Mai Po Biodiversity: Fish Ponds
by Thomas Gomersall
It’s easy to see why Mai Po Nature Reserve gets so much attention for its birds. They’re the most easily spotted animals there and the reserve is managed largely for their benefit. But with so much focus on birds, it’s easy to forget that the reserve is also home to a vast array of other organisms, including 33 species of mammal, eight species of amphibian and 105 species of butterfly, to name a few.
With the theme of this year’s Walk for Nature — happening 2–3 November at Mai Po Nature Reserve — ‘Birds and Beyond’, this is a good time to talk about both the birds and some of the lesser-known species that inhabit each of Mai Po’s six habitat types, starting with the fish ponds.
In the past, these ponds formed part of a thriving aquaculture industry. Today, they form a buffer zone around the more ecologically sensitive conservation area of Mai Po to help shield it from human influences. Many of these ponds are still managed by fish farmers using traditional management practices that benefit the local wildlife including ones listed below.
Tufted Duck (Aythya fuligula): During the winter migration season, one of the very first animals to greet visitors on their way into the reserve is the tufted duck. Large flocks of this bird gather in the ponds close to Castle Peak Road, where they frequently dive for food. Like many ducks, this species is sexually dimorphic, with the female being dark brown and the male being black and white, although in a certain light he can sometimes appear almost purple. Both sexes also sport a short head crest, although it is much shorter in the female bird (Tipper, 2016, p. 20).
Chinese Pond Heron (Ardeola bacchus): Many birds undergo plumage changes between the breeding and non-breeding seasons and in Hong Kong, this transformation is perhaps no more dramatic than in the Chinese pond heron. For much of the year, this small, short-necked heron has a drab, greyish-brown body and speckled breast and head. But in the summer breeding season, its appearance changes radically, switching to a chestnut brown head and breast, a black back and white underparts (Tipper, 2016, p. 26). It feeds on frogs, fish, insects and crustaceans.
Little Grebe (Tachybaptus ruficolis): The little grebe is a common sight on the fish ponds and reservoirs of Deep Bay and is one of the very few waterbirds that stays here year-round. It belongs to a family of birds that are specialised to live almost entirely in the water, diving for small fish and building floating nest platforms out of water plants. During the breeding season, it develops dark chestnut feathers on its neck and cheeks (Viney et al, 2005, p. 36).
Black Drongo (Dicrurus macrocercus): Not every bird around the fish ponds is a water bird. The area’s open, lowland environment with its scant trees is also home to several smaller, open habitat species like the black drongo. This fork-tailed little bird is often seen perching prominently on wires, which it uses as a launching pad when hunting for insects. Though its plain appearance makes it look harmless, it is extremely aggressive towards larger birds like crows and will viciously harass them in flight, often in pairs. Its call is a cat-like hissing sound (Tipper et al, 2016, p. 95; Viney et al, 2005, p. 216).
Long-tailed Skink (Eutropis longicaudata): A common lizard in Hong Kong, the long-tailed skink really likes to soak up the sun, often being seen basking on exposed boulders or concrete roads during the day. However, the presence of danger can very quickly stir it from this sluggish state and send it scuttling rapidly for the shelter of a crevice or thick vegetation. During the spring, females will seek out enclosed, sheltered places such as rock crevices or holes in walls, in which they will lay a clutch of up to 16 eggs. It has a similar appearance to the brown forest skink, but can be distinguished from that species by its longer tail and longer head with a less pointed snout (Karsen et al, 1998, p. 96, p. 99).
Walk for Nature takes places on 7–8 November 2020 at Mai Po Nature Reserve, with the theme “Our Habitat, Our Home”, spotlighting the rich biodiversity of this Ramsar site.
References:
· Karsen, S.J., Lau, M. and A. Bogadek. 1998. Hong Kong Amphibians and Reptiles: Second Edition. Provisional Urban Council, Hong Kong. 96pp, 99pp.
· Tipper, R. 2016. A Naturalist’s Guide to the Birds of Hong Kong, John Beaufoy Publishing, United Kingdom. 20pp., 26pp., 95pp.
· Viney, C., Phillipps, K. and C.Y. Lam. 2005. The Birds of Hong Kong and South China. Information Services Department, Hong Kong SAR Government, Hong Kong. 36pp., 216pp.
