Rodents like it Warm
It is getting cold outside and you may wishfully be thinking that all furry animals will start to hibernate or go south for the winter. Perhaps you can attribute this belief to Mr. Disney. Rodents, however, seek out warmer environments when it gets cold - they do not hibernate or migrate. If you do have new occupants, you may not see them because they are usually out of plain sight. However, their presence is easy to detect. Indications of an infestation are: rat droppings in garages, storage buildings/shed; rodent damage to fruit or nuts in your yard; rat nests behind boxes, garage drawers, or wood piles; burrows under garbage cans, compost piles, or garden plants; or rats traveling along utility lines or fence tops at dusk.
The roof rat is smaller than the Norway rat and their tails are longer than their body and head combined. They are agile climbers and live outside in trees, shrubs and dense ivy. In buildings, they favor enclosed elevated spaces such as attics, walls, false ceilings, and cabinets. Norway rats are stocky and larger than roof rats. They tend to nest in the ground in burrows along building foundations, under woodpiles, or rubbish, and in moist areas of gardens. In buildings they are found more frequently in the basement or ground floor.
To get rid of rats, remove food, water, shelter, and seal entryways. Pet food should not be left outside. Keep garbage in tight-fitting containers. Remove climbing vines or trees near your house or roof to at least 3 feet. Seal all foundation cracks that are ¼ inch or larger. Make sure eaves and roof flashing are intact. Keep doors and windows fitted with tight closing screens.
For a more detailed discussion of rodent control measures see this rat PestNote, and QuickTips. If questions arise please consider contacting our Help Desk and get advice from a UCCE Marin Master Gardener.