Occupancy patterns of the invasive rainbow lorikeet (Trichoglossus haematodus) in Tasmania and the effect of urbanisation on native nectarivores

Abstract

Anthropogenic development has affected ecosystems all over the world through many different processes. One process is the invasion of non-native species facilitated by human development. The impact of invasive species is not often fully understood, however this phenomenon is one of the most devastating mechanism of biodiversity loss on the planet. The rainbow lorikeet (Trichoglossus haematodus), native to continental Australia, is a competitive nectivore with invasive populations in Perth and Tasmania. The population in Tasmania is still small and the effects of this invasive species upon the native avifauna a still not yet known. Tasmania is home to many endemic and endangered species that share a similar lifestyle to the rainbow lorikeet, placing them at risk of displacement. The rainbow lorikeet is well adapted to the urban environment and it was hypothesised that the urban environment would play a large role in this species establishment. It was predicted that this species would occupy areas of Hobart that provide an abundance of parks and open areas. To fully understand the extent of the effect of urbanisation and the presence of rainbow lorikeets on the local avifauna, the occupancy patterns of 5 native nectivorous species were also recorded. It was also hypothesised that the presence of flowering Eucalyptus would be the strongest predictor of rainbow lorikeet occupancy. The results showed that this was not the case and that the strongest predictor for rainbow lorikeet occupancy was a positive correlation with number of buildings within 50m of the site. All the study species avoided the heavily urbanised city centre and, however a difference between native and invasive occupancy patterns could be seen in the use of the more rural areas on the edges of Hobart. The native species experienced an even spread of occupancy throughout the study area while the small population of invasive rainbow lorikeet was restricted to suburban sites. No significant negative influences of the invasive species upon the native avifauna was detected, however it is expected that competition for resources will increase with population size. This study has identified a positive association between the invasive rainbow lorikeet and the suburban landscape, which suggests the possibility of a facilitated population expansion. At the current population size most management options are still feasible and I would suggest action is taken as soon as possible. Show more