Aspects of the behaviour and ecology of Gurney's Sugarbird Promerops Gurneyi verreaux, 1871, in Protea Woodland, South Africa

[摘要] English: Several aspects of the ecology of Gurney's Sugarbird were studied in the Lydenburg area(Mpumalanga) and at Sterkfontein Dam Nature Reserve and Qwaqwa National Park (Free State) during theperiod April1980 to June 1998.The distribution pattern of Gurney's Sugarbird is closely associated with that of Protea roupelliae alongthe Drakensberg escarpment in the Grassland Biome. Nectarivore densities at Protea clumps were affected bythe size of clumps, flower availability and grasssland fires. Sugarbird densities were higher during winter,spring and early summer when sufficient flowers were available.Male sugarbirds were significantly larger than females in all body measurements, except tarsus length.Significant correlations were recorded between culmen/total head length and wing/tail length of the two sexes,and between maximum width of the bulged P6/wing length in males. Monthly variations in body mass wererecorded in both sexes, and birds were heaviest during the November-March breeding season. Adults with long,fully-grown tail ornaments usually had longer wings, while males had wider bulged P6. Primary moult occurredbetween November to March, coinciding with the breeding season. Tail moult also occurred during this periodand were replaced as soon as their condition worsened.The sugarbirds have a September-March breeding season, with a peak from November to December inthe Lydenburg area. P. roupe/liae were usually selected for nesting sites, while P. caffra was also occasionallyused. Nests were completed within five days by the female; mean nest height was 1,85 m. Nests were linedwith the brown, fluffy seeds of P. roupelliae. Incubation period was 16-17 days, nestling period 21-23 days, andpost-nestling period 20-30 days. Breeding success was 41,4%, higher than that of the Cape Sugarbird.Sugarbirds foraged mostly on the nectar of P. roupelliae, but during winter they fed on A/oearborescens in nearby suburban areas and on mountain cliffs. Insect orders which predominated in the diet ofGurney's Sugarbird were Coleoptera and Hymenoptera. These insects also comprised the main arthropod faunain P. roupelliae flowers. Bees and ants were recorded in both stomachs of sugarbirds and Protea flowers.Sugarbirds foraged on P. roupe/liae flowers by probing several times into a flower whilst moving clockwise onit. Beetles were taken from flowers and small flying insects hawked from the air.Movement and survival data for 93 individuals were obtained from 553 captured sugarbirds in theLydenburg area. Recaptures showed fidelity to mountain sites, local movements between mountain sites,seasonal movements and individuals recaptured at the same suburban localities during winter. Peak inoccurrence in suburban areas was from late May until early July, coinciding with the flowering season of Aloearborescens. Sugarbird movements were after the peak flowering periods of P. roupelliae, birds leaving burntProtea veld after fires and after seasons characterised by low annual rainfall.Annual survival in the Lydenburg area was estimated at 80,7%. Life expectancy was 4,6 years. Twoindividuals were recaptured after periods of 88 months and one after 74 months. Recapture data suggests alongevity of beyond seven years for this species. This longevity data represents the first of its kind for thespecies.The conservation of Gurney's Sugarbird and the' management of its Protea roupelliae habitat is apriority. Uncontrolled fires in grassland with P. roupe/liae trees, and logging of wood for fuel, have negativeinfluences on bird and protea populations. The recommended fire regime for P. roupelliae woodland is duringdry winter periods (June/July), rotated biennially, or as late winter-spring fires (August/September). Theapplication of regular block burns or firebreaks in montane grassland will ensure less damage to tree canopiesduring accidental fires.

[发布机构] University of the Free State