Wildlife

BEST MANAGEMENT PRACTICES

INTRODUCTION

Nonpoint source pollution from wildlife is generally not a problem. Nutrients and pathogens are potential pollutants from wildlife. Water resources that are capable of supporting sufficiently large populations of higher vertebrates to result in nutrient or bacterial loading are often remote or of nutrient-poor composition, minimizing the likelihood of serving as sources of concern. However, certain species can potentially alter water quality. Waterfowl and beavers are species that can beneficially and detrimentally impact the waterways on which they depend. In nitrogen-saturated waters where waterfowl converge, their wastes can drive ammonia concentrations up causing algal mats that lead to exaggerated dissolved oxygen cycles. On the other hand, waterfowl are a vital part of the food chain. Beavers flood small watersheds, killing trees and crops and causing excessive amounts of turbidity. Yet, beaver ponds can remove nutrients and provide habitats for many types of wildlife, creating possibilities for sportfishing and hunting.

Where the presence of wildlife is determined to be problematic, control and management consist of two basic approaches: nonlethal and lethal. Discouraging habitation in the initial stages may prove to be the key management practice.

BEST MANAGEMENT PRACTICES

Waterfowl Environmental Impact Potential and Management

Habitually, wading birds (herons, egrets, ibises, Anhingas, etc.) nest in colonies. Most colonies are located in trees and bushes over water (ponds, marshes, and swamps). Ammonia sources from wading birds originate from eggs, young, and wastes that fall into the water (Dusi et al, 1971). Most species colonize in mid-March to late summer with the exception of the Great Blue Heron and the Common Egret which stay throughout the year. The larger colonies are typically found in the lower South Atlantic and Gulf states (Dusi et al, 1971).

According to Dusi et al, colonized swamps showed elevated levels of ammonia and organic nitrogen . The impact of the wading birds on the colonized swamp was so profound that ammonia content showed an increase of 2 to 10 times that of the uncolonized swamps nearby. In turn, more duckweed and larger algal mats developed in the colonized swamps, affecting water quality and other aquatic life. If such impacts are determined to be significant contributors to an ongoing water quality problem, and all other more significant contributors have been addressed, possible management practices to counter the impacts include the introduction of herbivorous fish species to control aquatic weeds and liming the waters to control pH, which falls as ammonia and is converted to nitrate.

Other waterfowl activity can increase pollutant loading. In the flightless stage of the molt, the eclipse, swans and snow geese can be extremely destructive, particularly to agricultural crops and marshlands along the Atlantic Coast where they winter. They graze, pull up sprouts, "muddle" (trample) during wet weather, and leave droppings. This increases the sediment and ammonia in runoff (NCAES, 1984).

Where this is determined to be a significantly detrimental contribution to pollutant loading, and where all other more significant contributions have been addressed, birds should be discouraged before they become "imprinted" (regularly return to the area); successful methods of discouragement and control should be quick and persistent.

Nonlethal:

• Install moving objects like scarecrows, gas-filled balloons, or plastic flags. One flag (a large black plastic trash bag on a four foot post is very effective) per acre is recommended. The combined use of flags or balloons with gas exploders and/or racket bombs is even more effective.
• Dogs and passing vehicles also discourage waterfowl.
• Live trapping that requires a permit is impractical on a large scale and gives only temporary results.

• Hunt by permit near unharvested fields and in other heavily damaged areas.
• Note: Contact your state supervisor of U.S. Fish and Wildlife Service or state Wildlife Resources Commission for information of permits and current regulations.

Beaver activity has been thought to negatively affect trout streams by increasing siltation and by raising temperatures via reducd flow rates and increased sunlight penetration. Overpopulations of beavers can cause serious economic losses to owners of small tracts of forestry and agricultural land. This is particularly true in the flat, hardwood bottomland of larger river systems in the coastal plain where a single colony can flood hundreds of acres. Specific problems include blocking or damaging water control devices in farm ponds and reservoirs, felling commercially valuable timber and fruit trees, flooding or consuming row crops, and allowing algae and mosquito increases. A major problem related not only to the beaver but also to other wild and domestic animals is their role in transporting the protozoan parasite Giardia lamblia via feces. In humans this parasite causes giardiasis, a disease marked by chronic diarrhea, abdominal cramps, fatigue, and weight loss. Since normal concentrations of chlorine used in the treatment of water is not sufficient to kill Giardia cysts, filtering surface water is required (NCCES, 1991).

Control and management of beavers --
Nonlethal:

• Inhibit young, dispersing beavers during late spring and early summer by installing fencing across stream bottoms in small, low order streams. Install fencing perpendicular to the stream flow and between 200 to 400 feet on each side of the stream.
• Install fencing along stream banks near row crops, pine tree plantations, or intensively managed plantings.
• Along or around water control structures, install fencing early and allow beavers to build their dam against the fence.
• Wrap the bottom 3 feet of appealing trees with hardware cloth.
• Install a drainage device in a beaver dam. The inflow end should extend far into the beaver pond as to discourage beavers from covering the pipe with debris.
• Least effective nonlethal methods include: chemosterilants, electric fences, scare techniques, scents, and live traps.

• Note: Contact your local Wildlife Resources Commission or Agency concerning permit regulations and depredation laws.

Muskrats favor still or slow-moving bodies of water and occasionally streams where they burrow in the banks to make "dens". The entrance of the burrow is 6 to 8 inches below the surface of the water and curves upward at an angle into dryer soil up to 15 feet away from the entrance. They are nocturnal vegetarians principally and sometimes build "houses" from aquatic vegetation. Environmental impact potential from muskrat activity includes bank erosion, property damage (man-made earthen dams and sometimes crops), and Giardia lamblia via feces. In humans this protozoan parasite causes giardiasis, a disease marked by chronic diarrhea, abdominal cramps, fatigue, and weight loss. Since normal concentrations of chlorine used in the treatment of water is not sufficient to kill Giardia cysts, filtering surface water is required (NCAES, 1984).

Control and Management of the Muskrat--
Nonlethal:

• Lay 6- to 12-inch layer of sand, pea gravel or rip rap on the inner surface of a dam, 2 to 3 feet above and below the water line.
• Add a concrete filled trench to an earthen dam, 3 feet below the water line and 1 foot above.
• Obstruct burrowing by laying 1- to 2-inch mesh along the bank, 1 foot above and 3 feet below the water line.
• Construct new farm pond with a berm.

• Use Conibear No. 110 quick-action trap. Since these traps are capable of killing an adult beaver by breaking the neck, read and follow manufacturers' instructions carefully.
• Construct or buy a slide wire "quick-drown" device.
• Note: Contact your local Wildlife Resources Commission concerning permit regulations and depredation laws.

Dusi, Julian L., Rosemary T. Dusi, Darrel L. Bateman, Cathryn A. McDonald, Jeanne J. Stuart, John F. Dismukes. Ecologic Impacts of Wading Birds on the Aquatic Environment, Water Resources Research Institute, Bulletin 5, Auburn University, Alabama, 1971.

North Carolina Agricultural Extension Service. North Carolina Animal Damage Control Manual: Muskrats, Number 14, 1984.

North Carolina Agricultural Extension Service. North Carolina Animal Damage Control Manual: Waterfowl, Number 5, 1984.

North Carolina Cooperative Extension Service. Beavers in North Carolina: Ecology, Utilization, and Management, Publication Number AG-434, 1991.

NCSU Water Quality Group

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