A pack of wolves and a flock of birds are heading in my direction.

but

A pack of wolves along with a flock of birds is heading in my direction.

A pack of wolves => Noun
a flock of birds => another noun
Connecting two nouns with "and" so the verb will be plural verb.

So it will be:
A pack of wolves and a flock of birds are heading in my direction.

As a general rule, use a plural verb with two or more subjects when they are connected by AND.

(X and Y are...)

Hence: A pack of wolves and a flock of birds are heading in my direction.


Use a plural verb if the subject after or/nor is plural:

Either a pen or two erasers are what I can buy for $1.


Use a singular verb if the subject after or/nor is singular:

Either a pen or a pencil is what I can buy for $1.

Got it, thanks Joi!