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Explosion in Hong Kong butterfly population

Christian Fernsby ▼ | April 2, 2020
Hong Kong’s butterfly population hit its highest level in at least 14 years in 2019, the warmest year on record in the city, causing a local green group to suggest the increase in numbers could have been linked to climate change.
Butterflies in Hong Kong
Warming   Butterflies in Hong Kong
Environmental group Green Power recorded 127 species of butterfly and more than 7,800 individuals across Shing Mun Country Park and Tai Po Kau Nature Reserve, both areas under environmental protection. The locations were selected to allow the survey to focus on the effect of climate on butterfly populations and minimise other factors from human activity.

“Our 2019 survey showed climate change had induced a sharp increase in the butterfly population. In the long term, this may not be a good thing,” said Matthew Sin Kar-wah, senior environment affairs manager at Green Power, which has been surveying butterfly numbers annually since 2005, and has never counted a bigger population than last year’s.

Green Power found 113 species in 2018, and last year’s numbers were 50 per cent higher than the average population from 2005 to 2018.

Average temperatures in February and March 2019 were 4.4 degrees Celsius higher than usual. During those two months, there was a drastic rise in the butterfly population, particularly of the Satyrinae, Danaidae, Lycaenidae, Papilionidae, Nymphalidae and Pieridae species, the group’s survey found.

Two species of very rare butterflies were recorded for the first time in the survey: the Sullied Sailer and Tiny Grass Blue. The Tailless Lineblue, last seen a decade ago, was also spotted, along with the Swallowtail and Banded Awl, both ranked as rare by the Agriculture, Fisheries and Conservation Department, and both also spotted for the first time in the survey.