The species of this genus are all of large size, in fact, embracing the largest of the American slender-billed oscine birds. All the species differ in structure, varying especially in the length of the bill, as above stated.
Harporhynchus rufus.
It is useless to attempt a division of this genus, for there is such a gradual chain of characters between the two extremes of form (rufus and crissalis), that they even seem almost one species, when the numerous intermediate forms, shading so insensibly into each other, are considered. However, as this view would be rather extreme, in view of the really great difference of form between the species mentioned, we may consider the following as good species, several of them with one or more varieties: rufus, with longicauda and longirostris as varieties, the former scarcely appreciably different, the latter ranking as a permanent race; ocellatus, cinereus, curvirostris, the latter with one well-marked variety, palmeri; redivivus, with most probably lecontei as a well-marked variety, and crissalis.
The seasonal differences in the plumage often make it difficult to determine these several forms; but if the following facts are borne in mind, the
trouble will be greatly lessened. In every species there is a more or less decided ochraceous tinge to the crissal region (sometimes extending forward over the flanks); except in crissalis, in which the lower tail-coverts and anal region are deep chestnut. In autumn and winter this ochraceous tint becomes very much deeper, as well as more prevalent, than in spring and summer; the whole plumage becomes softer, the colors more pronounced, and the markings more distinct, than when faded and worn in summer.
Synopsis of Species of Harporhynchus.
A. Spots beneath sharply defined and conspicuous,—much darker in color than the upper parts.
1. H. rufus. The markings lineo-cuneate; wing bands sharply defined.
Above rufous; markings below dark brown; outer tail-feathers diluted at tip; wing, 4.00; tail, 5.20; bill from nostril, .79, nearly straight; tarsus, 1.30; middle toe, .90 (1,377 ♂ Carlisle, Penn.). Hab. Eastern Province United States … var. rufus.