Analysis of acoustic echoes from bat-pollinated plants

In this paper, we analyse a real set of data containing high range resolution profiles (HRRP) of unpollinated corollas of Cobaea scandens and of an inflorescence of Rhytidophyllum auriculatum, which are plants typically pollinated by bats. These were collected by transmitting a synthetic wideband linear chirp with an acoustic radar capable of a very high range resolution. Two C. scandens flowers taken at different stage of maturity were measured to investigate if and how the information contained in the flowers’ echo acoustic signatures changes as the flower wilts and hence stops producing nectar and loses attractiveness. These were then modified, by manually removing the petals, in order to study feature-specific contributions to the scattering. The acoustic signatures of the C. scandens and the R. auriculatum do not change as a result of pollination by a bat and indeed the same individual flower can be pollinated multiple times as long as it contains nectar. The analysis presented in this chapter is subtly different from investigating pre and post bat fed plants but it demonstrates the acoustic changes as the flower degrades, and hence it is a valid experiment for this bat-pollinated plant species. The signatures are analysed and results are discussed with respect to the task of classification of manmade targets.