Sibling rivalry exists in almost all families, and in almost all species. The first baby eagle born makes it his job to push the others out of the nest. Fratricide is the most extreme result of sibling rivalry. But before that point is reached, a sibling might be driven by another sibling from what had been his home.
This is the best-case scenario I can think of, in a coyote family which I have been observing for two years now. The more submissive of the twin male siblings had been bullied and dominated for several months. Although when this happened he would always increase the distance between himself and his brother, more recently he had been standing up for himself by growling and snapping back, and even remaining close by — as if stating that he wasn’t going to be pushed around. Then, one morning, I heard unusual coyote sounds: these were complaining-like squeals which lasted about five minutes before petering out totally. Charles Wood has suggested that those squeals might have been from the type of fight that produced the rump wounds I had seen and posted earlier on. I don’t know if this is related or not, but the day I heard those sounds marks the last time I saw the more submissive of the two coyote siblings which I had come to know as a family. Until that point, he was the one that was most visible and out in the open. His disappearance was very sudden and very total.
Did he just disperse, or did something worse come to pass? Charles Wood has suggested another possibility: that this coyote might have been banished from contact but not from the area — hiding in the day and eating at night. If I see him again I will post it, but it has been a month now since I last saw him. Worst-case scenarios also exist, brought to mind by hearsay and conversations I’ve had with individuals in the parks. Although highly unlikely, these possibilities include kidnapping either for breeding purposes or as bait for pit bull fighting — an illegal practice which continues in this area, or even removal by park visitors who have been wanting coyotes “relocated” for some time. Let’s cross our fingers that any of these is not the case.
Coyote Yipps 
