How long does it take for cats to grieve?

I was wondering, how long it takes for cats to grieve the loss of the other fellow cat?

After Fancy passed, my mother's cat was howling for her.

Like humans, it probably varies.

When we lost Chessie a year ago, Casey was noticeably upset. He became quite clingy and vocal with me. The first few days, he'd take off running and looking all over at the slightest sound. Going to work was rough on him as he would literally put himself between me and the front door and refuse to move. I'd step over or around him, and then he'd quickly get in front of me again.

It was about five weeks afterwards that I brought Smokey home. I wasn't sure about getting another cat so soon after losing Chessie, but a coworker told me about a litter of kittens at an animal hospital he'd been to near where we work. I went to check them out, and Smokey won me over. While Casey wasn't happy at first, after about four days, they were grooming each other and sharing food, water, both litterboxes, and all of their toys.

Princess was at the hospital 5 days before she died. Butler missed her from the moment she left the house. He looked so lost and confused. I wasn't sure if I should bring home another kitty, but I needed to, in order to help myself. Butler feel in love with Bentley instantly. It was magic. I believe that he has grieved Princess and now is amused at this little and funny thing that is chasing him everywhere.

I agree it probably varies on the 2 cats relationship, personality and situation. I lost a cat to cancer in June 2010 and the other male cat that grew up with him, meowed and bellowed every night for 3 weeks, during the night hours, when it had been their play and run around the house time.:(

Sorry about your cat Fancy. Just give the cat extra love and care. It might take few weeks for her to recover and act like that. In the mean time, good luck, and keep a close eye on her.