Native to North America
Before the arrival of European settlers with their hunting, forest clearing and timber extraction, flocks of hundreds of wild turkeys could be found throughout North America. By the start of the twentieth century, they were on the brink of extinction. Through conservation and reintroduction efforts, however, they recovered and today, although not quite as many as the ten million estimated during the 1600s, they number about six million and are resident in every state except Alaska. While this proliferation has been deemed a conservation story by many—maybe even the greatest wildlife conservation success of the last century—there is considerable debate surrounding the introduction of wild turkeys into California and their place in its landscape.
Despite the quarter million or more now making themselves at home in the golden state, this specific species—Meleagris gallopavo (comprising four distinct subspecies and their hybrids with the Rio Grande subspecies being the most widespread)—is not considered native to California. Some 10,000–12,000 years ago, another smaller species with different morphological characteristics, the extinct Meleagris californica, did exist in southern California as evidenced by the more than 11,100 bones from at least 791 different birds found in the Rancho La Brea Tar Pits in Los Angeles. In fact, the second most abundant fossils in the Tar Pits belong to M.californica. Exactly why M. californica—originally described as a peacock—became extinct thousands of years ago in California is not known but it has been suggested that decreasing rainfall led to a loss of essential vegetation.
As part of a major state-sponsored recreational hunting program, the California Fish and Game Commission introduced thousands of farm-raised turkeys into the wild from the early 1900s through the 1950s. In spite of these introductions, the population remained flat, probably because these turkeys lacked the skills to survive in the wild.
From 1959 through 1999, however, the Commission, now the California Department of Fish and Wildlife, imported and released thousands of live-trapped wild turkeys (mostly of the Rio Grande subspecies from Texas) at over 200 locations, and these had no problem adapting to the California environment. Their population rapidly increased and their territory expanded throughout the state.Today, descendants of these turkeys occupy over 29,000 square miles of California—about one quarter of the state. They can make a living almost anywhere: agricultural fields and orchards, golf courses, university campuses, residential areas, urban sidewalks, freeway entrances and exits, and state and national parks to name just a few.
While most of the media coverage focuses on complaints from urban and suburban residents being harassed by rafts of invading turkeys, there may be a more critical issue at stake and important questions that need to be answered: Are they causing damage to the environment and decreasing biodiversity?
According to Christina Donehower, an environmental scientist at the Natural Resources Division, California Department of Parks and Recreation, much of the long-term data needed to reliably answer these questions and guide management actions is lacking. Donehower explains, “It is very likely that wild turkeys are affecting the ecological communities that they have come to inhabit in California. However, at this time, State Parks has limited capacity to devote to the monitoring and management of turkeys.” And so far, she says turkeys in California have received relatively little attention from the scientific community.
Daniel Ryan, the Invasive Wildlife Biologist at Pinnacles National Park, agrees with Donehower. Ryan maintains “we need far more good scientific research on this species and the effects it has had since being dropped into the state. We need concrete answers and we don’t have the time or money to find out.”
Scott Gardner, a senior environmental scientist for the California Department of Fish and Wildlife echoes these views. He says “it is obvious that the turkeys are here to stay and that long-term scientific studies are needed.” These pleas are nothing new. Concerns about the turkey’s potential impact on the native flora and fauna are raised by both government agencies and the public in the early 1990’s.
In 2007, the California State Department of Parks and Recreation identified three potential negative environmental impacts of turkeys as being of immediate importance: their consumption of endangered reptiles and amphibians, their competition with ground-dwelling birds for resources and their contribution to the spread of a tree disease called sudden oak death. Also in 2007, the Laguna Santa Rosa Watershed suggested that the effects of the wild turkeys on oak recruitment, soil disturbance, and damage to sensitive native species should be investigated.
To date, none of these concerns have been addressed in any long-term, comprehensive study. A short-term study conducted at one of Audubon Canyon Ranch’s Sonoma County preserves by Daniel Gluesenkamp in 2001, showed that “turkeys ate a broad variety of plants and animals and caused a tenfold increase in soil disturbance as well as a decrease in terrestrial invertebrates, herbivores, and decomposers fundamental to an ecosystem.”
In 2005, Reginald Barrett, a UC Berkeley retired professor emeritus of wildlife ecology and management, conducted another short-term study on the feeding habits and behavior of wild turkeys inhabiting Annadel State Park. He found no evidence of them spreading sudden oak death, eating endangered and/or vulnerable plants, insects or eggs, or causing harm to their surroundings, e.g. through rooting up soils or damaging vegetation.
In 2007, during another short-term study, Angela Gillingham found that turkeys were coexisting with quails within the same macrohabitat types without significant detrimental effects on either species. Gillingham felt that, while there was a great deal of dietary overlap, since both species have such diverse feeding preferences, barring any extraordinary environmental disasters or dramatic changes in population numbers or resource and/or habitat availability, it is unlikely that turkeys will come to monopolize available food sources.
The results from these short-term studies have created controversy. The California Native Plant Society, an organization dedicated to protecting and preserving California’s native plant heritage for future generations, feels that “while little is known about the impact turkeys are having, the data available indicate that the populations are too large, are in areas where they shouldn’t be and that they are affecting the environment by disturbing habitat, and eating a broad variety of native plants and animals”. On the other hand, The National Wild Turkey Federation, whose mission is “the conservation of the wild turkey and the preservation of the nation’s hunting heritage,” insists that there is much evidence that the birds are important both socially and economically, and no evidence that they are having a detrimental effect on the habitat or on any endangered species. As pointed out by the California Department of Fish and Game, however, such effects may be too subtle and too difficult to detect in the short term.
When the California Department of Fish and Game began releasing turkeys into the wild, they thought the program would result in economical and recreational benefits. Unfortunately they could not foresee the ensuing problems. Gardner says that while “the original turkey introductions weren’t an environmental concern at the time, because of their overabundance in some areas and geographic spread and our current environmental concerns—especially drought— with hindsight the department might have made a different choice about introducing them.”
According to Barrett and Gardner the turkey population is not now out of control or of major immediate concern for the environment. Overpopulation and increasing limited resources, however, could increase those concerns and turkeys could start to out-compete native birds for food resources. This is especially true since wild turkeys are “generalist feeders, and will eat animal matter, vegetable matter, you name it,” said Barrett.
So, is there a wild turkey crisis in California? Are they creating ecological problems now? Will they in the future? Possibly. Possibly not. According to Ryan, “Perhaps it will be necessary to pull out all the stops to halt their range expansion or maybe they will settle into a very normal niche in their regional environments. Turkeys, like many other introduced or reintroduced species, will probably continue to be a contentious subject in California as their population and range expand and they become more noticeable in the lives of Californians”. Perhaps then, more detailed studies will provide much-needed answers. If so, the only question left might well be whether or not the answers have come too late.
Reprint Scientific America, March 2016 by Dawn Starin