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Rattus Rattus 

Black Rats (above) tend to be more arboreal than Norway Rats (below). Photo from UC Berkeley Placental Mammals Photo © 2004 Larry Jon Friesen

Rattus Norvegicus 

Rodents like this Norway Rat (an introduced species) can gnaw small holes in attics and crawlspaces and pave the way for larger intruders. Now is the time to do those needed repairs to keep them out.

Rat on bird feeder

Birds aren't the only creatures that love birdseed!

Great Egret eating a rat. Photo by Earl McCowen

Doesn't everyone love a good rodent for lunch? The rodents that have been poisoned are easier to catch, but a slow death from secondary poisoning for the predator is a high price to pay for a meal. Photo by Earl McCowen

Bobcat eating a rodent. Photo by Trish Carney 

This is the ultimate snap trap -- bobcat with a gopher. Photo by Trish Carney

Lizard on a sticky trap
Sticky traps meant for mice and rats are indiscriminate killers of birds and reptiles too. They are inhumane for any and all species. Photo by Melanie Piazza 
Rat damage

Rats take advantage of small openings and enlarge them by gnawing. This paves the way for larger wild animals.

Rat and mice poison
Rat poisons also kill the animals that eat rats. Never use poisons!

Do I Hear Gnawing?

Rodents breed all year long, but the peak season for rodent nesting begins in February. This year-round breeding cycle makes sense. Rodents are the dietary staple of almost every land-based carnivore, so they have to be prolific. If one is at the low end of the food chain, a good biological strategy is to breed early and often.

Two species of rats have plagued (pun intended!) people for thousands of years. They came here with our European ancestors. These introduced rodents joined our ancestors in cities and suburbs. Marin County's only native rat, the Dusky-footed Woodrat, shuns our homes, and still prefers its laboriously-engineered stick nests out in the woods.

The common names of our two non-natives give clues to what to expect from them. The Norway Rat (Rattus norvegicus), is also known as the Sewer Rat, and is a large rat that prefers to live near water in underground burrows. The most common rat around Marin homes is the arboreal Black Rat (Rattus rattus) aka the Roof Rat. It likes trees and attics, although there is some overlap in the two rats' habitats. The House Mouse (Mus muscalus) is the mouse most likely to invade your cupboard.

A rodent's teeth continue to grow throughout its life. Gnawing on hard objects such as wood and bone is essential to maintaining a rodent's teeth. This gnawing behavior is the primary cause of damage to buildings. Rats can make use of openings as small as 1/4", and enlarge them enough to allow access for squirrels, raccoons, skunks and other species of wildlife. That is when rodents can go from being a carnivore's delicacy to a home-owner's nightmare.

How to Control Rodents Humanely

Rodents are an integral part of the environment, and they are the primary food source for most of the predatory animals in our area. It is not possible, nor is it desirable, to eradicate rodents outside.

However, most people do not want rodents inside their homes or damaging their property. The following information will help you effectively eliminate rodent problems without resorting to the use of rat poisons.

The best method of rodent control is prevention. Rodents tend to set up camp in our homes and businesses when food and space are made available to them.

Remove potential rodent homes like yard debris, trash, construction waste, etc. Remove ivy from on and near structures. Consider removing dense ground-covering plants too.

Eliminate food sources. Keep your garbage completely sealed with lids closed and secured. Keep bulk food, seed, and dry pet food in metal cans with secure lids.  Pick up fallen fruit. Take birdfeeders inside at night.

Exclude rodents from your home. Seal openings 1/2 inch or larger around the outside of your house with metal, concrete, or Stuf-fit Copper Mesh Wool, which can be found online or at hardware stores.

Include natural rodent predators in your solution. A family of five owls can consume up to 3,000 rodents in breeding season. Placing a nest box to encourage a family of owls to make your property home can be a great alternative to commercial pest control methods. DO NOT erect an owl box if you or anyone in your neighborhood is using poison, however. Please visit www.hungryowl.org for more information.

Use catch-and-release traps as a safe, sanitary, and humane solution. Catch-and-release traps will allow you to remove rodents from inside your home, but you must prevent their return by sealing entrance and exit holes and removing attractants (see above). Remember it is illegal in the state of California and cruel to relocate animals (click to learn why), so trapped rodents should be deposited outside once entry points have been sealed.

Learn more about rats to help control them

Black Rats may establish nests in bamboo, ivy, palm trees, yucca, pampas grass, honeysuckle, blackberries, cypress, jasmine, juniper and other heavy shrubbery or thickly matted plants. Wood and lumber piles, storage boxes and sheds frequently provide shelter and safety.

Norway Rats may live in burrows along outside walls of homes, holes under shrubs or vegetation, and under the edges of sidewalks or patios. These nocturnal, opportunistic foragers are attracted to pet food, fallen bird seed from feeders, and fruit fallen from trees.

Garden problems almost always involve food and water sources. In most cases, solutions to these situations are often very simple. Learning what is attracting rodents and eliminating access to food will help solve the problems.

Rats and Rodenticides

Rodenticides, even though they are available for purchase everywhere, are dangerous poisons that can cause secondary poisoning in the beneficial species that prey upon rats. Hawks, owls, bobcats, raccoons, skunks and other carnivores all depend on rodents for food. These wild predators, and even pet cats and dogs, are in danger of being poisoned by these toxic, unnecessary products. Rodenticides are also ineffective, because rats breed too quickly to be managed by poisoning. Click to learn more about the dangers of rodenticides to hawks, owls, foxes and other rodent-eating predators.

Rat Control

Killing rats outdoors rarely solves a rodent problem, because if the attractions remain, more rats will take the place of the killed rodents. It is not possible to eliminate all rats from the environment, but they can be controlled. Keeping your home and garden unfriendly to rats will allow their natural predators to keep rodent population numbers in balance. As described above, excluding rodents from your building, sealing their access points, and eliminating any rats trapped inside are the only long-term solutions.

Rats and Traps

Glue traps, like poisons, kill indiscriminately and are incredibly cruel and inhumane means of death. Small birds, reptiles and non-target mammals are all attracted to the traps for the same reason the rats are.Once stuck to the glue trap, the animal slowly dies of dehydration and starvation, often injuring itself with struggles to escape the sticky trap. Learn more about why you should NEVER use glue traps here...

Snap traps, used correctly as part of a professional exclusion program, deliver a fast, humane death, and are WildCare's recommended method for use indoors if necessary. Like glue traps, snap traps used outdoors are dangerous to many species of non-target birds and animals, especially young ones. Rats establish runways along walls, and are very wary of new things in their environment. Dead rats should be removed from traps immediately, because any live rats will avoid an area where they see another rat has been killed.

Exclude the Intruders

Many wild animals will take advantage of a rodent's opening in a warm, dry house. To protect your home, the most humane option is also the best one for your resale value. Clean up and repair your property so rodents can't get in. Now is a good time to do it – before you have a problem.

WildCare receives hundreds of calls on our Living With Wildlife Hotline from people looking for advice on how to rid themselves of rodents. Our best answer is always the same: exclude them from your home and remove the food source that is attracting them.

If you have questions or problems about damage in or around your home, WildCare Solutions service can help. Call 415-456-SAVE (7283).

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