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   家鴉問題 The House Crow Problem

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Topic: 家鴉問題 The House Crow Problem (Read 7587 times)

Webcreeper
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Re: 家鴉問題 The House Crow Problem
« Reply #15 on: Jun 9^th, 2004, 10:33pm »

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一個小小的有關家鴉的網站，可以看到牠們在全球的分佈。

A small web site on House Crows. You can see how they have spread worldwide.

http://colin.ryall3.users.btopenworld.com/index.htm

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鳥友Ａ(BWA)
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Re: 家鴉問題 The House Crow Problem
« Reply #16 on: Jul 8^th, 2004, 10:59pm »

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昨晚聽了資深鳥類研究者 Mike Leven 先生的家鴉講座，內容頗為豐富，值得和鳥友分享，現將內容摘錄如下：

各地的家鴉問題
家鴉原藉印度次大陸，但是人類有意無意的將牠們帶到世界各地。目前在馬來西亞、也門、波斯灣、肯尼亞、桑給巴爾、坦桑尼亞、南非、埃及和紅海、約旦/以色列和毛里求斯等地都已經建立了繁殖種群。此外，遠至歐洲、美國的東西兩岸、南美洲的智利和日本等地都有發現。

新加坡的家鴉問題尤其嚴重，現在已達13萬隻，當地政府要持續的每年殺4萬1千隻，才能將情況穩定下來。

家鴉生性合群，常在城市、鄉村和港口活動，愛在大樹上棲息，食性很雜，任何可以吃的東西都會吃。牠們的繁殖能力驚人，在新加坡平均每巢產2.8隻，每年繁殖可達4次之多。

家鴉在香港
遠自1974年香港便有第一個記錄，此後數目逐漸增加，到2000年西九龍便有20隻，而漁護署最近的調查則估計目前超已過200隻。曾發現家鴉的地點主要是九龍塘和深水[土步]，另外在長沙灣、葵涌貨柜碼頭、大埔、米埔和尖鼻嘴都有。

在市區內，家鴉常在公園內的大樹上棲息，喜接近民居、貨柜碼頭和批發市場活動，因為那裡容易找到食物。其他地方如新市鎮、鄉村、農地、后海灣的魚塘都是牠們理想的生活環境。

家鴉的為害
家鴉對本港的不良影響包括

對生態：

襲擊本地原生雀鳥的蛋和雛鳥
驅走市區內的其他「清道夫」（如八哥）
控制家鴉的方法（如毒殺、播放噪聲、砍樹等）可能會間接殃及其他生物

對人類：

家鴉可能會襲擊人類（如果人類接近牠們的巢）
噪音
鳥糞
疾病
惹起人對其他雀鳥的反感

如何控制？
除了在故鄉印度之外，家鴉在世界各地都成為破壞生態的有害物種，如果不馬上著手控制，問題可能會一發不可收拾。各地控制家鴉的成效不一，有些地方稍一鬆懈，家鴉的數目便在幾年間同復原狀。連貧窮落後如非洲國家都要花錢對付，可見問題之大。澳洲和塞舌爾群島就實行「就地射殺」，防止入口的家鴉建立種群。

對付家鴉的方法，包括用鎗射殺、下毒、破壞鳥巢、殺死鳥蛋、設置陷阱、減少食物來源（保持地方清潔）、減少停棲地點（如大樹）等，各有長短，但是最後兩種只可以治標，還會將鳥趕到其他地方擴散。

漁護署今年曾試用播放驚叫聲和殺死鳥蛋的方法，並且正在試驗捕鳥裝置。

一點個人意見

防患未然，現在正是控制家鴉問題的最重要時機，如果不立刻採取果斷的行動，讓種群坐大，我們很可能會步新加坡的後塵，到時就後悔莫及。

鳥友可以做甚麼
目前漁護署的調查只集中在市區，各位鳥友如果在其他地方發現家鴉的縱跡，請向漁護署報告（電話 2150 6923），並在本新聞組留言，協助當局監察問題的發展。

« Last Edit: Jul 9^th, 2004, 8:51pm by Webcreeper »

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假鳥迷
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Re: 家鴉問題 The House Crow Problem
« Reply #17 on: Jul 9^th, 2004, 12:17pm »

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我估計家鴉的分佈廣泛了很多，最近平年我每早上班時，在九龍站對出西隧收費廣場都見到有一、兩隻家鴉。

不知鳥友們有沒有在其他地方見到他們的蹤影。

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Re: 家鴉問題 The House Crow Problem
« Reply #18 on: Jul 9^th, 2004, 3:06pm »

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其實可不可以幫牠們絕育的

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Re: 家鴉問題 The House Crow Problem
« Reply #19 on: Jul 14^th, 2004, 11:31am »

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Thanks for Mr Mike Leven sharing with us his presentation on House Crow. Please find below PDF file for members' reference:

http://www.hkbws.org.hk/fileServer/Projectofficer/conservation/House%20C rows.pdf

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Webcreeper
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Re: 家鴉問題 The House Crow Problem
« Reply #20 on: Dec 13^th, 2004, 12:37pm »

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家鴉似乎已擴散到荃灣海濱花園，如果各位在野外見到這些「灰背心(Etta 語)黨」，請馬上向漁護處報告，並將消息貼在這裡。

It seems that House Crows have already spread to Riveria Gardens in Tsuen Wan. If you see any members of these "Grey Vests" (after Etta) in the field, please report immediately to AFCD and leave a message here.

« Last Edit: Dec 13^th, 2004, 5:30pm by Webcreeper »

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Etta
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Re: 家鴉問題 The House Crow Problem
« Reply #21 on: Dec 13^th, 2004, 2:19pm »

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嘻，家鴉的「灰背心」辨識方法也是跟鳥界前輩學的，
希望家鴉不會四處「聚眾成黨」囉～～

Etta

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Little Dolphin
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Re: 家鴉問題 The House Crow Problem
« Reply #22 on: Dec 13^th, 2004, 3:36pm »

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It only seems that the house crows are spreading further...

Introduced species are a very serious problem worldwide. For example, in Hawaii, only less than 20% of the species of animals there are native.
There's a very good documentary film on the threats of introduced species (and other threats to wildlife as well) by Sir David Attenborough called "State of the Planet" (《地球命運在你手》).

Have anyone here been to Vancouver? The crested myna was introduced there about 100 years ago. Great flocks of them used to fly around the city (and displaced many other birds), but in recent years they are being displaced by yet another introduced species. Now they are almost extinct in Vancouver. Want to guess what displaced them?

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Re: 家鴉問題 The House Crow Problem
« Reply #23 on: Dec 13^th, 2004, 4:16pm »

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QUOTE : Competition from introduced species such as the European starling also put pressure on the myna population.

source : http://www.vancourier.com/issues02/101102/news/101102nn1.html

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Re: 家鴉問題 The House Crow Problem
« Reply #24 on: Dec 13^th, 2004, 5:24pm »

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Yes, one reason of the crested myna's decrease in Vancouver is displacement by European starling. Never thought the people there miss the mynas so much, though.  

Perhaps people will miss the house crows after they are eliminated from Hong Kong as well, or perhaps not?

The house sparrow mentioned in the article given by Owen is also introduced into Vancouver, and is now one of the commonest bird there. So are the pigeons (i.e. rock dove) in the article.  

« Last Edit: Dec 13^th, 2004, 5:24pm by Little Dolphin »

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Any man's death diminishes me, because I am involved in mankind, and therefore never send to know for whom the bell tolls; it tolls for thee.
--- John Donne (1572-1631)

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Re: 家鴉問題 The House Crow Problem
« Reply #25 on: Dec 13^th, 2004, 9:13pm »

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Around 15 House Crow were found in the Kowloon Reservior during the Winter Atlas count on 5 December 2004. It seems that the House Crow has dispersed to the area around Sham Shui Po.

William

(Webcreeper 譯)

今年12月5日做冬季鳥類普查時在九龍水塘見到約15隻家鴉，牠們好像已從深水[土步]向週圍擴散。

« Last Edit: Dec 13^th, 2004, 9:33pm by Webcreeper »

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Jimmy_choi
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Re: 家鴉問題 The House Crow Problem
« Reply #26 on: Dec 14^th, 2004, 12:35am »

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  I played frisbee every sunday (3pm - 6pm) in the glass field at Tai Hang Tung, Kowloon (near Mong Kok stadium) and saw this species hanging out in large flocks, at least 10 individuals, since November.

  Crows and corvus spp. in general are smart birds, scientific studies found that they are tool user and have learnt to use human being - A type of crow in Japan learnt to use motor cars to crack open chestnut or something that would otherwise not be available to them. Most corvus sp. are opportunistic feeder and do really well despite human development.

    Hong Kong is actually a bit weird not to have many crows or corvus spp. Of course, it doesn't mean that the house crow should not be controlled. We should in fact resolve the problem as soon as possible since the corvus sp are usually fast breeder.

(Webcreeper 譯)
每逢週日下午三時到六時，我都會在九龍大坑東（旺角球場附近）玩飛碟，今年九月開始見到大群家鴉在那裡留連，最少有十隻。

鴉科鳥類大都並常聰明，研究發現牠們懂得使用工具，包括利用人類－日本有一種烏鴉會借助駛過的汽車打開栗子。多數鴉科鳥類都會順應環境調整食性，能夠在有人為發展的地方開枝散葉。

香港的鴉科雀鳥不算多，實在有點奇怪。當然，這並不表示我們不用控制家鴉的數目，反而要盡早處理，因為牠們的生育率甚高。

« Last Edit: Dec 14^th, 2004, 11:30pm by Webcreeper »

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Koel_Ko
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Re: 家鴉問題 The House Crow Problem
« Reply #27 on: Dec 15^th, 2004, 5:25am »

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I think that a conservative method is more applicable here.

1. I suspect that House Crow has a limited scope of expansion in HK because the environment in HK is different from that in Singapore. There are far more mountainous and woodland area in HK, and our cities are more densely populated. This means that House Crow, as a commensal of man, may find it difficult to expand on both fronts GIVEN that feeding CEASES.

2. Methods of dealing with House Crows may bring about a larger than acceptable risk to native species such as Large-billed Crows (!NATIVE!) and other corvids. Poisoning potentially threatens other scavengers (other corvids again). I think intensive monitoring suffices for the time being, but control methods should be formulated in case a sharp rise is detected.

3. Competition from Crows and Magpies + parasitism from Koel (is it observed in the field IN HONG KONG?) may be checking expansion of House Crows already.

4. If the problem escalates, SPECIES SPECIFIC methods may be better - targeting nests, RELEASING STERILISED INDIVIDUALS (this has been successful in other animals but I don't know about birds).

Of course I'm not researching in the field - so please correct if it sounds funny.

A last note - the more people speak about it the more it helps in such a complex environmental issue. Go on!

« Last Edit: Dec 15^th, 2004, 5:32am by Koel_Ko »

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