Get A Load Of This Buffoon
The thing about Twitter, and the internet as a whole, is that it's full of fucking liars. For starters, only two of those birds are pelicans. The other is a shoebill stork, also known as nature's largest mistake. Some have argued they could be closely related to the pelican family, but the one thing pelicans and I agree upon is that they're fucking storks. Secondly, these fellas are just yawning.
Yawning and making sure their gullets are properly stretched out for the next fish they swallow whole, like sociopaths. So not even remotely related to cooling off. Regardless, the original point the poster was trying to get at is that these birds look like absolute buffoons doing whatever you think they're doing here. Yawning, cooling off, doesn't matter. Spines are for backs and necks, pal. Certainly not to push out the front of your largest face hole. That's just insanity. You're begging for a big time accident playing it so fast and loose with your spine like this.
Going back to the shoebill stork for a second, the way they actually do cool off? Glad no one asked. The way the shoebill stork is set up is that they have warm blood in their legs and feet. So, naturally, the way they cool themselves off is to take a big ol' dump on themselves. Nothing like some stork turds to drop the temperature a few degrees. The way I like to cool off, once the Sun really starts to blaze and the Summer begins to become hot? Buddy, there's no better place...