Small Ground Finch Geospiza Fuliginosa Research Articles

FOUR CASES OF DIFFERENT PLUMAGE CHROMATIC ABERRATIONS IN GALAPAGOS BIRDS

Plumage chromatic aberrations usually represent a problem for field ornithologists. Chromatic aberrations are originated by genetic mutations that result in a pigment deficiency, drastically altering the typical colour of individuals, and can vary both within and between species. Here, we present four different colour aberrations in four bird species native and endemic to the Galapagos Islands: Lava Gull Leucophaeus fuliginosus, Brown Noddy Anous stolidus, Floreana Mockingbird Mimus trifasciatus, and Small Ground Finch Geospiza fuliginosa. These records expand taxonomically the occurrence of chromatic aberrations on Ecuadorian birds and in the Galapagos archipelago.

Galapagos ground finches balance investment in behavioural and immunological pathogen defences

The scientific community has long recognized the importance of individual behaviour in pathogen spread in wild animals. Furthermore, recent studies have highlighted the potential for behaviour to act as a pathogen defence mechanism. In line with these studies, the pathogen defence optimization hypothesis (PDOH) posits that individuals balance investment in costly behavioural and immunological defences against pathogen infection. Here, I test the PDOH using data from observations of wild Galapagos finches (Medium Ground Finches Geospiza fortis and Small Ground Finches Geospiza fuliginosa) at feeders, combined with immune data collected in the field. Both within and between species, those groups engaging to a greater extent in high transmission‐risk behaviours (not investing in behavioural defences against pathogen exposure) invest more heavily in immune pathogen defences. These data provide the first support for the PDOH in a wild population.

The ecology of clutch size variation in Darwin's Small Ground FinchGeospiza fuliginosa: comparison between lowland and highland habitats

This study examines the ecology of clutch size variation between two contiguous populations of Small Ground FinchGeospiza fuliginosathat breed in geographically distinct habitats (lowlands, highlands) on Santa Cruz Island of the Galapagos Archipelago. Small clutch size is considered an adaptive response to high predation risk (to reduce behavioural conspicuousness at the nest and lower the energetic costs of re‐nesting), whereas high food abundance is predicted to favour large clutch size. This study has two main objectives: (1) to present descriptive data on clutch size variation inG. fuliginosabetween habitats, and (2) to test life‐history predictions for clutch size variation based on food abundance and nest predation hypotheses. The highlands on Santa Cruz Island were characterized by high nest predation (52%), high annual rainfall and high insect abundance across the year, whereas the lowlands were characterized by low nest predation (5%), seasonal rainfall and high insect abundance during the breeding season. The highland birds had smaller clutch size and a shorter re‐nesting interval. Patterns of nest attendance differed significantly between habitats. The percentage of time incubating per hour was comparable between habitats, but the mean duration per incubation event was longer in the highlands (with fewer events per hour), which is consistent with the prediction of reduced behavioural conspicuousness at nests under conditions of high predation risk. There were no significant differences in nestling feeding levels between habitats, probably becauseG. fuliginosais a multiple prey loader.

Isospora geospizae, a new coccidian parasite (Apicomplexa: Eimeriidae) from the small ground finch (Geospiza fuliginosa) and the medium ground finch (Geospiza fortis) from the Galapagos Islands

Isospora geospizae n. sp. is described from the faeces of the small ground finch Geospiza fuliginosa and the medium ground finch Geospiza fortis from Santa Cruz Island in the Galapagos archipelago. I. geospizae oocysts are spherical to subspherical, with a one-layered, smooth, colourless wall, 15.5×14.5 (13–17×12–17) μm with a large polar body and no micropyle or residuum. Sporocysts are ovoid, 10×7.5 (10–12×6–9) μm with small Stieda and subtieda bodies and a smoothly contoured, but irregular-shaped residuum containing coarse, non-uniform granules. Sporozoites are sausage-shaped with large refractile bodies at each end and randomly arranged in the sporocysts. Three of 34 (8.8%) G. fuliginosa and one of nine (11.1%) G. fortis were infected with I. geospizae.