Green Power announced the latest results of the butterfly survey (1) which was conducted from June to October this year, encompassing ten butterfly hotspots, with 170 species of butterflies recorded, representing around 65% of the total number of butterflies in Hong Kong (2). The three butterfly hotspots with the highest numbers of butterflies are Yuen Tun Ha, Sha Tau Kok and Luk Keng, with 132, 117 and 113 species of butterflies, respectively, while Yuen Tun Ha has the most rare species of butterflies. The numbers of “rare” and “very rare” species of butterflies are 18 and 10, respectively.
Matthew Sin, Senior Environmental Affairs Manager of Green Power, said the numbers of butterfly species found in a number of hotspots were higher than last year’s record. It is worth noting that the annual butterfly survey starts in June, when butterflies are most active, and continues until May in the next year, meaning the five-month survey this year has already recorded more butterfly species than the annual record in the previous year at eight out of ten sites, with the increases ranging from 2% to 54%. The number of total and rare butterfly species recorded at Yuen Tun Ha reached a historic high, with the former increasing by 20% and the latter increasing by 40% compared with last year.
In addition, Matthew pointed out two special records of this year: Euthalia niepelti and Silver Forget-me-not (Catochrysops panormus). Euthalia niepelti was first recorded in 2008, and had a sparse distribution in Hong Kong, but was surprisingly found at Luk Keng, Wu Kao Tang, Lam Tsuen and Sha Tau Kok this year. Silver Forget-me-not, a “very rare” species, was only recorded in literature at southern Hong Kong Island, Sha Lo Wan and San Shek Wan, and formerly found at Fung Yuen. Its first record at Luk Keng in the current survey is a very important discovery.
Matthew was pleased about the survey records this year, as the increases in both total and rare butterfly species suggest the hotspots' environments were generally well protected. “In the past, we revealed destruction at the butterfly hotspots and reported them to the government at once for follow-up," he said. "The butterfly data we collected was also sent to the government for establishing conservation measures for butterflies. This year’s survey record shows our work is effective in stabilising butterfly diversity.” He believes more butterfly species will be found in the future and hopes previous records can be broken.
At the same time, he suggested that the increase in butterfly species may be related to the more abundant rainfall this year. Until October 2016 (latest information from the Hong Kong Observatory), the total monthly rainfall records of several months this year were higher than same-period records in recent years. Abundant precipitation encourages plant growth, and is thus beneficial to butterfly reproduction and growth.