Just like you and me, birds need water to survive. Most birds drink some water every day, but they don’t drink the way we mammals do. Their anatomy is obviously quite different from ours. For one thing, they don’t have cheeks and lips! With a few exceptions, birds lack the ability to suction liquid into their throats, as horses do. Most birds drink water by filling their bill with the liquid—often from morning dew on leaves—then tilting their head back, using gravity to send the liquid into their digestive tract.
Most birds can, however, lap water into their bill, akin to the way cats and dogs drink. But then birds must tilt their head to swallow.
Swifts and swallows skim a billful of water as they fly over lakes, ponds and rivers.
Pelicans are known to collect rain in their bucketlike bills, but brown pelicans also drink salt water. Most pelagic species have that ability. They are anatomically equipped for desalinization, allowing them to absorb H2O and exude salt in their urine or through salt glands and ducts near their eyes or nostrils.
Pigeons and doves are among the few birds that can suck water while their head is down. They don’t need to look skyward to swallow.
A few birds don’t usually drink water at all, including some desert species whose sole source of water is what is extracted from their food; and raptors, which similarly get the water they need metabolically from their moist, meaty diets.
Hummingbirds don’t drink water, but their primary calorie intake is sugar in liquid form: nectar. Hummingbirds don’t need to tip their head to swallow nectar, but neither do they suck it into their bills. Rather, they have a grooved tongue that draws nectar into the bill via capillary action.
Even though birds don’t have sweat glands, they still lose water through the skin through evaporation, especially during hot, dry weather. Small birds need to ingest more water than large birds because they have a higher ratio of surface area to volume, and so lose water faster.
You can attract more bird species with water than with seed and suet. Only a handful of bird species eat the kind of food humans are likely to provide, but all birds need water, and not just for bathing.