Answers to Mar-Apr issue's Do You Know?
Due to an oversight, the answers to the Mar-Apr issue of Do You Know was not printed in the May-June issue. We are printing it here. Apologies. --Editor

After the platypus, it is the turn of birds. Do you know the answers to these bird questions?
1. Woodpeckers (as their names suggest), hammer on tree barks. How come they don’t injure themselves in the process?
Ans: Woodpeckers have strong bills that they use for drilling and drumming on trees, and long, sticky tongues for extracting food (insects and larvae).  The bill's chisel-like tip is kept sharp by the pecking action in birds that regularly use it on wood.
Woodpeckers do not experience brain damage or headaches because their bodies are evolutionary marvels. Woodpeckers can slam their heads into trees up to 20 times per second with forces exceeding 1,000 times gravity without getting concussions. Their brains don't hurt because of specialised features.
They have spongy, plate-like bones, unlike human skulls, that act like an internal bicycle helmet. These absorb and distribute the kinetic energy of every blow before it reaches the brain tissue.
Also, the hyoid bone of the woodpecker, which supports their extremely long tongue, winds around outside the entire back of the skull through a special cavity, thereby cushioning the brain. When they peck, it tightens to act as a safety harness, securing the skull and brain in place. 
Combined, this anatomy helps the beak absorb mechanical stress. They have asymmetrical Beaks: their lower beak is longer and stronger than their upper beak, helping to divert kinetic energy away from the brain. 
Even small things matter. Woodpeckers align their necks and bodies perfectly in a straight line with the tree when pecking. This prevents dangerous twisting (angular) forces on their head and neck.
Research shows that tree and bill contact only lasts about 0.5 to 1 millisecond. Because this impact time is so short, their brains aren't subjected to sustained trauma. Their brain is relatively small and smooth, with less space inside and very little cerebrospinal fluid surrounding it. This snug fit prevents the brain from moving around inside the skull during pecking. This limits brain movement and prevents the sloshing of the brain that floats in cerebrospinal fluid in humans and causes concussions. Along with the short duration of contact, this minimises damage to the brain.
Computer simulations have shown that 99.7% of the energy generated in pecking is stored in the form of strain energy, which is distributed throughout the bird's body, with only a small remaining fraction of the energy going into the brain. The pecking also causes the woodpecker's skull to heat up. So they often peck in short bursts with brief breaks in between, giving the head some time to cool.
Finally, during the millisecond before contact with wood, a thickened membrane closes, protecting the eye from flying debris!  These membranes also prevent the retina from tearing. Their nostrils are also protected; they are often slit-like and have special feathers to cover them. What a wonderful adaptation!

2. Can crows really recogniseand differentiate human beings?
Ans: Yes, crows can absolutely differentiate individual humans. They are highly intelligent birds that can recognize specific human faces, voices, and gaits. Most importantly, they can remember how particular people have treated them in the past. So watch out!
Wildlife biologist John Marzluff and his students at the University of Washington in Seattle found that crows are highly adept at recognizing human faces. “As soon as we started paying close attention to them—either catching them or going to their nests—you could tell they were acting differently when we were around,” he says. “If you got within several hundred meters, the birds were alert, they stopped whatever they were doing, and they were watching you as opposed to what you wanted to do, which was watch them.”
In 2006, the researchers conducted an experiment in which they netted and banded sets of crows at various sites on campus and around Seattle while wearing rubber human masks.
A few days later the researchers walked through the same areas wearing assorted masks and recording how the birds responded. At each site the crows ignored all but the particular mask that had been worn during the banding, which they greeted with loud scolding cries and the formation of small mobs. The response was only to the masks, and not to the clothing or any other features of the researchers.
The ability to recognize human faces may not be as rare among nonhuman animals as one might think. In lab research, biologists have found human facial recognition among species ranging from dogs and pigeons to sheep, octopuses and even honeybees. More recent studies have found similar skills among free-roaming magpies in South Korea and mockingbirds in Florida.
Research also shows that they can differentiate between familiar and unfamiliar human voices. In fact, crows can categorize humans as "dangerous" or "friendly". If a crow has a negative experience (like being trapped or harassed) with a specific person, it will remember that face and scold or mob that person whenever they appear. Conversely, if you regularly feed them, they will remember your face positively and may even bring you "gifts" like shiny trinkets or bottle cap.
What is even more amazing is their ability for social Learning: crows communicate these threats to one another. Studies have shown that even younger crows that were not present during an initial negative event will learn to recognize and harass a specific human face just by watching the older crows react. So if you've harassed a crow, be prepared to be harassed in turn by generations of crows!

3. Why are flamingoes pink in colour?
Ans: Flamingos are not born pink. When they hatch, their fluffy down feathers are dull gray or white. It takes about three years for them to transition into their iconic pink color as they continually filter-feed on pigment-rich aquatic life.
They consume tiny crustaceans and blue-green algae in their wetland habitats that are packed with carotenoids. Enzymes in the flamingo's liver break down these pigments. The pigment-rich fats are then absorbed and deposited into their growing feathers and skin.
So flamingos are pink because of their diet, which is rich in carotenoids—the same natural orange-red pigments that give carrots and pumpkins their bright colors. As they filter-feed on algae, brine shrimp, and fly larvae, their liver metabolizes these pigments, depositing the color into their feathers, skin, and even their eggs.
The shade of pink signals a flamingo's health and readiness to breed. Brighter, deeper pink or orange birds are generally healthier, meaning they attract mates faster and begin breeding earlier. Because color is entirely dependent on food intake, a flamingo deprived of carotenoid-rich foods will eventually lose its vibrant color and turn white or pale gray as it molts its feathers.
Not all flamingos are the same shade of pink. The depth of their color depends entirely on how many carotenoids are present in their specific local diet. For example, flamingos that consume higher concentrations of beta-carotene will display a more intense reddish-orange color, while others might appear a pale pink. If a flamingo's diet lacks these pigments, its newly grown feathers will gradually revert to white.
This is particularly true for captive flamingos: even if adequately nourished, they may turn a pale pink if they are not fed carotene at levels comparable to the wild.

4. Are any birds poisonous?
Ans: There are no known venomous birds that can actively inject toxins through bites or stingers. However, several species are poisonous—meaning they are toxic to touch or eat because they extract poisons from their diet, much like poison dart frogs. Some of the poisonous birds are listed below.
Hooded Pitohui: Found in the rainforests of Papua New Guinea, this songbird's skin and feathers contain batrachotoxin—the same deadly neurotoxin found in poison dart frogs. It absorbs the poison by eating Choresine beetles.
Blue-capped Ifrita: Another New Guinea native, this small bird stores the same neurotoxneurotoxin in its feathers and skin, causing numbness if handled.
Brush Bronzewing Pigeon: Native to Australia, this pigeon absorbs toxic fluoroacetate (a lethal compound found in rat poison) from the Gastrolobium plant, making its flesh highly toxic to predators.
Spur-winged Goose: Found in Africa, this large bird sequesters cantharidin from blister beetles, which can make its meat lethal to eat.
The Common Quail: It migrates to southern India during the winter, and is known to cause a rare toxic syndrome known as coturnism. During migration, the quail consume large amounts of hemlock seeds, which are poisonous to humans. While the toxins do not harm the bird, eating the meat can lead to severe muscle degradation (rhabdomyolysis) and kidney failure in humans.

Sources: Wikipedia; 
https://birdsoftheworld.org/bow/home