Spectrum Scientifics Blog

The drinking bird is a classic science toy that has been entertaining kids and adults for decades. The science behind the drinking bird is fairly straightforward, but first let’s have a quick look at the drinking bird in action:

The drinking bird’s is simple: Take a thin liquid sealed in a glass tube or other shape along with some air, then cover the top with a sponge of some sort, and balance it all out on some legs to allow it to tip over when it gets top-heavy.

How it works is a wonder of thermodynamics. If you get the spongy material wet, the water will evaporate, cooling the air in the glass. When the air is cooled it contracts and draws the liquid up the glass tube. This makes the bird top heavy and causes it to tip over. If you put a glass of water under where the bird will tip it will re-wet the sponge. After tipping, the liquid pours back into the lower portion of the bird and brings the bird back up. If you keep the glass filled with water the bird will keep on drinking!

But the drinking bird is not perfect. There is noticeable change in bird performance when the weather is cold & cloudy vs. warm and sunny. The birds also may have balance issues out of the box and need much adjusting to properly ‘tip’ and drink.

Its not certain how long the drinking bird has been around, but we have found them in an old catalog from 1962. As you can see from the picture, the bird has undergone quite a few changes:

Compared to its modern counterpart:

The design is interesting, in the old version is a simple glass tube vs. the modern dumbbell shape. The ’sponge’ also doesn’t wrap around the head either, it appears to be a cap with a pinwheel head. We can’t be certain how well this bird worked, but one rumor about the older birds is that they actually worked better since the liquid in the container was much thinner and pliable to atmospheric changes (i.e. the air contracting) but was actually a much more dangerous liquid. All we know is that these days manufacturers go out of their way to point out that the liquid in the drinking bird is harmless (but it can stain clothes).

Incidentally, the drinking bird’s opposite is the Hand Boiler
. With that item you use heat to expand the air in a sealed glass tube to cause the liquid to ‘boil’. Both work on the same principle, just in opposite ways. You can actually ‘hand boil’ a drinking bird or draw the liquid up a hand boiler by putting a wet cloth on the top of the boiler. Neat fun!

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Filed under: Physics