A lot of biology: Rodents

Well, there are rodents and then there are rodents. We had close encounters with our beloved western grey squirrels last year. In a more sinister turn, I just realized there is a fox squirrel inhabiting the yard and, possibly, the crawl space. The distressing thing other than the prospect of evicting it from the yard and house, is that fox squirrels aren’t from around here. Not only are they not local, they are in the class of exotic, non native species that are also ecosystem destroyers. The mammalian equivalent of a noxious weed.

I wrote to the Oregon Dept of Fish and Wildlife to inquire how bad it was to have this invasive species on our burgeoning restoration project. The reply was quick and decisive – essentially, “kill it, kill it now”:

Fox squirrels are a nonnative non protected species and were brought to Oregon from the Eastern United States and have established themselves in urban and suburban habitat through the state. They are the most common tree squirrels found in Portland and have contributed to the decline of native squirrel species.

Fox squirrels are reddish brown in color with large bushy tails and tan undersides. Oregon’s fox squirrels are notorious for breeding “out of season” and infant and very young squirrels found later than October 1st and earlier than April 1st are typically members of this species.

They are true omnivores, because they have also been known to eat insects. Not only that, but fox squirrels are also not above robbing the eggs from temporarily empty bird nests. Fox squirrels can compete for food and nest sites with your local western gray squirrels. Now is the time to rid yourselves of this invasive species. Fox squirrels have no protection and can be shot or trapped on your property. They can not be relocated and should be euthanized.

OK, I agree.

  • But I am not a euthanizer of mammals this big. I have mousetraps, and occasionally I accidentally get a chipmunk in the trap, which is cause for hand-wringing. I have successfully set rat traps, I have trapped moles (I am doing penance for that – it was earlier in my life when I was ignorant. I like moles now, and I defend them to everyone).
  • I can’t poison them (that’s the coward’s way anyhow) because they will poison whatever eats them afterward.
  • I don’t use guns and my neighbor declined to use hers on them. I could not possibly drown anything.

Eds. UPDATE (May 2014):  Not actually fox squirrels. What we have are California ground squirrels. They are native, but probably increasing with landuse that encourages them, also our brush piles that are great habitat for birds, but also other animals. Three years ago we had one squirrel below the garden which turned into many in subsequent years. The extended family now inhabits many corners of the yard and our ongoing battle with them is chronicled elsewhere in this blog. Suffice it to say, they are tenacious digging machines, have all the time in the world to get around many defenses, and have lovely pelts that would make nice clothing. If they don’t get under the buildings, things are all happy between us.


Okay on to another rodent. We live in Gopher Valley. We have lots of gophers. Also lots of signs on telephone poles advertising gopher “control” as if it were a standard maintenance procedure like mowing your lawn.

Here’s the deal with gophers – they ARE from around here, and they’re part of the ecosystem. They have a niche and fit in like part of a jigsaw puzzle. I’ll let these nice biologists ‘splain it, because this video is very entertaining:


We have this species and one other in western Oregon, if my Internet surfing is correct. The other is the Camas Pocket Gopher Thomomys bulbivorus – how appropriate because there are so many species of bulbs here. In the process of eating bulbs, they redistribute them (if you’ve ever dug up bulbs, you remember there are smaller baby ones that get inevitably get left behind), mix them with soil and aerate the seedbed, thus promoting the growth of more bulbs. Gophers are one of the factors responsible for the abundant bulb fields that existed before large-scale development and agriculture. They add fertilizer to the soil, too.

Gophers are endemic, functional species of the wild ecosystem, but of course once agriculture and horticulture enters the picture, they become pests. People think they need to control them in order to carry on the soil-compacting, mono culture farming of economically important crops like, um, Fescue for suburban lawns.

Consider this passage from the Fish and Wildlife Service fact sheet on the mazama pocket gopher:

Current subpopulations of Mazama pocket gopher continue to be threatened by loss of prairie habitat due to residential and commercial development, invasive plants, and encroachment of non-prairie plants due to an altered fire regime; small-population effects; trapping and poisoning; predation by cats and dogs; and trampling and crushing of burrows due to heavy equipment use.

Who can cope with that and survive? Pretty good that there are still some around.

Here’s another thought: biodiversity is valuable because there are many species and many kinds of species adapted to a range of climatic and environmental conditions. If there are several species that can occupy a particular spot in the food web, that’s good, because redundancy equals protection against total loss of necessary species in case of say, climate change, or massive disease outbreaks. Here is the full list of subspecies (genetic variants, below the species level) of this one gopher in this little old corner of the US (western Oregon and Washington).

Mazama pocket gopher Thomomys mazama (ssp. couchi, douglasii, glacialis, louiei, melanops, pugetensis, tacomensis, tumuli, yelmensis)

A couple of subspecies are already assumed to be extinct.