Documenting floral visitors to rare Hawaiian plants using automated video recordings

Abstract

Many plant species require the services of an animal pollinator. In Hawai'i most endemic plant species are declining, yet their pollinators are often unknown because floral visitors are uncommon, or because visits occur at night, making them difficult to observe. Information about the pollination ecology of rare plants is needed to help develop a conservation strategy. We used an automated, infrared-equipped video system to record animal visits to the flowers of rare plant species on the island of O'ahu, Hawaii. Over 500 hours of recordings were made on four plant species. For the first time, a nocturnal moth was observed visiting Cyrtandra hawaiensis. Also for the first time, native masked bees, presumed to be Hylaeus connectans, were recorded visiting the flowers of two endangered lobeliads, Cyanea pinnatifida and Cyanea superba. An introduced bird, the Japanese White-eye Zosterops japonicus also visited the Cyanea species, but it appeared to act as a nectar robber. A third lobeliad, Clermontia kakeana, was observed continuously for several days and nights but only visits by ants were recorded and no fruits were produced. While it was not always possible to determine the actual species of invertebrate floral visitors, the continuous nature of our video recording allowed us to document floral visitors that were not previously known. Furthermore, the recordings can be made without potential artefacts introduced by the presence of human observers near the flowers. This methodology can be used to document many difficult-to-observe ecological interactions between animals and rare plants.