What level of organization is the human heart and how does the level of organization relate to the cells and organ system?

It is on the organ level. The heart consists of cardiac muscle tissue and is part of the cardiovascular organ system. It is basic for the human body to work properly since it provides oxygen for the human body. 

The return of the wolf to yellowstone national park will probably affect the bird population to some degree, not significantly. while wolves will hunt birds when necessary, they prefer to hunt larger prey. the bird population will most likely only be affected when hunting is scarce for the wolves. birds of prey will also probably not be affected as much as other birds who spend more time on the ground hunting for food as the tend to spend more time in the air or in trees since they do not need to stay on the ground for long due to the nature of the way they hunt.