There is one event, which occurs routinely in Goleta that you will never see posted on Indy’s event page. It’s an affair concerning winged critters that accumulate in specific eucalyptus trees; a phenomenon much less publicized than our famous monarch butterfly display. It’s one for which a Google search produces scant results.
When the topic is brought up at dinner parties (as I inadvertently discovered more than once), wide grins turn rigid.
I’m talking about our local squad of turkey vultures, their communal roosting routine, and an interloper.
Every morning, in the eucalyptus grove near the Bacara, the birds sit poised, some with six-foot wingspans outstretched. After the fog lifts, they depart, taking flight, sometimes en masse. Flapping until a warm air thermal is caught, where they can maneuver while conserving energy.
Coasting, circling, soaring, and reporting to nearby orchards and roadsides for cleanup duty, they rid Goleta of many decaying remains. I couldn’t help but do a calculation here. With a peak local vulture population of, say, 110 (I’ll guess an average of 110 in Goleta for the sake of the exercise, though this number can be per roost and there are more roosts in the area), and with each bird eating roughly one third of a pound per day, I estimate more than 900 squirrel-sized animals are processed monthly.
Because a carrion diet is replete with bacteria, the scavengers are equipped with extreme gut acidity that enables quick meat digestion and immediate destruction of harbored pathogens. Their tendency to eliminate rotting carcasses may explain the turkey vulture’s Greek/Latin scientific name, Cathartes aura, which can be translated to “golden purifier.” The term golden might describe the head’s hue, which resembles a the red on a turkey’s head. Even though the scavenger is associated with the idea of purifying the putrefied, it has its limits and prefers to feed on the relatively—within a day or so—freshly deceased.
Chemicals released and volatized during decomposition are detected by turkey vultures at small quantities. Using a highly adapted sense of smell (an unusual characteristic for a bird) these animals can sniff out dead things as well as, interestingly, the synthetic dead. In 1938, a compound associated with decomposition, ethyl mercaptan, was added to gas when it was discovered that leaks in an extensive gas line could be detected by looking for a congregation of presumably disappointed birds.
While their bald heads allow them to explore deep into the caverns of a washed up seal and emerge relatively free of tissue ripe for decay, their propensity for consuming small animals whole probably enables them to supplement a high protein diet with mineral nutrients that are generally excluded from soft tissues. Ingested teeth, claws, and bones are regurgitated as pellets and left for ornithology types to dissect while they make inferences about local wildlife and traffic conditions.
But as of late, bird enthusiasts are spotting more than pellet contents in the turkey vulture roost. A new arrival has appeared. First reported in September of last year the official rare sighting was only the fourth documented black vulture in California. The common name reflects the fact that its head is black.
Joan Lentz, chief compiler of Santa Barbara Audubon Society’s Christmas Bird Count, is a local naturalist, teacher, and author of An Introduction to Birds of the Southern California Coast. When she first heard of the black vulture’s appearance, she drove to Goleta at top speed. “When I got the call last September from Hugh Ranson, who is a Goleta school teacher and ardent birder,” she said, “we County Listers were excited. … I saw the bird flapping when I was driving along Old San Marcos Road and it flew right over my head! I was totally thrilled!”
Watchful birders have recorded black vulture spottings at various locations every week or two during the last few months. A message-board rings out: “Hollister,” “Farren Road,” “Storke,” “El Capitan … disappeared into the west … ”.
Joan believes the rare bird came here by accident. “Instead of moving south toward the end of summer, it somehow wandered north,” she said. “Some birds are born with their internal compasses mixed up, and they will then be off by 180 degrees.” Since the black vultures’ range is between southeastern United States, northern Mexico, and South America, it is probably lost. “Usually, these patterns repeat in an individual, which is why we think it might be the same bird,” she explained. Though somebody reported seeing two of the black heads, which, if confirmed, may complicate the rationale.
Black vultures (Coragyps atratus), with a mere five-foot wing span, are slightly smaller than turkey vultures. They also flap more, have white wing tips, and lack that olfactory superpower.
In areas where habitats overlap, it’s not uncommon to see black and turkey vultures roosting together. In fact, black vultures at times seem to rely on the turkey vulture to smell out their day’s meal. They wait for the turkey vulture to descend, then share or co-opt the spoils.
While scientific documents refer to the roost as a site for communication regarding food, I imagine these vocal-chord deficient animals interact more through their cursive-like motions in the sky.
In any case, after a day of patrolling, the vultures that left hours earlier, red-headed and black-headed alike, descend back into tall branches. A 1929 description by Frank A. Leach captures the creatures’ past, present, and likely far-into-the-future nightly routine: “With the closing of a day these most graceful flyers come soaring in to the chosen spot, at times singly, but more commonly in two’s or three’s or even greater numbers … ”
As a side note, only experienced birders—and probably not even they—should gaze at vultures while driving. You can park in a lot devoted to public beach access near the Bacara. It is connected to a short walking trail, which flanks the roost. To view the active vultures during sunshine hours, hiking up Farren Road will guarantee a spectacular vantage point.
For a more extensive list of references and related websites, see Lisa’s blog, Stimulating Aliquot.