they disappear before the embryo hatches. Even in close-up photos of birds, such as this photo of a Northern Flicker, feather tracts cannot be seen.
An interesting, but unrelated fact, woodpeckers do not have true down feathers.
#8 — Heart Rate in Birds
The heart in birds is larger than in comparable sized mammals. The larger heart of a bird pumps more blood per heartbeat than does that of a mammal, and birds at rest typically have a slower heartbeat than a similar-sized mammal. Activities such as flight quickly elevate the heart rate, and small birds have a more dramatic increase in heart rate with exercise than do large birds. A large gull may go from 150-200 beats per minute while at rest to over 600 beats/minute during flapping flight. Hummingbirds may go from a resting heart rate of 500 beats per minute to over 1200 heartbeats per minute while flying. At night a hummingbird goes into torpor and the heart may drop to 40 beats/minute.
#9 — Eagle Eyed
Do eagles really see 7X better than we do? Well, that depends upon what you mean by better. Eagles, and other birds of prey, do see an object that is 7X larger than we do. The difference is in resolution. In the central part of the eye (macula is the term used in humans and fovea is the term used for birds and most other animals) will be found the highest number of cones. Cones are responsible for color and sharpness. We have approximately 200,000 cones per square millimeter. Eagles have over 1,000,000. Think of it as similar to pixel on a computer screen—the more pixels, the higher the resolution and the sharper, more detailed the image. If you look at a barcode of a grocery store item from across the room, you probably can’t see the lines clearly. If you simply magnify it the image will be bigger but just as fuzzy. The eagle can still “resolve”, or clearly see those lines across the room with magnifying them. It’s not just eagles and raptors that have this ability, Swifts and swallows need to see flying insects while flying fast themselves and flycatchers need these visual skill to see their prey.
#10 — Bird Ovaries
In most birds the females have only one functional ovary and oviduct, usually the left one. The right ovary and oviduct typically degenerate early in embryonic development. Eggs nearly ready to be released from the ovary, contain the yolk material. When an egg is released from the ovary, it typically takes only one day for the egg to travel down the oviduct, acquire albumen and additional materials added. Once it reaches the uterus at the end of the oviduct (a process that takes 4-5 hours) a shell put on to surround the egg and make it ready to be laid. This takes about 20 more hours. The egg will then turn and be pushed from the body large end first.
If both ovaries and oviducts were functional and contained mature eggs, the females of many species would have great difficulty, or even be unable to fly until unburdened of one or even both eggs. This situation actually occurs in some steamer ducks that are nearly unable to fly even without the weight of an egg and cannot fly for a day or two while carrying a mature, unlaid egg.
#11 — Some Birds Eat Ash
Some birds have been seen at ash pits. Look closely if you see this behavior. Maybe they are searching through the ashes for insects, but maybe, they are actually eating some of the ash.
Strange as it seems, hummingbirds, especially in the southwest, will sometimes eat ashes. This seems like an odd diet for a hummingbird. It is always the females in most species that eat ash, rarely do males do so, and other species of birds eat ashes as well
Ash is high in calcium and eating ash is a quick way to help return lost calcium. Why females? To produce a clutch of eggs, females often become deficient in calcium used to produce the shell.They often even deplete some of the calcium in their own bones. Eating bits of eggshell fragments or the fecal sacs of the young can provide a quick way to obtain some calcium, but charcoal is also a possible source. Campfires that are heavily doused with water may leach out the calcium into the surrounding soil but fires allowed to extinguish naturally are usually higher in calcium. This was the findings from a study done on Boreal Chickadees in Newfoundland in the 1980s. In that study, the Boreal Chickadees ignored ash pits with low calcium content.
Crossbills have a different reason for eating ash and in crossbills, males also eat ash. These birds may feed on ashes more than any other North American bird. Crossbills feed on conifer seeds by prying open young cones. The immature seeds that they feed on have not yet dried and are still somewhat resinous. This sticky resin can cause digestive problems. To help moderate this problem and facilitate digestion, crossbills eat from clay deposits and charcoal where available. This helps absorb some of the resin, allowing the birds to digest the seeds more easily.
An interesting related behavior is observed in some macaws in South America. Their massive bill allows them to feed on the seeds of some trees that other birds cannot eat. Some mammals may have the teeth to break apart these seeds but ignore them because they contain compounds that are mildly toxic. (Or in the case of the liana tree, very toxic. Those seeds contain strychnine.) The macaws feed on these seeds with immunity, but only for one reason—After eating these seeds, they fly to areas with large exposed clay deposits. Again, their large beak assists them in obtaining large amounts of clay that they readily consume. The clay absorbs the toxins awhich are then passed out of the body harmlessly.
#12 — Deep Forest Voices
Some birds, like some owls, have deeper-pitched voices than other similar birds. Is this just happenstance or is there some reason for this? In owls, those that live in dense forests have deeper voices than owls that live in open country.
Sound carries relatively well in open country but is quickly absorbed by vegetation of forests and bushes. Lower frequencies travel farther, even in dense vegetation, than do higher frequencies. So, Great Horned Owls, Spotted Owls, and other. forest-dwellers all tend to have low voices. If there is a need to hold a large territory, the voice may be even lower to reach a longer distance. Flammulated Owls are small, yet they have very low voices. Their territory is quite large. larger than similar-sized Screech-Owls, and their voice is lower, traveling a longer distance into the woods. The male is the one who most defends the territory and his voice is lower than that of the female, even though she is larger is size.
Other birds, like Sooty Grouse, also have very low voices. These grouse are generally solitary birds and when the time comes to attract a mate, they must attract the attention of females who may be at a considerable distance from them. The first method of attraction is by voice and the very low voice of Sooty or Spruce Grouse carries a long distance through the forest.
Of course, not all forest-dwellers have low-pitched voices. Pacific Wrens have a long high-pitched song. The voice is quickly absorbed by the vegetation, but the wren has no need for its voice to travel far. It holds a small territory and its high voice is very effective for its needs. His neighbors can hear him well and there is no need to be heard by distant wrens.
Low frequency sounds travel far but can be difficult to locate. High frequency sounds are quickly absorbed by leaves and other vegetation but are easily pin-pointed. Golden-crowned Kinglets make high-pitched vocalizations as they travel through the conifers, high above the ground. Such high sounds don’t travel far to attract the attention of others, but they help with flock integrity, allowing each bird of the group to easily locate their neighbors and stay together.
#13 — Very High-Altitude Flying of Birds
The Bar-headed Goose of Asia, migrates at high altitudes. It can fly over the highest parts of the Himalayas, including over the summit of Mt. Everest. By doing so, it can take advantage of the jet stream and reach flight speeds of over 90 mph allowing completion of a 400-600 mile journey in a single day and avoid a multi-day journey at lower elevations around the mountains. Even Mallards have been recorded flying over 21,000 ft. in altitude and a Golden-crowned Sparrow was struck by a small plane at 10,000 ft. To fly over 20,000 ft. means that the birds encounter an air pressure that is less than ⅓ of the pressure found at sea level and temperatures are nearly -60°F. To survive, special adaptations are needed. Birds that fly at high elevations often have two forms of hemoglobin, the oxygen-carrying molecule of the blood. The second form of hemoglobin is able to capture and release O2 with greater efficiency at high altitudes and this form is equal to or is more concentrated in the blood than the “normal” form in such high-flying birds. Additionally, because oxygen is at lower concentrations at high altitudes, the birds must breathe faster, and the exertion of flying increases the breathing rate even more. This causes the carbon dioxide (CO2) to become more concentrated in the blood which increases the pH of the blood (making it more alkaline). The normal pH of the blood is 7.3-7.4. In this very high-altitude flying, the blood of these birds may reach a pH of 8.0, a condition that would be fatal to humans. No one yet knows how these birds survive such extremes of pH, but all of these marvelous adaptations allows the annual migration of these geese to be possible.
#14 — Staying On A Perch
How does a bird perch on a twig without becoming unbalanced? Even more curious, how does a bird sleep on a perch through the night without falling off? It seems like the muscles must get tired gripping tightly through the night. In fact, the muscles don't need to do any work at all. A special arrangement of tendons helps hold the foot securely.
When looking at a birds foot, many people assume that the knee bends backwards as compared to our knee. But that rear pointing joint is actually the ankle and what we think of as the birds’ foot, is just its toes. In a bird, the long bones between the ankle and toes are fused together and elongated into one long bone. The knee works the same as ours, but it is usually hidden from our view by the body’s feathers. The muscles of the leg are above the knee. A tendon runs from these muscles down the length of the lower leg, wraps around behind the ankle, extending to the toes, and branching out underneath the bones of each toe. As the bird sits upon a perch and the ankle bends, this tendon is stretched. In doing so, the bones of the toes are pulled together and curl around the perch, holding the bird tightly in place. Additionally, in songbirds, the tendon is wrapped in a sheath which has tiny ridges along its length. These ridges match corrugations in the tendon. As the weight of the bird pushes down against the perch, the corrugations of the tendon interlock with the ridges of the sheath and this prevents the tendon from sliding in its sheath as the bird sits on the perch. With this adaptation, the muscle does no work and the bird easily sits in place without concern of falling off. As the bird takes flight, it pushes upward, releasing this locking mechanism and relaxing the tendon, making it easy to release from the perch. It should be noted that a bird can voluntarily open its foot anytime it wishes while perched, but this adaptation makes sitting on a perch easy to do without the need to constantly grip it.
#15 — Eating Poison-oak
Poison-oak is a plant we should all know how to identify and avoid. It causes an irritating rash on the skin of many people and can make you very ill is taken internally (inhaling poison-oak smoke or using twigs to roast hot dogs). But humans are one of the few species to react negatively to this plant. It is an important native plant and several kinds of birds will use poison-oak.
Poison-oak thickets provide cover for nesting for some birds and its berries are eaten by many different species of birds. If fact, for some birds, poison-oak berries can be 5-10% or more of the berries they eat. Those birds in the west include: Red-breasted Sapsucker, Downy Woodpecker, Northern Flicker, Ruby-crowned Kinglet, Hermit Thrush, Wrentit and several other species in other parts of the country. Other species with less dependence on these berries, but who still have been seen eating them are: Ring-necked Pheasant, Wild Turkey, California Quail, Lewis’s Woodpecker, Hairy Woodpecker, Warbling Vireo, Black-billed Magpie, American Crow, Black-capped Chickadee, Mountain Chickadee, Chestnut-backed Chickadee, Bushtit, Swainson’s Thrush,Varied Thrush, Cedar Waxwing, European Starling, Yellow-rumped Warbler, Spotted Towhee, Golden-crowned Sparrow, White-crowned Sparrow, Dark-eyed Junco and Purple Finch.
In addition to the berries some mammals will also eat the berries and even the foliage. These include: Black Bear, Muskrat, mice, and Black-tailed Deer.
So, while you may not like making contact with this plant, it is an important native species in our ecosystem and should not be eradicated in natural areas.
#16 — Townsend’s Warblers and Honeydew
Honeydew is a sugar-rich liquid secreted by some aphids and scale insects. As the insect pierces into the phloem of a plant the pressure causes the sugary liquid to be extruded from the insect’s anus. Some ants tend aphids so that they can feed on the honeydew. But ants aren’t alone in dining on the sugar-rich food source. During the winter months, many Townsend’s Warblers migrate to Mexico. Insects gleaned from the surfaces of plants are the primary food throughout the year for these warblers. But some migrate to an area of Mexico where there is an abundance of scale insects. Here, Townsend’s Warblers have found another food source—honeydew from scale insects. So important is this as a food source that the warblers setup and defend a territory where these insects are abundant, Certainly a unique and interesting food source for one of our most beautiful western birds.
#17 — Brood Patch
The feathers on the breast of a bird provide a very efficient insulation layer. If this layer of feathers were between the adult’s body and eggs in the nest, then transfer of heat from adult to eggs would not be adequate to keep the developing embryo warm. To overcome this problem, most birds develop a brood patch (also known as an incubation patch). This is an area on the breast of the adult bird (male or female) that is devoid of feathers, thus allowing direct contact between eggs and bare skin and a more efficient transfer of heat. The skin of this patch becomes soft to wrap around the eggs and the region becomes engorged with blood to bring more heat to the eggs.
A brood patch can develop as a single region, which is the case in most songbirds, or it may develop in two or three smaller patches with normal feathering in between, as is found in gulls. Waterfowl do not form a true brood patch but pluck down feathers from their breast (which are then often used to line their nest) and spread these feathers away from the eggs prior to sitting on the eggs.
Where incubation duties are equally shared, both sexes form patches. In many songbirds, both male and female form a brood patch but in some species, especially where the female is mostly responsible for incubation, the males have a much less developed patch or none, even though they occasionally sit on the eggs.
While direct contact with the skin is the normal method for incubation, some birds have evolved other mechanisms to warm their eggs. Boobies usually lay two eggs and the eggs are warmed by wrapping their feet around the eggs. Gannets most often use this same technique, but have only one egg. The webbing of the feet is highly vascularized and allows efficient heat transfer.
#18 — Baiting for Fish
Many kinds of birds catch and eat fish, but the Green Heron actively uses bait to attract fish, making it one off only a few tool-using birds. Green Herons hunt for fish in shallow water usually waiting patiently, as do other herons, for a fish to swim by closely enough to be captured. But, sometimes a Green Heron will seek out some bright object and gently place it on the surface of the water. This attracts the attention of fish which come to investigate. In doing so, the Green Heron has a easy opportunity to capture the fish. If the object has drifted away, the heron may grab it again and once more place it on the water nearby to wait for another fish. A small, yellow leaf or any other bright object can serve as a good natural bait, Once, Barbara and I were visiting nature reserve (Bolsa Chica, south of Los Angeles) where we watched a young Green Heron snatch a goldfish cracker that someone had left near the edge of the water. The heron picked up this small, yellow cracker and gently placed it on the water. Sure enough, it was soon rewarded with the easy capture of a fish that came to investigate.
#19 — Shorebirds & Biofilm
Many shorebirds have beaks designed for pecking at the surface or probing below the surface. Invertebrates have long been considered the primary prey. But, it has been found that invertebrates alone cannot account for all of the nutrition in some species. Many of the smaller species, especially the genus Calidris, have small spines at the tip of their tongues. It has been recently demonstrated that these spines assist with the uptake and consumption of something called biofilm. Biofilm is a complex matrix of bacteria and/or other single cells that adhere together and often on a surface. Dental plague is a type of biofilm. A kind of biofilm covers many intertidal mudflats. It consists of bacteria and algae, mostly diatoms, concentrated in a sticky mucilage. The bacteria and diatoms coat the surface of intertidal kelp and other seaweeds. As it is washed off of the plants, the mucilage helps them to adhere to the mud rather than be washed out to sea as the tide retreats. Until recently, it was not known that this is vital as a food for many migrating small sandpipers. So as they forage along the mudflats, they are gathering more than just invertebrates living in the mud.
#20 — Rictal Bristles
Birds that feed by catching insects on the wing—swallows, flycatchers, and especially nightjars—often have many elongated bristles around the base of the mouth called rictal bristles. The gape at the base of the mouth is called the rictus, hence the name of these bristles located there. The bristles are modified feathers that have only a shaft, no barbs. These were once thought to serve partly as an insect trap but this idea has long been disproved. Work with flycatchers shows that the flycatcher catches the insect with the tip of the beak and these bristles are not involved, They may help protect the eyes from nearly missed insects, from the moving legs of captured, long-legged insects, or from small objects in the air while in flight.
Rictal bristles are found in many species of birds that are non-insectivorous, or at least not entirely so. Most thrushes have rictal bristles at the base of the mouth as do kiwis and many other birds. For many birds, sensory cells have been found at the base of these bristles and movement of the bristle stimulates these sensory cells. Most ornithologists now believe that the bristles are sensory in nature and provide some feedback about the surrounding environment. However, there is very little direct evidence about the role of these bristles in most species and it it possible that there are other functions we are not aware of. There is some evidence that these bristles arose independently over the course of evolution in totally unrelated groups of birds. If so, the functions may vary among the different orders or families of birds having bristles.
#21 — How Vultures Can Stay Cool
Storks and New World Vultures (but not vultures of Europe, Asia and Africa) all share a common way of keeping cool. They urinate and defecate on their legs. The term for this urohidrosis (often misspelled as urohydrosis). It sounds very unsanitary to us, but it works very well for these birds. Birds don’t have sweat glands so moisture evaporating from the droppings on their legs provides the same evaporative cooling as sweating in humans would. Additionally, these birds eat carrion and are exposed to. disease and parasites and defecating on the legs can help act as a barrier to some parasites and disease. (Seals and Sea Lions sometimes use the same trick, peeing on their hind limbs, when spending time on land.)
The black color can also help keep vultures cool. This may seem contradictory as black absorbs heat and you will often see Turkey Vultures holding out their wings early in the morning to absorb sunlight and warm themselves. During this time the feathers are pressed close to the skin so that the sunlight penetrates to help warm the bird. Later, especially while in flight the feathers are lifted slightly above the skin. The sun warms the black feathers and this causes a slight air current to occur between the feathers and skin which causes the warm air to be pulled away from the skin and help cool the skin, keep the bird from overheating. Crows, Ravens and other black-colored birds of warm climates use the same trick to stay cool.
#22 — Eating Feathers
All species of grebes share a common behavioral trait—they all eat feathers. And not just any feathers, they pluck feathers from their own breast and swallow them. The first meal many newly-hatched chicks get is a feather plucked from their parent’s breast. This would seem to provide little nutrition so why do grebes do this odd behavior?
The feathers are not digested and do not pass beyond the stomach. Up to 50% of the stomach may be filled with feathers. It is thought that these feathers provide a barrier and help protect the stomach from being pierced by sharp fish bones. Grebes are fish-eating birds and swallow the fish whole. The proventriculus (fore-stomach) is responsible for enzymatic digestion and is usually well-developed in fish-eating and meat-eating birds. But in grebes, it does not dissolve the bones and the gizzard does not completely crush the bones. So, feathers, swallowed by the birds, provide a protective barrier. The fish bones are trapped by these feathers and eventually some of these feathers that now contain fish bones will be regurgitated as a pellet and disposed of by the grebe. Pied-billed Grebes eat fewer fish than most grebes and the Least Grebe eats the fewest fish of all grebes and has the smallest feather ball in its stomach and the Pied-billed Grebe only a few more. Apparently, fewer swallowed feathers are needed if fewer fish are consumed.