Roof rat best management practices

Did you know that rats can squeeze through cracks one-half of an inch wide?  Did you realize that rats have been known to jump eight feet from a tree to a house?  While these facts may be more of a curiosity than a concern to most homeowners, preventative measures can pay off to keep rodents away from your property.  Rodent proofing, sanitation, and encouragement of predators are good practices to ensure a rat- free future.

The roof rat is a non-native species originally found in southern Asia.  Roof rats are now the number one rodent pest in Florida. By nature, these rats are nocturnal and very secretive preferring to live and travel above ground in trees, and across wires, vines and fences.  Roof rats are up to fourteen-inches long which includes a tail that is longer  than their body.  The fur color ranges from black to brown to gray with a light colored underbelly.  The droppings are fairly easy to identify being  black, banana-shaped, and a quarter to a half-inch long. Having up to forty babies per year, female roof rats are highly prolific. 

While roof rats really like fruit (aka fruit rat) they will eat a wide variety of domestic animal feeds, bird seed and garbage.  Roof rats will travel up to one-hundred and fifty yards from their nests to forage for food or water.  They also prefer to keep their nests in attics, soffits, hollow trees, and the old fronds on palm trees, but will also nest  in piles of debris stacks on the ground.

Prevention is always the best practice.  Before rat activity is detected, consider rodent proofing using materials such as twenty-six gauge or heavier sheet metal, nineteen gauge or heavier hardware cloth with openings no more than one-quarter inch, and brick with mortared joints.  These materials are placed where rodents gnaw such as the edges of doors, windows, holes where pipes enter buildings, ventilation holes in foundations, roof vents, exhaust fans, and eave vents.   Fruit trees can be protected by twenty-four inch wide sheet metal rat guards secured around the tree.  Keep fruit trees branches from touching fences or wires where rats could access these runways.  Also prune lower tree branches so that rats cannot climb up into the trees. 

Sanitation is also an important task where food items are kept away from rodents.  Many of these practices are common sense such as cleaning up garbage and rubbish and keeping it in metal garbage cans with tight fitting lids.  Keep all pet food and birdseed in rodent proof containers.  Pick ripe fruits and vegetables before rats get to them, and locate and eliminate sources of water.  Also keep hiding places removed such as general junk and garbage in your yard. 

Beyond the juvenile rats that cats may occasionally catch, local natural predators can be very helpful in suppressing this pest population.  Birds of prey, especially owls, feed on rats.  The literature indicates that a pair of barn owls can kill several hundred rats a year.  Many non-poisonous snakes are also great rat controllers.  Snakes such as rat snakes, king snakes, pine snakes, black racers and coach whips catch and eat rats. 

If you have an infestation of rats, and  find gnawed areas, droppings, etc.,  it is time to take action.   Rat traps are good first step.  Attach traps to tree branches or fences with rubber bands for best results.  Limiting trap setting from dawn to dusk will help avoid accidental trapping of birds and squirrels during the day.  The use of live traps will also  help with this issue.  If you choose to use rat poison, certain precautions must be taken.  Rat poison must be secured in a tamper-proof bait station so that children, pets and wildlife cannot gain access – this is stated on the label and it is the law. 

Keeping roof rats away is a worthwhile venture.  Some simple preventative measures, as outlined above, will go a long way in controlling these four-legged pests! For more information on all types of pest control, please call our Master Gardener volunteers on the Plant Lifeline on Mondays, Wednesdays and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer.  Don't forget to visit our other County Plant Clinics in the area.  Please check this link for a complete list of site locations, dates and times - http://charlotte.ifas.ufl.edu/horticulture/Plant%20Clinics%20Schedule.pdf.

Resources:

Koehler, P.G. & Kern, Jr., W. H. (2013) Rat and Mouse Control, The University of Florida Cooperative Extension Service, IFAS.    

Kern, Jr., W. H. (2015) Control of Roof Rats in Fruit Trees, The University of Florida Cooperative Extension Service, IFAS.