Explore the literature on any bird species, and you may well become astonished at how little we know about the most common ones. This is one reason among many that my copy of The Birder's Handbook, published 27 years ago (update, anyone?) sits in its tatters beside me pretty much whenever I write about birds. I don't get any money from Amazon by linking to it, by the way. This book was and is a landmark in the world of bird lore. One reason is that in the species accounts, whenever some fact about a bird was unknown, the authors placed a question mark in the account, a very intentional cue to keen observers that they could contribute to our wealth of bird knowledge and ultimately conservation. Thus, for Blue Jay, we see for example, "MONOG?" This means that in 1988, we suspected but didn't know if Blue Jays mated for "life." "Life" is in quotes because if one member of a pair of birds of a species with a long-term pair pond dies, the other immediately seeks a mate. You can't make babies without a mate, and making babies (and thereby passing on your genes) is what it is all about in the natural world. Also, scientists long ago established through DNA testing that even "monogamous" birds cheat on each other all the time.
Fast forward to 2013, when the Birds of North America Online account for Blue Jay was last updated. It would appear that we now know that Blue Jays mate for "life" (there are those quotation marks again), and that the basic social unit for the species is the mated pair, accompanied by dependent offspring after hatching.
Neat stuff. But wait. The BNA account, which is overall excellent, also calls the Blue Jay "Resident throughout most of range." Anyone who has been to Cape May, NJ in fall or Whitefish Point, MI in spring knows that this is a bunchabloody nonsense, especially in flight years, when flocks of hundreds of Blue Jays appear at these and other locations. Blue Jays are active diurnal (daytime) migrants, and we don't yet understand exactly what they are doing or why. The BNA account mentions, but glosses over, some Blue Jay migrations that had been reported prior to 2013, citing for example migrations in Maryland with flocks averaging 11 birds and 29 at maximum. Those are pitiful flock counts compared to what one sees at Whitefish and Cape May.
Remember, we're talking about Blue Jays here, not Spoon-billed Sandpipers or Colima Warblers. Shouldn't we kind of know everything about them by now?
Well, I hope not. We'll never know everything about anything.
Blue Jays get a bum rap because they scare away birds at your feeder (often artfully imitating a raptor call to do it) and are well-known nest predators made infamous beginning with J.J. Audubon's 1842 portrayal of a pair devouring somebody's future babies (eggs) in his magnum opus, The Birds of America. So what, says I? Birds have to eat, and birds have to die. Who's yelling at the lions for eating the gazelles?
These are fabulously amazing, fascinating birds. I happen to know that Blue Jays are my famous best friend, Pete Dunne's, current favorite species. While we are out deer hunting, we love watching them move in lines of skirmishers through the woods, in constant contact, always ahead of, behind, or beside the enemy, never being caught.
Now we get to the heart of the matter: the best part of birding begins AFTER you have identified the bird.
Last Friday, October 30, 2015, a group of friends, me included, witnessed some remarkable Blue Jay behavior during a bird walk I was leading. Friday was a day when I expected a significant land bird migration which to my surprise did not unfold, at least not at Edwin B. Forsythe National Wildlife Refuge, near Atlantic City, NJ. [If you haven't yet liked the refuge Facebook page, please do and pass it on. It's the best place to get the latest news on Forsythe, including bird news, closures, and more.] So we were "forced" to observe and enjoy common species, like Blue Jays. Poor us, right?
I began by pointing out that on careful observation, one will quickly realize that autumn Blue Jays are often busy caching "hard mast," especially acorns. From October to March, hard mast accounts for at least two thirds of a Blue Jay's diet.
Typically Blue Jays will find acorns in one area and transport them to another, sometimes only a hundred yards away, but sometimes several miles away, all for later consumption when times get hard. This acorn dispersal by Blue Jays is key to the spread of oak trees, and has been ever since the last glaciation. Blue Jays are much better at acorn dispersal than squirrels, since jays fly far while squirrels hop short.
With more careful observation, you may discover that in any given area in fall, Blue Jays with acorns are always flying in one particular direction, and Blue Jays without acorns are flying in the exact opposite direction. At Forsythe, we soon discovered that some jays near the visitor center were hitting two particular Scarlet Oak trees near the Children's Nature Discovery Area (a.k.a. the refuge's nature playground), plucking multiple acorns from the trees themselves (which is safer than getting fallen ones from the ground), and flying a relatively short distance east to wherever it was they were caching them.
Neat! We spent some time watching and photographing them. But it gets better.
Towards the end of the walk, we found ourselves in the spot, more or less, where the Blue Jays had been heading with their prizes. I saw a jay flush ahead of us as we approached, but after that. . .no jays.
I asked the group, "What's happening here?" I didn't even mention the jays. I can be kind of a jerk when I am teaching something important.
Eventually I added a clue. "What's NOT happening here?"
After a long pause, someone said, "There are no Blue Jays."
I asked, "If you were a Blue Jay, would you want an apparent herd of large mammals to know where your acorn cache was?"
We walked a bit farther, and heard a Blue Jay sound. Quoting the BNA account, "...the total vocabulary of Blue Jays is immense and precludes precise categorization." They are not kidding. If you hear an unfamiliar bird in the woods, it's either a jay or a titmouse.
The sound we heard was a sort of a mew. And looking back where we had been, we saw a single Blue Jay perched on an exposed perch. We were being watched.
I said, "There's the sentinel. We won't see any more caching behavior until we are well away from here."
When the walk concluded, my SCA intern and I hid in the shade of the Visitor Center and watched from afar. Soon the procession of jays, maybe 6-8 birds in all, began again. East with acorns, west without.
Again: the best part of birding begins AFTER you have identified the bird.
[A professional Blue Jay. Two Scarlet Oak acorns in the bill, and who knows how many in the crop (there's another question that we don't know the answer to!)]