most of the Asian species. The African trogons are generally green on the back with red bellies. The New World trogons similarly have green or deep blue upperparts but are more varied in their lowerparts. The Asian species tend towards red underparts and brown backs. The wings are short but strong, with the wing muscle ratio being around 22% of the body weight. In spite of the strength of their flight, trogons do not fly often or for great distances, generally flying no more than a few hundred metres at a time. Only the montane species tend to make long-distance flights. Shorter flights tend to be direct and swift, but longer flights are slightly undulating. Their flight can be surprisingly silent (for observers), although that of a few species is reportedly quite noisy. Calls The calls of trogons are generally loud and uncomplex, consisting of monosyllabic hoots and whistles delivered in varying patterns and sequences. The calls of the quetzals and the two Caribbean genera are the most complex. Among the Asian genera the Sumatran trogon (Apalharpactes) has the most atypical call of any trogon, research has not yet established whether the closely related Javan trogon has a similar call. The calls of the other Asian genus, Harpactes, are remarkably uniform. In addition to the territorial and breeding calls given by males and females during the breeding seasons, trogons have been recorded as having aggression calls given by competing males and alarm calls. Behaviour Trogons are generally inactive outside of infrequent feeding flights. Among birdwatchers and biologists it has been noted that "[a]part from their great beauty [they] are notorious ... for their lack of other immediately engaging qualities". Their lack of activity is possibly a defence against predation; trogons on all continents have been reported to shift about on branches to always keep their less brightly coloured backs turned towards observers, while their heads, which like owls can turn through 180 degrees, keep a watch on the watcher. Trogons have reportedly been preyed upon by hawks and predatory mammals; one report was of a resplendent quetzal taken while brooding young by a margay. Diet and feeding Trogons feed principally on insects, other arthropods, and fruit; to a lesser extent some small vertebrates such as lizards are taken. Among the insect prey taken one of the more important types are caterpillars; along with cuckoos, trogons are one of the few