Introduction

About as long as the Norway rat, Rattus norwegicus, at 14 to 16 inches from head to tail tip, adult roof rats are more mouse-like in appearance than the heavier Norway rat. A more slender body, prominent eyes, proportionally large ears and a tail slightly longer than the combined length of their body and head distinguish them from other rat species. Their behavior is markedly different from that of the Norway rat as well. Unlike the Norway rat, these rodents seldom nest in burrows.

They prefer attic spaces, and are just as happy scurrying around in insulation held in place with plastic sheeting as they are hiding in more conventional attic spaces. Roof rats will even nest high in the rafters or along the sills of open ceiling barns. Easily the most acrobatic of all the common rodent pests, roof rats are able to scurry along overhead cabling and water lines as they move through the poultry house. The roof rats are extremely secretive rodents, and may often go undetected until they have caused a great deal of damage in the poultry house.

General sanitation and exclusion practices are effective for rats and mice alike. Clean up all feed spills where possible inside and outside the buildings. Dispose of damaged eggs and/or mortality properly every day. Collect floor eggs every day as well. Limit entry points by sealing gaps around conduits, water pipes and feed lines where they enter the building. Repair damaged foundations and curtains; repair or replace damaged cooling pads.

Be sure all entry doors are well fitted, and equipped with a heavy duty sweep or weather stripping as needed. Repair malfunctioning louvers at vents. Although none of these practices will eliminate rodents from your facility, they will help limit their access to food and water and simplify baiting efforts by reducing the areas of concentrated rodent activity in many cases.

Scouting and other practices for effective roof rat control require a sharp eye and a slightly different approach to baiting. First, don’t underestimate just how secretive roof rats can be, and certainly don’t assume that overhead areas behind plastic barriers, attic spaces, or even open rafters are rodent free. Look up. Look closely. Make a thorough examination of such areas on a regular basis. Look for fresh damage to plastic barriers and bits of insulation raining down from above or pushed into gaps along the eaves.

Examine louvered eave vents for rat droppings or other evidence of roof rats. Where overhead areas are accessible, climb up and look around. Be sure to bring a big, bright spotlight and look in the farthest, darkest reaches of the attic. If there is little or no insulation left, it is riddled with rodent tunnels, or piled up between ceiling joists in some areas while others are bare, suspect roof rat activity. Use pellet, single dose baits in the infested overhead areas. Watering stations filled with a solution containing one of several multiple dose rodenticides are also effective in overhead areas.

Bait or water stations should be inspected and replenished as needed every few days until the roof rats are reduced. Block baits are very useful when nailed or wired near entry points near the ceiling. Finally, step up bait placements in all areas of the poultry house whenever it is vacant. Roof rats and other rodents will be forced to forage over wide areas when food and water are scarce. Down time between flocks is often the best time to make real progress in reducing any rodent infestation.

Summer 2006