NECTAR AND FLOWER PRODUCTION OF LOBELIA-TELEKII INFLORESCENCES, AND THEIR INFLUENCE ON TERRITORIAL BEHAVIOR OF THE SCARLET-TUFTED MALACHITESUNBIRD (NECTARINIA-JOHNSTONI)

The alpine zone of Mount Kenya is a typical equatorial, high-altitude habitat with a harsh environment, large fluctuations in physical condi tions and an impoverished flora and fauna. A common flowering plant is Lobelia telekii, which has large inflorescences with up to 2000 flowe rs. The long hanging bracts of this plant ameliorate the physical envi ronment around the flowers, damping the fluctuations in temperature an d relative humidity. The scarlet-tufted malachite sunbird (Nectarinia johnstoni) is a highly active nectarivore that obtains most of its foo d from the nectar of L. telekii Sunbirds are more likely to visit the younger, male flowers at the apex of the inflorescence, which are larg er and contain twice as much sugar as the older, female flowers lower down the spike. Male flowers will gain from multiple visits by exporti ng more pollen, while female flowers probably need to be visited only a few times for successful fertilization Male sunbirds were resident o n their territories all year and vigorously defended them from conspec ifics. All territories contained about four times the number of flower s visited by the territory occupants in a day. Males on territories wi th a large number of flowers suffered more intrusions than males on lo w quality territories and spent more time in flight. After an intrusio n the resident male frequently fed near where the intrusion took place . Males that subsequently attracted mates defended about twice as many flowers as males that did not breed, although undefended inflorescenc es were present. Some males apparently defended territories suitable f or a pair, others only for a single bird. (C) 1996 The Linnean Society of London