The avifauna of the Galapagos islands is characterized by a small number of endemic species, including the 13 species of Darwin's finches. The introduced fly parasite Philornis downsi reduces nestling survival and growth rate of altricial birds, and can cause mortality and morbidity of the nestlings. We examined the occurrence of Philornis downsi among islands and at different elevations. The parasite was found in nests from 11 of 13 islands sampled. The two islands on which P. downsi was not found were Espa�ola and Genovesa, both arid islands with no humid highlands and distant from the centre of the archipelago. Parasite infection intensity was greater in nests at higher elevations, and on islands that have moist highlands, which may serve as a reservoir for the files. A full understanding of the fly's ecology may permit the development of eradication or control methods, or at least mitigation of its effects on the birds.
The pygmy rabbit (Brachylagus idahoensis) is endemic to the sagebrush steppe landscapes in the western United States. Pygmy rabbits have adapted to this region by depending on big sagebrush (Artemisia tridentata) as a source of nutrition and concealment from predators. Being a central place forager, and a dietary specialist makes pygmy rabbits an ideal subject to study foraging tradeoffs. Our objectives were to determine if pygmy rabbit foraging patterns are influenced by the nutrient content of individual sagebrush, or the size and location of individual sagebrush. We first developed a near infrared spectroscopy assay that can be conducted in the field, with whole plant foliage, to determine individual sagebrush crude protein (CP) and acid detergent fiber (ADF) contents. We then measured the size, location, protein, and fiber contents of >1,500 foraged and non‐foraged sagebrush plants surrounding pygmy rabbit burrows in 2 field sites in northern Utah, USA. We found significant site differences in sagebrush CP levels and significant season differences in sagebrush ADF levels; sagebrush closer to central burrows were higher in protein and lower in fiber. Pygmy rabbits preferred to forage on taller sagebrush plants that were closer to the central burrow but only marginally higher in CP (0.2%) and lower in ADF (1%). Sagebrush plants with a >50% chance of being foraged, were <5.6 m from the burrow, >0.67 m tall, >10.4% CP, and <34.95% ADF. The selection of closer, larger, and more nutrient‐dense sagebrush may be influenced by pygmy rabbits' need for concealment from predators or a way to minimize foraging effort. © 2020 The Wildlife Society.
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