We have a standard poodle, 45 lbs or so, that I do trust with the chickens. When we first got chickens, we were very careful to teach him that the birds were MINE, and he wasn't to touch them. The ladies free range in our yard all day, weather permitting, and he loves to follow them around and eat chicken poop.
He'll also try to sneak in their run and eat any treats that are lying around - oatmeal, corn, etc. But, he's so good with them that I try not to mind (except when he ate too much scratch and threw up all over). He has chased away hawks, and I've seen him herd them back towards their run when hawks are nearby - which is funny, since standard poodles are bird retrievers, not shepherds.
He has never been aggressive towards them, but he is curious to meet any new girls we bring into the flock. We keep all new birds in a separate quarantine area about 150 feet away from the regular coop/run area. He likes to go sniff them, but he's learned not to stick his nose too close. He's been pecked enough times to keep his distance.
We've never allowed babies to free-range, though, too many hawks in our area. He'll lie next to their enclosed tractor run and watch them - I think it's the way they move and the peeping. I have a picture somewhere of him lying in the grass with three 5 or 6-week old chicks roosting on his back.

He has never been aggressive towards them, but he is curious to meet any new girls we bring into the flock. We keep all new birds in a separate quarantine area about 150 feet away from the regular coop/run area. He likes to go sniff them, but he's learned not to stick his nose too close. He's been pecked enough times to keep his distance.
We've never allowed babies to free-range, though, too many hawks in our area. He'll lie next to their enclosed tractor run and watch them - I think it's the way they move and the peeping. I have a picture somewhere of him lying in the grass with three 5 or 6-week old chicks roosting on his back.