There's no web site for Birdwell with this link. I surfed, snorkeled, and hung around the beach with two pairs of Birdwell Beach Britches for almost ten years. They held up against the salt water and abuse better than wetsuits I'd occasionally wear over them. If their current products are anything like what I owned I can recommend them without hesitation.
I am from Hudson originally and have had Arrow moccasins since I was 17, over 40 years ago. I want one last pair if I can get them. I have an email into them. Since he passed a couple of years ago they are not making any new ones. So get them while you can they are a great value for the money.