Assessing the risks of introduced chickens and their pathogens to native birds in the Galápagos Archipelago

Abstract

Poultry production is an important economic activity on inhabited islands of the Galápagos archipelago. There has been a recent surge in both small-scale backyard chickens and larger scale broiler production associated with growth in the human population and the tourist industry. With increased poultry production, concerns have been expressed about the increasing risk of transfer of disease from chickens to native Galápagos bird species that may have little resistance to introduced pathogens [Wikelski, M., Foufopoulos, J., Vargas, H., Snell, H., 2004. Galápagos birds and diseases: invasive pathogens as threats for island species. Ecology and Society 9(5). Available from: URL:http://www.ecologyandsociety.org/vol9/iss1/art5]. This study evaluates risks posed by chicken disease to endemic and native Galápagos bird species, based on empirical evidence of pathogens present in chickens on the islands and a literature review of eVects of these pathogens in wild species. Pathogens identiWed in domestic chicken populations of immediate avian conservation concern are Newcastle disease, Mycoplasma gallisepticum, and the proventricular parasite Dispharynx sp. Newcastle disease (avian paramyxovirus-1) poses an imminent threat to Galápagos penguins (Spheniscus mendiculus), Xightless cormorants (Phalacrocorax harrisi), and lava gulls (Larus fuliginosus), species with very small population sizes (less than 1500 animals each). Additionally, litter from broiler farms could aVect ecological processes in local ecosystems. Improved poultry biosecurity measures are urgently needed on the Galápagos Islands for avian disease management, yet developing these strategies presents political, social, and economic challenges. 

Hematology, Plasma Chemistry, and Serology of the Flightless Cormorant (Phalacrocorax Harrisi) in the Galápagos Islands, Ecuador

“…Although our study provides no evidence that WNV has arrived in the Galá pagos, continued vertebrate and mosquito surveillance is needed, as well as strict quarantine and inspection at the main port of entry. On Isabela Island, where part of the flightless cormorant population resides, backyard chickens and broiler chicken farms are found and antibodies to Newcastle disease virus (NDV) have been reported (Gottdenker et al, 2005). Mortality associated with NDV has occurred in double-crested cormorants in North America (Glaser et al, 1999), and it is uncertain how naÏve flightless cormorants would respond to infection.…”

“…Since then, domestic chickens have been found seropositive for avian adenovirus type I, avian encephalomyelitis virus, avian paramyxovirus type 1 (Newcastle disease virus), infectious bronchitis virus, infectious bursal disease virus, reovirus, Mycoplasma sp. and Chlamydophila psittaci (Gottdenker et al, 2005). Antibodies to avian adenovirus type I and avian encephalomyelitis virus have been reported from waved albatrosses (Phoebastria irrorata) endemic to Españ ola Island (Padilla et al, 2003).…”

Towards locally adapted livestock production in the Galápagos islands : Characterizing & defining potential redesign strategies for the local poultry and pig production systems of Santa Cruz - Galápagos Islands, Ecuador

“…Among the possible negative effects of this trend we find, for instance, the possible introduction in the archipelago of invasive species by means of feed ingredients, or pathogens which can affect native birds by the import of one-day old chickens for the poultry production systems (Gottdenker et al, 2005;Deem, Cruz, Higashiguchi, & Parker, 2010). Moreover, a poor and, probably, dangerous management of animal husbandry waste (e.g., of pig production systems) has been observed (Chiriboga et al, 2006;Cherrett, 2010).…”

“…It has been argued that, moreover, the introduction in the archipelago of invasive species also occurs by means of feed ingredients, or pathogens which can affect native birds by the import of chickens for the poultry production systems (Gottdenker et al 2005;Wikelski, Foufopoulos, Vargas, & Snell 2004;Deem et al 2010). Two thoughts in this regard are that, first, if we are afraid of the introduction of seeds that might grow into invasive plants through the import of animal feedstuffs, then, we could just allow into the island grinded feedstuff.…”

“…o By means of the import of chickens or feed ingredients for the poultry production systems, pathogens which can affect native birds might be introduced in the Galapagos (Gottdenker et al 2005;Soos et al, 2008;Deem et al 2010). However, one could argue that migratory birds might pose a relative 'bigger' threat to the local wild fauna, and that native diseases might pose a threat to imported chicks… o Research suggests 'that backyard chickens may pose a greater threat to Galápagos avifauna because they are more likely to be infectious, have a high seroprevalence for numerous pathogens, and interact directly with wild birds or wild bird habitat, with no biosecurity measures employed' (Soos et al, 2008).…”