A novel threat from invasive Lantana: stem exudate clogs the feet of small birds

ABSTRACT

A hard, black deposit was found clogging birds’ feet at Ferncliffe Nature Reserve in South Africa. The reserve is infested with invasive Lantana (Lantana camara). We hypothesised that small frugivorous, nectarivorous and insectivorous birds which foraged in Lantana would be most affected by the hard deposit, which could enclose the toes, making the foot unusable. We investigated which bird species were affected by the hard deposit on their feet, and used liquid chromatography-mass spectrometry to compare samples of the deposit from the birds’ feet to samples from young Lantana stems. White-bellied Sunbirds (Cinnyris talatala), Tawny-flanked Prinias (Prinia subflava) and Spectacled Weavers (Ploceus ocularis) were the three species whose feet were most affected with this deposit, and results confirmed that these deposits originated from exudate on young Lantana stems. This is the first time that Lantana stem secretions have been reported to adversely affect birds, but we believe the phenomenon may occur more widely in Lantana’s native and invasive range.

KEYWORDS:

• Lantana
• Lantana camara
• stem exudate
• chemical defence

Acknowledgements

We thank everyone who helped with the mist-netting, particularly Peter Taylor, Richard Taylor, Moses Chibesa, Stacey Webb, Morgan Pfeiffer and Jaccy Pickard. We are grateful to Msunduzi Municipality, particularly Rodney Bartholomew, for permission to conduct mist-netting in Ferncliffe Nature Reserve, and Chris Metherell, for access, maintaining tracks for mist-netting and providing rainfall data. Alison Young and Thokozani Zungu also supplied rainfall data, and John Davies allowed the use of his reference library. We thank Unathi Heshula, Alan Urban, Terry Olckers, Martin Hill and Michael Day for helpful discussions.