Ecological Effects of Hunting

The ecological effects of hunting are no less diverse than its history. While hunters act as apex predators in ecological terms, human hunters rarely conform to the assumptions of the Lotka-Volterra equations (predator-prey equations). Human hunters can and often have operated as keystone predators, exerting a disproportionate effect on prey populations relative to human numbers. The ecological effects of modern hunting, however, are mediated by governmental regulations. Throughout much of the twentieth century, the maximum sustainable yield paradigm guided hunting regulations. During the latter half of the twentieth century fixed harvest quotas based on maximum sustainable yield decimated many global fisheries and whale populations. This failure led to regulation of hunting effort (season timing and length, bag limits, means/methods (archery vs. firearms)). Such regulations control harvest indirectly by altering hunting effort and hunter efficiency. Because hunter effort required to bag an animal increases as prey abundance declines, effort-based harvest regulations are less risky than quota-based systems should initial prey populations be overestimated. This allows regulators time to adap-tively implement changes designed to decrease take should this be required.

Idealized narratives of indigenous cultures suggest early humans evolved sustainable hunting systems in a delicate balance with local ecosystems. While some indigenous cultures clearly exhibit sustainable hunting practices (e.g., the Amazonian Korubo, Artic Inuit, South African Bushmen), the apparent stability may reflect historic extinctions of most species vulnerable to indigenous hunting techniques. Many indigenous hunters actively manipulated ecosystems to facilitate hunting. Early hunters in every continent transformed ecosystems by setting fires to drive animals into traps, facilitate tracking animals, and create favorable habitat for prey species. The landscapes greeting European colonists in North America and Australia reflected the fires aboriginals used to create habitat for hunted species.

The overkill hypothesis for the Pleistocene megafauna extinction event represents the paradigm case of unsustainable hunting (Figure 1). Radiation of hunting cultures into North and South America around 10 000BCE coincided with extinction of 33 of 45 and 46 of 58 large mammal genera in each continent, respectively. Since 1600, hunting caused 23% of all known animal extinctions. The list of species driven to extinction (e.g., passenger pigeon (Ectopistes migratorius), heath hen (Tympanuchus cupido cupido)), extirpated from most of

0 100

cs 100

0 100

0 100

cs 100

0 100

Africa

Australia

North America

Madagascar

Africa

Australia

North America

Madagascar

H. sapiens enters Large mammal the continent population of continent

Figure 1 Timeline of large mammal extinctions and entry of humans in Africa, Australia, North America, and Madagascar. Adapted from Martin 1989 by Elin Whitney-Smith.

their range (e.g., bison (Bos bison)), or threatened (e.g., most whale species) by commercial hunting is staggering. Such changes wrought by hunting often have ripple effects throughout ecosystems. For instance, as domestic livestock replaced extirpated bison, brown-headed cow-birds (Molothrus ater) adopted the sedentary lifestyle of their domestic symbionts and became North America's most notorious avian brood parasite. Recreational hunting has had more mixed ecological impacts. In some contexts (e.g., Medieval and Colonial Europe), hunting motivated preservation of forest ecosystems as game preserves. Aristocratic sport hunting, however, nearly led to extinction of the Bengal tiger (Panthera tigris tigris).

Hunting became an almost universally positive ecological force during the conservation movement of the late 1800s and early 1900s (to which prominent hunters including Theodore Roosevelt contributed heavily). In the United States, federal excise taxes on hunter purchases (>$200 million annually) support most state-level wildlife management programs in the United States, and the mandatory purchase of Federal Duck Stamps by migratory waterfowl hunters since 1934 helped purchase more than 20 000 km2 of wildlife habitat in the National Wildlife Refuge System. Recreational hunters also contributed to restoration of North America's decimated game species including white-tailed deer (Odocoileus virginianus), pronghorn (Antilocapra Americana), black bear (Ursus americanus), wild turkey (Meleagris gallopavo), and wood duck (Aix sponsa). Hunters also contributed to establishment of wildlife reserves and conservation-hunting programs throughout the world. The conservation-hunting programs epitomized by Zimbabwe's Communal Areas Management Programme for Indigenous Resources (CAMPFIRE) provide locals in developing nations a sustainable supply of money and meat and preserve local wildlife species. Finally, in areas dominated by private land ownership, hunting provides economic incentives for protecting natural and agricultural lands from suburban or commercial developments.

Some ecologically questionable practices, however, have evolved to capitalize on the growing economic value of hunted species, including high fencing, supplemental feeding, and landscape manipulation to support economically valuable species. While these practices may render keeping private lands in a somewhat natural state more economically viable, they are ecologically problematic. High fences effectively fragment landscapes for many species, supplemental feeding increases the risk of disease transmission, and landscape manipulation intended to help commercially valuable wildlife can threaten other species.

Modern hunting also provides an important tool for managing overabundant wildlife species. Hunting allows natural resource managers to control populations of species before they exceed carrying capacity of their habitat, damage vegetation, threaten other species, or threaten human health and safety. Managers also can use hunting to control a wildlife population's density in efforts to minimize risks associated with wildlife-related diseases (e.g., Lyme disease, bovine brucellosis). In 2005, hunting became a major tool to fight degradation of saltwater marshes caused by growing populations of lesser snow geese (Chen caerulescens caerulescens) along the Hudson Bay. Some groups assert reintroducing predators would achieve the same benefits as hunting. Such reintroductions, however, prove politically problematic. Further, considerable evidence suggests prey species typically control predator abundance rather than vice versa.

10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment