The following list includes typical signs of a squirrel invasion:
Tiny nibble marks around entry points like the roof, attic, crawl space, or other storage areas
Unusual scratching noises within your walls, ceiling, or attic
Distinctive foul odors emanating from enclosed areas
Accumulation of fecal matter
Torn and scattered piles of insulation
Damaged and loose shingles with scratches and underlying holes
Accumulations of acorns and twigs in your gutters