Mate, spawn, and die

[chard]

It's summer in Japan, and that means the semi (蝉, Japanese cicada) are out in the trees. You don't see them all that much, but boy do you hear them. In fact, if you're standing within about 5 metres of one it's difficult to talk to someone standing next to you.

I'm curious about just how much energy they're putting out. Must be more than a

Comments

[ashley_y]

Yes, I seem to remember that even a lot of sound isn't very much power at all.

[ashley_y]

In other words, higher frequencies of the same power seem louder to us?

[gareth_rees]

Sucrose has an energy content of 17 kJ/g. Putting out 1 mW for two weeks takes 1.2 kJ.

As for the birds, they have to find food all year round, whereas the cicadas are only plentiful in the summer. Indeed, some species of cicada have multi-year life cycles with prime-number periods so that they aren't a predictable source of food for predators (for example Magicicada species with life cycles of 13 or 17 years).

[chard]

As far as I know there are plenty of semi out every year here. The big black crows seem to eat human garbage mostly. I am very curious as to where they've gone. Perhaps they can't take the heat of the summer and head north to Hokkaido. Given that birds can move around easily you might expect a big population to arrive every summer just to eat semi, but it doesn't seem to happen. When I backpacked around Japan I remember thinking that there weren't many birds anywhere. This could be a naturaly phenomenon, or something to do with the wholesale destruction of the environment by the Japanese.