Overwintering Butterfly Numbers Surge 3.9-Fold, Deep Water Bay Records 1,408 — Second Highest in 17 Years
AM730 · 2 SOURCESabout 2 hours ago5 MIN
Summary
Green Power's latest overwintering butterfly survey has documented a remarkable rebound in Hong Kong's butterfly numbers, reversing a four-year declining trend. The 2025–2026 winter survey recorded 1,693 butterflies across four designated survey sites, a staggering 3.9-fold increase from the 345 butterflies tallied the previous winter. Deep Water Bay emerged as the primary stronghold, hosting 1,408 butterflies — the second highest count at this location in 17 years. Green Power's Environmental Affairs Manager, Sin Ka-wa (單家驊), attributed the surge to favorable conditions at Deep Water Bay, which has historically drawn massive congregations of migratory butterflies during the winter months.
Key Points
- Four survey sites recorded 1,693 butterflies total: Deep Water Bay (1,408), Fen Liu (182), Siu Leng Shui (84), and Shui Hau (19)
- The count represents a 3.9-fold increase from the previous winter's 345, breaking a four-year consecutive decline
- Deep Water Bay's 1,408 butterflies is the second highest ever at that site, trailing only the 1,566 recorded in 2020
- Over 90 percent of butterflies at Deep Water Bay and Siu Leng Shui belong to "crow-type" species such as Blue-spotted Purple Emperor and Mythical Purple Emperor
- Super El Niño is forecast for October–December 2026, with meteorologists predicting potential impacts on butterfly migration routes
Why It Matters
The surge in overwintering butterfly numbers highlights how localized conditions at key habitats like Deep Water Bay can drive population recovery even amid broader environmental uncertainty. As climate models predict a Super El Niño event this winter, researchers will be watching closely to see whether shifting wind patterns and temperatures alter traditional migration routes — potentially redistributing butterflies to sites like Siu Leng Shui, which recorded 1,596 during the last Super El Niño in 2015 .
The surge in overwintering butterfly numbers highlights how localized conditions at key habitats like Deep Water Bay can drive population recovery even amid broader environmental uncertainty. As climate models predict a Super El Niño event this winter, researchers will be watching closely to see whether shifting wind patterns and temperatures alter traditional migration routes — potentially redistributing butterflies to sites like Siu Leng Shui, which recorded 1,596 during the last Super El Niño in 2015 .