Douglas’s squirrel (Image: WDFW)

A few years ago I took a walk at the Arboretum while waiting for my partner to finish an appointment. It was a crisp Fall day and being mid-week and late morning, the many trails were mostly free of pedestrians and I wandered about enjoying some idle time outside. Turning down a small path beneath towering Douglas firs, I stumbled upon a pile of fir cones that had been pulled apart and heaped atop a small log.

I was amazed, because I was almost certain who had created this mess: a Douglas’s Squirrel, Tamiasciurus douglasii.

Finding the sign of a squirrel at an urban park is far from a shocker. Most of us go through our day to day seeing and summarily ignoring most of the Eastern Gray Squirrels, Sciurus carolinensis, we encounter (except for the ones that gulp down our bird seed). However, Douglas’s Squirrel was not expected. At the time, I was certain they only existed in small pockets of mature(ish) coniferous forest in Seattle, like Discovery or Seward Park. But here was nearly irrefutable proof, a telltale sign I’d come to recognize from decades of hiking and naturalizing across Western Washington.

Douglas’s Squirrels are diminutive, brown and rusty red colored, and by far the most common tree squirrel west of the Cascades in Washington. Being rodents, it should be no surprise to find one cropping up unbidden and unnoticed (and I wouldn’t blame anyone if they didn’t share my immediate enthusiasm for this). That’s exactly how Eastern Gray Squirrels have shown up across the US. They hitch a ride or are accidentally transplanted. Eastern Gray Squirrels may be introduced, but they have thrived in our cityscapes, finding plantings of street trees offering them the nuts and acorns of their native ranges and bountiful other food sources for their flexible, omnivorous diets.

Douglas Squirrels may be common outside the city, but only because of a deep association with the coniferous trees that blanket much of our landscape. However, most of the Hill lacks significant stands of Douglas Firs and hence, on a daily basis, Eastern Gray Squirrels would be the present day norm. Though certainly part of the problem, Eastern Gray Squirrels have been blamed for extirpation of Douglas’s Squirrels. Cited as nest predators and bullies, which they are, just like so many other scapegoat species, the more overarching culprit is likely habitat change.

An Eastern Gray Squirrel that was stalking my bird feeder during a cold spell. (Image: Brendan McGarry)

One of my favorite things about Douglas Squirrels, and indeed most tree squirrels, is that they are hardly shy. In a world where most animals actively avoid us, these bold balls of energy like to let the entire forest know we have arrived and even if this is merely telling everyone a predator has arrived, I find it refreshing. They are the heralds of the deep forest, boldly chirruping when they see you coming (their other name, Chickaree, is clearly an onomatopoeia), and often hanging about to get a closer look, peering around a tree trunk, ready to flee but also a touch curious. Take the time to watch them and you’ll probably become exhausted, because like most tree squirrels, Douglas’s Squirrels are obscenely athletic with excellent eyesight and reflexes that propel them through their arboreal world. They never stop moving and if you sit still for a moment they’ll quickly lose interest, propelled by their caloric needs.

(Larry Hubbell, author and photographer at the blog Union Bay Watch, who generously allowed use of photos in this article, told me he timed a Douglas’s Squirrel dissecting a pine cone: “The squirrel looked a lot like a human eating corn on the cob. It took almost exactly 60 seconds – from start to finish.”)

The pile of cone bits I’d discovered tells us a lot about Douglas’s Squirrels (I never saw the owner who made the pile I discovered, and never saw one of its species at the Arboretum until a couple years later).

Called midden piles, they are mostly heaps of picked apart conifer cones, but they also serve as a cool dry place to store food for future lean times. This is so well known that foresters of the past used to raid Douglas’s Squirrel middens to find high quality seeds for tree propagation. If this doesn’t quite make sense, consider that most conifers produce cones nearer their canopy and this had made them inaccessible for people before tree climbing and timber nursery trees were commonplace. Douglas’s Squirrels spend much of their lives dropping cones to the forest floor for later storage in midden piles, doing so before the cones mature and the seeds fly loose or are spoiled by exposure.

Douglas’s Squirrels may be tied to conifers for a large part of their diet (as are all the members of their genus, generally referred to as “Pine Squirrels”), but that doesn’t mean they can’t branch out. Like most rodents they are happy to eat bird eggs, flower blossoms, berries, nuts, and mushrooms. Scientists call Douglas Squirrels scatter hoarders because it’s not just one midden, food is stored in hundreds of places throughout the forest. Nuts in particular often get stashed away, potentially planting a new Beaked Hazel when they are forgotten. Mushrooms take a bit of extra work and enterprising Douglas’s Squirrels collect and hang them to dry on the underside of branch crotches before stowing them away. This is one of those behaviors I have only read about but would swoon if I got to witness; can you imagine something cuter than a little squirrel hanging up mushrooms to dry? Talk about Cottage Core.

Conifer cones like this ripening Douglas Fir cone are key to Douglas’s Squirrel survival. (Image: Brendan McGarry)

A huge Douglas’s Squirrel midden, made of Sitka Spruce cones, that I found on the Olympic Peninsula. (Image: Brendan McGarry)

Though their population can peak and trough like other rodents, particularly ones tied to fluctuating cone crops, Douglas’s Squirrels themselves are important food for a wide range of species. Owls, hawks, bobcats, weasels, and more will gladly catch them and despite their speed and agility, it seems they are often on the menu. I have personally seen Barred Owls and Pine Martens hunting Douglas’s Squirrels – the marten was successful and the owl simply spiraled around a tree trunk looking absurd. It may sound macabre to list the things that eat these new friends of ours, but their presence offers predators reliable food and can be seen as a good thing for biodiversity and resilient ecosystems.

Douglas’s Squirrels live solitary lives within territories of around 10,000 square meters. Only when breeding and raising young is there tolerance of interlopers and only for brief periods of the year.  At this moment, mothers are starting to think about kicking the year’s youngsters out on their own after months of brooding, weaning, and learning their vertical world. The average squirrel mother has between four and six young and the turn around to full size and sexual maturity is quick – eight months or so. She has no interest in sharing her winter hoard with half a dozen full grown kids and away they must go to find their own space.

This form of post-breeding dispersal is probably how an isolated patch of Douglas firs at the Arboretum wound up with Douglas’s Squirrels naturally reintroducing themselves. In theory, a nearby mother kicked her brood to the curb and they went out in search of new homes. If I had to stretch this theory further, I imagine a few adventurous young ones following the patches of forest north along Lake Washington from Seward Park, maybe colonizing small stands of coniferous trees in fits and starts, taking several generations to get all the way to the Arboretum. Or maybe it just happened all in one go. And the most reasonable explanation of why it might be happening over the last five years is that the Douglas firs in the arboretum are now mature enough to produce a reliable cone crop.

Thanks to an increasingly ecologically minded city, somewhat natural forest exists in the green spaces abutting the Arboretum and beyond, (Common Ravens have also found their way to breed here in recent years, though their arrival by wing is a bit less hard to imagine). Douglas’s Squirrels may sleep summer nights away in homespun squirrel nests called dreys, perched on branch tips and crafted from leaves, bark, and twigs. But when the weather turns cold they move into tree cavities. Without dead standing trees where natural cavities and old woodpecker nests abound, Douglas’s Squirrels would struggle to maintain a foothold.

A Douglas’s Squirrel demonstrating an interest in snags. (Image: Larry Hubbell of Union Bay Watch)

I am curious why Interlaken Park doesn’t seem to be another location with our little native squirrels, but maybe time will tell. An observer on iNaturalist spotted a lone individual at Volunteer Park and I wouldn’t be surprised if, over time, more crop up. Who knows, maybe you have a tip for Pikes/Pines!

We might not have the biodiversity of less human dominated spaces on the Hill, but clearly that doesn’t mean interesting things aren’t happening under our noses. We urban naturalists just have to pay attention and elsewhere these details have painted interesting pictures for how our cities have influenced other creatures. According to work by the Field Museum in Chicago, chipmunks across Chicagoland have been slowly getting larger bodies and smaller teeth over the past 125 years, probably because of changes in diet associated with urbanization. In the same study, vole specimens from urban areas had smaller auditory bullae, bones involved in hearing, suggesting that these small rodents have physically adjusted to city noise. And because of everyday observers on iNaturalist, a new study has demonstrated that city dwelling Northern Raccoons are showing early signs of domestication.

Now maybe these examples don’t sound quite like stories of mammalian change worth celebrating, but they are undoubtedly interesting and paying attention to such shifts is vital to understanding the world around us and being better stewards. We live in a fluid, ever changing world, which is simultaneously frightening and fascinating. Douglas’s Squirrels may only stick to their forest patches, but I certainly hope they are here to stay because in a way their presence gives me hope that we can redeem ourselves in places overwrought by our footprints. Who might be the next species to find or regain a foothold on or near the Hill?

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