Be on the look out for band-tailed pigeons! Reports this month indicate band-tailed pigeons, California’s only native pigeon, are utilizing areas where they haven’t been in years. Observers have reported flocks of 50 to 100 birds in locations where pigeons haven’t been seen in at least 15 to 20 years. These seemingly erratic movements are directly tied to available food resources. During the winter, band-tailed pigeons feed primarily on acorns. They are one of the few species that actually swallow acorns whole!
Adult band-tailed pigeon showing the characteristic white crescent and iridescent greenish-bronze patch of feathers on the hind-neck. Photo by Gary Kramer, 2008.
Acorns on a coast live oak (Quercus agrifolia), a favorite wintertime food of band-tailed pigeons. Photo by Krysta Rogers, 2011.
Acorn productivity fluctuates among oak species and between years. In some years, oaks may produce large quantities of acorns, in other years acorn production can be spotty. If acorns are not available, pigeons will rely on other food items such as madrone berries or pine nuts. However, the availability of all these plant foods are dependent upon weather conditions including temperature and the timing of rain, which leads to changeable food resources. Band-tailed pigeons must be adaptable to these variable conditions and seek out food resources across the landscape.
The observations of pigeons using “non-traditional” locations this winter may possibly be influenced by recent drought conditions. In Sacramento County, acorn productivity this season was very high and, in fact, bird watchers reported seeing flocks of band-tailed pigeons along the American River during fall migration. In contrast, a recent trip to the Los Padres National Forest in Monterey County, a location known to be especially reliable for both acorns and band-tailed pigeons, revealed neither acorns nor band-tailed pigeons this winter! Instead, pigeons were observed at lower elevations where abundant food was available.
Flock of band-tailed pigeons in oak tree in Santa Clara County. Photo by Krysta Rogers, 2014.
Also likely related to drought, was the increased incidence of Trichomonosis in band-tailed pigeons this summer. Trichomonosis is a disease caused by a single-celled microscopic protozoan parasite, Trichomonas gallinae. The parasite lives in the mouth and throat of infected birds, causing caseous (“cheese-like”) lesions to develop in the birds’ mouth or esophagus. The lesions eventually block the passage of food, causing the bird to become weak and emaciated. Infected birds die from starvation, or suffocation if the lesions block the airway.
An adult band-tailed pigeon showing signs of infection with Trichomonas parasites. Notice the drooped wings, ruffled feathers, and open-mouth breathing. Photo by Krysta Rogers, 2012.
Band-tailed pigeons are highly susceptible to infection with Trichomonas gallinae. Traditionally, large-scale die-offs occur during the winter months, in some years. However, this year the Wildlife Investigations Lab received reports of increased mortality of band-tailed pigeons in several locations along the central California coast between May and August. Drought conditions likely resulted in increased contact between individual birds at limited food or watering sites, resulting in rapid spread of disease. This increased mortality of band-tailed pigeons is concerning because the band-tailed pigeon population has been declining for the past 40 years. Die-offs due to Trichomonosis can remove hundreds to thousands of pigeons from the population in a relatively short period of time.
This winter, be on the look out for band-tailed pigeons in your area. If you see pigeons, enjoy the spectacle, it may not occur at that location for another 20 years! And if you happen to observe pigeons that appear sick, such as showing signs of weakness, labored breathing, breathing with their bill open, drooling, reluctance to fly when approached, or are dead, you can help by reporting the mortality to the Wildlife Investigations Lab.
If you have any questions, or would like to report sick or dead band-tailed pigeons, contact Krysta Rogers at 916-358-1662.