Seeking my Father's birthfamily

My name is Claire and I am trying to learn about my father's birth family. I have been left with VERY limited information as his adopted status was hid from even him until he was grown with his own family. I am afraid he has given up the idea of looking, but I would still like to. My father, Dana Colton Martin, was born on or around 12-14-41 and is a white male with reddish blonde hair and green eyes. His adopted parents were Adam George and Clara Jane (Colton) Martin. He was raised in Warwick, RI and, I believe his birth certificate said, he was born in Providence. But the certificate was altered to have his adopted parents names as his birth parents, so we are not entirely sure if the city information is accurate. His adopted mother passed away Feb of 1977 and his adopted dad passed away in May of 1983. I know this isn't much at all to go on, but if anyone knows anything about this or recognizes any names, please don't hesitate to respond. Thank you all for your time and I wish you all the best in your own searches!! Claire Jane Martin