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17 tive in repelling mallards and ring-billed gulls. Stevens and cowbird feeding activity, but at lower rates did not. Man- Clark (1998) tested MA in an aerosol form as an irritant for gone was slightly more effective at lower concentrations, but captive starlings. The MA aerosol was effective as an irritant consumption of mangone-treated millet was similar among and starlings did not habituate to repeated exposure. Aerosols one-choice tests. may hold promise as a hazing technique for some species of birds; however, more research is needed on their effectiveness Dolomitic limestone has been hypothesized as a taste and proper application concentrations. aversive for birds (Clark and Belant 1998). Belant et al. (1997) tested if adding limestone in the form of a dry substance or Anthraquinone slurry reduced consumption of grain. Results were mixed, as reductions of total food intake decreased for both cowbirds Dolbeer et al. (1998) evaluated an anthraquinone formulation and geese during one-choice tests with lime and grain. How- [tested as Flight ControlTM (FC)] as a feeding repellent for ever, body mass was not affected during two-choice tests. In Canada geese and brown-headed cowbirds. The formulation treated grass plots, goose feeding was reduced for 2 to 3 days was applied to turf within small pens housing captive geese. after application of lime in both forms. Similarly, tests of They found 2.5 times more bill contacts/min observed on dolomitic lime, activated charcoal, a silica-based compound untreated plots compared with treated plots during a 7-day (tested as Nutra-lite), and white quartz sand as taste aver- trial. Presented with untreated millet or millet treated with sives on cowbirds and Canada geese revealed that lime and FC, caged cowbirds avoided the treated seed and lost body charcoal showed potential as repellents (Belant et al. 1997b). mass during the 3- to 4-day trials. Cummings et al. (2002) However, Belant et al. (1997b) reported short-lived efficacy conducted a field evaluation of anthraquinone (tested as FC) of the silica-based compound for geese. in newly planted rice fields. Seed was treated with FC at a 2% (g/g) concentration at day of planting. Blackbird abun- Chemical-based Tactile Deterrents dance and seed damage were significantly lower in treated fields compared with untreated fields. Blackwell et al. (1999) Tactile deterrents are perhaps the least studied bird deterrent tested the possible enhancement of anthraquinone (tested as approach. Most tactile repellents are sticky substances that FC) with the addition of a plant growth regulator [tested as deter birds from sitting on perches, such as building ledges, StrongholdTM (SH)]. The plant growth regulator alone was not antennas, and airfield lights and signs. Reidinger and Libay effective in reducing herbivory of grass by geese. However, a (1979) tested glue applied on perches to deter birds near rice- combination of anthraquinone and the plant growth regulator fields. The authors found the glue to be effective during the reduced geese presence by 62% and reduced foraging activ- short treatment period (5 to 8 days). Clark (1997) tested sev- ity by 88%. Blackwell et al. (1999) also reported a continued eral dermal contact repellents to deter starlings from using effect of the treatments 22 days after initiation. The plant structures. In theory, these repellents cause irritation to the growth regulator (tested as SH) greatly enhanced anthraqui- bird through contact with the dermis on the foot and birds none (tested as FC) as a repellent for geese on turf grass. avoid such areas subsequently. Starlings demonstrated agita- Blackwell et al. (2001) again used anthraquinone (tested as tion in response to 5% oil extracts of cumin, rosemary, and FC) and methyl anthranilate (tested as ReJeX-iT AG-36), thyme (Clark 1997). Furthermore, starlings avoid perches but in this instance sandhill cranes (Grus canadensis) were treated with R-limonene, S-limonene, or -pinene. used in pen trials with corn. Both chemicals were effective in reducing corn consumption by cranes. Cranes consumed 8.6 Conklin et al. (2009) tested surface modifications in times more corn in the untreated pens compared with corn an effort to deter cliff-swallows from nesting on highway treated with MA (tested as FC) and consumed 9.8 times more structures. Polyethylene sheeting proved to be effective in untreated corn compared with corn treated with MA (tested reducing nesting activity; however, swallows were still able as ReJex-iT AG-36). Methyl anthranilate applied with a plant to build nests. regulator appears to provide repellency against birds at food sources for up to several weeks (Blackwell et al. 1999). EXCLUSION METHODS Miscellaneous Chemicals Various devices and materials have been used to provide Dolbeer et al. (1988) tested the effectiveness of naphthalene as perceived or actual barriers to exclude birds from unwanted a repellent for starlings around structures. No differential use areas to prevent loafing, nesting, foraging, and other activi- was found in treated or untreated nest boxes. No recent inves- ties. Exclusion methods used include razor wire, overhead tigations of napthalene as a repellent have been conducted. wires, netting, covers (floating and other), and floating balls such as those shown in Figure 9 (Harris and Davis 1998). Belant et al. (1997a) compared the effectiveness of Total exclusion measures for birds are generally impractical d-pulegone and mangone, both taste aversives, on captive and cost prohibitive; therefore, other partial exclusory tech- brown-headed cowbirds. The 0.01% d-pulegone lowered niques and "virtual" barriers are more typically employed.

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18 maximum of 16 m spacing on a food warehouse roof. Nest- ing by ring-billed and herring gulls was reduced by 76% and 100% in the first year and 99% and 100% in the second year, respectively, compared with pretreatment data. FIGURE 9 Bird balls at Heathrow (Source : USDA/APHIS/WS Ohio Field Station). Overhead Wires Overhead wires, such as those shown in Figure 10, are likely the most researched and used exclusion method for birds FIGURE 10 Overhead wires on water source (Source : USDA/ (Amling 1980; Blokpoel and Tessier 1984; Laidlaw et al. APHIS/WS Mississippi Field Station). 1984; Lefebvre and Mott 1987; Agero et al. 1991; Belant and Ickes 1996) and can be highly effective. The use of over- Clark et al. (2004) experimentally tested how overhead head wires is typically effective at deterring use of an area lines affected red-winged blackbird nest survival. Collec- by birds; however, most tests have been conducted on small tively, the presence of overhead wires decreased daily nest water bodies or rooftops. The logistics and costs associated survival probabilities, but inferences on line spacing could with using this technique on larger areas will likely limit its not be elucidated. Lowney (1993) tested overhead wires as a application at airports. McAtee and Piper (1936) produced deterrent to Canada geese around water sources. An 8.3 m the initial work on excluding birds from water resources grid was placed over small ponds on multiple sites. This sys- in the early part of the last century; subsequently, several tem was successful in deterring geese from water sources. other authors have published material on overhead wires (McLaren et al. 1984; Pochop et al. 1990; Agero et al. 1991; Antiperching Wire or Metal Clark et al. 2004); in many cases wires proved to be effec- tive. Belant and Ickes (1996) evaluated the effectiveness of Antiperching devices, such as that shown in Figure 11, overhead wires to reduce roof-nesting by ring-billed (Larus appear to be effective for large birds, but less so for smaller delawarensis) and herring gulls (Larus argentatus). In this species. As larger birds are generally more hazardous to instance, wires were configured in a spoke-like pattern at a aircraft (Dolbeer et al. 2000), use of antiperching devices Netted/Bottom-Lined Ponds Mitigate Attractiveness of Stormwater Ponds to Hazardous Birds at Seattle-Tacoma Airport The SeattleTacoma International Airport (SEA) uses netted/bottom-lined storm- water detention ponds to minimize vegetation growth, reduce attracting hazardous waterfowl, and lower long-term maintenance costs. The use of netting and pond liners is preferred to use of a floating ball or blanket cover because unrestricted access to the ponds was an important design criterion for these facilities. Research was needed to ensure that this practice did not compromise aircraft safety by caus- ing birds to repeatedly fly over ponds when attempting to get below the netting. During fall 2008, 1,000 hours of sampling effort was archived from three avian radars and postprocessed to compare the average time (seconds) targets spent over each of three netted/bottom-lined ponds compared with a paired control site. Paired sites were located an equal distance from the radar antenna. Radar data collected from altitudes 0450 ft above runway level suggested bird use of netted/ bottom-lined ponds was similar or less than control sites.

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19 is common. Birds perching on fences, signposts, light fix- aviary setting. The device was effective in reducing perch tures, ledges, or any structure in the airport environment can use by all species. Blackbirds and starlings were, however, lead to problems with aircraft (Federal Aviation Adminis- capable of using the perches, but only for a short time. tration 2007, 2008). Avery and Genchi (2004) tested anti- perching devices in an effort to deter birds from perching Miscellaneous Techniques on the FAA's Low Level Wind-shear System (LLWAS). Six different antiperch devices were tested on five bird species. A wide variety of control techniques have been employed No single device proved effective for all species involved in to reduce bird use of airports but not formally evaluated. tests. Categorically, larger birds such as owls and vultures Examples include use of remote-controlled vehicles such as require different devices than do smaller species [e.g., cow- radio-operated model aircraft and boats, in addition to many birds and fish crows (Corvus ossifragus)]. The combination varieties of nonlethal projectiles, including rubber slugs and device (Figure 11) provided the best protection for all species; paint balls. Also, lasers emitting green beams, personnel however, 100% deterrence was not achieved. Seamans et al. in vehicles, and various forms of netting have been used. (2007) tested an antiperching device to deter brown-headed Although several of these techniques may actually be effec- cowbirds, European starlings, red-winged blackbirds, rock tive in reducing bird use, the lack of quantitative and rig- pigeons, and common grackles. In this case a commercial orous assessments precludes categorizing their utility and antiperching device (tested as BirdwireTM) was tested in an application to wildlife damage application. FIGURE 11 Antiperching devices used to deter birds from a low level windshear alert system (Source : Steve Osmek).