Control of wild and feral birds in urban areas

Public Health Significance of Urban Pests Birds 263 262 effective decontamination of the soil under communal roosts infected with sapronotic fungi H. capsulatum is possible by repeated 3–4 times use of 3 formaldehyde Tosh et al., 1967; • reducing the number of nest boxes available for starlings; • trapping birds in nets or various bird traps and euthanizing the captured birds, if per- mitted; and • sterilizing birds chemically, with a treated grain bait, if permitted. These activities should be carried out in an integrated approach to bird management, since individual steps alone do not produce success. Furthermore, inspection and control measures must be performed by, or under the supervision of, veterinary public health agencies – and only when they are substantiated and necessary. Ornithologists, wildlife managers and citizen representatives such as consumers should be involved in imple- menting the control measures. The integrated approach to bird management also needs a public education component media and a legal regulatory component – that is, poli- tical support – as necessary parts of the process. Finally, a risk–benefit analysis should also be performed.

8.4.4. Techniques for dispersing birds in cities

Birds can be dispersed by various techniques Frings Jumber, 1954; Bickerton Chapple, 1961; Schmitt, 1962; Brough, 1969; Gorenzel Salmon, 1992, 1993. Briefly, they include the use of: • tape strips; • airport strobe lights and flashlights; • fireworks, rockets and shell crackers cartridges that contain no lead shot against approaching flocks which, although effective, are less acceptable in cities; • shooting, pistols, explosives and screamers; • tape-recorded distress or scary calls of birds such as those of owls; • falcons and other trained raptors; • water-mist sprayers; • plastic netting; and monitoring of avian populations and surveillance for associated zoonoses and saprono- ses. The majority of the public health problems caused by wild birds are associated with feral pigeons, gulls, blackbirds, grackles, starlings, corvids and house sparrows. For instance, at least 800 reported transmissions of a pathogen mostly C. psittaci from feral pigeons to people have been found Sixl, 1975; Pospíˇsil et al., 1988; Glünder, 1989; Haag- Wackernagel Moch, 2004, this probably being only the so-called tip of the iceberg. Similarly, hundreds of cases of histoplasmosis in people have been acquired via the air- borne route during, or after, work on communal roosts of birds in urban areas in North America Furcolow et al., 1961; Murdock et al., 1962; Ajello, 1964; D’Alessio et al., 1965; Dodge, Ajello Engelke, 1965; Tosh et al., 1966, 1970; Younglove et al., 1968; Latham et al., 1980; Storch et al., 1980; Waldman et al., 1983; Chamany et al., 2004. Public health surveillance should involve both a passive and active monitoring approach, the former based mainly on reports of disease, while the latter also includes serological surveys of urban birds and city dwellers, further microbiological examination of compe- tent haematophagous invertebrate vectors and avian hosts their infection rate, and inves- tigations of habitats as sources of disease. Monitoring population density of the avian hosts and invertebrate vectors, and their spatial mapping and temporal seasonal distribu- tion, is also necessary. Management priorities should then be established and objectives defined for prevention and control of bird-related infections.

8.4.3. Control of wild and feral birds in urban areas

The control of wild bird populations especially those of feral pigeons in urban and sub- urban areas is difficult and sometimes ineffective. However, a few so-called public- friendly methods are available to control potentially infected urban bird populations. To prevent risks that arise from the presence of infections in birds or infectious materials in their droppings, several tasks should be performed, as soon as microbiologists and epi- demiologists have demonstrated an infection zoonosis or sapronosis Lesaffre, 1997; Haag-Wackernagel, 1995, 2000; Rödl, 1999. These tasks include: • restricting feeding at public places; • inhibiting breeding on buildings, by mechanically blocking the loft orifices and per- ching sites in, on and below the roofs, using netting, spikes, repellent gels and electros- hock deterrent systems; • collecting and inactivating avian pigeon eggs; • controlling scavenging birds, such as gulls and corvids, on landfill sites garbage depo- sits; • controlling seagulls at harbours and airports if their numbers create hygienic and safety problems; • controlling and sanitizing large communal roosts of birds in city parks – for example, Public Health Significance of Urban Pests Birds 265 264 References 2 Ajello L 1964. Relationship of Histoplasma capsulatum to avian habitats. Public Health Reports , 79:266–270. Alekseev AN et al. 2001. Evidence of ehrlichiosis agents found in ticks Acari: Ixodidae collected from migratory birds. Journal of Medical Entomology, 38:471–474. Anderson JF, Magnarelli LA, Stafford KC 1990. Bird-feeding ticks transstadially trans- mit Borrelia burgdorferi that infect Syrian hamsters. Journal of Wildlife Diseases, 26:1–10. Anderson JF et al. 1986. Involvement of birds in the epidemiology of the Lyme disease agent Borrelia burgdorferi. Infection and Immunity, 51:394–396. Babudieri B, Moscovici C 1952. Experimental and natural infection of birds by Coxiella burnetii . Nature, 169:195–196. Baker JR 1977. The results of post-mortem examination of 132 wild birds. The British Veterinary Journal , 133:327–333. Benton C et al. 1983. The contamination of a major water supply by gulls Larus sp.. Water Research , 17:789–798. Beran GW, section ed. 1981. Viral zoonoses, Vol. 1. Boca Raton, CRC Press. Berg RW, Anderson AW 1972. Salmonellae and Edwardsiella tarda in gull feces: a source of contamination in fish processing plants. Applied Microbiology, 24:501–503. Berger J 1966. Zur Epidemiologie der Toxoplasmose. I. Die Toxoplasmose der verwil- derten Stadttauben. Zeitschrift für Medizinische Mikrobiologie und Immunologie, 153:68–82. Bergman F 1963. Occurrence of Cryptococcus neoformans in Sweden. Acta Medica Scandinavica, 174:651–655. Biancifiori F et al. 1986. Avian toxoplasmosis: experimental infection of chicken and pigeon. Comparative Immunology, Microbiology and Infectious Diseases, 9:337–346. Bickerton BM, Chapple W 1961. Starling roosts and their dispersal. Agriculture, 67:624–626. Bjoersdorf A et al. 2001. Ehrlichia-infected ticks on migrating birds. Emerging Infectious Diseases , 7:877–879. Blackmore DK, Keymer IF 1969. Cutaneous diseases of wild birds in Britain. British Birds , 62:316–331. Böhm KH et al. 1974. Infektionsversuche an Tauben und Hühnern mit Cryptococus habitat modification, by thinning, clearing or even eliminating the vegetation such as reeds, brush and trees on communal roosts. Birds, however, usually get accustomed to being disturbed by various acoustic or light signals. Some of the methods could be used only under certain circumstances and should be used respectfully in residential environments.

8.4.5. Economic impact of wild urban birds on human health and of controlling birds