25th of January, 2021: Aliens roaming in New Delhi.
Alien species are spreading across southeast Asia
and could reach India — either due to escaping captivity or after being
intentionally released, researchers with the University College London (UCL)
warned on Monday.
In a study published in 'Nature
Ecology & Evolution', researchers show how the alien species such as the
zebra dove are a threat to India, as the Himalayas are particularly prone to
the spread of non-native birds.
Native in some of the Southeast
Asian countries, the zebra dove (Geopelia Striata)has spread across the
region. Now it has alien population in Thailand and Laos, among other
countries.
Alien Birds:
The study says once a bird has
established itself as an alien species in a new region, living alongside native
birds, it is most likely to continue spreading to other areas where those same
native birds are present.
The study improves on the
existing methods to predict the spread of alien species.
The researchers found that
areas such as the Himalayas and parts of sub-Saharan Africa, which so far have
not seen many alien species, could be under threat in the coming decades.
Alien species
— those that have been introduced to new areas outside their native range — are
one of the leading causes of global biodiversity loss. Driven by human actions,
alien species also represent a growing threat to food security, human health
and many economies. Predicting where they will spread next, so that we can find
ways to mitigate the damage, is an urgent global challenge. The
researchers reviewed data of 339 bird species which have already become
established as alien species outside of their native range, distributed all
across the globe.
To see if they could predict, in hindsight, where these alien species had spread, the researchers first investigated how similar areas across the globe are in terms of their existing native bird species — what is called biotic similarity.
The type of biotic similarity (which they call environmental resistance, where an area with a very different makeup of native birds exhibits high environmental resistance) is a stronger predictor of the spread of already established alien birds than comparing an area's climate to the conditions where an alien species lives in its original native range.
In particular, parts of
Southeast Asia stretching from Sumatra, through the Malay Peninsula, southern
China and along the Himalayas as well as sub-Saharan Africa appear to be at
risk.
These areas currently have just a handful of alien bird species that have spread far beyond major urban areas, but are at risk from the spread of up to 10 times as many alien bird species — without even including the risk from alien species that have yet to be introduced anywhere new.
The Alien species have now invaded South India too.
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