What exactly are they doing?

You'd be surprised how easy they can surface with only their bill to get a quick bit of air, only to go back under with just the smallest ripple, especially if they know they're being persued.

Wait till you see one "snake" away from you with only their eyes and bill above the surface. Makes it extremely hard to get a water swat on em to finish the deed, since the dog usually can't see this at all from their lower point of view.

15 minutes under water I don't believe. What is more probable is he poked only his snoot up and got air while he was hiding from you or the dog. They are extremely crafty that way. He was trying to make an exit and you wound up seeing him 15 minutes later.

I would have called BS on it too, but I have seen one stay down twice as long and still be alive. No way this duck snuck up for air. I'm not at liberty to tell the rest of the story.

Dadgum greenhead!!!!

I heard the story. I wish there was video of that one!!

Wait till you see one "snake" away from you with only their eyes and bill above the surface. Makes it extremely hard to get a water swat on em to finish the deed, since the dog usually can't see this at all from their lower point of view.

Oh, that is exactly what they do. I will not even send my dog on a bird that can dive, it must be wounded enough where it cannot dive, otherwise it is useless sending your dog they can spend hours out there chasing a diving bird.

Here is what you do, wounded bird on water, just watch the bird, it will head to shore, go about 5 feet and just sit there. Wait awhile, say 10 minutes or even longer (bird will sit there all morning), then send your dog, bird will not move after being on shore and your dog will pick it right up.

If you send your dog after a wounded bird, and bird dives, call dog off, then watch for bird, they will not stay under long, maybe a minute max, you will see them come up and “snake away” as said above. With no wind and water is glass you will see a small wake where duck is swimming off, looks like a snake swimming because body is under water just the bill/eyes above water. If there is wind and ripples in the water, very hard to see bird swimming off, but they are not committing suicide, lol. I have seen all this (what I posted here) countless times.