You are pretty much right mice can get through 1 2 x 1 weldmesh they can t get through 1 2 x 1 2 but that gives little more headroom than the biro you mention.
How to get rid of starlings in my roof.
For large flocks or agricultural applications starlings can be removed or deterred with a well timed organized scare campaign using strategically placed sophisticated audio or visual repellents as well as deterrents that irritate the starlings other senses.
Starlings are not fans of bird feeders so you can put up a bird feeder for cardinals grackles blue jays etc.
In my backyard starlings go crazy for suet but only if it has cracked corn peanuts or other shelled seed inside.
The reason why birds like starlings nest under your eaves is it s safe from predators and natural elements.
Keep in mind that call and audio related deterrents should not be put in place after starlings have already started nesting they have to be implemented before the breeding season.
One thing you can do is to make the slope steeper by installing an additional board or reconstructing this part of your roof.
European starlings can be one of the least wanted backyard birds but also one of the most challenging to get rid of.
Good fun to watch the greedy barstewards get though a gap then gloat on seed and try to get back monkey with the hand in the cookey jar taken to the extreme.
It serves as an instant roof and if the slope isn t too steep your house becomes an easy choice.
Because of their soft and pointy bills starlings like any seed that has already been cracked open such as sunflower chips.
Backyard birders who want to get rid of starlings don t have to give up however and it is possible to make a yard less starling friendly without driving away other feathered guests.
Suet with corn peanuts etc.
Remove immediately to help get rid of starlings.
Bird baths are very useful too.
Where have all the starlings gone.
Audio visual and other repellents.