Ugh.  Geese are the worst.  What's a word that means "flocks" but is a lot bigger?  My thesaurus is coming up short...  I'll wing it:
There are a whole ****load of Canada geese up in Northern Colorado.  They're part of the logo for Fort Collins, Colorado.  They were once rare, but now they have "native populations" -- birds that decided that migrating was "for the birds."
They really are majestic as all hell when they're flying en masse.  Once they're on the ground, though, it is a different story.  They leave little land-mines EVERYWHERE.  At my old job, they put up signs every year: "DANGER - AGRESSIVE NESTING GEESE".  It was cute to see all the goslings every year, but nothing will unman you quite like being chased by an animal 1/8th your size... 
 
 
Also, as infuriating as it can be, it really is sort of funny when traffic comes to a halt while a line of 20 of them decide they're going to saunter across the street right then.
Argh...
My new office has hawks.  Even cooler.