Estrategias de extracción de néctar por pinchaflores (Aves: Diglossa y Diglossopis) y sus efectos sobre la polinización de plantas de los altos Andes

Strategies of nectar extraction by Flowerpiercers (Aves: Diglossa and Diglossopis) and their effects on the pollination of high Andean plants

Abstract

The flowerpiercers (Aves: Diglossa and Diglossopis) have been considered parasites of hummingbird-flower interactions because they are highly specialized nectar robbers. Nevertheless, there are documented cases where these birds realize legitimate visits to extract nectar and apparently function as pollinators of some plants. I studied some ecological aspects of these two strategies of nectar extraction by four species of flowerpiercers in the Colombian Eastern Andes. I analyzed different morphological characteristics of birds and flowers relevant to their interaction, quantified the frequency of use of both strategies by identifying the marks left by the bills on the corollas and analyzed pollen loads from the bodies of flowerpiercers. The morphology of the maxillary hook, the position of the flower and the length of the corolla were the most important characteristics determining the strategy of extraction used by the birds. The species with the shortest bill and the most strongly curved hook (Diglossa albilatera) preferred to rob the nectar while a species with long bill and less pronounced hook (Diglossopis cyanea) used both strategies in equal proportions. Tubular and erect flowers with long corollas and a high caloric production were robbed with high intensity. The flowerpiercers transported pollen from plants with pendant flowers and medium to short corollas that they visited legitimately. They could be important pollinators of native and introduced plants in high Andean ecosystems as Macleania rupestris, Brachyotum strigosum, Axinaea macrophylla, Eucalyptus globulus, Gaiadendron punctatum and Clusia multiflora.