The article on the distribution and habitat preferences of Chinese Grassbird in HK is very good. The authors conclude that most sites at which grassbirds have occurred in the past continue to support the species. The overall density of birds in appropriate habitat is estimated at 0.13 birds/ha, while the HK population is estimated at 490. Both these are higher, and no doubt more accurate, than the back of envelope calculations that Paul Leader and I made in our paper. It occurs in grassland dominated by Miscanthus sp. at altitudes from 200m up; as the authors point out, that leaves local populations vulnerable to hill fires, as was vividly shown in recent years at Robin's Nest, one of the strongholds of the species.
If the paper has any drawbacks, it is these. Firstly, I'm not sure how valid it is to estimate the HK population by extrapolating across all grassland above 200m, as grassbirds appear to prefer 'rich grassland'. Not all grassland in HK is of this quality, and for this reason I feel the population estimate may be a little high. Secondly, while the paper rightly points out that almost all sites with records of the species are inside protected country parks, there is no mention of the (in my opinion) significant threat posed by vegetation succession, whereby grassland turns to shrubland. It seems to me that there is a need to assess the practicality of preserving via habitat management swathes of grassland in different areas of HK in order to conserve the populations of this and other grassland-specialists such as Lesser Coucal, the locally-breeding taxon of Richard's Pipit A.r. sinensis, Upland Pipit, Chinese Francolin, Savannah Nightjar and Eagle Owl.
A very good and interesting paper though, and well worth reading.
