Before ridge vents became the gold standard for exhausting your roof and attic, most critter jobs could be completed without having to put much work into the older style can or box vents. We are finding more frequently critters shimming their way under ridge vents and into homes. For that reason wildlife products are being developed to keep critters out of your roofs ridge.
Ridge vents allow for heat and moisture to escape your attic and mange the heat of your roof. Critters seek warmth coming from holes on homes to gain entry. For this reason critters are drawn to the heat escaping from the ridge vent. The solution to the problem will need to allow the ridge to breath and exclude critters.
There are now vented metal guards that line the perimeter of a ridge vent to keep critters out. These guards are designed to protect a vulnerable part of newer roofs. They are also proving beneficial in proactively keeping critters out of attics.