Invasive and Non-native, are these two terms interchangeable? Invasive species generally refer to an introduced species of flora or fauna that harms the native ecosystems. Additionally, invasive species may also have an adverse economic or public health impact. With the introduction of an invasive species, native wildlife might struggle to survive as the demand for resources increases and the rapid increase in the invasive population floods our natural ecosystem. On the other hand, non-native species are introduced species as well, yet these species do not adversely impact the native ecosystem.
Singapore’s NParks one of the statutory boards under the Ministry of National Development, manages invasive species. Laws like the Animals and Birds Act or the Control of Plants Act are enforced by them. These laws aim to control the exchange of animals and plants with other countries to minimize the possibility of the introduction of non-native species to Singapore. Several species of animals that many of us will recognise have been highlighted as invasive species by NParks. The red-eared slider a common household pet. The American Bullfrogs that sometimes manage to escape their farms or are at times deliberately released or the variable squirrel. Yet what sets these species apart from other non-native species that are not called invasive? Should both invasive and non-native species be seen as inherently bad?
Ecosystems all around the globe vary and thus a species that is labelled invasive in one area, may not be considered “invasive” in other contexts. There are many issues scientists or conservationists face when dealing with invasive species. Among them would be the argument that the food web may be too complex for us humans to adequately judge which introduced species are doing harm and its extent of invasiveness. Context matters– if a non-native species introduced disturbs the ecological balance, then it is called an invasive species. If it has limited impact on local wildlife it would be called non-native and if it is outcompeted in its new environment, it would simply die out.
An example of an invasive species would be the red-whiskered bulbul. It was introduced as a caged bird. This bird is part of the 100 of the World’s Worst Invasive Alien Species. Yet its population size in Singapore is relatively small. It is an alien species in Singapore, yet it does not thrive. As the red-whiskered bulbul originates from Asia up till Northern Malaya, this seems to me that as it is not too far from its native land in Singapore and thus this limits its advantages it has over native bird species in Singapore. Thus, is it fair just to label the Red-whiskered Bulbul as invasive when it’s impact on native birds is limited, at least from my point of view? Context matters and as the saying goes one man’s trash is another man’s treasure, in this case, one man’s invasive species is another man’s introduced species.
With our globalised world and economy, more occurrences of new invasive species will undoubtedly occur. This is a consequence of trade processes, whereby potential invasive species may be carried onboard cargo or ballast tanks. Singapore’s position as a port city makes us all the more susceptible to the aforementioned implications. What can we do to prevent the spread of invasive species? As of now, NParks spearheads educational initiatives to have the populace recognise the potential damage introduced species will have on our local wildlife. In terms of our response to invasive species, there has to be careful evaluation of the suspect alien species prior to any culling, so resources are used to deal with actual invasive species. What do you think?
Written by: Li Zhe