We see birds flapping around and hanging out all over the place in just about any natural habitat.

We often hear even more of them as they sing and call to each other.

But then, as the sun sinks below the horizon and evening comes on, the birds disappear and go quiet.

These diurnal birds, the ones active in daylight, find places to settle in for the night, places to sleep.

I'm not sure why, but this nightly disappearing act amazes me.

But it makes perfect sense, of course, that all the

birds I saw that day would get sleepy and hide themselves away until the next morning. It's nothing

miraculous. I guess what impresses me is that I have only rarely come across a wild bird sleeping at night.

My best example is when I was leading a birding tour on the

west coast of Mexico. My group and I were in a small boat cruising through a crocodile-infested

mangrove forest at night. In some places the mangrove branches closed in overhead, interlacing,

turning the channel into a dark tunnel. More than once, I was thrilled when I saw a belted kingfisher perched on a branch,

passing just inches over my head.

These birds were trying to sleep,

but this loud boatful of apes had rudely awakened them.

They looked offended.

But it was really cool to see where these kingfishers were tucked in for the night.

So all these sleeping birds are out there in the dark.

You and I have probably been surrounded by dozing birds every time we've walked around a natural area at night.

I've fantasized about having heat vision goggles that would allow me to see sleeping birds as little glowing blobs in the

forest. It turns out that other people had the same idea and they actually did something about it.

In 2019, scientists in Australia published a study where they surveyed forest birds at night

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