Frick W. F., Price R. D., Heady P. A. I., Kay K. M., Insectivorous bat pollinates columnar cactus more effectively per visit than specialized nectar bat, The American Naturalist, 2013, 181(1):137-144, doi: 10.1086/668595
An experiment on female Pachycereus pringlei flowers compares pollen deposited during a single visit by two bat species. Measurements from stigmas are combined with a separate dataset on visitation frequency. The findings distinguish effectiveness per visit from the modelled contribution of a pollinator over a night.