LEK BEHAVIOUR AND BREEDING OF GUY'S HERMIT HUMMINGBIRD PHAETHORNIS GUY

Abstract

SummaryGuy's Hermit Phaethornis guy, a large forest hummingbird, was studied for 21/2 years in the Northern Range of Trinidad. Regular observations made at a lek of 16 males showed that leks are occupied from November until the beginning of July, and that individual birds retain their lek territories from year to year and use the same perches.The usual song is a monosyllabic note regularly repeated, but the quality of the note varied between different leks and between different parts of a lek, and a few males had a disyllabic song. Young males join the lek between April and June and learn the song of their immediate neighbours. Their plumage, when they first join, is similar to a female's, with distinct pale super‐ and subciliary stripes. The acquisition of the dark head of the adult male probably takes four years.Before they land on their lek perches, males perform an elaborate aerial display in which the red gape is flashed open and a loud tock is uttered. When males visit each other they rapidly change places on the lek perch, the airborne bird performing the tock‐display over the perched bird. A similar tock‐displaying with changing of place occurs when females visit males; twice these were seen to culminate in mounting. Periodically all males at the lek ‘false‐mate’ with a leaf or other piece of vegetation near their lek perches, after tock‐displaying above it. Young males false‐mate much more frequently than older males.The breeding season lasts for eight months, the peak of breeding coinciding closely with the period when the two most important sources of nectar (Heliconia bihai and Pachystachys coccinea) are available. Males occasionally visit nests, and possibly assist in defending them. Undefended nests are quickly dismantled by other birds in search of nest‐material. Of 19 nests found before the clutch was complete, five (26%) were successful. The incubation period is 17–18 days, and the fledging period 21–23 days.