Happy New Year to all! The weather in Hong Kong has finally turned cooler, giving us some refreshment as we wandered up and down the mountain, opening and checking the nets. It was an incredibly quiet day today, but none the less with some wonderful birds!

各位新年快樂！香港天氣終於變得涼快，為戶外環誌工作帶來一絲涼意。儘管今天樹林非常安靜，但幸好我們仍成功捕獲了一些有趣的鳥類！ 

A quick reminder for everyone that, now we are in 2024, all our birds have gained 1 calendar year. This means that young birds, 1st calendar years in Autumn, will now be 2nd calendar years. In addition, adult birds, 2nd calendar year or older, will now be 3rd calendar year or older.

順帶一提，踏入2024年意味所有野鳥的鳥齡也增加了一歲。換言之，2023年出生的幼鳥在秋季時是1齡，現在就是2齡了。至於2齡或以上的成鳥，現在已經3齡或以上了！ 

註：「齡」指的是以日曆上的一年計算年數，而非滿一年的歲數。 

First up was a gorgeous Chestnut Bulbul, showing a beautiful uniform wing, and adult-type red iris. We believe that these guys carry out a Summer Complete moult in both adults and juveniles. In Autumn, we would age them by the iris, but now, so late in the season, we cannot be sure that this is not a young bird which has developed an adult-type iris. Thus, we age this bird as a 2nd calendar year or older.

首先捕獲的是一隻栗背短腳鵯，牠擁有一片羽毛均勻的翅膀，以及成鳥特有的紅色虹膜。雀鳥的羽毛和虹膜顏色是推斷雀鳥年齡的重要工具。一般而言，大多鵯科成鳥和幼鳥會於夏季完全換羽——即是替換全身所有羽毛。在秋季，我們會透過虹膜顏色來判斷牠們的年齡，但由於現在已經是春季，我們無法確定這是否是一隻發育為成鳥虹膜的幼鳥。因此我們估計這隻栗背短腳鵯是2齡或以上。 

Next up was a beautiful little Eastern Crowned Warbler! This species is common during spring and autumn period but relatively very scarce in winter months. These guys have a little more complex moult, with adults carrying out a Complete Summer moult, while juveniles carry out a very restricted Summer partial moult, which usually does not affect the wing. In Autumn, it can be difficult to differentiate the adult and juvenile feathers. However, but the new year, juvenile feathers, which are of a lesser quality than adult feathers, are quite noticeably more worn. Furthermore, in the winter, both adults and juveniles carry out Winter partial moults. This means that, though both adults and juveniles will show moult limits in Spring, the moult limit (also known as moult contrast) is far more obvious in juveniles (with their retained and very worn juvenile feathers) than adults.

此外，我們捕獲了一隻十分漂亮的冕柳鶯！柳鶯科的換羽比較複雜，成鳥會於夏季完全換羽，而幼鳥只會小範圍地於夏季局部換羽，而且通常不會更換飛羽。因此在秋季很難區分成鳥和幼鳥的飛羽。然而在新一年，由於幼鳥的羽毛較成鳥的質量較差，有更明顯的磨損，加上成鳥和幼鳥會於冬季局部換羽，這意味著成鳥和幼鳥會在春季出現換羽反差，當中幼鳥的反差會更明顯，因為幼鳥的羽毛有較嚴重的磨損。 

Saying this, there are still many individuals that may be tricky to age (and some that are best left unaged). Our individual has quite a nice wing, however the PCs are clearly worn and bleached. Furthermore, the tail is also clearly juvenile, being loose and bleached with narrow and pointed feathers. Therefore, we can conclude that this is a 2nd calendar year bird!

儘管可根據雀鳥的換羽狀況推斷年齡，但仍很難判斷許多雀鳥的年齡，有些無法判斷的則列為年齡不詳。而我們這次捕獲的鶯的翅膀羽毛狀況良好，但初級覆羽有明顯磨損和褪色。此外，尾羽明顯是幼鳥的羽毛——結構鬆散、有褪色、形狀狹長又尖銳，因此推斷牠是2齡。 

The day drew on, and we ended with another beautiful phylloscopus warbler that we do not catch so often- Goodson’s (also known as a Hartert’s) Leaf Warbler! This is a much larger Leaf Warbler than the similar Pallas’ Leaf Warbler, and lacks the yellow rump seen in Pallas’, with a crown stripe that differs it from the similarly sized/shaped Arctic/Pale-legged Leaf Warblers.

這天以一隻顏色鮮艷的柳鶯——華南冠紋柳鶯作結。過往我們的鳥類環誌工作較少捕獲到這種柳鶯，牠外形與黃腰柳鶯相似，但體型大很多，腰部並非黃色，而且頭頂上有明顯的冠紋，可藉此區分出大小及形狀相若的極北柳鶯及淡腳柳鶯。 

When it comes to ageing, these guys are similar to the Eastern Crowned Warbler, with adults Summer Complete, juveniles summer partial, but fairly difficult to differentiate in Autumn. Both adult and juveniles also carry out a Winter partial moult, but the extent of this is not entirely known. Interestingly, our bird showed three retained GCs (outermost) and the rest moulted. By studying these, as well as the unmoulted PCs and outermost alula feather, we can determine that these are juvenile feathers. In further support of this, we can see in the tail that two feathers are moulted (R1 & R6 on the right side), and are significantly broad and denser than the retained feathers. Again, this means these old feathers must be juvenile, and this bird must be a 2nd calendar year!

年齡方面，華南冠紋柳鶯與冕柳鶯的換羽規律相似，成鳥於夏季完全換羽，幼鳥則於夏季局部換羽，所以同樣地於秋季難以區分成鳥和幼鳥。而在冬季，成鳥和幼鳥會局部換羽，但難以掌握牠們換羽的程度。值得一提的是，這隻華南冠紋柳鶯具三根未換羽的幼鳥大覆羽（最外側），其他則換成了新的大覆羽。根據牠覆羽的換羽程度，我們推斷這些是幼鳥的羽毛。此外，由於牠尾羽上有兩根成鳥尾毛（右側的R1和R6），比還未替換的尾毛更寬及更緻密，意味著這些舊羽毛必定為幼鳥的，由此可判斷這隻鳥是2齡。 

Daily Totals 全日總數 

*Please note that all wild birds, their nests, and eggs are highly protected (under Wild Animals Protection Ordinate, Cap. 170) in Hong Kong. It is an offence to wilfully disturb, take, remove, or injure wild birds or their nests/eggs. The actions described here were undertaken by trained professionals holding the necessary licenses and permits issued by the AFCD.*

註：根據香港《野生動物保護條例》第 170 章，任何人未經許可，不得捕捉或故意干擾、帶走、移除或傷害任何野生雀鳥或其巢或蛋，否則即屬違法。香港觀鳥會的鳥類環誌研究已獲得漁農自然護理署發出的特別許可證。所有鳥類環誌員都受過專業訓練，由資深鳥類環誌員帶領，一切以雀鳥為先。