By Paul Heiple
This year, 2015, the turkeys (Meleagris gallopavo) have arrived in Edgewood. This is no surprise to most people since they are large birds that often gather in open areas and have been seen by most frequent visitors. But what does it mean for Edgewood, and what can we expect?
The first item that everyone wants to know: is it a native bird? The birds we are seeing are not native to California. They were successfully introduced for hunters by the California Department of Fish and Game (Fish and Game; now, Fish and Wildlife) over a long period of time and with great effort. The first introduction was on Santa Cruz Island in 1877 by private ranchers (just what the island vegetation needed after goat introductions!). Fish and Game started releasing turkeys in 1908, in the San Bernardino Mountains. Releases of captive-raised stock occurred from then until 1951. About 4600 birds were released during this period with no known success. In 1959, the program started again, but this time wild-caught birds from the Rio Grande area of Texas were released. From 1959 to 1988, 2924 birds were released. Releases continued from 1989 to 1999 with species that could establish themselves at higher elevations. A 2004 report stated an estimated total of 242,000 turkeys spread over 29,168 square miles of California.
In the past, California did have a species of turkey, Meleagris californica. This animal’s fossils are found in southern California, and most of them come from the tar pits at Rancho La Brea. The birds went extinct 11,000 years ago, about the same time that all the large mammals went extinct. The reason is not known, probably because humans were the cause and our species does not like to admit that we do such things. The California turkey was most closely related to M. gallopavo, compared to any other species, so the Fish and Wildlife releases are of this most closely related turkey. We will never know what different behaviors the extinct species had nor how it fit into the ecosystem, which was very different from the ecosystem we have now. We therefore cannot say whether the introduced birds will be a perfect fit to replace the extinct bird.
Turkeys are opportunistic omnivores, eating mainly nuts, fruit, and seeds. Acorns are high on the list of favored foods. They eat insects also, but the percentage of insects eaten declines with maturity. Turkeys occasionally eat vertebrates. They will also eat plants and tubers; bulbs were not mentioned in the literature I read. An encouraging study in San Luis Obispo County found that the staple food was slender wild oats (Avena barbata) and brome (Bromus) species. I wonder if wild oats (A. fatua) is also on the menu; the turkeys could be helping the weeding effort.
BreedingThe reproduction biology of turkeys starts with the breeding season in the spring, when males compete for females by strutting and gobbling. The females then disperse to dig shallow nests on the ground and lay 4 to 17 eggs. The eggs hatch 25 to 31 days later. The chicks spend one day in the nest and then feed themselves under the protection of the mother. The females may bring their broods together to form larger flocks. The males do not participate in raising the chicks.
Predation comes from many species. Snakes, raccoons, skunks, foxes, and a number of other predators eat the eggs. Chicks are the targets of coyotes, bobcats, foxes, and owls. The adults are so large (females about 9 pounds, males about 16 pounds) that few predators can tackle them. Also, they can fly quite fast, and at night they roost in trees.
Why did the turkeys show up in Edgewood this year, the same year they showed up at Jasper Ridge? It might have to do with the drought and the fact that turkeys need to drink up to twice a day. I do not know which spring they were using at Edgewood, but they must have had access to some surface water. Perhaps the water supplies they had been using before dried up, forcing them to look for new habitat. Will they remain in Edgewood? The answer to that question is not known at this time. Under article 4.1.3 of the Strategic Plan for Wild Turkey Management of Nov. 2004, Fish and Wildlife will work with a park’s management objectives to control or remove when the turkeys conflict with the park’s objectives. Since Edgewood is a natural preserve whose primary management objective is to protect, preserve, and restore Edgewood’s natural resources, this is a possible avenue to take if the turkeys become a problem.
Photos for this article were taken at Edgewood Park and Natural Preserve, San Mateo County, CA, USA by James Dudley and Grace Wu.