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13 Wildlife PoPulation Control Understanding both the habitat and wildlife found on air- ports is critical in effective integrated wildlife population management. Wildlife is present at airports because of the availability of food, water, and shelter. As a result, remov- ing, reducing, and eliminating these key habitat attractants is paramount. Examples of habitat modification success and considerations on airports is addressed by Seamans et al. (2007), Bernhardt et al. (2009), Hoen et al. (2009), Linnell et al. (2009), Barclay et al. (2011), Martin et al. (2011), and Carragher et al. (2012). Thus, in most cases, the first and most effective step in wildlife management on airports is habitat modifi- cation. This subject is covered in detail in Transport Can- ada (2002), Cleary and Dolbeer (2005), Cleary and Dickey (2010), and Belant and Martin (2011) and is not detailed in this synthesis. However, it is important to note that the removal of individual animals prior to eliminating these key habitat attractants may eliminate an immediate hazard, but will not provide a long-term solution, as other animals will often replace those that have been removed because suitable habitat still remains (DeFusco et al. 2007). Under certain circumstances, the removal of wildlife from airports using traps, chemicals, egg and nest removal, and live-ammunition shooting is necessary. Transport Canada (2002) suggested that wildlife removal may be effective in situations in which: 1. The species involved is not mobile and is unlikely to be replaced immediately. 2. The species involved is of a solitary nature with low- density populations unlikely to be found in areas sur- rounding airports. 3. The immediate removal of a few animals is required expecting short-term effectiveness. 4. A large population of concealed animals (e.g., rodents) must be reduced. 5. The removal of a few animals by shooting enhances the effectiveness of nonlethal frightening tools such as pyrotechnics. Wildlife population control methods require both political and ethical sensitivity on the part of wildlife control person- nel. In all cases, the integrity of the wildlife population man- agement program relies on ethical and respectful treatment of targeted species using acceptable techniques (Gosser et al. 1997; Smith et al. 1999). In addition, safety is paramount and wildlife control personnel should be vaccinated, wear protective heavy gloves at all times, follow procedures that exercise caution against potential animal-borne diseases, and be trained in the proper use of chemicals, firearms, or other equipment. If at any time airport wildlife control personnel are uncomfortable with or cannot follow appropriate safety measures, then professional wildlife exterminators can be consulted and used (Cleary and Dolbeer 2005). Lastly, because wildlife is afforded various levels of pro- tection under federal, state, and local laws, the importance of consulting with local USFWS, USDA/WS, and state wildlife and environmental agencies before and during wildlife popu- lation management planning activities cannot be overstated. SPeCifiC Wildlife PoPulation Control MethodS In general, wildlife control alternatives are as varied as the spe- cies targeted. Once the targeted species or guild is identified, airports must choose the most appropriate wildlife control method to achieve management goals. Direct and indirect wildlife control methods are covered to different degrees by DeFusco and Nagy (1983), Hygnstrom et al. (1994), Harris and Davis (1998), Transport Canada (2002), Cleary and Dolbeer (2005), Cleary and Dickey (2010), and Belant and Martin (2011), and provide excellent references for wildlife popu- lation control alternatives and their potential effectiveness. Prey Control Wildlife is often present on airports because of the ready availability of food. Certain prey species occupying airport habitat attract predators such as coyotes, foxes, mesomam- mals, raptors, gulls, egrets, herons, and cranes. In most cases, the targeted prey species include smaller and very abundant organisms such as insects, earthworms, rodents, and fish. However, plant material such as berries, fruits, and seeds can also be considered forage, but are most often controlled using indirect habitat manipulation. If the predator relies strongly on specific prey for food, then predator density on the airport will likely increase with increasing prey numbers. Effective wildlife control measures to reduce prey species include insecticides, pesticides, rodenticides, avicides, fumigants, lethal and nonlethal trapping, and live-ammunition shooting chapter three Wildlife PoPulation Control teChniqueS
14 (see Figure 10). As with all wildlife control techniques, air- ports should consult with the USFWS, USDA/WS, and state and local wildlife regulatory and licensing agencies before ini- tiation to ensure that the control technique is the most appropri- ate and effective, as well as meets regulatory and depredation permit and licensing requirements (see Figure 11). lethal trapping Lethal (kill) traps are most often used on small animals; how- ever, they can also be used on larger animals such as beavers, muskrats, and foxes (see Figure 12). In all cases, the appro- priate size and type of lethal traps shown to be effective for FIGURE 10 Crop duster applies pesticide to control insect prey at Salt Lake City (SLC) (Source: SLC). FIGURE 11 Chemicals (rotenone) used to remove pelican food source (carp) at SLC (left) (Source: SLC) and American White Pelican (right) (Source: BASH Inc.). FIGURE 12 Small mammal snap trap line set along airport perimeter fence (Source: BASH Inc.).
15 ping, especially with leg-hold traps and snares, requires a high degree of skill and experience. In addition, airports are advised that state and local regulations may restrict the use of some types of traps, as well as the ability to relocate live- trapped animals. Live traps can be used to capture birds, with those captured either euthanized or removed from the airport and relocated to preapproved areas. Birds can be live-trapped using mist- nets, cage traps, cannon-nets, or large funnel-shaped lead-in traps. Although time consuming and relatively costly, live trapping is most often employed against state and feder- ally protected and high-profile species that are relocated from the airport. In addition, live traps are used to capture sedentary birds such as pigeons and house sparrows (see Figures 14â16). Other birds such as starlings, blackbirds, and crows may also be captured; however, trapping these species the targeted animal or bird species must be used. Lethal traps should be checked frequently to minimize attract- ing scavenger species and diminish potential ethical and public concerns. Depending on state and local laws, body gripping traps can be used to remove most medium-sized mammals (mesomammals) that create problems at airports. Neck snares can also be used to capture coyotes, beavers, and certain other mammals, but require a high degree of skill and experience to selectively capture the target animals. In all cases, it is important that airport personnel consult refer- ence guides and knowledgeable USFWS, USDA/WS, and state and local wildlife and regulatory agency personnel dur- ing trap selection, when establishing a lethal trapping protocol, as well as ensuring that regulatory and depredation permit requirements are met, if necessary. Hygnstrom et al. (1994) and Harris and Davis (1998) provide detailed descriptions of various trap designs for reference. live trapping Live traps range from simple restraining snares and leg-hold devices to box and barrel traps used for various sizes of ani- mals, from sparrows to bears. For avian-targeted species, Swedish Goshawk traps, bal-chatri traps, walk-in traps, net- guns, starling traps, pole traps, and many others are available. To comply with regulatory requirements, live traps must be checked frequently to evaluate trapping success, minimize captured animal distress, and reduce potential ethical and public concerns when such methods are used. To capture live deer, specialized drop-door traps, drop nets, or rocket net setups can be used; however, live capturing of deer is gener- ally not recommended on airports. Basket or box-type live traps can be used to capture medium-sized mammals such as raccoons, skunks, woodchucks, beavers, and feral dogs (see Figure 13). Leg-hold traps and snares can be used to capture coyotes, feral dogs, and raccoons. Successful mammal trap- FIGURE 14 Humane trapping of sedentary birds in walk-in pigeon trap (Source: JFK). FIGURE 13 Humane trapping of urban scavenger raccoon in a box-type trap at Daytona Beach Airport (DAB) (Source: BASH Inc.). FIGURE 15 By permit, trapping and relocation of Great Horned Owl trapped using Swedish Goshawk trap at Rosecrans Memo- rial Airport (STJ), St. Joseph, Missouri (Source: STJ).
16 is often not an effective method for lowering overall popula- tion numbers in the long term. Hygnstrom et al. (1994) and Harris and Davis (1998) provide detailed descriptions of var- ious trap designs. Airport personnel should consult reference guides and knowledgeable USFWS, USDA/WS, and state and local wildlife and regulatory agency personnel during trap selection and when establishing a live trapping protocol, as well as ensuring that regulatory and depredation permit requirements are met, if necessary. Large mammals, such as deer, can be captured with tran- quilizer guns when the use of firearms is not safe or practical. However, the disposition of the captured animal can be prob- lematic. Live capture and relocation of deer is not recom- mended or allowed in most states because deer populations are at or near carrying capacity and to prevent the possibility of disease transmission. Capturing animals with tranquilizer guns requires personnel with a high degree of skill and expe- rience in their use, as well as, in some cases, certification (Hewitt 2011). When used in an airport environment, safe- guards must be in place to ensure that partially tranquilized deer do not enter runway areas or areas in public view. Feral pigs are becoming more of a problem in many areas of the country, particularly in southern states. As with deer, shoot- ing is the preferred strategy for removing pigs from airports. However, where shooting is not allowed or impractical, trapping is the best alternative for capturing and removing pigs (West et al. 2009). As with other social animals, pigs are susceptible to proper trapping methods and many can be captured in a short period of time. Unlike with some other species, however, most states do not allow trapped pigs to be released into new environments. egg/roost Site Manipulation Canada Geese, Mute Swans, gulls, and other hazardous species must not be allowed to nest on airport property, and any nests with eggs found at an airport can be destroyed by breaking the eggs and removing nest materials. At the time of nest destruction the adult birds must be dispersed from the airport. It is necessary to check the area weekly for new nesting or re- nesting until the end of the nesting season. Mute Swans and Canada Geese are protected by federal and often state laws. It is important that the nests of pigeons, starlings, and house sparrows also be destroyed whenever they are encountered in airport buildings and structures. These nonnative species are generally not afforded federal protection. As a long-term approach, egg addling, shaking, oiling (see Figure 17), or puncturing, whereby the birds continue to incubate nonviable eggs, are not generally recommended on airports, as it encourages the nesting birds (and any non- breeding birds associated with them) to remain at the airport, but may be considered in surrounding areas. As an alternative FIGURE 16 Bal-chatri live trap used for permitted trapping and relocation of federally protected or high profile species (left) such as Ferruginous Hawks (right) (Source: JFK and BASH Inc.).
17 âIntegrating New Technology and Techniques and into Airport Wildlife Controlâ Chicago International Airport (ORD) We are conducting research on various problem bird species to learn more about their movement patterns and airport use, as well as evaluate the effectiveness and/or potential of new wild- life population control tools and techniques. Several studies are ongoing to investigate new technologies, methodologies, and the efficiency of wildlife hazard management. These include: 1. Determining the effectiveness of grid wires over open creek areas. 2. Examining attractiveness of green roofs to wildlife in an airport environment. 3. Determining if the height of pole traps influence spe- cies captured and efficiency of trapping. 4. Evaluation/validation of avian radars at a large com- mercial airport. 5. A mark and re-sight study on Red-tailed Hawks to determine if relocation distance from ORD [Chicago OâHare International Airport] has any influence on return rate to the airport. 6. Use of GPS [Global Positioning System] satellite transmitters on Red-tailed Hawks to learn about their movement patterns in and around the airport. Mobile avian radar (Source: BASH Inc.) and Red-tailed Hawk fitted with radio transmitter and wing tag [Source: Portland Inter- national Airport (Oregon) (PDX)]. FIGURE 17 Egg oiling at SLC (Source: SLC).
18 to harassment, any nesting birds could be taken by lethal con- trol or trapping (see Figure 18). Eggs should not be broken as the birds will likely re-nest at another location that may not be found, resulting in a successful hatch being imprinted to the area. Egg addling, shaking, or oiling whereby the birds continue to incubate nonviable eggs can be a very effective long-term method of controlling geese on other public and park land or pond where lethal control is not an option. Water spray has been used as a direct lethal control method or an indirect method to prevent birds from roosting or nesting in urban and agricultural areas. Water cannons and sprinkler systems, using water or water with wetting agents (surfactants), can be employed to control âpestâ birds (see Figure 19). The surfactants allow water to penetrate bird feathers, potentially resulting in death by hypothermia as feathers become wet and body temperatures drop. When applied at night in roost loca- tions, nontoxic surfactants have been successful in local roost control for some abundant species. Surfactants were widely used for the control of blackbird and starling roosts between 1974 and 1992. Over this period, an estimated 38.2 million blackbirds and starlings were killed through the application of these agents (Dolbeer et al. 1997). In this report, it was shown that surfactant applications did help solve local roost prob- lems; however, the overall population reduction effect beyond the local area was not conclusive and no evidence using North American Breeding Bird Survey data showed that surfactant applications caused declines in regional breeding populations of these species. It is generally accepted that destruction or alteration of the roost site itself, such as by removing trees and brush or preventing access with other deterrents, is more effec- tive than killing birds outright (see Figure 20). Airport personnel should consult reference guides and knowledgeable USFWS, USDA/WS, and state and local wild- life and regulatory agencies personnel before establishing an egg/roost site manipulation protocol and meet regulatory and depredation permit requirements if necessary. FIGURE 18 Falcon with eggs on ledge in airport hangar at JFK (Source: JFK). FIGURE 19 Water cannon use to remove cliff swallow nests under support structures at SLC (Source: SLC).
19 live-ammunition Shooting Firearms are heavily restricted and are to be used only after all other wildlife control methods have failed to produce the required results, or in cases where immediate removal of per- sistent and problematic animals is necessary (see Figure 21). Both the FAA and USDA support live-ammunition shooting as an âeffective practiceâ for wildlife population reduction (Cleary and Dolbeer 2005). Shooting birds in an airport environment generally falls into two main categories: quietly or loudly as a reinforcement of audio and visual repellant techniques. When pigeons use hangars, bridge girders, and other sites they can be shot at night with an air rifle. If done quietly and discretely little disturbance results, allowing the maximum number to be removed. In the second category of shooting, common birds such as gulls and geese that are not respond- ing to various repellent methods can be shot with a 12-gauge shotgun. Although limited in their application, shotguns act in support of scare and dispersal tactics. With flocking birds, the occasional shooting of one bird may be needed to illus- trate the significance of loud, sharp noises to the rest of the flock. This is done during daylight and in the open so that other birds are exposed to the audio and visual effects of the shooting. Shooting birds can have several effects on a flock: 1. It reinforces other audio or visual repellant techniques; 2. The loud noise, coupled with the death of one or more of the flock members can frighten away the rest of the flock; and 3. The target birds are permanently removed. FIGURE 20 Turkey Vulture roost sites near airports can be managed by removing roost trees (Source: BASH Inc.). FIGURE 21 Live ammunition shooting at Dallas/Fort Worth International Airport (DFW) (Source: BASH Inc.).
20 Cleary and Dolbeer (2005) suggest four cardinal rules when considering shooting problem birds: 1. Use only personnel who have an excellent knowledge of wildlife identification and are trained in the use of firearms. 2. Use the proper gun and ammunition for the situation. 3. Have necessary federal and state wildlife kill permits in place, and keep accurate records of killed birds by species and date. 4. Notify airport security, air traffic control (ATC), and, if appropriate, the local law enforcement authority. Airports are highly encouraged to adopt a âzero toler- anceâ policy for deer and other large vertebrates at air- ports. Shooting is the best procedure for removing the deer if fencing is inadequate to keep them away from an air- port or if they breached the airportâs fence (see Figure 22) (Hewitt 2011). Nighttime shooting is often the most effec- tive means and can help to keep the program out of public view (see Figure 23). Deer and other large mammals are managed and regulated at the state level. The shooting of deer at airports must be coordinated with the appropriate state wildlife agency to comply with regulatory require- ments. In removing large and particularly dangerous ani- âUnique Wildlife Control Problems and Applicationsâ John F. Kennedy International Airport (JFK) Live ammunition shooting has been used since 1991, primar- ily targeting numerous gull species that overfly the airport and nest on property adjacent to the airport. Shooting has reduced Laughing Gull strikes by 62% to 99% and other gull strikes by 48% to 88%. In addition, we have received permission to live- ammunition shoot Osprey, a species of special concern. Because local population numbers of Osprey are high, we cannot trap and relocate them. We have received permission to shoot and remove nests of Ospreys that are not responding to nonlethal methods. Since 2009, problems with diamondback terrapins have been increasing. Trapped animals are measured and micro-chipped and then released to other locations on the airfield. Research on terrapin populations, as well as terrapin deterrents is ongoing. Canada Geese nesting on the airport have been eliminated using egg oiling, followed by egg and nest destruction. An off-airport wildlife refuge harbors large numbers of Canada Geese, with a population exceeding 1,700 observed during the molt period. Thus, a very effective goose roundup was conducted. Terrapins awaiting microchip insertion and relocation at JFK (Source: JFK). Ospreys perched on antenna structure and nest bordering JFK (Source: JFK).
21 mals, firearms may be required to deliver immobilizing drugs. This technique is particularly useful for removing problem bears, which are usually first snared or caught in culvert traps. When using firearms, it is always important to recover empty casings and treat them as FOD, as they can cause serious damage if ingested into turbine aircraft engines. For maximum effectiveness and safety, integrated wildlife control programs involving firearms require close cooperation among airport staff and skilled field biologists experienced with firearms. If firearms must be used, education programs instituted to raise public awareness are recommended. Airport personnel should consult reference guides and knowledgeable USFWS, USDA/WS, and state and local wildlife and regula- tory agency personnel before establishing a live-ammunition shooting protocol, as well as meeting regulatory and depre- dation permit requirements, if necessary. Chemical euthanization (Pesticides, insecticides, fungicides, rodenticides, fumigants) Chemicals used to kill wildlife fall into three categories: 1. Acute toxins that kill after ingestion of a single lethal dose. 2. Anticoagulants and decalcifiers requiring the ingestion of several doses over a period of days. 3. Fumigants that suffocate burrowing animals in the ground. Poisons are generally confined to use on small animals, specifically rodents (Witmer 2011) because: 1. Bait placed in confined areas including burrows is not accessible by other animals (see Figure 24). 2. Small amounts of poison treat large rodent populations at relatively low costs. 3. Problems associated with rodent carcass disposal are minimized, as the carcasses are generally concealed in burrows reducing predator attraction and public concern. Registered chemicals undergo controlled testing to dem- onstrate their efficacy and safety. These tests determine: 1. Chemical toxicity. 2. The qualifications required to handle chemical products. FIGURE 22 White-tailed Deer (left) (Source: STJ) and Black Bear (right) (Source: USDA) deterred from entering airports due to fencing. FIGURE 23 Night spotlighting at JFK (Source: JFK).
22 3. Potential health hazards. 4. Possible adverse effects on food and drinking water. 5. Overall environmental impact. In the United States, the oral toxicant, DRC-1339, or Starlicide⢠(active ingredient 3-chloro-p-toluidine hydro- chloride) is currently the only product registered with the EPA for use in bird population management. Starlicide (0.1% active ingredient) is formulated in a pellet bait for use at feedlots to control starlings and blackbirds. DRC-1339 (98% active ingredient) can be formulated with a variety of baits and used to control starlings, pigeons, gulls, ravens, house sparrows, and blackbirds under certain conditions, some of which might be applicable at airports. The control of pigeons around airport buildings and starlings roosting at or near an airport are the situations most likely applicable. Only USDA/WS personnel or persons working under their direct supervision can use DRC-1339. âZero-Tolerance Policies for High Hazard Speciesâ Dane County Regional Airport (MSN) We have a zero tolerance policy for deer inside the perim- eter fence. Since 2006, during March to May of each year, a spring herd reduction is conducted targeting deer observed by aerial observation within 1.5 miles of the airport. We also upgraded to the FAA-recommended 8-ft chain link fence with 2 ft of barbed wire to deter deer entrance onto the airport. Overall, the deer population has been signifi- cantly reduced. Wildlife control measures are approved for Bald Eagles. Regular observations combined with accurate documen- tation with photos assisted us greatly in expediting the permitting process. Aerial observations of deer near airport (Source: BASH Inc.). Aerial and ground-level view of airport perimeter fence at MSN. Note golf course, agriculture, and stands of trees that attract deer and other wildlife near the airport boundary (Source: BASH Inc.). FIGURE 24 Rodenticides placed in polyvinyl chloride (PVC) pipes to prevent non-target species exposure on airport. Note Burrowing Owls on ground squirrel mound in foreground (Source: BASH Inc.).
23 The use of toxic baits to kill target birds without affecting nontarget species requires considerable skill and patience. Daily movement patterns of the target birds among feed- ing, loafing, and roosting sites must be determined so that attractive bait sites that are controlled to prevent public access (such as a roof top) can be selected. The proper bait (a highly desired food) must be selected and the sites then pre-baited, often for a week or more, to ensure good bait acceptance and that nontarget animals are not visiting the bait site. Proper pre-baiting is the most critical step of a successful program. Caution must be exercised in an air- port environment as pre-baiting is designed to attract birds to the control site and may compromise flight safety if not properly placed. During the baiting period, all uneaten bait must be removed daily to avoid affecting nontarget spe- cies. With DRC-1339, birds typically die one to three days after bait ingestion; therefore, areas surrounding bait sites will need to be searched for several days after baiting to remove dead birds. If den locations are known, fumigation can be used to manage coyotes and other predators. Burrowing rodents such as woodchucks (groundhogs) and prairie dogs can be killed by fumigation of burrows with either gas cartridges or zinc phosphide tablets. Before fumigation, it is impera- tive that burrows are monitored to ensure that the targeted species occupy the location and other nontarget species will not be affected. Gas cartridges, ignited from a burning fuse after placement in the burrow, generate carbon monoxide at fatal levels. Zinc phosphide pellets react with moisture in the burrow to produce phosphine gas, also at fatal levels. It is necessary to plug all burrow entrances with sod after placement of the cartridge or pellets in the burrow. Gas car- tridges are a general use, over-the-counter pesticide. Zinc phosphide pellets can only be applied by certified pesticide applicators and might not be available in all states. As with all pesticides, it is critical to make sure the chemical targeted at the hazardous wildlife species treated is registered by the state. Occasionally, propane pumped into burrow systems, sealed, and then ignited is employed, but many airports con- sider this a potentially dangerous option and prefer not to use this technique. Knowledge of proper handling methods is critical to ensure the safety of the user, but also the environment and nontarget species. All chemical pesticide product labels include safety precautions and instructions for use. These products must be used only as directed and to meet regula- tory requirements. If not used properly, poisons may seep into soil and ground water, poisoned animals may be con- sumed by predators, and toxic carcasses could be eaten by scavengers that may potentially result in secondary poison- ing. Thus, proper placement of poisons is critical, as well as the immediate removal of exposed dead animals. Although definitive information on the secondary effects of acute poi- sons is inconclusive, current research indicates that scav- engers are not likely to be seriously affected by eating the carcasses of rodents killed by anticoagulants. However, in areas occupied by endangered species, the possibility exists that nontarget species may eat baits targeting rodents. This concern can be reduced by using enclosed bait stations that also provide protection from inclement weather. All chemi- cals used in pest control including those employed to man- age wildlife must be registered with the EPA, USDA/WS, and state regulatory agencies. This includes chemical herbi- cides (weed control), insecticides (insect control), fungicides (mold and fungi control), as well as all animal and insect chemical repellents. Wildlife PoPulation Control effeCtiveneSS Direct wildlife population control measures on airports are often not used because of concerns about the effect of such actions on the overall species populations outside the air- port boundaries (see Figure 25). The population of a par- ticular species on an airport is part of a larger-scale local, state, regional, and continental population, or metapopula- tion. Healthy wildlife populations remain relatively stable through a balance in reproduction with a variety of natural mortality factors. These factors include predation, disease, parasites, starvation, aging, and intra- and inter-specific competition. In populations approaching their carrying capacity, an increase in any one mortality factor is gener- ally offset by a reduction in other factors including poten- tial increases in reproductive success. This population-level response is known as âcompensatory mortalityâ (Ricker 1954). For example, if increased predation were to occur, the remaining population is compensated by lessened com- petition for resources and therefore reductions in mortality directly from that competition, or indirectly from disease transmission or starvation in response. State and federal agencies structure their hunting seasons and quotas to main- tain sustainable populations based on these principles. Many studies are detailed in the literature as described in the following examples. From 1974 to 1992 an estimated 38.2 million blackbirds and starlings were killed in the south- ern United States by surfactant applications to winter roosts (Dolbeer et al. 1997). These management operations had no detectable impact on subsequent nesting population levels in the northern United States (Dolbeer et al. 1997). The great- est number of birds removed during a single winter was 4.2 million Common Grackles in 1977. A simulation with population models of the annual population cycle of Com- mon Grackles in the eastern United States demonstrated the minimal impact of removing 4.2 million birds during Janu- ary. From 1991 to 1997, biologists shot 47,600 Laughing Gulls flying over JFK airport from May to August, reducing gull strikes by 66% to 89% (Dolbeer and Bucknall 1998). Neither the national or northeast regional (Virginia to Maine) population of Laughing Gulls declined during the years of the shooting program, based on North American Breeding Bird Survey results from 1966 to 1996 (Burger 1996; Sauer et al. 1997). From 1991 to 2008, 101,832 gulls were killed
24 FIGURE 25 Standing water and cattail growth along edge of airfield drainage ditch (Source: BASH Inc.). âWetland Mitigation Successâ Rosecrans Memorial Airport (STJ) We removed approximately 180 acres of cattails that bor- der the airport on the southern and western edge. Using a contracted aerial sprayer, we achieved a 100% cattail kill rate using aquatic herbicide. This resulted in dramatic reductions in various waterfowl and blackbirds that were previously attracted to the cattail habitat. Extensive wetland habitat and cattail marsh surrounding STJ (Source: BASH Inc.). Cattails before and after application of herbicide to remove habitat used by various species at STJ (Source: STJ).
25 (2,263â14,866/year), comprised of 88,009 Laughing Gulls and 13,823 other gulls. The number of aircraft striking Laughing Gulls was reduced by 62% in 1991 and 76% to 99% annually from 1992 to 2008, compared with the mean of 157 strikes/year from 1988 to 1990 (Washburn et al. 2009). Overall, populations demonstrate compensatory mortality in response to population reductions on airports allowing for the reduction of local population numbers on the airport with negligible effects to the overall metapopula- tion (Ricker 1954; Dolbeer et al. 1993, 1997; Dolbeer 1998). Thus, with few exceptions, airports should not be concerned that their actions will have dramatic negative consequences on the populations of the target species outside the airport boundaries.
