Pale crag martin to do so, it would cast doubts on their specific distinctness. There are several subspecies differing in plumage shade or size, although the differences are clinal, and races interbreed where their ranges meet. The pale crag martin of the nominate subspecies "P. o. obsoleta" is 12–13 cm (4.7–5.1 in) long with light brown upperparts, becoming paler on the lower back, and a short square tail that has small white patches near the tips of all but the central and outermost pairs of feathers. It has a pale grey throat, upper breast and underwing coverts, and the rest of the underparts
Pale Fire novel", and the critic Harold Bloom called it "the surest demonstration of his own genius ... that remarkable tour de force". It was ranked 53rd on the list of the Modern Library 100 Best Novels and 1st on the American literary critic Larry McCaffery's . Starting with the epigraph and table of contents, "Pale Fire" looks like the publication of a 999-line poem in four cantos ("Pale Fire") by the fictional John Shade with a foreword, extensive commentary, and index by his self-appointed editor, Charles Kinbote. Kinbote's commentary takes the form of notes to various numbered lines of the poem.