Pollen Loads of Honey Possums (Tarsipes Spenserae) and Nonflying Mammal Pollination in Southwestern Australia

Abstract

Pollen loads were analyzed from 30 honey possums in the Albany region of southwestern Australia. The pollen of Banksia attenuata was the major component of the pollen loads followed by Adenanthos cuneata and Banksia coccinea. The data from pollen loads and flower-head morphometrics indicate that Tarsipes is the primary pollinator of Banksia attenuata, and not birds as might be surmised from other characteristics. Tarsipes also visits typically bird-pollinated plants such as Banksia coccinea and Adenanthos cuneata, but little or no pollination would be expected from such visitation. The lack of distinct flowering seasonality in the southwestern Australian flora is correlated with the presence of a high percentage of long-lived, resident pollinators such as birds and nonflying mammals. A number of plant genera are mentioned which show possible adaptations for pollination by nonflying mammals. Several groups of small mammals which might play a role in pollination are also discussed. Pollination by nonflying mammals has been the subject of renewed interest in recent years (Rourke & Wiens, 1977; Wiens & Rourke, 1978; Sussman & Raven, 1978; Holm, 1978; Carpenter, 1978; Hopper, unpubl. man.). There is, however, a dearth of definitive and, especially, quantitative data on the subject. Any general analysis of pollination by nonflying mammals must consider the unusual biota of southwestern Australia. This region has the highest concentration of plants presumed to be pollinated by these animals. One of the most unusual mammals in southwestern Australia (if not the world!) is the mouselike marsupial honey possum (Tarsipes spenserae). The incredible adaptations of this animal to a presumed diet of nectar (and pollen?) were summarized by Rourke & Wiens (1977) and Holm (1978). Various aspects of its biology were discussed by Vose (1972, 1973) from observations on animals in captivity. It is widely assumed, especially by Australian biologists, that the honey possum is a coadapted pollinator of various plants in the region, but we are unaware of any published information to corroborate these assumptions. The primary object of the study, therefore, was to determine if captured feral honey possums carried pollen loads, and if such pollen is positioned to effect regular pollination of those flowers involved.