Rats are creatures of habit. They will return again and again to certain food sources and areas of their habitat that they have deemed safe. Rats also shun unfamiliar objects in their paths and will avoid them. That's why traps and baits can take a longer time for rats to investigate and regard as safe enough to approach.
Rats create tracks that they will follow indoors and outdoors. Indoor paths can be identified as greasy markings along the baseboards or walls near the floors of homes. In attics, these trails are seen along rafters or beams. Rats rub along these routes to follow them safely by scent. Outdoors, rats will create tracks in the tall grass or brush. The series of paths that they create can be evidenced by trampled, long runs that are hidden by overhead vegetation.
Rats also leave evidence of their existence along these tracks in the form of droppings or urine. Both of these waste products can be extremely harmful to humans. Rat droppings can contain Hantavirus. This virus can cause heart and kidney problems, which can lead to death. The urine of a rat can cause leptospirosis, which is a kidney and liver disease that causes failure of these organs.
Rats also show signs of their existence in homes by the teeth marks they leave behind. Rats have large, sharp teeth that they use to gnaw wood and plastic, along with other solid surfaces. Look for clues of rat behavior along beams or other wood surfaces in walls or basements.
A professional should deal with any evidence of rats in your home or yard. Pest control experts are quite familiar with the signs to look for when it comes to rat or mouse infestations. They can eliminate these pests safely and quickly. Rats are very dangerous and should be handled with extreme care.