Mark Callaghan, a long-time on-air personality and program director for Townsquare Media Northern Colorado, is leaving to join a Denver radio station.

Starting April 2, Callaghan will serve as program director for KOSI 101.1 after 16 years with four Townsquare Media radio stations in Windsor. KOSI 101.1 is owned by Entercom Communications Corp., one of the largest radio broadcasting companies in the United States with more than 100 stations in 23 markets.

Callaghan has worked in radio, including formats from country to adult contemporary, for more than 25 years.

"I have loved KOSI 101 ever since I first landed in Denver nearly two decades ago," Callaghan said in a statement issued by Entercom. "I've followed KOSI very closely over the years and I just can't wait to hit the ground running at Entercom Denver."

Callaghan will lead on-air morning, afternoon and evening shows.