Identification of dirt mound from suspected rodent. #125810 - Ask Extension

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Identification of dirt mound from suspected rodent. #125810

Asked May 07, 2013, 4:50 PM EDT

I have recently noticed dirt mounds in my yard. They are about a foot in diameter and 4-5 inches high, there is one hole about 1.5-2 inches in diameter at ground level under the center of each mound. Thus far, I have located 7 mounds, all appearing in the past week. All but two are located along the edge of the house foundation or concrete patio. I suspect they are from rats, however, I have not located a single entry or exit point to the tunnel system that isn't under an excavation mound. This makes me think it may be a mole. The extent of the tunneling has me concerned. I am wondering if dirt mounds like I described are found in association with rat populations, or if I am more likely dealing with moles?

Multnomah County Oregon

Expert Response

Hello, and thank you for your question. Thank you also for such a thorough description of what you're seeing - that really helps! I am fairly certain that you're dealing with moles. Moles and gophers create similar-looking mounds of dirt, but the key to IDing the culprit is the location of the hole. The way I remember is "moles in the middle," so if you're seeing signs of exit holes right in the middle, you likely have moles. Number of mounds is not well correlated to number of moles, so you might have just 1 very industrious mole. Moles are insectivores, so poisoning is of limited utility. They're digging in your yard to hunt earthworms, lawn grubs, and other soil organisms. One of the mole species we have in W Oregon does sometimes munch on below-ground plant parts such as bulbs, but in general, the moles are just signaling that they are finding food such as grubs and worms. Some people use grub-reducing pesticides on their lawns to diminish the effects of the grubs themselves (such as crane fly larvae) and in so doing, reduce the "attractiveness" of the area to moles. Consider visiting this publication http://icwdm.org/handbook/mammals/Moles.asp for some nice illustrations of both how the moles make those mounds and how to set traps, should you choose to do so.
I hope this information is helpful,
Dana

Dana Sanchez Replied May 08, 2013, 1:27 PM EDT

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