I have a number of rodents living in a pipe on my property. How can I reduce their population while still maintaining grass and herb varieties nearby?
Answer: Your management of these critters will depend, in part, on the size, location and length of the pipe, as well as its use. You did not mention if the rodents were mice, rats, squirrels, gophers or other critters, but generally speaking, you might want to avoid grasses as mice and rats will feed on grass seeds.The simplest approach is to simply try to exclude the rodents’ access to the pipe by placing an appropriate sized mesh over the mouth of the pipe. This approach will depend on what the pipe is used for.A second approach is trapping using lethal traps, such as rat traps. If you’re battling mice, their reproduction rate is generally too high for trapping to make significant inroads in the population. Again, this will depend on the pipe location and also what other critters have access to the pipe and may be attracted to the bait (peanut butter works well with mice and rats).You might consider planting native perennial forbs or shrubs in the locations around the pipe, as these would provide some habitat for native snakes and other small predators of the rodents. Aromatic herbs such as sage, rosemary and other shrubs may also be appropriate. Also, consider installing raptor perches and/or owl boxes for barn owls around your property. These approaches will not solve the problem, but will reduce the size of the problem. The ATTRA publication Farmscaping to Enhance Biological Control outlines some of these approaches. It is available at https://attra.ncat.org/attra-pub/summaries/summary.php?pub=145.The general principles involved here are to reduce the habitat for the pest critters and to increase the habitat for the predators of the pests. Reducing the habitat for the pests means reducing access to food, nesting sites, and safe shelter. You want to do just the opposite for the predators of the pest. If you use lethal traps, make sure you’re not impacting any endangered native mouse populations.