How to secure an abandoned building that has pigeons, etc.?

["autonut843" <hmjunk31415@xxxxxxxxxxx>]

Hi,
This'll sound wierd and some may think I have an alterior motive.
I don't, I'm just curious.  Years ago I ran across the book 'The New
American Ghetto' by Camilo Jose Vergara at the library.  It chronicles
the decline of buildings as they go from useful to abandoned to torn
down.  I never would have thought about stuff like this but I found the
book fascinating.  One of the buildings it has pictures of is the
Michigan Central Train Station in Detroit.  This week for some reason I
got curious, 'I wonder what ever happened to that building?'  (Did it
get torn down, fixed up, still abandoned?)  (I live many states away
from Detroit.) so I started googling.  Found out that LOTS of people
have wandered through the empty building and have pix on the web
showing what they saw.  Amazing.  One person mentioned that now the
building is sealed up with alarms so nobody can get in any more.

So that got me thinking.  Here you have this huge building that has all
the windows broken out, has been severely vandalized over the years,
has an immense perimeter, but has been a magnet for people to go
exploring and vandalizing in.
let's say they brick up the lower two or 3 floors of windows and secure
that.  I assume they would put standard magnet switches on the secured
lower perimeter doors.  But, since (As Vergara's book documents)
frequently people will just bread a hole in the wall to get in, or
maybe climb up to an upper window that wasn't bricked up.  How would
you alarm a building like this?  I would think you'd HAVE to have
interior motions of some sort, but I would think that the pigeons and
any other animals that get in would cause lots of false alarms.

Before someone starts thinking that I want to go in some building and
bypass the security.  That's not my intention at all.  I've got too
much to lose to risk wandering through abandoned buildings. (wife,
kids, mortgage...)  I just can't see how you could secure something
like that economically and not have tons of false alarms.  I know how
to secure an enclosed building that is maintained.  I am just curious
how one would handle a partially open situation like this?

Thanks,
Middle Aged Curious Nerd