IN ENDANGERED KANGAROO RAT HABITAT
This study was undertaken in association with the California Department of Fish and Game and California Department of Food and Agriculture. Funding was provided by the Vertebrate Pest Control Research Advisory Committee (Bait surcharge funds).
Simple modifications to existing bait stations were found to exclude kangaroo rats while still allowing ground squirrels access to poison bait.
I. Inverted "T" design
45 degree elbows and additional pipe can be placed on each entrance of the traditional station such that the entrance to the station is 12 inches above ground level. Ground squirrels generally begin visiting these bait stations at the same time as they would visit the traditional station (between 1 and 6 days). In the event that ground squirrels do not visit the modified station, the extensions should be removed, and the station pre-baited with clean (i.e., no poison) grain. Once the squirrels begin feeding from the station, the extensions can be replaced, poison grain added and the squirrels will continue to visit the station.
Traditional and modified inverted "T" bait stations
Specifications:
1. The entrances must be at least 12 inches above the ground
2. Vegetation should be cleared from around the entrances. Kangaroo rats will be able to climb into the stations if dense vegetation is present or if the stations are placed against a 1/2 inch (or finer) wire mesh fence. Keep entrances away from fence posts and large rocks that might be used by kangaroo rats to gain access.
3. Rain or sprinkler irrigators will result in water collecting in the bait stations. In locations or at times when this is likely, it may be necessary to further modify the bait station (e.g., by adding an additional horizontal extension; drilling a hole in the bottom of the station to drain water, etc.). It is important to remember that ground squirrels will not take moldy bait.
4. In kit fox range, the entrance to the station should be no greater than 3-inches in diameter. This can be achieved by fitting a 4-inch to 3-inch reducer or 1/2 an endcap.
II. Platform for other bait station types
Almost any type of bait box may be elevated on a 12-inch high platform. Any material may be used for building the platform but due to kangaroo rat behavior, it is important to adhere to the specifications.
Ground squirrels generally begin visiting these bait stations at the same time as they would visit the traditional station (between 1 and 6 days). In the event that ground squirrels do not visit the modified station, the station should be placed at ground level and pre-baited with clean (i.e., no poison) grain. Once the squirrels begin feeding from the station, it can be elevated, poison grain added and the squirrels will continue to visit the station.
Specifications:
1. The platform should be 12-inches high.
2. The platform must not have a solid base. Kangaroo rats are able to jump or climb to heights of up to 24 inches if they're presented with a solid base. Even a platform top with a 3-inch overhang over a solid base is easily negotiated by kangaroo rats.
3. The legs of the platform should be inset at least 2-inches to stop kangaroo rats from climbing into the station. Ramps or wire mesh should not be added to improve accessibility by ground squirrels as kangaroo rats will learn to use these to climb into the bait station.
4. Vegetation should be cleared from around the base of the platforms. Kangaroo rats will be able to climb into the stations if dense vegetation is present or if the stations are placed against a 1/2 inch (or finer) wire mesh fence. Keep entrances away from fence posts and large rocks that might be used by kangaroo rats to gain access.
5. It may be necessary to add a lip to the top of the platform to stop grain spillage. Any grain spilled from bait stations should be picked-up daily.
6. In rangeland areas, bait stations should be firmly secured to the ground to avoid them being tipped over by livestock.
7. In kit fox range, the entrance to the station should be no greater than 3-inches in diameter.