Habitat Management to Deter Wildlife at Airports (2014)

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14 ANTENNAS, LIGHTS, SIGNS, AND ELECTRICAL POSTS Airports are often very open areas interspersed with tall structures, a combination attractive to many species of birds for resting or hunting with an excellent view of their surroundings. Antennas, lights, signs, and electrical posts are common structures on airport facilities, and excellent perches for raptors and passerines (Belant and Martin 2011). Modification of these structures may be necessary to discourage these birds, and many deter- rents have been developed to reduce such use. Reducing the horizontal surface area of these struc- tures, and/or replacing them with smooth curved and sloping surfaces with sharp domes or points, can make it are more difficult for birds to perch. Strips of metal or plastic spikes can be glued on flat surfaces and plastic cable ties can be used on more narrow and irregular surfaces (Figure 5). Another useful device is called a “granddaddy long-legs,” because with its arching metal wires attached to a central base, it resembles a spider. All of these devices are intended to make perching birds feel uncomfortable on a structure or prevent them from landing on a structure at all (Cleary and Dickey 2010). ROOFS Almost any flat elevated surface will be attractive to some species of birds, and many will not be deterred by human activity in the area. Roofs on airport buildings can serve as excellent places for species to nest, especially those closely associated with people, such as pigeons. Reducing the horizontal surface area of these structures is another general method for reducing attraction to perching birds. Smooth curved and sloping surfaces with sharp domes or points are less adaptable as perches. Where the expanse of roofs makes anti-perching devices infeasible, suspended nets and overhead wires can be used to prevent birds from accessing the flat stable surfaces (Ickes and Belant 1996). Internal ledges or ceilings are similarly attractive to many small bird species for nesting. The cover and protection provided by garages, covered hangars, and large culverts, etc., give birds a sense of security. These areas can be blocked with hanging strips or chains that prevent the birds from being able to fly freely into the covered area (Figure 6; Cleary and Dickey 2010). CULVERTS Culverts and drains are used by numerous species, including coyotes and raccoons (Procyon lotor; Clevenger et al. 2001; Wolf et al. 2003). Some of these structures may not be recognized as wild- life habitat, but may be used by wildlife as short-term travel corridors and accesses to other areas, or long-term nesting or denning structures. Understanding the timing of denning for wildlife spe- cies of concern can help airport operators plan when to clear out these structures, such as winter and spring, when many mammals will seek out these areas. Grates and covers over culvert open- ings can effectively exclude use by wildlife (Figure 7); however, storms and prolonged water flow may cause grates and covers to become clogged with debris, which must be cleared to maintain drainage. chapter four AIRPORT STRUCTURES: PERCHING, NESTING, AND DENNING

15 FIGURE 5 Antiperching devices on airport structures can include clockwise from top left: flexible wire set, metal spikes, and plastic cable ties in both bottom photos (Credit: H. Woods and F. Humpal).

16 FIGURE 6 Plastic strips (left ) and metal chains (right ) prevent swallows and other birds from accessing protected areas attractive for nesting (Sources: Port of Portland and H. Woods). FIGURE 7 Covering over a culvert to prevent use by wildlife (Source: A. Johnson).

17 Airport Structures—Perching: Gainesville Regional (GNV) The very high frequency omnidirectional navigation system antennas (VOR) at GNV used to attract as many as 30 roosting turkey vultures (Cathartes aura) and black vultures (Coragyps atratus) daily. Area wildlife biologists recommended that GNV try deterring the birds with an effigy of a dead vulture. The effigy was not immediately effective, but since the roosting birds were frightened away with pyrotechnics, no new vultures have been observed on the VOR. The taxidermy vulture needs to be replaced about every year at a cost of about $275, and a depredation permit for collecting vultures was required from U.S. Fish and Wildlife Services. A state permit may be required for take and use of wildlife as well. The FAA granted permission to use the effigy, and operators have considered the technique effective. Taxidermy vulture effigy (left) hung upside-down from VOR antenna to deter vultures from perching at GNV (right) (Credit: S. Blevins). Airport Structures—Nesting: Southeastern U.S. Wildlife habitat modifications do not always go as planned. An airport in the southeastern U.S. had a concern with ospreys nesting on a communications tower. Removal of the nest was approved, and a cover was placed over the tower to help pre- vent future nesting attempts. However, because the cover still created a flat supportive surface, ospreys were able to con tinue nesting there. A pointed and sloped shape such as a cone or pyramid would have been more effective at preventing nest- ing. Understanding the resource preferences of a species is very important to knowing how to deter them. Osprey nesting on a communications tower at a southeastern U.S. airport.

18 Airport Structures—Nesting: East Coast, United States Osprey are common near aquatic habitats in the eastern U.S., and will often seek out tall posts, poles, or antennae that can support their large nests. Management options are limited by federal protection afforded to all migratory birds, but each state may have additional restrictions or permitting processes concerning control efforts can be taken. Operators at a small airport in the eastern U.S. wanted to remove an osprey nest from an electrical pole on airport property. However, the pole belongs to the local electrical company, so the airport limited in its actions. All actions and control techniques had to be approved and carried out by the elec- tric company. In addition, the state wildlife agency required a permit to remove the nest, which cost $1,500 (for permitting and staff costs) and involved monitoring the nest to assure that it was inactive before removal was approved. Ultimately, the nest was removed, and wiring on the electrical pole was altered to deter future osprey nesting attempts. Osprey nesting on an electrical support pole at an airport in the eastern U.S. (left) and the pole after modification to remove nesting support beams (right). Airport Structures—Perching: Chicago’s O’Hare International (ORD) All new buildings in the city of Chicago, including those at O’Hare, are now being constructed with a “green roof” or “eco roof” as required by Executive Order (Chicago Department of Transportation, 2007). Three green roofs, comprised of Sedum-based vegetation, were constructed at O’Hare between 2006 and 2010, including the four-acre roof on the FedEx cargo sorting facility, which is the largest green roof on any airport in North America. Research conducted by U.S. Department of Agriculture (USDA) Wildlife Services during the past few years has shown that wildlife hazardous to aviation use green roofs and traditional (i.e., gravel-based) roofs similarly, with most use during the summer. Green roof at ORD (Credit: B. Washburn, USDA Wildlife Services).

19 Airport Structures—Perching: Port of Portland (PDX) A glass and metal canopy that protects patrons from rain at PDX was attractive to several species of passerine birds. Installation of bird spikes and other perching deterrents was not feasible because of the surface area involved. Instead, operators installed a net to hang under the canopy support beams and prevent birds from reaching most, though not all, of their desired perch sites. Walkway canopy at PDX (left) with a net preventing birds from perching on a majority of support structures (right) (Source: Port of Portland). Airport Structures—Nesting: John F. Kennedy International (JFK) Most animals are resourceful and will take advantage of opportunities for access to food, water, and shelter, including many human- made structures that can serve as excellent nesting habitats. An old aircraft hangar at JFK was serving as shelter for nesting peregrine falcons (Falco peregrinus). Because peregrine falcons were considered threatened with extirpation, airport operators worked closely with the state wildlife agency to develop an approved harassment program for the falcons. First the hangar doors were closed, but holes in the roof and sides of the structure still allowed the birds to enter. Eventually, harassment with lasers and pyrotechnics deterred the birds from nesting in the building long enough for the hangar to be demolished. Ledges and rafters of an old hangar at a northeast airport (left) served as nesting habitat for peregrine falcons (right) (Credit: L. Francoeur).