The size of Upcher’s Warbler (Hippolais languid) is 13-14 cm in length. It is a larger and grayer than Olivaceous, particularly in comparison with smaller eastern race elaeica, with which it overlaps in range. Upcher’s Warbler also has noticeably darker flight feathers and particularly the tail, which is waved, cocked, and partly fanned as it moves through the foliage or hops on the ground.
It should be borne in mind that wings and tail are darkest when plumage fresh (wearing lighter with abrasion) and that away from breeding grounds tail-cocking and waving are more subdued. This warbler has somewhat longer primaries than Olivaceous, and in new plumage shows whitish edges to secondaries which form a moderately clearwing panel (in fresh plumage Olivaceous shows a weak pale buff wing panel, but fresh Olivaceous is altogether buffered than Upcher’s).
Olivaceous also shows distinct tail movements, although these are confined to downward flicking and slight opening, rather than upward cocking and fanning with circular movements shown by Upcher’s. In abraded plumage, the wing panels of Upcher’s fade away and the tail is less clearly darker, making identification less easy.
The bill of Upcher’s is stouter than in eastern Olivaceous and the crown a little less flat, with the peak a little further forward, more or less above the eye when feathers are not sleeked down (more to the rear of the eye in Olivaceous). Upcher’s movements are more lumbering and slower than those of Olivaceous, which enhances its heavier appearance, and it keeps to scrubby bushes, where it frequently descends to ground level (a pattern not shared by Olivaceous, which favors taller bushes and trees).
Upcher’s Warbler flying low between bushes has a distinctive habit of gliding for the last few meters with tail slightly raised, a habit seemingly not shown by Olivaceous but exhibited to some extent by even larger Olive-tree Warbler. The juvenile birds have pinker legs than adults, latter having grayish or grayish-pink legs. In autumn, first-years are in fresh plumage, whereas adults are heavily worn.
The call of Upcher’s Warbler call is a soft, deep ‘tak’ or ‘chuk’, often repeated; seemingly very similar to the call of Olivaceous Warbler. The song is more ponderous in delivery and softer than that of Olivaceous, with mellow fluty notes, pauses, and stuttering phrases interspersed; phrases repeated three or four times as in Blyth’s Reed Warbler.
Upcher’s Warbler is locally not uncommon but distinctly scarce on passage. The warbler breeds on arid scrubby hillsides and mountainsides, in bushy gullies and semi-desert scrub, and in thickets, groves, and orchards in dry country.
