Inconstant Star is novel by Poul Anderson set during the Man-Kzin Wars in Larry Niven's Known Space Universe. The novel is actually a fix-up, combining two previously published works in the Man-Kzin wars saga. The short stories used to make the novel are Iron, from The Man-Kzin Wars, and Inconstant Star, from Man-Kzin Wars VII. 
"When humans and kzinti met, the kzinti introduced themselves with a scream-and-leap of joyous anticipation. But - surprise! - the monkey boys and girls of Planet Earth not only fought back but won! How, how could the Warrior Race have fallen prey to slinking cowardly (albeit clever) leaf-eaters who didn't even possess weapons?
After long hard thought the Kzin have come up with an answers: the first time they didn't leap hard or fast enough! After all, no matter how clever the humans may be, they won't stand a chance if it all happens so suddenly that monkey cleverness never has a chance to come into play. So when Eric Saxtorph and his crew stumble across the secret of the Great Attack the kzinti are more than a little upset.
And when kzinti are upset, you know what they do..."