By Glenn Martin
Wild turkeys, artificially introduced to southern Maine by 1980, and the disruption in the food web they have caused, are likely to blame for the state’s extremely large and growing tick population and tick-borne diseases such as the Lyme epidemic.
Turkey relocation continued across the state for 20 years by netting birds from established New England flocks. The goal of the program was to increase hunting opportunities. Regulated permit-only hunting kept the birds safe and propagated the current population.
Increased wild turkey populations have caused disruptions in the bug food chain. Voracious, shoulder-to-shoulder eating habits have stripped tracts of woods, edge and grassland of large protein-filled grasshoppers, caterpillars, worms, grubs, beetles and spiders, among others. The resulting reduction of bug life is detrimental to many wild creatures (migratory song birds, snakes, shrews, voles and moles) and beneficial to others (gypsy moths, Japanese beetles and ticks).
The wild turkeys’ aptitude for fast growth and large food consumption has decreased the protein-producing bug numbers. Many species of spiders and insects rely on other bugs for food. These creatures are called predator bugs. Their populations reflect the amount of protein a particular area’s bugs are producing. Foliage and grass-eating insects convert vegetation into protein. Subterrestrial beetles, grubs and worms convert decaying vegetation into protein. Eggs and larvae (protein) are the currency of the bug world. When a caterpillar is eaten, it doesn’t mature to lay eggs as a moth. Reduction of eggs and larvae is reflected in reduced bug populations.
As mammals depend on protein in milk, insect and spider populations depend on protein in eggs and larvae. Tick populations have not suffered because their protein source is warm-blooded animals. A tick’s largest predator is other young spiders and insects eating their eggs and larvae. Reduced predator bug populations provide sanctuary for tick eggs and larvae.
History shows a balanced food web will not allow for an exponential growth in tick population. The natural predators must be restored to their past levels, when ticks were virtually nonexistent. The disruption turkeys caused in the complex food web is the primary reason we have a tick-borne disease public health crisis.
Many publicly funded studies and reports were consulted to better illustrate this connection. A passive, statewide tick surveillance was initiated in 1989 to record the species, size, season, location, host and age, with a report published in 2007. The Maine Department of Inland Fisheries and Wildlife made a wild turkey assessment, recording a basic timeline and reasoning behind the turkey program. Public records clearly show that where wild turkey populations have grown, tick populations increased exponentially.
In 2010, the Maine State Legislature required the Maine CDC to record all incidences of Lyme disease and other tick-borne illnesses. Up-to-date wild turkey harvest records are available from IF&W. The help of numerous state wildlife biologists, the vector-borne disease research group led by Chuck Lubelczyk and the wisdom of the Maine State Legislature made the pieces available to put this puzzle together.
Glenn W. Martin II is a Master Maine Guide. He lives in Montville.