The Mysterious Movements of Santa Barbara Birds

An unprecedented irruption of montane birds is in progress.

No, that’s not a typo. 

Irruption (Merriam-Webster): a sudden sharp increase in the relative numbers of a natural population usually associated with favorable alteration of the environment.

Birders were alerted that something unusual was afoot when there was a report of Clark’s nutcrackers seen atop La Cumbre Peak on September 5. Clark’s nutcrackers, a bird of high coniferous forests, are a rare bird anywhere in our county, and in the following days many birders made the trek up to the peak and were treated to an astonishing spectacle.

Those of you who spend time in the High Sierra, and who pay attention to birds, will be familiar with the Clark’s nutcracker. They are raucous birds with a loud, gravelly call. They are usually seen in flocks, feeding in pines or flying on broad floppy wings to the next stand of pines where they pick seeds out of the cones with their long, sharply pointed bills. They are crow-shaped but a little smaller, with pale gray bodies and black-and-white wings.

Beginning in September, nutcrackers begin collecting pine seeds and cache them as a food source to help them through the winter, usually in trenches dug with their bills. They have excellent memories and can relocate these caches up to nine months later. They don’t recover all the seeds they’ve hidden, and it’s thought that many high-elevation coniferous forests owe their existence to the nutcracker and its habit of hiding seeds.

We don’t have the forests or the elevation in our county to attract nutcrackers, and any sighting here is considered a rare occurrence; this is why birders were keen on documenting their appearance on La Cumbre Peak. Following the September 5 report, there were daily observations made of nutcrackers flying west over the peak, most not stopping. The birds were seen in flocks, some of considerable size. 

Each day the numbers increased, until an incredible 1,200 birds were tallied flying by on September 14. This is almost certainly a record-high daily count for this species anywhere. When you consider the global population is estimated at 230,000, this is an impressive number. As of the time of writing (early October), birds are still being seen, though not in such staggering numbers.

Birders began to wonder where the birds were heading to as there were few sighted west of San Marcos Pass, and far fewer in the mountains to the east. We still don’t know the answer as counties to the north haven’t reported such huge numbers of nutcrackers. Some were curious if we were seeing the same birds that were flying in large circuits, but to me this doesn’t make sense. 

Birds are smart: if they are looking for food, they wouldn’t go to places where they’d already been unsuccessful. So the question of where they are going remains a mystery. And why do they concentrate at La Cumbre Peak? Perhaps once they pass the peak, they spread out in search of food. Birds have been seen in Baja California, in the Bay Area, and some have made it out to Santa Cruz Island. One lost bird has even been seen in Kansas.

The Merriam-Webster definition of an irruption tells us that such behavior is usually favorable. Irruptions can occur when birds (or other creatures) have had a particularly good breeding season, and pioneering birds will head out to look for new areas to colonize. The discussions I’ve read, however, suggest that something more sinister is at play, especially considering the massive, unprecedented scale of the irruption. 

One conjecture is that there has been a catastrophic cone crop failure in the Rockies and the Sierra, meaning that nutcrackers have few seeds to cache to see them through the winter, and hence, they are leaving their mountain homes in a quest for survival. A big question many are asking is: Will the wandering nutcrackers be able to find enough food to make it through the winter away from their usual winter homes, or will we witness a huge population crash?

Nutcrackers are not the only birds involved in the current irruption. Another species, the pinyon jay, with only a handful of previous records in our county, has been moving through in unprecedented numbers in flocks as large as 100 birds. Pinyon jays feed largely on pinyon pine seeds, and it seems likely that the pinyon pine crop has failed. Red-breasted nuthatches seem to be everywhere. Evening grosbeaks and Cassin’s finches, also birds of the high forests, are being seen in large numbers. Of course, it’s enjoyable to see these unusual species, but as one birder put it, these are large gray, black, and white canaries telling us that all is not well in the coal mine. 

There are certainly a number of possible reasons for this exodus from the mountains — forests destroyed by wildfires, insect damage to the trees, a drought-caused collapse of the nut crop. It might be some combination of all of the above, all of which are caused by the climate crisis. How long this historic irruption will continue is anyone’s guess, as is the long-term health of these species that are on the move. We can only hope that the predicted winter precipitation will help the western forests rebound.