No 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. 

Galapagos penguins (Spheniscus mendiculus) and flightless cormorants (Phalacrocorax harrisi) live in small, isolated populations on the westernmost islands of Isabela and Fernandina in the Galápagos Islands, Ecuador. Between August 2003 and February 2005, 4 field trips, 2 in the cool, dry season (August 2003 and August 2004) and 2 in the hot, rainy season (March 2004 and February 2005), were undertaken; 298 Galápagos penguins and 380 cormorants were sampled for prevalence and intensity of hemoparasites. Microfilariae were found in both the penguins and the cormorants. Blood smears were negative for the presence of other species of hemoparasites. Overall prevalence of microfilariae across seasons was 42.0% in cormorants and 13.8% in the penguins. Intensity of infection was generally low (mean = 3.2-31.7 in 25 fields across seasons and species) with the exception of a few individuals with markedly high intensities of parasites (>300 in 25 fields in 1 cormorant). Prevalence of microfilariae increased significantly over the 4 sampling periods for cormorants, but not for penguins. Prevalences were significantly higher in cormorants than in penguins for 3 of the 4 collecting trips. Male penguins had higher prevalences than females; however, there were no gender differences in cormorants. No relation was detected between body mass and either presence or intensity of parasitism. Morphological characteristics of the microfilariae are also described and specimens from each host species were similar in all characters measured. DNA sequence data from the mitochondrial cytochrome c oxidase subunit I gene were consistent with the morphological evidence and together demonstrate that the penguins and cormorants are likely to be infected with the same species of microfilariae.

The Critically Endangered mangrove finch Cactospiza (=Camarhynchus) heliobates is now confined to Isabela Island in the Galápagos Islands and is exclusively found in mangrove forests. Formerly it occurred also on neighbouring Fernandina Island, but is apparently extinct there. The population size and ecology of the species was relatively unknown until 1994. We conducted surveys, habitat assessments and behavioural observations of the species between 1996 and 2000. Although Isabela Island has approximately 760 ha of mangrove forests, breeding was confirmed at only two sites, comprising 32 ha in total, on the north-western coast. Our estimate of the population in these two areas is 100 individuals. Additionally, 3–5 territories (which probably contained breeding individuals) were discovered on the south-eastern coast. A comparison of habitat parameters showed that tree height and amount of dead wood were significantly higher within than outside territories, and these are therefore likely to be important habitat components for this species. As considerable structural differences were detected between the two sites holding the main populations and all other mangrove stands on Isabela, it seems possible that the latter are sub-optimal habitat. We therefore conclude that one of the reasons for the very limited distribution of the species is habitat degradation caused by hitherto unknown factors.