The Spotted Antbird is an elegant bird of the lowland tropical rainforests and is one of the most well-studied of all Neotropical birds. The name Hylophylax derives from the Greek words "hule" (woodland) and "phulax" (a watcher or guardian). The species name "naevioides" derives from Latin "naevius" (spotted) and the Greek suffix "-oides" (resembling) (Jobling 1991). This impression that the Spotted Antbird is a "spotted watcher of the woodland" is also mirrored in Panama's Darien province where the species is locally known as 'corregidor' (mayor) for its apparent behavior of directing the activities of other birds found with it, presumably at army ant swarms (Wetmore 1972). Male Spotted Antbirds are unmistakable among other antbird species given their white chest that bears a necklace of large, black spots. They are frequent--though not obligate--followers of mixed-species foraging flocks that track insect-flushing swarms of army ants across the forest floor. Due to their small size (11.5 cm length, 16-18 grams) relative to competitors, Spotted Antbirds are low in the pecking order at these army ant swarms. They defend year-round territories year-round but, like many tropical birds, exhibit very low levels of testosterone throughout the year (even during the breeding season). They have high adult survival rates and have a small clutch size. Their natural history, life-history trait variation, and physiology have been extensively studied in central Panama at both mainland (contiguous forest) site and disturbed, island sites (Barro Colorado Island). thus, most of the information in this account derives directly from these sites. A detailed documentation of the natural history and basic behavior ecology of Spotted Antbirds is provided in the monograph by E.O. Willis (Willis, 1972), who studied the antbird community of Barro Colorado Island in Panama in the 1960s. This species account attempts to summarize that work, but readers seeking additional details of the natural history and ecology of Spotted Antbird should consult that text in full.