This feminisation may lead to the eventual extinction of crocodiles in this area. Chromolaena odorata, also known as the trifid weed, was accidentally introduced into South Africa last century in seed-contaminated goods from ships in Durban harbour. This alien invader spread rapidly throughout the region, growing along building sites, railways, forest edges and streams, overshadowing native plants in its path. It finally invaded the Greater St Lucia wetland park, a World Heritage site. It is now widespread throughout the area, where it is having a significant impact.
Female crocodiles prefer to lay their eggs in open, sandy and sunny areas close to water.
They normally return to the same nesting site year after year despite intrusion by the trifid weed into their nesting areas. They dig an egg chamber and carefully bury their eggs in the warm sand. Each female then actively guards her nest, viciously attacking any intruders, until her young hatch some three months later. Alison Leslie and James Spotila, from Drexel University, USA, and the department of nature conservation, University of Stellenbosch, South Africa, reporting in the journal Biological Conservation, have discovered that Nile crocodile mothers abandon previous nesting sites if they encounter the exotic plant's fibrous roots. This does not bode well for crocodile breeding success in the area.