Attic vent question (pic)

I used an attic vent that I bought from Habitat for Humanity for $5. It is on the west facing wall. We get some big winds here that typically will blow in from the southwest - so that wall will get a lot of wind. My two roosts are close to that vent. As far as I can tell, the way the attic vent is made hardly any wind blows in but it allows for ventilation. I climbed in the coop just now & just stood there & no wind blew in from the vent & it is very windy today with gusts to 50 mph! (but I do feel drafts from the roof - see further in this post) In the winter, should I make a covering for the top of this attic vent to keep cold air out? We get into the 20's at night and sometimes into the teens. I could make it so that the bottom stays open for ventilation.

Here's the outside of the vent - it is 24" wide x 30" tall.



Here is the inside - you can see the roost in front of the vent (there are 2 - 2x4s, 2 ft apart):




I am having drafts from the opening under the roof - any suggestions with the roof area? You can see the attic vent to the left. The older vents are from interior ac vents that do close. The drafts I feel seem to be coming from under the roof.





Thanks everyone!

 

Thanks everyone for the responses!

I do think I need to "fill in" some of the gaps under the roof line - I will work on that this weekend - I'm think a 1x4 or 2x4 under the roof between the supporting 2x4s. That will fill in most of the larger gap but maintain the smaller gaps that are due to the natural undulations of the roof.

How about covering up part of that big attic vent? Do you think I should?