Tag Archives: behavior

Daylight Saving Time, Saving Energy, Saving Lives?

I don’t think I ever fully realized how fraught the concept of Daylight Saving Time was and what controversy surrounds “falling back” or “springing ahead” an hour.

Disorienting? Sure.

Annoying? Occasionally.

But life-threatening? Seems a touch dramatic.

Yet NPR highlighted a study finding an increase in violent street crime and robbery that occurs when we “lose” an hour of daylight in fall evenings. Apparently robbers like to sleep in as much as I do.

(But I doubt they’re aware of the price of that extra hour of shadowy mischief-making: they and everyone else also have an increased risk of heart attacks, traffic accidents, and injuries in the workplace on the Monday immediately following the end of Daylight Saving Time. Researchers tend to blame disruptions to sleep patterns for some of these effects.)

Economists Jennifer Doleac of the University of Virginia and and Nicholas Sanders of William and Mary took advantage of the Energy Policy Act of 2005 extending Daylight Saving Time (DST) by an extra three weeks in the spring and one week in the fall. They compared neighborhood crime rates during the switch to DST in spring and fall of 2005 and 2006, before the law took effect, and with the same time periods in 2007 and 2008. Their study [PDF] uncovered a 7% drop overall in robberies after DST takes effect, stealing an extra hour of darkness from the evenings when ne’er-do-wells would prefer to not do well and take your wallet under the cover of darkness.

So, Daylight Saving Time may save you from getting hit by a car and hit up by a robber, but does it live up to its perennial justification of saving energy?

Well, various reports conclude that … it depends.

If you live in Indiana, then it may slightly increase residential energy use [PDF]. (This state actually used to be split, with some counties observing DST and others never paying attention to a time change. Having lived there during that time, I can attest that was truly annoying.)

If you live in California, it may actually sorta save some energy (perhaps 0.93% of your daily energy bill [PDF]).

And if you live in all of the United States at the same time (I think that’s how national averages work), extending Daylight Saving Time cuts about 0.03% of annual U.S. electricity consumption [PDF], which is at least better than a coal-fired punch in the face.

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I Flew Over the Cuckoo’s Nest

Baby got snack: A Reed Warbler feeds a Common Cuckoo in its nest.

Baby got snack: A Reed Warbler feeds a Common Cuckoo in its nest. Credit: Per Harald Olsen/Creative Commons Attribution-Share Alike 3.0 Unported license

Earlier this week, I was researching and writing a story for Natural History Magazine about some cuckoos that have taken on the plumage patterns of local hawks and other raptors in order to frighten away other birds from their nests.

“Dressing” like a known predator allows the cuckoos to swoop in and lay their own eggs in the nests, tricking unsuspecting sets of bird-parents into raising the cuckoos’ young. This sometimes happens to comedic effect when you consider how much bigger cuckoos can grow than their host parents.

(By the way, you should read the bio of Thanh-Lan Gluckman, one of the scientists who published the study on cuckoo-raptor plumage; she has taken a fascinating, if self-described “convoluted,” path to evolutionary biology.)

In the course of researching this story, I followed an interesting tangent: In 350 B.C., the ancient Greek philosopher Aristotle made observations in his work “The History of Animals” about both the behavior of cuckoo parents and their striking resemblance to hawks. Stringent scientific studies today support these observations as well as the maxim shared with me by my college ecology professor: Basically, ecology confirms what we already know.

One thing I found amusing about reading these early descriptions was the moral lens through which the cuckoo is viewed for its habits (emphasis is mine):

The cuckoo, as has been said elsewhere, makes no nest, but deposits its eggs in an alien nest, generally in the nest of the ring-dove, or on the ground in the nest of the hypolais or lark, or on a tree in the nest of the green linnet. It lays only one egg and does not hatch it itself, but the mother-bird in whose nest it has deposited it hatches and rears it; and, as they say, this mother bird, when the young cuckoo has grown big, thrusts her own brood out of the nest and lets them perish; others say that this mother-bird kills her own brood and gives them to the alien to devour, despising her own young owing to the beauty of the cuckoo … The cuckoo shows great sagacity in the disposal of its progeny; the fact is, the mother cuckoo is quite conscious of her own cowardice and of the fact that she could never help her young one in an emergency, and so, for the security of the young one, she makes of him a supposititious child in an alien nest. The truth is, this bird is pre-eminent among birds in the way of cowardice; it allows itself to be pecked at by little birds, and flies away from their attacks.

~Aristotle, “History of Animals,” Book IX, Part 29, 350 B.C.

Yes, the cuckoo is full of “cowardice” and is quite aware of it, thank you. On the other hand, the foster-parent bird purportedly “despis[es] her own young owing to the beauty of the cuckoo.” Naturally, they’re going cuckoo for cuckoo chicks!

This tangent took me further down the rabbit hole to the 1891 work of Alfred Russel Wallace, “Darwinism: an exposition of the theory of natural selection.” Wallace makes further reference to how similar several species of cuckoos appear to sparrow-hawks and other “aggressive” birds, despite–or rather because of–the cuckoos’ “exceedingly weak and defenceless” nature.

Darwinism: an exposition of the theory of natural selection, with some of its applications

“Darwinism: an exposition of the theory of natural selection, with some of its applications,” by Alfred Russel Wallace, 1891.

It’s worth noting that not all cuckoos (the family Cuculidae) exhibit these parasitic adaptations to reproduction. But approximately 41% of them do.

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