I said yesterday that the nutcracker in the park was a provisional choice. When I reviewed the iPhone video
I took the next day in a tiny park in Lulea, I knew I had to make a change. This bird was making a variety of sounds as
I sneaked up on him. Some are subtle and exotic, as corvids can be when they want to be. Two more days and you will see
what I mean. Many of them are harsh and noisy, as corvids are most of the time. I have added the 8/3 nutcracker to the bottom of
this page for good measure.
The world has three of these jewels, Clark's, Eurasian, and Kashmir. They are most famous for storing, rather than cracking, pine seeds.
The Clark's Nutcracker can carry over 80 weighty pinyon seeds in its sublingual pouch. This pouch is under the tongue, not part of the
mouth. It's analogous, I would think, to the fur-lined cheek pouches of some rodents. Back in the 80s I would see these small gray crows each fall at Cottonwood Gulch,
which is in the pinyon zone. They were their to poach pinyon seeds from their cousins the Pinyon Jays, and lesser seed cachers such as
chickadees and nuthatches, and take them back to their homes at 8500 feet in the Zuni Mountains. Their staple food up there is the large
seed of the Southwestern White Pine. The nutcrackers, and the Pinyon Jays, which have the same adaptive strategy but evolved it independently,
require pine seeds, which in a few species are quite large. The southwestern part of the U.S. and adjacent Mexico have
several such species, which are called pinyon pines. The Stone Pine, source of the pine nuts used to make pesto, is another of these species.
Russ Balda and his students at Northern Arizona
University did years of clever experiments on seed-caching corvids, and showed that they were able to remember exactly where they cached their
seeds, for up to 6 months. They did it by memorizing the configuration of naturally occurring sticks and stones on the ground around
their storage sites. Amazing! These high-reward seeds actually coevolved with the nutcrackers and pinyon jays. Most pine seeds are wind
dispersed, but the large ones are made to be harvested and stored by birds. All the pines need is for the occasional nutcracker to forget
one of its caches, or to meet a hawk before revisiting it, and it, the pine, has had its seeds planted for it. This is called "mutualism."
Nature is full of it.