There’s an invasion happening on the Hill. They’re coming from the south, following a landscape that’s urbanizing and opening up. They’re alright with a drying climate, cause that’s what it’s like back home. Possibly they’re pushing out the locals. No, I’m not talking about Californians, I’m talking about Western Scrub Jays (Aphelocoma californica). Most of us know the more common Steller’s Jay (Cyanocitta stelleri), the raucous, wobble-crested tricksters that creep about the Hill.

They appreciate trees, and in the Pacific Northwest (their range extends from Alaska to Nicaragua), are most at home in coniferous forests that once blanketed almost all the land west of the Cascade crest. Steller’s Jays aren’t threatened at this point and they take to the urban landscape quite well, but they’re still losing ground on the Hill, because the trend is to get rid of big trees. Go to the north side of the Hill near Interlaken, I bet you’ll find some. Stray to the south near Seattle University, I have a feeling you’d have to work a lot harder.

Western Scrub Jays weren’t a bird I grew up seeing in Seattle. They were a species I enjoyed when we visited family in Portland, which used to be near the Northern end of their range (extending South into Central Mexico). There the open and drier Willamette Valley extends North and is also where one of the scrub jays’ favorite food trees are more prevalent. Garry oak, or Oregon white oak (Quercus garryana) are undoubtedly a source of food for the Western Scrub Jay in this part of the country (although they are opportunistic and will eat insects, fruit, lizards, and seeds. Where there’s oaks, I’m never surprised to find this bird. I’d also never expect to find a scrub jay in the midst of a dank temperate rainforest, because it’s just not their place.

I’ve found no demographic study of the northern expansion of the Western Scrub Jay. Nor do I actually believe they’ve pushed Steller’s Jays out of the way (there’s anecdotal evidence that Steller’s Jays are more aggressive). This isn’t a data driven piece. However, scrub jays expanding up the Puget Sound lowlands are a real thing and I think we can generally assume it’s related to habitat. Humans, the great habitat disturbance that we are, have opened up things nicely for scrub jays, and in many cases we’ve planted oaks (non-native but still bearing acorns) as street trees. We’ve essentially laid out a path for their expansion.

If the dark blue of a Steller’s Jay is made for the deep forest, then the light blue of the Western Scrub Jay is made for more open country. I think scrub jays seem less rakish, likely because they lack a crest, but they’re no less beautiful nor smart. Being common species, they’ve become the focus of many studies, particularly those looking at animal intelligence. Adult Western Scrub Jays have a brain to body mass ratio not far behind ours. Wielding this hefty cranium, these birds have demonstrated to researchers that they are capable of remembering over 200 different food caches. While it may sound ridiculous to non-scientists, this ability to remember and a purposeful caching behavior have led scientists to challenge the notion that only humans have the ability to think to the future and plan (here’s a very technical paper about it).

Is it a problem that Western Scrub Jays are becoming more numerous in our area? Probably not. Despite the fact that like Steller’s Jays they’re considerable nest predators for other songbirds, I doubt there will be a marked impact. Species have been colonizing, being out-competed, and generally moving around as the world changes long before we were around. Not to make light of our impact, but there are other things to worry about than a few new jays who mainly want to eat some insects, fruit, and acorns. Scrub jays may never take over the Hill, but I think it’s worth knowing they’re our new neighbors.