Its a play invitation.
I used to watch sooty, magic and tucker bring their "prey" to the kittens when they were still tiny .... and sooty would yowl at them to get them to come eat(play)
2 boxers Miki & Monty
Boy Cats: Tucker,Freeway,Tyson,Copicat,Mike
Girl Cats : Magic, Garfield, Buggie,Lexie,Spike,Ginger,Blue,Spooky,Rotten, Trouble
2 Conures,2 African Greys,1 Black winged Jardine