Mai Po Biodiversity: Reedbeds
by Thomas Gomersall
Covering about 45 hectares of shallow water gei wai towards the centre of the reserve, the beds of common reed (Phragmites australis) at Mai Po are of considerable conservation importance. For one, it’s the largest reedbed in Hong Kong and possibly even the whole of Guangdong Province, making it a vital habitat for a wide range of reedbed-dependent species in this region.
Nearly 400 invertebrates (including some new to science) have been recorded in the reedbed, providing much-needed food for the migratory and resident birds that roost and nest here. They are also an important habitat for some of Mai Po’s most reclusive and rarely seen birds, which make good use of the sheer density of reeds to hide themselves from predators and, frustratingly, birdwatchers.
Purple Heron (Ardea purpurea): Named for its purplish-grey wings, the purple heron has a similar body shape to the grey heron. However, it is shyer and very rarely seen out in the open (in Hong Kong at least), preferring to stick almost exclusively to dense reedbeds. Usually the best chance of spotting one is when it flies between reed beds (Tipper, 2016, p. 40).
Oriental Reed Warbler (Acrocephalus orientalis): Whereas most warblers are small, shy birds, the oriental reed warbler is large and easy to spot as it flies from place to place. As its name suggests, its preferred habitats are reedbeds and other grassy areas in Deep Bay, particularly those near water. (Tipper, 2016, p. 115; Viney et al, 2005, p. 182). Studies by the Hong Kong Bird Ringing Group have found that these birds show a great degree of affinity to the reedbeds at Mai Po, with one individual returning there every winter for 11 consecutive years, highlighting the conservation importance of protecting reedbeds (WWF-Hong Kong, 2015).
Eurasian Bittern (Botaurus stellaris): The Eurasian bittern is a bird supremely adapted to reedbeds. Not only does its dappled plumage provide perfect camouflage, when alarmed it will hold its head and bill vertically and remain completely still so as to blend in with the reeds. Like the purple heron, it sticks exclusively to the reedbeds and is most commonly seen when flying, though even then it’s not easy to spot as it tends to fly low (Viney et al, 2005, p. 44).
Yellow-bellied Prinia (Prinia flaviventris): Superficially similar in appearance to the closely related plain prinia, the yellow-bellied prinia can be distinguished not only by its more colourful belly but also by its call, which sounds a lot like a cat’s mew. Although its preferred habitats are reedbeds and tall grasses, it is not quite as shy as many other reedbed birds and will often sit on exposed perches to sing (Viney et al, 2005, p. 178).
Chinese Penduline Tit (Remiz consobrinus): This species belongs to a family of birds so named for their pendulum-shaped (penduline) nests that hang from branches. Breeding may also have something to do with its preference for wetland habitats, as building a nest above water may reduce predation of eggs and chicks (Zheng et al, 2018). Unfortunately, you won’t get to see one of these nests in Hong Kong as the Chinese penduline tit is a winter migrant and thus does not breed here (Tipper, 2016, p. 103).
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:
· Tipper, R. 2016. A Naturalist’s Guide to the Birds of Hong Kong, John Beaufoy Publishing, United Kingdom. 40pp., 103pp., 115pp.
· 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. 44pp., 66pp., 178pp., 182pp.
· WWF-Hong Kong, Oldest reedbed bird and new-to-science beetle species found in Mai Po Nature Reserve. The good news marks the beginning of the birdwatching season, [website], 2015, https://www.wwf.org.hk/en/?14320/Press-release-Oldest-reedbed-bird-and-new-to-science-beetle-species-found-in-Mai-Po-Nature-Reserve-The-good-news-marks-the-beginning-of-the-birdwatching-season (Accessed: 9 August 2019).
· Zheng, J., Li, D.L. and Z.W. Zhang. 2018. Breeding biology and parental care strategy of the little-known Chinese Penduline Tit (Remiz consobrinus). Journal of Ornithology, vol. 159 (3): 657pp.–666pp.
