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December 14, 2011
Feeling vs. Reality of Security in Sparrows
Sparrows have fewer surviving offspring if they feel insecure, regardless of whether they actually are insecure. Liana Y. Zanette, Aija F. White, Marek C. Allen, and Michael Clinchy, "Perceived Predation Risk Reduces the Number of Offspring Songbirds Produce per Year," Science, 9 Dec 2011:
Abstract: Predator effects on prey demography have traditionally been ascribed solely to direct killing in studies of population ecology and wildlife management. Predators also affect the prey's perception of predation risk, but this has not been thought to meaningfully affect prey demography. We isolated the effects of perceived predation risk in a free-living population of song sparrows by actively eliminating direct predation and used playbacks of predator calls and sounds to manipulate perceived risk. We found that the perception of predation risk alone reduced the number of offspring produced per year by 40%. Our results suggest that the perception of predation risk is itself powerful enough to affect wildlife population dynamics, and should thus be given greater consideration in vertebrate conservation and management.
Seems as if the sparrows could use a little security theater.
Posted on December 14, 2011 at 1:22 PM
• 13 Comments
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"Seems as if the sparrows could use a little security theater."
No, they couldn't, they could do with a eliminating the *insecurity* theatre.
The experiment was one in artifically breaking the link between percieved risk and actual risk. Sparrows behaved in a way which would be rational if the risk was real.
The experimenters are playing the role of the TSA and the scaremongers, and hyping the threat.
What is required is to bring perception and reality into line. Security theatre doesn't do that, it boosts the perception of the threat.
A quick Google turned up the actual .pdf at this link so you don't have to worry about the paywall.
I'm not normally impressed by most science these days but this is actually a well-done study. I'm impressed.
The only issue that I wish they had addressed is possible impacts of mean vs deviation. This other recent article talks about the fact wolf mortality is driven by the mean environmental affects and not the variability them. Given the way the sparrow study was done it's not obvious as to what pattern of perceived predation the birds are actually responding too.
@Ben - "... they could do with a eliminating the *insecurity* theatre ..."
I think Bruce is saying that a placebo is the optimal cure for a psychosomatic condition - just watch out for those pesky side effects.
This finding, if it applies to humans, would certainly explain why the prevailing population is gullible - Machiavellian mindsets do not possess equivalent Darwinian fitness under this model, thence, Duggars everywhere!
@Z.Constantine: I realize that is what Bruce is saying.
But if sparrows or people are only afraid because they have been lied to about the nature of the threat, that is not psychosomatic, it's a rational response to the available information. The cure is not to lie to them again about fake security measures, but to stop lying to them about the threat.
If the police tell the community there is a prowler about, women will be cautious about going out. That's rational. If the police step up patrols, that will make women less cautious about going out, again, rational.
But if there is no prowler, it makes no sense to say that the cure for women's heightened fear of going out is more patrols. Tell them there is no prowler.
Once upon a time, there was a non-conforming sparrow who decided not
to fly south for the winter. However, soon the weather turned so cold
that he reluctantly started to fly south. In a short time ice began to
form on his wings and he fell to earth in a barnyard almost frozen. A
cow passed by and pooped on the little sparrow. The sparrow thought
it was the end, but the manure warmed him and defrosted his wings.
Warm and happy, able to breathe, he started to sing. Just then a large
cat came by and, hearing the chirping, investigated the sound. The cat
cleared away the manure, found the chirping bird and promptly ate him.
The moral of this story:
1. Everyone who poops on you is not necessarily your enemy.
2. Everyone who gets you out of poop is not necessarily your friend.
3. And, if you're warm and happy in a pile of poop, keep your mouth
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