Hermit crab wood and stone are used by some species). The tip of the hermit crab's abdomen is adapted to clasp strongly onto the columella of the snail shell. Most hermit crabs are nocturnal. Hermit crabs can be divided into two groups: As hermit crabs grow, they require larger shells. Since suitable intact gastropod shells are sometimes a limited resource, vigorous competition often occurs among hermit crabs for shells. The availability of empty shells at any given place depends on the relative abundance of gastropods and hermit crabs, matched for size. An equally important issue is the population of organisms that prey
White-browed hermit the very similar Reddish Hermit ("Phaethornis ruber") which generally occurs at lower elevations, and identification criteria between the two species is still not well known. White-browed Hermit may be slightly paler with more bronze coloration in the tail. The range extends along the base of the Andes from central Peru south to central Bolivia, in an elevational band from 350 m to 1400 m. The species is generally encountered most often within forest interior, although individuals occasionally forage along forest edge. Like most hummingbirds, it feeds mostly on nectar from a variety of flowers, but also consumes some small insects.