This fall has proven to be one of the most dramatic ones in recent years for several montane (mountain-dwelling) species in the lowlands of California.
Every few years, individuals of species normally found in the high mountains drift down to the lowlands, mainly living in planted pines for a few months before disappearing in early spring. Some, like the Mountain Chickadee, irrupt nearly every year, and are probably present more winters than they're absent (I had a small flock at the edge of the hills near Schabarum Park a couple weeks ago). Others, like the Golden-crowned Kinglet, are on a longer cycle, here in the lowlands every 3-5 years and totally absent otherwise.
So it was a nice surprise to find two of these kinglets this morning at The Park in La Habra Heights (along Hacienda Blvd. just north of East Rd.). Their calls are very faint, but distinctive once learned - a three-note "see-see-see", invariably coming from pines.
Based on sublte differences in calls and plumage, these montane invaders often represent Great Basin or Rocky Mountain forms (rather than nearby Sierra Nevada/Transverse Range ones) of the species involved, indicating that their irruptions are part of a larger, region-wide phenomenon when they occur; not just local birds moving down from Mt. Baldy or Lake Arrowhead. Indeed, one of the best places to see montane species like Red Crossbill and Red-breasted Nuthatch during these "invasion winters" is far out in the Mojave Desert, where ranchyards planted with Aleppo pines are the only trees for miles around. Here in the coastal lowlands, they often occur in Canary Island pines, which became hugely popular as street trees in the L.A. area in the 1960s.
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