One of my Labs was a chocolate male from parents that weighed 65 and 75 pounds. He was 92 by six months, and around 100 at maturity when lean and mean. He was the best retriever and waterfowl Lab I've owned, but you could not hunt him in the uplands during September and most of October unless right next to a cool stream, and even then he'd only last an hour or so. On December pheasant hunts he'd roll around in snow to cool off. But he could bust brush, both to flush and retrieve pheasants, as well as he could retrieve Canada geese.
The present 60-pound female we deliberately bought when she was 18 months old, to make sure she would be the right size for early-season upland hunting. The breeder we bought her from lives on a ranch, and we got to take a winter walk with our potential dog and two other Labs while sizing her up. She soon started acting birdy, with her nose in the air rather than down on the ground, and followed the scent to a covey of Huns 250-300 hundred yards away, the other two Labs following along behind her acting puzzled. She's not as good on Canada geese as the big dog was, but she can hunt upland birds in September, and we hunt far more upland birds than waterfowl anymore.
