Overview of Damage Prevention and Control Methods
Removal or elimination of water from loafing sites (e.g., flooded fields) can cause pelicans to abandon a site. Other modifications may include eliminating open wetland sites by planting perennial woody vegetation.
Exclusion may prevent pelican predation and disease transfer. Selection of a barrier system depends on the size of facility and whether the barrier will interfere with other operations. Other considerations include possible damage from severe weather and the barrier’s effect on site aesthetics in visually sensitive areas. Care must be taken to construct any physical barrier so that it does not become a lethal object to non-target birds, especially threatened and endangered species. The barrier material should be visible to birds to minimize accidental entrapment and/or injury. Avoid using loosely hung, small mesh netting such as mist netting, as it will cause excessive bird loss and draw public and regulatory attention.
Although often cost prohibitive, near total exclusion can eliminate up to 90% of pelican access to individual ponds. One aquaculturist in south Mississippi used a combination of overhead grid wires, perimeter electric fencing, and harassment to exclude about 90% of brown pelicans from landing or entering his fish ponds. The producer reported a cost of “nearly $3 million” to set up the exclusion devices at five 6-acre ponds.
In general, enclosing ponds and raceways to exclude all fish-eating birds requires 1- to 2-inch mesh netting secured to frames or supported by overhead wires. In addition, gates and other openings must be covered. In areas with harsh winter conditions, nets must have an adequate framework or support cables to prevent ice or snow accumulation from ripping the netting.
Some hatchery operators use mesh panels placed on the raceway walls above the water to effectively exclude birds. Secure small mesh wire or net less than 1 inch to wood or pipe frames to prevent feeding through the panel. Design panels to accommodate demand or automatic feeders and feed blowers that feed through mesh-covered raceways. Since panels may interfere with feeding, cleaning, or harvesting operations, they may be more appropriate for seasonal or temporary use.
All exclusion structures must be strong enough to prevent the weight of large birds and their activities from making the net sag to within feeding distance of the water. Construct all exclusion structures to allow use of fish maintenance equipment and, if necessary, to withstand wind and the accumulation of snow and ice. Nonrigid exclusion structures such as suspended netting may need lines, pulleys, and counterweights to facilitate lifting and lowering during adverse conditions or maintenance.
Although complete exclusion may not be practical, various barrier techniques may limit pelican access to ponds or to the fish in these ponds. Nets suspended over catfish farm levees can prevent pelican depredation. However, use of these nets is impractical as most catfish farm levees are not wide enough to accommodate support structures for the net and still allow vehicle access. Plastic and wire grids over catfish ponds can deter pelican flocks from landing and taking off, but do not necessarily exclude individual birds. Some success with simple parallel overhead wires spaced on 26-foot centers has been reported, but in other studies, birds simply landed on the levees and walked under the wires into the ponds.
Frightening devices and techniques modify behavior and discourage birds from feeding, roosting, or gathering at a location. American white pelicans are typically diurnal foragers, but often forage at night, especially in areas where daytime harassment is effective. During daylight hours, pelicans forage mainly during early morning and late afternoon and loaf during mid-day. However, pelicans quickly adapt to standardized harassment schedules. Pelicans have been observed leaving a loafing site to forage at catfish farms less than 15 minutes after the harassment person left the facility for lunch and returning to their loafing site about 10 minutes before the harassment person returned. Alternating harassment methods typically is most effective, especially harassing the birds at their loafing sites near catfish farms cause the birds to abandon the site and often reduce or eliminate predation at nearby facilities.
- In south Louisiana, bright spotlights have been successful in dispersing nocturnal foraging pelicans from catfish ponds.
- Pyrotechnics can be effective in dispersing pelicans from foraging and loafing sites if other techniques are available as needed. Possession and use of pyrotechnics may require a permit from the local, county, and/or state fire marshal. Harassment by personnel on foot, ATVs, boats, or other vehicles combined with pyrotechnics can be effective. Lethal reinforcement is often necessary when pelicans become habituated to other techniques such as pyrotechnics and propane canons. As pelicans begin to ignore harassment techniques, shooting one or two pelicans often will cause the entire flock to leave the area.
As with all firearms, make sure it is safe to discharge a firearm in a particular area. Because American white pelicans are large birds, accuracy is essential to ensure immediate death. Dispatch wounded birds quickly. Use a shotgun, 12-gauge or larger, with T-shot or larger. Use a centerfire rifle of .22-cal or larger (e.g. .223, .22-250) for shooting individual birds. Shot birds should be disposed of as soon as possible in accordance with permit instructions. Leaving bird carcasses on a facility can attract other predators, can be illegal, and generally is viewed as poor management by the public.
- Foothold traps
- Rocket nets
Pelicans are protected by the MBTA. Removal of nests and any human activity in nesting colonies during the breeding season are regulated by the USFWS and state/provincial agencies.
Any nest removal, egg oiling, or addling activities in nesting colonies is regulated by the USFWS and state/provincial agencies.