Monday, February 9, 2009

The inconvenient truth about wildlife gardening: squirrel control

This post is intended for wildlife gardeners in the western U.S. or in other places where squirrels have been introduced and have displaced native squirrels and native birds. Eastern fox and gray squirrels are both native to the mid-Atlantic states and west to the eastern part of South Dakota. Both species eat a variety of foods ranging from seeds and grains, to buds and fruits, insects, birds' eggs, birds (both nestlings and adults) and even reptiles.

Both species have been introduced outside their native range over the last century. Populations continue to expand coinicidental with developemt along the urban interface and developemnt of wild areas. Changes in land use and cover, including fire suppression, planting trees, and alteration of flow regimes in rivers, have increased forests and woodland corridors, especially along riparian areas west of the Mississippi. In addition to range expansion following development, non-native squirrels have also been purposely introduced into cities and towns in the western U.S. and even into Europe. Both non-native species are tolerant of humans and developemnt and thrive in urban and suburban settings. In these new environments, there are no natural controls and squirrel populations quickly expand (especially thanks to bird feeders).

Although they thrive around human development, they don't just stay in town. Their populations expand from urban centers out to the urban fringe or interface zones, and utimately into natural areas. Introduced squirrles are more then a nusience, they are a real conservation problem. In their introduced ranges they threaten and displace native squirrels (the western gray in some western states and the red squirrel in western Montana) and non-native squirrels are a huge problem for cavity nesting birds.

There are many books and web sites that claim that if you simply feed squirrels they will leave you, your birds and your bird feeders alone. Do not believe it. This just creates more squirrels and just creates a larger problem, especially for birds. Squirrels do not just eat bird food set out at feeders by well-meaning gardeners, they take nesting cavities, nesting places (see picture above of squirrel in flicker nest box), displace birds, kill nestlings and monopolize ground foods for ground feeding birds.

Dealing with squirrels is not a part of wildlife gardening that most people look forward to. Nevertheless, it is necessary to control their numbers. Notice I say “control their numbers” not “eradicate.” It would be impossible to eradicate them, but with intensive management you can control their densities and limit their effect on other species. Controlling non-native squirrels will improve conditions for bids and other small wildlife in your yard, and in your neighborhood. Since reducing the number of squirrels in our yard, we have a lot more ground foraging birds, and they spend a lot longer in the yard.

How to control squirrels
The first step is to reduce or eliminate anything that is benefiting them. Make sure your feeders are squirrel-proof, and there are a variety of ways to do this. Also, look around your neighborhood and see if any of your neighbors are specifically feeding squirrels, or if they have feeders that might be feeding squirrels. Talk to neighbors and try to get a concerted approach to this- it will be more effective and a great opportunity for education and outreach. Removing a source of food and nesting areas may be enough to reduce the density of squirrels in your area. Unfortunately, it might not be, and you might have to take more drastic steps.

How to remove squirrels or reduce their density around your yard. The best thing to do is kill them. This is not fun, but it is necessary. If you live in a city or urban area, there is probably an ordinance that prohibits shooting, even with a pellet gun or BB gun. If you can shoot squirrels legally, use a .22 or a shotgun. A pellet gun is quiet, but a .22 is not much louder, and much more effective for a quick, humane kill.

In any case, I think it is best to use a live trap (like this one). This is what I use. You can easily bait the trap with peanut butter on a small piece of cardboard. Place in an area where squirrels congregate like under a bird feeder. Once you set the trap, you will need to check it at least twice a day. It is imperative you do not leave the squirrel trapped for too long- the shorter it is trapped the less stressed it will be, and more humane. Occasionally, dark eyed juncos will get trapped in the cage, but they are easily released unharmed. This is another reason for checking the trap frequently.

Once you have caught a squirrel in the trap, the next step is to kill it. There are a few methods here all are quick, and humane. You can drown them- this sounds awful but it is remarkably quick. Another approach I have not tried is to use carbon monoxide. You can place the trap (with the squirrel still in it), in a bag and attached the bag to your tailpipe. This sounds like of strange and elaborate, but evidently the squirrel will fall asleep and die in minutes. Surprisingly, drowning takes much less than 1 minute. If it is legal to discharge a firearm in your area, the best thing might be to shoot the squirrel in the head with a pellet gun while it is in the trap.

Once you have a dead squirrel, what do you do with it?
You have a few options (I have tried a combination of most of these at some point):
  • Eat them
  • Allow birds and insects to eat them
  • They make great nesting material for chickadee nests (see here)
  • Compost them
  • Donate to raptor rehabilitation (or similar) in your area
It is amazing how many squirrels there are in a small area. To give you an idea, the first year I started trapping squirrels, I killed over 230. Last year, I only killed 26. Although as I mentioned, this is really not the fun part of wildlife gardening, but it is really important and it really does benefit native wildlife, and you can have a significant difference.

It is remarkable how the birds have responded to having fewer squirrels in the yard. Ground feeding birds are much more common and they spend more time foraging, like white-crowned sparrows, hermit thrushes, song sparrows, and northern flickers.

In closing, remember that while squirrel control is not the most fun aspect of wildlife gardening, but it is a part of making a wildlife haven in your yard. The non-native squirrels are yet another human impact to the world that decreases native species’ chances at survival.


  1. I had no idea that there were native and non native squirrels. Never gave it much thought. I have shot them while hunting but i would have a hard time killing them once i catch them. Im weird that way. Im glad that i dont have a big problem with them though.

  2. Mmm. An inconvenient truth indeed. I think I'll start by not feeding and see how it goes from there. I do think I have only native squirrels, but a pretty large number of them. Is there a way to feed them birth control pills?

  3. Thanks for your comments, Town Mouse. Not feeding birds may help. Without knowing where you live, it is hard to say whether the squirrels you have are native or not. In general, the native Western gray squirrel is pretty shy, and it is now restricted to the foothills and wooded mountains, occupying a fraction of its former range in California. Populations of the western gray squirrel have been locally extirpated in many parts of southern and northern California largely as a result of non-native Eastern fox squirrels.

  4. Thanks. Just to clarify, I wasn't feeding them before, but they got at my fruit trees, which amounts to feeding. This year, we'll be better at netting.
    Also just bought a bird house with one of those squirrel protection screw-on hole covers. We'll see how that goes...

  5. I like my squirrels. I called Wildlife Rescue when a squirrel was chattering with an injured foot a few months ago (they came and whisked it away to a squirrel nursing home). I think ours must be native, here in the Sierra Nevada foothills, 2900 feet.

  6. yeah i just shoot them when ever i see them then throw them in the woods thats how its done in alabama

  7. We trapped and drowned our first squirrel a couple of days ago. You're right, it's NOT a fun part of gardening, but it has come to be necessary. Thanks for writing about this; it helps confirm our decision!

  8. 'until he extends his circle of compassion to all living things man will not himself find peace>" albert schweitzer

  9. I agree with the May 15 Anonymous post... :) Thank you for this David, the compassion I feel for native birds has motivated me to participate in squirrel removal.

  10. This year my neighbors pointed out the squirrels (all we have left here in town are non-natives) nesting in my garden shed. I knew they were damaging my trees by girdling the smaller limbs but learned they raided the neighbors' fruit trees (NO fruit harvest at all for the humans), ripped out house insulation, and of course were impacting the song bird population. I finally got a live trap. I used it for only one week, checking often, and got 8 squirrels. Drowning the first one was the most difficult. After trapping the fourth squirrel the first day I realized that they really were overpopulated and what I was doing was balancing things out a bit. Looking forward to seeing if squirrel management improves the songbird populations in the neighborhood.

  11. Thanks so much for your comments. Especially Allison and Anon, thank you for writing in with your experiences and comments. Killing squirrels is not the fun part of gardening, but it is really beneficial to native wildlife (and evidently people's homes!). Good luck out there, and thanks again for sharing.

  12. Yes, it is the ugly truth, and I think I am going to have to face up to it. The difficult thing will be convincing Walu, who is opposed to killing animals (and yes, he's a vegetarian and I am not). I don't think I'd actually be terribly bothered by shooting them, but I'm not sure about drowning.

    I like the idea of donating the carcass to raptor rehab. I'll call them this week and see what they think about it. It might help me make the case with Walu.

  13. Hi Susan,
    Welcome back from Buffa10. Yes, killing squirrels is not my idea of fun, nor is drowning them. The reason I suggested the trap and otherwise disposing of them is that shooting even with a pellet gun is not allowed inside most city limits (this includes even inside your wood shop once they are trapped in a cage too- I'm just saying). Anyway, welcome back and good luck.