Falling revenue and write-downs are wringing losses from Corus Entertainment.

The broadcaster posted a third quarter loss of $145 million, for the period ending May 31, below analyst expectations and a big swing from a profit of $37.7 million during the same period of 2008. The culprit was a $175 million broadcast license and goodwill impairment charge for Corus’ faltering radio division.

With the move, Corus joined a growing list of Canadian broadcasters that have written down the value of assets to reflect an advertising slump and a migration of audiences to the Internet.

Overall revenue was down 6% to $195.4 million. Corus’ TV revenue slipped 1% to $129.8 million, with its segment profit down 5% to $50.7 million. Radio fared worse, with revenue down 15% to $65.5 million and segment profit off 35% to $16.1 million.

Against these weaker results, Corus president and CEO John Cassaday reassured analysts on Wednesday that the broadcaster is aggressively cutting costs so it can reach full-year 2009 guidance of $250 million to $255 million in operating income.

That said, the tone of analyst questioning reflected questions over the stability of Corus’ radio and specialty channel earnings going forward amid the ad slump, rather than restructuring concerns as at conventional broadcasters.

Desjardins Securities media analyst Eric Bernofsky in a note said the Corus results indicated Canada’s advertising market continues to slow and negatively impact broadcast results.