深秋蝶影 Autumn Butterflies

深秋蝶影

今年的秋天姍姍來遲，近日天氣突然轉涼，才驚覺原來早已過了立冬。前天到大欖一帶遠足，山上陣風吹來，已感到點點寒意。大欖郊野公園早前經山火蹂躪，滿目瘡痍，只有少片山谷水源地帶未受波及。穿過這些倖存的小樹林，赫然發覺有蝴蝶在聚集，溪澗中亦散佈著蝴蝶的屍骸。到底這是因為山火令棲息地被毀所造成的後果，還是正常的集體越冬的開始，一時也說不清。

聽朋友說，在山的那一邊，也見到蝴蝶聚集的情景，程度達至「漫山遍野」。蝴蝶漫山遍野的情景，自己也有見過，但是這樣的情況，通常在十二份才出現。

大部份的蝶類，到了冬天就會死亡，牠們完成了一生的使命－繁殖下一代後，已很虛弱，天氣一轉冷，便紛紛死亡。但也有蝶類以成蟲方式度過寒冬，這些蝴蝶會聚在一起集體越冬，為了避寒，會像候鳥一般集體遷移到南方，在溫暖山谷裡等待寒冬過去，香港某些地方，是牠們集體越冬的地點。牠們有的整個冬天都在香港停留，有的則只停留一段時間便繼續南飛，例如虎斑蝶。捱得過嚴冬，這些越冬的蝴蝶就可以在春天北飛回繁殖地繁衍下一代。

早年有幸跟隨蝴蝶專家饒戈到小冷水考察冬天蝴蝶谷，濛濛冷雨中，藍點紫斑蝶漫山遍野的掛滿樹梢，的確是自然奇觀，但更震撼的，是滿地覆蓋的蝴蝶屍骸，經過長途跋涉的飛行，以為可以避過凍僵的下場，但虛弱不堪的軀體，始終捱不過寒冬冷雨的煎熬。此情此景，令人不禁嘆息生命是那麼脆弱。

如果遇上集體越冬的蝴蝶,，還望大家只可靜靜細心觀察，千萬不要作不必要的打擾。有些人為了拍攝蝴蝶滿天飛的奇景，特意驚擾牠們，使牠們亂飛，但是這樣會令牠們消耗體力，提早死亡，無法在第二年春天繁殖下一代。

梁山伯與祝英台為愛殉情，死後化作翩翩彩蝶，脫離俗世的枷鎖，雙宿雙棲，何等浪漫。但現實中的蝴蝶，卻是何等的脆弱，要面對的，是何等殘酷的生存環境。

Autumn Butterflies

Autumn came late this year after the hottest October on record. Only when it suddently got cooler these days that I realized it was in fact already late fall. I could feel the coolness in the air while standing on the hill top during a hiking trip in the Tai Lam area two days ago. The Tai Lam Country Park was in a horrified state after the recent disastrous hill fire. In fact the entire area was burnt to the ground with total loss of trees, leaving only small patches of bushes un-touched near the gully floors. As I walked through these patches of surviving greenery, I saw quite a number of butterflies gathering in the bushes, and dead ones at the dried stream bed too. I had no idea if this was the result of the destruction of their natural habitat by the fire, or was just the beginning of the normal winter gathering habit of the butterflies.

According to my friend, there was a gathering of the butterflies on the otherside of territories too, so many that it could be described as “covering the entire hillside”. I had seen this kind of situation too, but that would normally happen in the late Decembers.

Most species of butterfly die in winter. After having completed their life cycle by laying down clusters of egg at the end of the season, they have come close to exhausting their life and strength, and die as the temperature drops. Some species do gather in flocks and survive the winter in their adult form. In order to escape from the cold weather, they migrate like birds, stay in the warmer valleys in the south until the winter ends. A few spots in Hong Kong have been known to be the sites of such “Winter Butterfly Valleys”. Some stay in these valleys for the whole winter, but some (like the Common Tigers) continue their southbound journey after staying for a few weeks. Only those survive the winter are able to produce their offsprings in the coming spring back in the north.

I have had the privillege to visit one of the winter butterfly valleys in Siu Lang Shui with the local butterfly specialist Vor Yiu years ago. In the winter drizzle, the sight of tens of thousand of Blue-spotted Crows hanging on trees all over the hill-side was turly spectacular, but the valley floor covered by thousands of died butterflies was a much more shocking scene. After flying for thousnads of miles and hoping to escape from death by freezing, their exhausted bodies were eventually unable to survive the cold winter shower. By looking at that horrifying scene, one could not stop thinking how fragile life could be.

In order to take photos of a spectacular scene, some people would make the exhausted butterflies fly by disturbing them. I strongly against this kind of activity, since that will be a further and fatal drain on their already weakening strength.

In the romantic Chinese legend of the Butterfly Lovers, Liang and Zhu ended their own life in order to escape from the controls of their fathers and the patriarchal society, and transformed into a pair of butterfly, staying togather forever. However, the survival of a butterfly is by no means close to romantic but brutal in real life.