November 139

短 報 Short Communications

Jpn. J. Ornithol. 49:139-144, 2000

First Records on Nidification and Breeding Biology of Amami Thrush Zoothera dauma major (Ogawa), Amami Oshima, Japan

Aleem Ahmed KHAN and Yasuhiro YAMAGUCHI

Amami Thrush Zoothera dauma major is Thrush would help to carve the way for fu- the island endemic subspecies at Amami ture and immediate conservation efforts Oshima, Ryukyu Islands, Japan. There are needed to safeguard the small population two groups in Oriental Zoothera dauma sub- from extinction. species complex based upon their morpho- logical and vocal analysis. One group MATERIAL AND METHODS comprises four races and evolved from White's Thrush Zoothera dauma aurea, being Amami Thrush could be recognised due to the major related species. On the other hand, its number of field identification. It is over- second group consists of five races, origi- all quite large in size. Head is protruded. nated from Scaly Thrush Zoothera dauma Gape is yellow. Heavily spotted from upper dauma as being the major related species breast to belly. Under wing covert bands are living in the Himalayas (Khan unpublished). pale creamy white. Conspicuous light central Amami Thrush is believed to be the close band on upper wing coverts. Belly ground kin and relict subspecies of Scaly Thrush color is pale creamy white. On tail, the lat- (Cramp 1988). The population of Amami eral feathers dark gray brown fading to Thrush is critical and contains a sum of 75 whitey-brown on the outer most and tipped pairs in the wild (Khan and Takashi unpub- with white while central four feathers olive- lished). Hence, the present status of Amami brown. At the terminal end of upper tail- Thrush is critical and needs vigorous efforts coverts there are extended hammer shaped to safeguard its local habitat (BLI 1998, spots. There are 12 tail feathers (Kuroda Takashi et al. 1999). There has been no de- 1925) in case of minute analyses. Tarsus are scription on breeding biology of Amami pale yellowish gray. Thrush in the past. Since this island en- A total of 1,348 minutes observations demic sub-species is fast heading to the were noted through Digital Video Recording brink of extinction from its primitive haunts (20X) System (DVRS) for five days (Table at Amami Oshima, these maiden observa- 1). It excludes all those observations taken tions on the breeding biology of Amami separately without DVRS. Sound was re-

* Corresponding author , E-mail: [email protected] 140 Short Communications [Jpn.J.Ornithol. Vol. 9 No. 3

Table 1. The details of study period.

corded through highly sensitive parabola mi- placed at a height of 11.5 m on an old stand crophone (Telinga Ltd. Scientific of Elf tree Schefflera octophylla, with DBH as

Microphone) used for bird studies on Mini- 0.63 m (diameter at the breast height, 2m disc recorder (SONY MZ-R55). Observations /3.14=0.63), at approximately 45 •Kangled were also made with the help of 8x40 bin- slope near the forest track over Sumiyogawa oculars and 20x60 fieldscope. River. The nest was smartly placed in a fork

of an old stand of Elf tree.

Since the nest was deserted after May 26, RESULTS 1999 and had not been checked as precau-

The nest of Amami Thrush was found on tion to avoid disturbance, in case•Cparents

May 20, 1999 at Kamiya forest (28•Ž16' N, may reattempt for another clutch. The nest

129•Ž 24' E) down into the valley approxi- was carefully observed from a distance, for mately 100 m east of the Sumiyogawa River a number of times from May till August

Dam. The area comes in the vicinity of 1999 but it had not been tried again, as per

Sumiyo village (Fig. 1). The nest site was habit of the other members of this subspe- surrounded by a mixed stand of Oak and cies. On expiration. of nesting period and by

Elf trees with loose under growth, being observing the very partial uprooting of the steep. However, the over story was quite nest from northern side due to summer ty- dense since there were a number of old trees phoons, the nest was approached for the with bird's-nest fern Asplenium nidus grown first time on September 27, 1999. However, on most of these stands. The light penetra- to study further and to be of useful for fu- tion was at the minimum and also coupled ture scientists, the nest was secured on the for restricted undergrowth. The nest was same day and submitted to Yamashina built about 20 m inside the forest from the Institute of Ornithology, Abiko City, Japan. forest track and almost 40 m from the river- The nest was a wider cup-shaped with side. The positioning of the nest may help depth of cup 51-61 mm, made largely the bird to absorb the direct thrust of (>70%) with mosses and neatly lined with strong winds or typhoons often encountered twigs (15 to 20%), leaves (5%) and finer in the area. However, the nest was quite ob- rootlets. Foundation of the nest was rein- vious from the southern side and hence forced with twigs, mud and stones (11-12 most of the alert behaviour of the parent pieces, from 3mm in size to 19mm with one was observed while peeping on that side piece of l0mm rotten wood). Outer diameter throughout the study period. The nest was of the nest was 200mm from all angles, November 2000 Short Communications 141

Fig. 1. Location of Amami Oshima and the nest site.

while inner diameter was 127mm from all minimum daily requirements of food by sides, hence shaping the nest in almost Amami Thrush during the breeding period (95%) circular appearance. However, the net and, referred to as 13-14 earthworms per height of outer portion of the nest from the day. The gross average weight of earth- base of the tree-branch was 65mm in the worms at Amami is calculated as 3.6 grams east and 58mm in the west, while 75mm (SD = 0.128, n= 10) and hence the minimum each, to the north and southern directions daily food consumption of the species is esti- (Fig. 2). mated as 50 grams of biomass. Female left It was observed that the male sends a sin- the nest to stray mostly (64%, n=22) after gle vocal signal as whistle to the female at receiving food from male. least 20-70 seconds prior to supply food at It has also been observed that during the the nest. It is described "Chewee-wiop" as study period, female remained on the nest recorded by the help of highly sensitive pa- for 82.27% of the total time. During this rabola microphone on Mini-disc recorder. On time, she was found always incubating the hearing this call, female gets ready and eggs. However, the male stayed at the nest starts opening her wings for take off and for 12.88% of the total time observed and waits for the food. During the study period, had never incubated during his stay near male provided food to female (sometimes the nest. Male always showed surveillance showing typical begging behaviour) at nest and alert behaviour in the absence of female and hence the average time interval be- from the nest. It remained perched from 10- tween food supplies was calculated as 61.27 20 cm on the western side of the nest and minutes (SD=22.22, n=22). It has been ob- had always kept his eyes on the eggs. served that 95.45% of the diet obtained by However, among the 4.86% of the total female from male were earthworms. The time observed, the nest was left unattended male fed only one earthworm at a time to by either of the parents. During the study female. These results also reflect on the period, continuous alert behaviour was 142 Short Communications [Jpn.J.Ornithol. Vol..49 No.3 November 2000] Short Communications 143 witnessed by female on hearing the call (50- Thrush (Yamashina 1941). Amami Thrush 70 m from nest) of Lidth's Jays (Garrulus is comparatively larger than White's Thrush lidthi) and Jungle Crows (Corvus in size (Kuroda 1925) hence inner dimen- macrorhynchos). However, on 23 May a sions of the nest clearly conform the same Lidth's Jay approached within 10-12 m near difference (Table 2). the nest, female stretched her neck very Similarly, sharing of sexes in incubation straight up and left the nest at once. I heard follows the same pattern in both groups that a colliding sound of wings with branches, is Himalayan Scaly Thrush and White's which defines agonistic (chasing, mobbing Thrush (Yamashina 1941, Cramp 1988, or bill threat) behavioural displayed by the Roberts 1992). The male does not assist fe- female on approaching potential predator. male at all in incubation process except pro- She outmanoeuvred the Lidth's Jay, returned viding food at the nest. Roberts (1992) and resumed incubation. Therefore, it is con- observed a female of Himalayan Scaly cluded that 95.15 % of the total time of in- Thrush building a nest, as she sat inside the cubation period observed, the nest remained cup, shaping it by quivering motions of her protected against predators by the presence body. Male was not found helping at all dur- of either parent hence leads to better ing this process. Keeping our limited obser- chances of nest success. Furthermore, nests' vations in view, it is also presumed in much placement over 10 meters high also reduces the same, for Amami Thrush. In case of the risk of predation by snakes Trimeresurus White's Thrush, male has also been observed sp. to provide food for female at nest (Cramp 1988).

DISCUSSION Senior author is highly grateful to Japan There has been no previous record on the Society for Promotion of Science JSPS and nidification and breeding biology of Amami Monbusho for the post-doctoral fellowship and the financial support rendered for research at Amami Thrush prior to this observation. Whereas, Oshima. Special thanks are indebted to Mr. Ghalib both major related species i.e., Himalayan Yaqub for his help during the fieldwork. We ex- Scaly Thrush and White's Thrush also build tend our appreciation to Ms. Megumi and Mr. M. the nest structure as per our recent observa- Takashi for lending their tangible support. tions. (Baker 1924, Yamashina 1941, Cramp Thanks are also indebted to Dr. Noritomo Kawaji, 1988, Roberts 1992). However presence of Mr. Manabu Kajita, Dr. Morioka and Mr. Edward small stones placed deep inside the nest-bed Dickinson for their valuable comments. had only been recorded in case of White's

Table 2. Comparison of nest dimensions (mm) of Amami Thrush and White's Thrush. 144 Short Communications [Jpn.J.Ornithol. Vol.. 49 No. 3

間の4.86%で あ っ た. LITERATURE CITED Aleem A. Khan,山 口 恭 弘 Baker, E. C. S., 1924. The Fauna of British India,

including Ceylon and Burma. Vol. 2. Second ed. Authors' addresses; (A. A. Khan *) Department of

Taylor and Francis, London. Ecosystem Studies, Forest Ecosystem Studies Lab.,

BirdLife International (BLI), 1998. Checklist of The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Globally Threatened Birds. British Bird Tokyo 113, Japan, (Y. Yamaguchi *) Forestry and

Watching Fair. UK. Forest Products Research Institute, P.O.Box 16,

Cramp, S. (ed.), 1988. Handbook of the Birds of Tsukuba-Norin, Ibaraki 305-8687 Japan •§305- Europe, the Middle East and North Africa: The 8687茨 城県茎崎町松の里1森 林総合研究所 Birds of the Western Palearctic. Volume 5 (Tyrant Flycatchers to Thrushes), Oxford * Present addresses: (Aleem A . Khan) Zoology Univ. Press, New York. Division, Institute of Pure and Applied Biology, Kuroda, N. 1925. A Contribution to the Knowledge Bahauddin Zakariya University, Multan, of the Avifauna of the Riu Kiu Islands and the Pakistan, E-mail: aleemkusa.net (Y, Vicinity. Tokyo Printing, Published by the Yamaguchi) Applied Ornithology Laboratory, Author, Tokyo. National Agriculture Research Center 3-1-1 Roberts, T. J., 1992. The birds of Pakistan. Vol 2., Kannondai, Tsukuba, Ibaraki 305-8666, JAPAN, Passeriformes. Oxford University Press. 〒305-8666茨 城 県 っ くば 市 観 音 台3-1-1農 業 研 究 Karachi. セ ン タ ー病 害 虫 防 除 部 鳥 害 研 究 室 Takashi, M., Kawaguchi, K. & Ishida; K., 1999. Morphological Comparison of Living Zoothera (Received 17 March 2000; Accepted 24 July (dauma) major and Z. d. aurea and a 2000) Recommendation on the Conservation of Zoothera (d) major. Strix 17: 191-196. (in Japanese with English summary) Yamashina, Y., 1941. A Natural History of Japanese Birds. (Nikon no Chorui to Sono Seitai). Vol.2. Iwanami Shyoten. (in Japanese)

奄 美 大 島 に お ける オ オ トラ ツ グ ミの 営 巣 場 所 初 確 認 及 び 繁 殖 行 動 の 記 録 1999年5月20日,奄 美 大 島住 用 村 神 屋 地 区 に て オ オ トラ ッ グ ミの巣 を 一 巣 発 見 し た の で 報 告 す る.行 動 に 関 して はデ ジ タル ビデ オ を 用 い て5月21,23-26日 の5 日間,計1,348分 の 観 察 を 行 った.巣 は住 用 ダ ム の 東 方 約100mの 渓 谷 林 にあ り,胸 高 直 径0.63mの ス ダ ジ イ の 枝 に11.5mの 高 さ に作 られ て い た.巣 は カ ッ プ状 の ほ ぼ 円形 で 外 径200mm,内 径127mm,産 座 の 深 さ51- 61mm,巣 の厚 さ は58-75mmで あ った.巣 の 表面 は大 部 分 が コ ケで 覆 わ れ て お り,小 枝 や 小 根 が 混 じ って い た.土 台 は小 枝,泥,石 で 作 られ て い た.観 察 調 査 中, オ ス は巣 で メ ス に給 餌 してお り,そ の 間 隔 は平 均61.27 分 で あ った.観 察 で きた 給 餌 物 の95.45%は ミ ミズ で あ り,オ ス は一 日 に13-14匹 の ミ ミズを 給餌 して い る と推 定 され た.メ スの 巣 へ の 滞 在 は総 観察 時 間 の82.27%で あ り,そ の 間 は常 に 抱 卵 して い た.一 方,オ ス の 滞 在 は総 観 察 時 間 の12.88%で,抱 卵 す る こ とは な か っ た. メ スが 巣 に い な い 間,オ ス は 巣 の近 くで 警 戒 行 動 が 見 られ た.オ ス メ ス と もに 巣 に い な か っ た の は 総 観 察 時