Which of the following is not a fossil?

worm burrow tube from 400 million yeas ago

deer tracks left in wet mud this morning

marine shell that is 1 million years old

all of the above are fossils

The deer tracks in mud cant be a fossil it is not old enough or encased in a capsule of dirt to be aged 

A- a reduction in biodiversity

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.