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, who‘s 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
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