Why is a drinking bird colder than the ambient temperature?

[DDesulgon]

In a drinking bird, water from the wet on the outside of the head evaporates, causing the vapor inside the head of the bird to cool. This reduces the pressure of the vapor at the top, allowing the higher pressure in the lower bulb to push up the column of liquid.

But the bird's body (including the rump and neck) is also a bit colder than the ambient temperature (but not as cold as the beak). Why is that?

My idea is that when the liquid rises in the bird, the vapor pressure in the rump decreases. As a result, a part of the liquid evaporates. The necessary entropy is removed from the remaining liquid, which thus cools.

Is that a conclusive argument? Are there any other reasons why the drinking bird is colder than the ambient temperature?

On the other hand: Shouldn't there be a temperature compensation by heat absorption from the environment? Why is the bottom bulb colder than the environment at all?

Another idea: The liquid might cool when it rises to the head. So when the liquid flows back into the bottom bulb, as the bird goes back into the verticale, it's colder than originally.I would be very grateful if somebody who understands this better than I do could explain it to me. Thanks in advance!

PS: English is not my mother tongue, so please excuse my linguistic mistakes.

 

[.Scott]

When the water on the birds head evaporates, the latent heat of evaporation chills the head of the bird - bring in closer to the dew point temperature (and further from the ambient temperature). That cools the fluid in the head and ultimately the whole bird.

The fluid in the bird is moving, evaporating, and recondensing. So the method of getting the cooling effect to the bottom of the bird will involve both convection (moving the fluid) and evaporation (which is part of what forces the fluid to the head).