Data from: Promiscuious pollinators - evidence from an Afromontane sunbird-plant pollen transport network

Sunbirds play a major role in the pollination of Old World nectiverous
plants. However, with the exception of the Cape Floristic Region there is
a major knowledge gap around African nectivore interaction networks- a
stark contrast from the abundance of neotropical hummingbird-plant
networks. Here we describe a sunbird pollen transfer network (PTN) which
we use in conjunction with a sunbird- flower visitation network (FVN) to
explore levels of sunbird specialization within an Afromontane forest
habitat. Both networks were generalised compared with similar sized
hummingbird networks, reflecting the wide range of flower types visited,
the generalist diet and bill characteistics of sunbirds. Three sunbird
species from the genus Cinnyris accounted for 85% of flower visits and 77%
of all pollen transported. Of the 17 plant species across both networks,
15 are predominantly pollinated by insects while Anthonotha noldeae
(Fabaceae- Caesalpinoidie) and Globimetula braunii (Loranthaceae) depend
on sunbirds for seed set. Sunbird species average bill lengths varied
between 14.5 mm (the variable sunbird) to 23.6 mm (the green headed
sunbird) but while more pollen was carried on longer bills we found no
evidence for a relationship between bill length and type of flower
visited. Both networks were nested. Some specialization was observed in
both networks although this does not appear to be driven much by sunbird
–flower trait matching. Overall, our results suggest that in contrast to
nectivores elsewhere, factors such as phenology and/or environment, rather
than morphology may play important roles in limiting potential
sunbird-flower interactions and need further investigation.