Drought Causes Moles and Voles to Get the Worm!

Drought Causes Moles and Voles to Get the Worm!

Posted by Gillian Spence on Oct 26th 2014

In a blog article we posted on March 29 th, 2014 we talked about how birds need grubs for protein and that recent deforestation and pesticide spraying have dissipated much of this natural protein source. We also touched on how birds going through their molting process have an increased demand for protein to make new feathers. Today I’d like to talk about another reason why grubs naturally found in the soil are becoming scarce, and why it’s important that we do our part to replace the protein that is being missed from our wild bird’s diet.

Much of the west and southwest are experiencing a severe drought that appears to be intensifying. Americans living in these parts are having to take drastic measures to conserve water. In fact, because California is going through its fourth year of one of its worst droughts on record, Governor Jerry Brown has declared a statewide drought emergency and is calling for all Californians to reduce their water use by 20 percent. As you can see, the Palmer Drought Severity Index, a comprehensive drought indicator devised in 1965 and still used today, shows that the drought is spreading from the Southwest outward across the U.S.

Fig. 1: Here we can see the drought in September, 2014 with the driest areas occurring in the southern part of California.

Drought Index 2014

Fig. 2: Here we can see the drought on October 21 st, 2014 expanding, affecting more states throughout the West and Southwest.

So, why does this drought have anything to do with wild birds receiving adequate nutrition and protein sources? Because of moles. Moles are the natural predator of beetles, worms, and all things creepy-crawly. They are voracious feeders and eat their weight in grubs every day. In fact, it has been shown through experimentation that they literally are insatiable and will continue eating as long as they are provided with food of their liking. Moles can dig 15 feet per hour, and generally will dig around 100 feet per day (Washington Department of Fish and Wildlife, 2014). Because of this vast expenditure of energy, they need to match it with a vast intake of proteinaceous food like invertebrate worms (Henderson, 2005).

Mole Eats a Worm

In normal conditions where the soil is moist, worms are likely to venture to the top of the soil where they’re protected by the moisture of the grass. This makes for an equal playing field between the mole and the wild bird. Sometimes the mole might get the worm. Other times, the mole may be a little slower than the bird and “the early bird gets the worm.” However, this game is completely changed in the favor of the mole during drought conditions. When soil is dry and cracked near the surface, worms tunnel deeper and closer to moisture. Moles will follow them deep down into the soil, underneath sidewalks, and along sewer drain fields (Washington Department of Fish and Wildlife, 2014). All places that our friend the wild bird cannot follow! This makes for big, fat, strong moles and protein deficient, unhappy, brittle-feathered birds.

Greedy Mole!

How can we help? We can start by providing worms above ground where birds have access to them. Mealworms are an excellent source of protein for wild birds, and they can be offered either in a feeder, on the pavement, or in the grass! Because the ground is so dry, you don’t have to worry about moles stealing the worms because moles have trouble tunneling through dry compact dirt (Washington Department of Fish and Wildlife, 2014). By providing protein for our wild birds, we’ll help them flourish and promote future generations by encouraging their breeding with food sources. After all, it’s not just humans that need help during the drought, its wildlife too!


Association of California Water Agencies. (2014). Drought 2014: What You Need To Know .

Retrieved from Save Our Water:

Bostock, M., & Quealy, K. (2014, September 8). Mapping the Spread of Drought Across the

U.S. The New York Times .

Henderson, R. F. (2005). Moles. Retrieved from The Internet Center for Wildlife Damage


National Climatic Data Center. (2014, October 24). Historical Palmer Drought Indices.

Retrieved from NOAA:



Washington Department of Fish and Wildlife. (2014). Moles. Retrieved from Living with