Marked in red are the returns and the end of a ridge cap. Returns are a common place for grey squirrels, flying squirrels, red squirrels and bats to enter. The end of the ridge cap is common for flying squirrels and bats.
In this picture you will notice a the vent pipe is circled as well as the ridge cap. I could have circled the small coupela as well. Often times the flange on the vent pipe will flare up just enough to allow flying squirrels and bats to enter and sometimes, not often, they will chew through the rubber or plastic boot around the vent pipe. The ridge cap here is the type of cap that comes in four foot sections and is plastic. I have on many occasions had these style to be a problem due to where the nails will start pulling out causing the sections to life which then gives access to the attic. Squirrels will sometimes chew through the side of the ridge to gain access as well. This is a common spot for flying squirrels and bats to enter.
In this picture we have another style of ridge cap which is a metal roof. Very seldom is there anything underneath the metal caps. A very easy place for squirrels and bats to enter.
In this picture I am pointing out where the trim comes down and meets the return. There is quite often a gap between where the trim ends and the return starts which will give way for squirrels and bats to enter.
This is probably one of the most common areas for most nuisance wildlife to enter and that is the gable end vent. Usualy behind the vent there is a thin screen which is very much like the screen you would see on a screen door and window. The problem is that it is not strong enough. Bats, flying squirrels and grey squirrels love to enter homes through this area. If it is a grey squirrel most likely you will see a portion of the louvers chewed (baseball size).
I hope this is help for people visiting this website. I enjoy teaching others how to identify problem areas. I will be posting more on this subject in days to follow.