POTTSBORO, TEXAS -- Karl Haller is 97-years-old and has volunteered at Hagerman for 50 years.
He's won U.S. Fish & Wildlife's Volunteer of the Year and has a trail named after him on the refuge.
Today we got to tag along with him for one of his birding outings.
Every Tuesday and Thursday, Karl Haller, and fellow Friends of Hagerman, drive around the refuge, identifying and taking census of birds.
Haller drives the bus, while the others count the bird species.
Haller says he took a liking to birds at a young age, but his fascination for them grew while serving in World War II.
"During the war, I was in England. I went birding. I had a friend there who used to take me out once a week and we'd go various places," Haller said.
Haller grew up in West Virginia and came to Texoma in 1963 while stationed at Perrin Air Force Base. He's been volunteering at Hagerman ever since.
"Oh, I used to come out 5, 6, 7 times a week. I guess if a week had more days, I would've come out on a longer week," Haller said.
Haller has kept thorough records that have helped Hagerman better understand its bird populations.
"He'll say, 'Well, it was probably August of '63 when we had two of them come in.' His memory is incredible!" fellow birder Dick Malnory said.
After serving in the military, Haller taught biology, and other subjects, at Austin College, inspiring students like James "Sandy" Beach to appreciate birding.
"I guess when you start a friendship like that, you never expect it to last as long as it has," Beach said.
But more than anything else, Haller says birding has been his way to unwind for over half a century.
"Well, it's relaxing and it's just something to do and when you're tired or upset or something, go out and look at a few birds or something, it'll calm you down," Haller said.
Haller says birding has been one of his life's passions and he doesn't plan to stop anytime soon.