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Territoriality and changes in resource use by sunbirds at Leonotis leonurus (Labiatae) (1980)

Frost, S. K. ; Frost, P. G. H.

Springer

Oecologia 45 (1980), S. 109-116

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ISSN: 1432-1939

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Leonotis leonurus was studied with the aim of characterising nectar quality and quantity, and of monitoring the sunbirds' response to the resource. The flowers produced high quality nectar in low quantities. Nectar quality remained constant during the day and averaged 23.4% sucrose equivalents (an energy content of 3.8j/μl). Nectar production was highest during the morning when flow rates reached a peak of 3.3 μl/h. L. leonurus was visited by four species of sunbirds. In 1977 there were 7.8 visits/h to the flowers. The clump was defended by a single Olive Sunbird (Nectarinia olivacea) who defended the flowers intra- and interspecifically. On one day the territorial bird obtained approximately 57.1 kJ from the Leonotis flowers and expended 5.4 kJ on defence and 13.6 kJ overall while on the territory. Territorial behaviour and intruder pressure was a function of resource availability. When Leonotis nectar levels were high intruder pressure was intense and the territorial bird employed long chases as a defence behaviour. When nectar levels desreased intruder pressure was lower, the territorial bird chased less and employed vocalisations as a relatively inexpensive form of territorial behaviour. In 1978 there was an abundance of nectar sources in the study area due to the late onset of the dry season. Sunbirds were not territorial at Leonotis and visiting rates were lower than in 1977, averaging only 1.7 visits per hour. Instead the sunbirds concentrated on contemporaneously flowering plant species, particularly Halleria lucida.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00346715

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Sunbird pollination of Strelitzia nicolai (1981)

Frost, S. K. ; Frost, P. G. H.

Springer

Oecologia 49 (1981), S. 379-384

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ISSN: 1432-1939

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The role of sunbirds (Nectariniidae) in the pollination ecology of Strelitzia nicolai (Musaceae) was studied for one year in a coastal dune forest in Zululand, South Africa. It was found that S. nicolai produced large quantities of low quality nectar (1.74 j/μl); that nectar production was highest during the day-time; and that the flowers displayed several characteristics attractive to bird-visitors. The flowers were large, conspicuous and provided the birds with a perch, facilitating easy access to the nectar. Flowers were visited by four species of sunbirds: Olive Sunbird Nectarinia olivacea, Grey Sunbird N. veroxii, Black Sunbird N. amethystina, and Collared Sunbird Anthreptes collaris. Sunbirds visited the flowers throughout the year, and apparently cued into changes in the flower angle as an indication of nectar flow rates. Sunbirds perched on the flowers in a manner which effected pollination, the pollen being transferred to the stigma via the birds' feet. Besides the sunbirds, there were other visitors (bushbabies, monkeys and insects) to the flowers, but they did not visit the flowers frequently nor did they appear to be significant pollinators. The high seed set of S. nicolai in the study area attests to the efficacy of the sunbirds as pollinators.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00347603

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