Well, can they? If they can’t, would they be rendered flightless if they suddenly/mysteriously started sweating?
No, birds do not have sweat glands. They are air cooled.
The second part of your question is nonsensical.
Birds thermoregulate, if necessary, by panting, that is, by rapidly breathing in and out. As DrFidelius says, they do not have sweat glands.
I agree with the second part of his answer too.
Nah, it’s not nonsensical at all; just very basic.
Dig, the answer to the second part is no. Sweat glands aren’t that heavy, and feathers work even when wet. (Water off a duck, etc. etc.) Bats fly with sweat glands, so I see no reason why birds couldn’t.
Wrong, at least if a bird sweat heavily enough to wet its feathers thoroughly.
What?
Wrong. If they become completely wetted, feathers do not work and birds are unable to fly until they dry out. Most birds keep their feathers fairly waterproof by coating them will secretions from a gland at the base of the tail; this is especially true of ducks and other aquatic species.
Although bats have sweat glands, their distribution on the body is quite limited. In any case, bat wings, being made of skin, work even when wet. This is not a valid comparison with birds.
Allright, Mr. over-analyzing smart guy. Let’s break it down in terms of the question that was actually asked, shall we?
You’re right, most birds do keep their feathers water proof through secrections from the base of the tail. But, if seagulls can keep saltwater from affecting their feathers, then the hypothetical sweat glanded bird’s oil gland ought to be able to take care of a little sweat, no? Evolution is pretty good at fixing those types of problems.
It’s a hypothetical question. Hypothetical. And as a hypothetical, if bats can take the extra weight of sweat glands, then our hypothetical avian ought to be able to carry the extra weight, too.
I see no reason why a biological thermoregulatory system based on evaporation would hinder flight, whether the animal be avian, mammal, dinosaur, or whatever.
No. If you are going to go down this route then “evolution” can’t provide a solution. If feathers can’t get wet then they can’t wick water away from the skin. That makes sweating useless. Hairy animals can only benefit from water cooling if the water can be drawn away form the skin and evaporate. If the skin is covered by a layer of waterproof feathers the water remains trapped against the skin.
That is debatable at best. As Colibri pointed out birds and bats simply can’t be compared. The larger bats can exploit sweat glands because their flight style incorporates a lot of gliding and because the wing membranes are an excellent means of heat dispersal. Nonetheless bats have real troubles operating in the heat and even though they are nocturnal they often die of heat stroke on hot days. The whole package available to bats really isn’t an option for birds for all sorts of reasons.
You can’t reasonably conclude that even hypothetically birds can deal with the weight of effective sweat glands. It’s like saying that humans can deal with diving to 100 metres simply because other terrestrial animals do it.
Well the single biggest obstacle is that birds have almost no exposed surface to allow evaporation. Their legs, and some species have naked heads and necks and that’s it. That makes it doubtful if there is enough exposed skin to make surface evaporation effective. And if you want to use the feathered surfaces as wicks the way mammals use their furred surfaces then we are back at the initial problem of how to fly with wet feathers.
Though all birds have feathers, it doesn’t take too much creativity to imagine a bird that doesn’t. A lot of mammals have fur, but many have sparse hair. Just because Mother Nature hasn’t produced a bird that has sweat glands doesn’t mean She couldn’t. Yes, our hypothetical avian might need to lose a few feathers to allow the sweat to evaporate, but the feathers don’t make the bird.
Creativity, people. Prove to me that sweat glands and flight are mutually exclusive. That is the crux of ** question.
You can’t - hence the bat comparison.
So what you are basically saying is that if we produce a bird that doesn’t have key bird characteristics then that un-birdlike bird could fly with sweat glands?
And if may cat had wheels it would be a Volkswagon.
Let me make this simple. If the birds we know now had sweat glands, could they fly? No, but flight would be the least of their problems. Is an animal that has sweat glands, flight, and yet still an avian conceivable? yes
OK, I’m done. We’re getting dangerously close to being overly argumentative in GQ.
Well I dunno about birds sweating but if I ever show our pet duck the oven it shits itself
And if a frog had wings it wouldn’t bump it’s butt on the ground when it jumped. (Hypothetically speaking, of course.)
As Blake says, if a bird didn’t have the characteristics of birds then it might be able to thermoregulate by sweating. Sweating might be feasible for a kiwi or an ostrich, but most likely would not be very effective for a flying bird.
If you’re not prepared for overanalysis then GQ might not be the best place to hang out. 
So we could have a hypothetical bird with sweat glands on its naked head, but not with wet feathers? That would work, yes? Maybe in very hot climates, when the air itself is so warm that air-cooling isn’t sufficient?
My question wasn’t nonsensical. I was just asking, if they did in fact had sweat glands, could they fly? But it’s been answered, so thanks, guys !
It was in the way you phrased it - “if they suddenly/mysteriously began sweating” doesn’t make a lot of sense. If you had asked, “would it be feasible for a feathered animal to sweat and still be able to fly?” it might have been answered in a more straightforward way from the start.
Putting a little care in the way you formulate a GQ can help a lot in having it answered expeditiously.
I doubt it would be feasible for all sorts of reasons.
To start with birds have a massive respiratory system compared to their body size. IIRC somehting in the order of 75% of a typical bird’s volume is occupied by lungs and airsacs. And that’s just volume, the surface area of the respiratory system is really big. Something like a crow prooably has a respiratory surface area twice the size of of your garage floor.
To that area you are proposing to add the area of the head and neck, about the size of half a dozen quarters. I can’t see that it would make any measurable difference.
Then we have the problem of weight. Birds are designed very light so they can fly. Sweating wastes large amounts of water. That isn’t an insignificant problem for mammals, but at least mammals living in really hot climates can drink sizable fractions of their own body weight in a single sitting to deal with it. That becomes much more difficult for birds because the relative weight gain starts to become huge. If a 1 pound crow drinks just 2 ounces of water it has just increased its weight by 10%. That’s a significant load for a flying animal.
Air cooling is much more efficient because much of the water eveporated can be recaptured by the upper repiratory system on the way out. That isn’t an option with sweating.