The partridge is an unusual bird. When a predator approaches, it has been known to fly away from its nest (where its chicks rest), luring the dangerous predator away from the innocent. The partridge will fly for as long as necessary to distract the predator away until it can no longer find the nest. Sometimes, however, the tenacity of the villain is so great that the partridge can not lead him far enough away from the nest to ensure the safety of the chicks. In such cases the partridge will sacrifice herself in order to give the predator a full meal, thus leaving the nest alone.
The partridge, then, is the bird of self-sacrifice.
When we were without strength and could not save ourselves, Christ died for us (Romans 5). When we needed a savior, Christ was provided. He sacrificed Himself, bearing the punishment for our sins, allowing us access to Heaven someday.
He is our partridge, offered on the tree of Calvary for us.