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Sunday, May 8, 2016

How do hummingbirds get the energy for their high-octane lifestyle?.



 
Hummingbirds’ “fighter-jet” acrobatics are as dazzling as their plumage, but the same physics that sets them apart exacts a steep price.

As the world's smallest birds, hummingbirds have a high surface-area-to-volume ratio. That means they lose a lot of heat through their skin. The problem is compounded by a lack of downy feathers, the fluffy insulation that keeps most birds warm. Skipping the down shaves weight, but the birds must compensate by refueling constantly, consuming two or three times their body weight every day. 

That's also why hummingbirds love nectar. They will visit multiple flowers in a short time, lapping up three to seven calories daily. That may seem like a trivial amount, but when scaled to the size of a human, it translates to about 155,000 calories a day. If the birds were any smaller, it would be physically impossible for them to eat enough to stay alive. As a result, hummingbirds are territorial. They stake out flowers and feeders, defending a food source at all costs—even at the cost of having a social life.
Unlike many other birds, hummers don’t gather in flocks (except when they concentrate near food); males and females don’t even raise their families together. Mating takes about half a second, after which the female zooms off to build a nest, lay eggs, incubate them, and raise the eggs/chicks by herself.

Because hummingbirds have such high metabolism, even sleep could prove fatal. Going for several hours without refueling could cause them to starve. Luckily, the birds have evolved an extreme solution: At night they enter a state of controlled hypothermia, slowing their breathing and heart rate and drastically lowering their body temperature to save energy. On a particularly frigid night, a hummingbird’s metabolism can drop as much as 95 percent.
Because the birds have few natural enemies, life expectancy is mostly determined by their own biology. Hummers age about 10 times faster than humans. They seem to have a high rate of heart attacks, ruptures, and strokes—not all that surprising given the fast pace of their lifestyle (up to 6.2 beats per second). If a hummingbird slows down, it dies; its existence leaves no room for laziness. You can help prolong their lives by having multiple feeders, full of fresh, clear nectar. Also, lots of native flowers such as cherry sage, turks cap, lantana and mistflower.  But, in the end, these birds essentially blow themselves out. 

CAN A MACHINE GET RID OF MOSQUITOES? The simple answer is “no”. That doesn’t stop manufacturers from making carefully-worded claims, however,

Bug zappers for instance. They use ultra-violet light to attract bugs, which are then electrocuted. They’ve been found to be totally ineffective in eliminating biting insects. Numerous studies show that less than one percent of the insects fried by zappers are biting insects. Many are “beneficial” bugs (which eat other bugs) like lacewings, ladybugs and dragonflies. It’s other things that attract biting insects such as mosquitoes, like carbon dioxide and ingredients in mammalian sweat.

We now have more elaborate and expensive machines, and fancier claims. New studies have shown these expensive machines are nearly as ineffective against mosquitoes as the old bug zappers. Much of what they destroy, in fact, are harmless insects that are food for insect-eating birds such as wrens, kinglets and swallows. Also, almost all birds need insects to feed to their young.
    The best mosquito defense that I know of (short of moving to the desert) is to have lots of birds and bats around. As I said, many birds eat mosquitoes (the purple martin is said to eat up to 2,000 a day!) The bats in the north Texas area (despite a horrible reputation thanks to Hollywood) can eat more than that!

  

Owen Yost, in addition to blogging, is a Landscape Architect emeritus from here, whos worked in north Texas for over 30 years.  He is a member of the American Society of Landscape Architects (ASLA), International Society of Landscape Architects, the National BirdFeeding Society, National Wildlife Federation and the Audubon Society. He was honored with a Lifetime Achievement award by the Native Plant Society of Texas. His design office is at northwestern68@yahoo.com