The White-eared Night Heron (Gorsachius magnificus): from behind the bamboo curtain to the front stage

A heron bird, the White-eared Night Heron (hereafter WENH), Gorsachius magnificus, once, in the 1990s, was believed being the extremely rare one amongst those birds endemic to southern China and hence was considered Critically Endangered (CR) (Collar et al., 1994), then, from the beginning of the 21st century, the Endangered (EN) (BirdLife International, 2000, 2001) and "the most enigmatic Ardeid bird of the world" (Fellowes et al., 2001), furthermore, even as late as in 2004, the bird was still treated being a good sample showing "the main vacuity of knowledge of those critically endangered and endangered birds in China" (BirdLife International, 2004). Whereas, in the last few years, the bird has made us to add, in an accelerated rate, more and more marks of its records on map, showing much larger a distributional range that that night heron could have far been able to occupy.

Those new findings, firstly emerging from the beginning of the 21st century in Jiangxi of central southern China (He and Lin, 2004), led us to think that for a Ardeid bird occurring in such a vast area of southern China with "very similar in general character and natural productions" (Styan, 1902), why so far being reported only in such a strange horseshoe-shaped range of its known appearance (He et al., 2007a)?! With such a doubtful uncertainty in mind, we talked with colleagues in southern China provinces, convincing them to pay more attention on the possible occurrence of the bird particularly in the central south and southwestern China.

Very positive results have actually come out in the last five years — in fact, it took more than two years for confirming the occurrence of the WENH bird in Hunan (province) of central southern China (Li, 2006), about one year for finding the bird in Yunnan of far SW China (Zhao et al., 2006), then, a bit to our surprise, only three months for virtually recognizing the appearance of the bird in Guizhou of SW China (Li et al., 2008), and, quite recently, the record came out from SE Sichuan. Though gaps still seem to be appearing somewhere in SW China, the whole range of the occurrence of WENH that we now could have far learned looks much objectively rational and reasonable than ever before.

In fact, in early 2007, we had already outlined, though roughly, much larger a distributional range of the WENH bird (He et al., 2007a), and, soon after in the same year, based upon the very updated knowledge and understanding, we suggested that the WENH bird might be considered being of 11 subpopulations (He et al., 2007b), which made the viewpoint we offered in early 2007 dramatically out of date. Furthermore, the currently new findings of the bird (Yang et al., 2007; Li et al., 2008; Lin et al., 2008) evidentially revealed that that suggestion is quite rational and practical (See Fig. 1).

Figure  1.  Sketch map of occurrence of the White-eared Night Heron. Localities on the map presented in numerals are to follow Threatened Birds of Asia (BirdLife International, 2001) but for those localities in Guangxi only the ones at the county level remained; whilst, those localities presented in letters are either the newly found ones or the historical ones but newly annotated (He et al., 2007a, 2007b); in most cases the localities on the map are to show the central town of the county, and those letters in red color are to illustrate the localities reported since 2008.

BK = Baokang, BS = Baise, B & X = Ban Thi & Xuan Lac, Ch'An = Chun'an, DJK = Danjiangkou, GT = Gutian, HX = Hengxian, J'An = Jing'an, JD = Jingde, JGSh = Jinggangshan, LL = Lung Ly (Vietnam), LM = Longmen, LN = Longnan, LS = Leishan, LSh = Lushan, LuZ = Luzhai, LY = Liuyang, LZh = Liuzhou, MShH = Manshuihe, NJ = Nanjian, PJ = Pingjiang, PT = Putian, R'An = Rong'An, RY = Ruyuan, SCh = Suichuan, TN = Taining, WF = Wufeng, WeiY = Weiyuan, WX = Wuxuan, WY = Wuyuan, XCh = Xuancheng, XH = Xinhua, XP = Xinpin, XY = Xinyu, YN = Yongning, ZhF = Zhongfang. For Chinese names of the localities mentioned above, please see Appendix 1.

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It is interesting and meaningful to look at the sketch map of localities of the WENH bird recorded so far, from historical to very present, and, for a brief review on the development of the knowledge and understanding on this night heron bird. It therefore might be well noticed that:

1) It took (our species) a hundred years, from 1899, when Whitehead for the first time collected the skin of the WENH bird on Hainan island in the South China Sea and then Ogilvie-Grant recognized it a nova species to science, till 2001 that BirdLife International issued its milestone work Threatened Birds of Asia, to learn the bird though widely occurring in southern China, but being highly sparse, separated, or fragmented of its appearance, with some 20 localities at county level, only (see those numeral marks on the sketch map);

2) Whilst, on the contrary, more than 30 new localities of the bird got reported during the last 10 years with five more provinces, from southern central China (Jiangxi and Hunan) to the whole SW China (Yunnan, Guizhou, and Sichuan) in which there had been totally no WENH bird record in the past, included, and, therefore, making the distributional range of the bird at least twice as large as it used to be thought.

Although we have re-found the bird at a locality in Fujian [Fokien] rather close to the site that the bird once being frequently seen before the 1930s (Caldwell and Caldwell, 1931), which might illustrate a long-term occurrence of the bird to the region, still, we look forward to hearing, sooner or later, the rediscovery of the bird on Hainan Island, the type locality of the species, bringing to us such a true fact that the White-eared Night Heron could have survived for century long at a low population density in a rather isolated habitat of an island.

Whereas, for those very recent new findings, to us, we could hardly say that we have newly found them there, since those WENH birds might have been living there for generations, but, simply, we did not know the true fact since so far. It is hence more properly to say, rather, that those birds are to tell us or to show to us that they are such kind a tribe of bird much preferring to be living beyond human sights, and, on the whole, "the conduct of the bird was more like that of a bittern than of a heron" (Caldwell and Caldwell, 1931).

Now, what we would like to say is, supposing if the WENH is quite a new bird to science only for 10 or 20 years since the first description of it to science, and/or, but, with such an amount of records from almost the whole region of southern China, as those marks in letters on the sketch map have shown, it would be more likely than not that nobody would think the bird is under threat. And, if we treat the WENH as one of the representative birds to the sub-tropic broad-leaf evergreen and deciduous forests in the whole region of southern China including SW China, those recent records might reveal that the bird has conquered the due vegetation zone quite successfully, showing almost a perfect occupation to the whole region. Definitely and doubtlessly, the WENH birds have done it so well.

Even in late 2007, we had outlined a range of over 1000000 km2 that the WENH appeared in mainland China (He et al., 2007a) which soon extended to 1500000 km2 (He et al., 2007b), and now the range of the bird is up to 2500000 km2, according to the methodology recommended by the due Criteria for calculating the extent of occurrence for any species. In fact, the WENH is now, as far known, showing the largest distributional range amongst those birds endemic to southern China.

When looking at the oval-shaped range of the WENH on the mainland China, what we surely can say is that no longer is the WENH in small and highly fragmented flocks but rather well-distributed, and, particularly, when looking at the two axes, both the longer and the shorter, of the ellipse, they are almost totally consisting of those sites which got reported quite recently, that is, for the longer started from XCh in Anhui of E China, westwards to WY – LSh – J'An – XY – PJ – LY – XH – ZhF – LSh – BS till XP and NJ in central Yunnan of far SW China, while, for the shorter, just along the ranges of Mt. Mufu and Mt. Luoxiao running from north to south along the border of Jiangxi and Hunan to the South China range and extended to central Guangdong, rather concentrated are of 10 newly reported sites.

Our field studies on the White-eared Night Heron might be a good sample to illustrate that, for most threatened bird species mainly occurring in mainland China, the more the fieldwork being undertaken, the larger the range of the bird it might get revealed, particularly in southern China, a region strongly under monsoon impact and mostly with its vegetation of sub-tropic evergreen and deciduous forests.

At last, the White-eared Night Heron has been so far nominated a flagship species to those threatened birds occurring in southern mainland China, or, the (Chinese) Oriental Region on the mainland, and, if the status of endangerment of the WENH could be considered downgraded accordingly, it would be to imply that other threatened birds occurring in the same region might get re-assessed in a more careful and objective way.

Acknowledgements

Our sincere thanks might be due to Zoologische Gesellschaft für Arten und Populationsschutz e. V. (ZGAP) in Germany and the Royal Society for the Protection of Birds (RSPB) in the United Kingdom for their successive support on our field surveys in 2002–2003 (ZGAP) and then in 2005–2007 (ZGAP & RSPB) respectively.

Appendix 1

Chinese names for the localities appearing in Fig. 1

BK = Baokang (保康), BS = Baise (百色), B & X = Ban Thi & Xuan Lac (越南北部), Ch'An = Chun'an (淳安), DJK = Danjiangkou (丹江口), GT = Gutian (古田), HX = Hengxian (横县), J'An = Jing'an (靖安), JD = Jingde (旌德), JGSh = Jinggangshan (井冈山), LL = Lung Ly (Vietnam/越南), LM = Longmen (龙门), LN = Longnan (龙南), LS = Leishan (雷山), LSh = Lushan (庐山), LuZ = Luzhai (鹿寨), LY = Liuyang (浏阳), LZh = Liuzhou (柳州), MShH = Manshuihe (漫水河), NJ = Nanjian (南涧), PJ = Pingjiang (平江), PT = Putian (莆田), R'An = Rong'An (融安), RY = Ruyuan (乳源), SCh = Suichuan (遂川), TN = Taining (泰宁), WF = Wufeng (五峰), WX = Wuxuan (武宣), WeiY = Weiyuan (威远), WY = Wuyuan (婺源), XCh = Xuancheng (宣城), XH = Xinhua (新化), XP = Xinpin (新平), XY = Xinyu (新余), YN = Yongning (邕宁), ZhF = Zhongfang (中方)