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BWA 19/07/2008 14:33

633

游隼是燕鷗的天敵,
不時會飛去燕鷗島找吃的,
最近在某燕鷗島就曾親眼目睹一次。

游隼一出現,
所有燕鷗都飛到半空,一邊飛一邊叫,
就像全島都響起空襲警報。
燕鷗人人自危,不敢落下,
反應跟有人登島相似。

就如 Isaac 估計,當日的游隼可能是老手,
停在一塊大石下面不動,
燕鷗俯衝過去驅趕,由於要避免撞到石上,
飛到相當距離就要拉起爬升,
而游隼就可以安全地藏身在下面等候。

如是者擾攘了半小時,燕鷗的叫聲忽然轉急,
我們還未看清楚,已經見到游隼抓住一隻褐翅燕鷗飛過來,
而不少燕鷗就在後邊追趕。

由於燕鷗島離陸地較遠,
游隼不容易將獵物全身而退帶走,
所以選了一個安全地方就地解決。
牠藏身在另一塊大石下,拔毛進食。
雖然在場的燕鷗不斷俯衝驅趕,
但都不得要領。

由於海上浪大,
用 dc 拍 video 不斷震動,
只好摘錄了 4 格可以看得清的貼出來:
黑枕燕鷗俯衝攻擊游隼。
Black-naped Tern diving at Peregrine Falcon, which has taken a Bridled Tern.
[IMG]http://i89.photobucket.com/albums/k232/HKBWA/Birds/080718-dive-a.gif[/IMG]

標題何解 - 一齣老電影,
又許應該改為 Star Wars X Fighter Mission。

[[i] Last edited by BWA at 19/07/2008 14:40 [/i]]

gary 19/07/2008 23:19

不祥之兆!
一隻游隼對燕鷗的影響有多大?
我覺得很視乎那隻游隼在附近地區逗留多久。
依我觀察,當游隼發現一個取之不竭的食物庫(燕鷗島)後,牠便會重覆地回到該處獵食。
而且牠往往會在島上慢慢進食,並不懼怕燕鷗的滋擾。
這時燕鷗通常都會在空中驚叫亂竄,絕不會返回島上。
游隼進食的時間越久,燕鷗就離島越遠。
不幸的是島上的島蛋及雛鳥久久未有母鳥照料,但沒有一隻母島敢飛回巢。

如果游隼只是偶然突襲,那還不會造成太大影響,但當情況持續,那就大事不妙了。
每天重覆又重覆的追捕,令燕鷗疲於應付,至於鳥蛋及雛島就命途多舛。
直到最後所有雛鳥都沒了,那燕鷗島上母鳥也不戀棧小島,漸漸亦四處游蕩。

真的會發生這樣的事情嗎?
依我觀察,三年前的燕鷗島就是發生了這樣的事情,導致最後一隻成功出巢的雛島也沒有。(有無人見到?)

那為甚麼游隼每天都來獵食?
我最初覺得牠只是為了獵食而短暫停留。但及後當繁殖季節過後,我在遠處的山崖邊發現了一個似是游隼的棄巢。
這是解釋了為甚麼游隼每天都到訪了。亦令我記起有一次見到游隼吃力地把獵物帶走的場面。

雖然有人並不同意我的睇法,認為游隼一日只可食掉一隻燕鷗,兩會月只會吃走60隻,影響不至於令燕鷗島「鳥」去「島」空。
但我始終認為一隻游隼的影嚮力非常之大。

以生態學去解釋,捕獵者與獵物的關係是非常dynamic 的,當獵物充足時,便會吸引捕獵者,但當獵物都被吃得七七八八,捕獵者亦會離去。
物競天擇,燕鷗的一生就是這樣坎坷,亦解釋了為何牠們一直都沒有一個穩定的繁殖地。

[[i] Last edited by gary at 20/07/2008 14:54 [/i]]

isaac_chan 20/07/2008 00:19

這日燕鷗島來了一隻不速之客──一隻遊隼登上燕鷗島....
A Peregrine Falcon arrived on a tern island.
[img]http://farm4.static.flickr.com/3004/2681582591_d0839eb605_o.jpg[/img]

[img]http://farm4.static.flickr.com/3037/2681582885_9275003277_o.jpg[/img]

[img]http://farm4.static.flickr.com/3229/2681583163_4a521b8811_o.jpg[/img]

[img]http://farm4.static.flickr.com/3114/2682401836_599acf3924_o.jpg[/img]

[img]http://farm4.static.flickr.com/3086/2681583763_639363a0bf_o.jpg[/img]

牠看來很有經驗, 站在燕鷗不能直接攻擊的位置. 燕鷗無法趕走牠, 所以燕鷗只能在上空盤旋, 間中有一兩隻會降落, 但短時間內又會再起飛.
The Peregrine Falcon seemed to be experienced, it stood on a position where the terns could not attack it.

過了大半個小時, 氣氛急轉直下. 全島的燕鷗看來都十分緊張地飛, 當我們還在想是不是遊隼出擊的時候, 遊隼已經捕殺了一隻褐翅燕鷗. 其間燕鷗都似乎有嘗試攻擊.
Later, the terns seemed to be flying frightened. While we were thinking whether the Peregrine Falcon started its attack, we saw it already caught a Bridled Tern.
[img]http://farm4.static.flickr.com/3246/2682402248_1358b8a2b1_o.jpg[/img]

遊隼得手後, 仍然飛回去燕鷗島上, 只是找另一個, 也是燕鷗未能直接攻擊的位置開始進食.
Then it came back to the tern island, and chose another position where the terns also could not attack it and started its meal.
[img]http://farm4.static.flickr.com/3091/2681584223_3ab5d5a6d2_o.jpg[/img]

季初還奇怪為何不見了香港足旗的褐翅燕鷗, 但現時不用再找了....
Oh, it caught a Hong Kong flagged Bridled Tern.
[img]http://farm4.static.flickr.com/3267/2681584589_4cc337e015_o.jpg[/img]

[img]http://farm4.static.flickr.com/3255/2681584973_d1505792c8_o.jpg[/img]

[img]http://farm4.static.flickr.com/3085/2681585279_398fd8648c_o.jpg[/img]

[img]http://farm4.static.flickr.com/3240/2681585613_eb279d2731_o.jpg[/img]

[img]http://farm4.static.flickr.com/3221/2682404182_a7d3ec6f53_o.jpg[/img]

[img]http://farm4.static.flickr.com/3244/2681586323_57186d6b5b_o.jpg[/img]

我相信這遊隼確實很有經驗, 看牠站的位置就可以想像. 牠站的又是燕鷗不能夠攻擊的位置.
I believe that it is experienced, it stood on a position where the terns also could not attack it.
[img]http://farm4.static.flickr.com/3091/2682404902_cb018a27db_o.jpg[/img]

[img]http://farm4.static.flickr.com/3063/2682405186_6203cf2f22_o.jpg[/img]

[img]http://farm4.static.flickr.com/3151/2681587331_83e4be14f3_o.jpg[/img]

牠好像在說 “不要阻礙我開餐”.....
It seemed to be yelling "Not to disturb my meal"
[img]http://farm4.static.flickr.com/3258/2682405790_ea71074c15_o.jpg[/img]

拔毛....
Pulling off those feathers....
[img]http://farm4.static.flickr.com/3284/2681587945_84cdd2305f_o.jpg[/img]

[img]http://farm4.static.flickr.com/3097/2681588301_bc20f089c0_o.jpg[/img]

[img]http://farm4.static.flickr.com/3284/2681588659_f6afc971b9_o.jpg[/img]

[img]http://farm4.static.flickr.com/3132/2682407142_4e26c69fef_o.jpg[/img]

[img]http://farm4.static.flickr.com/3135/2681589361_ba059cb364_o.jpg[/img]

吃到肉了....
Eating the meat....
[img]http://farm4.static.flickr.com/3088/2681589719_98f58e0cf5_o.jpg[/img]

[img]http://farm4.static.flickr.com/3150/2682408270_f6eb145ef1_o.jpg[/img]

[img]http://farm4.static.flickr.com/3010/2682409742_f78ce6517d_o.jpg[/img]

[img]http://farm4.static.flickr.com/3278/2682408638_96751b29c8_o.jpg[/img]

[img]http://farm4.static.flickr.com/3032/2682409028_cd8b57a9b1_o.jpg[/img]

[img]http://farm4.static.flickr.com/3144/2681591225_3df7d1c3f6_o.jpg[/img]

[img]http://farm4.static.flickr.com/3038/2682410084_f3995072ea_o.jpg[/img]

遊隼料理桌....
[img]http://farm4.static.flickr.com/3097/2681592253_ddeddd9dfc_o.jpg[/img]

[img]http://farm4.static.flickr.com/3204/2682410716_0657063d0d_o.jpg[/img]

[img]http://farm4.static.flickr.com/3234/2681592959_e0ef46a12c_o.jpg[/img]

[img]http://farm4.static.flickr.com/3193/2682411416_f5c2829e82_o.jpg[/img]

當我們離去時這遊隼仍未吃完....
When we left there the Peregrine Falcon was still having its meal.

[[i] 本帖最後由 isaac_chan 於 20/07/2008 01:16 編輯 [/i]]

kmike 20/07/2008 00:44

Amzing series of pix Isaac - well done!

Looks like the tern was colour-ringed ringed in Hk from the leg flags.  

How many yaers has this been done? It wouldbeinteresting to know to give an indicator of how old the tern is.

Cheers
Mike K

BWA 20/07/2008 00:57

[quote]Original posted by [i]gary[/i] at 19/07/2008 23:19 [url=http://www.hkbws.org.hk/BBS/redirect.php?goto=findpost&pid=12366&ptid=5477][img]http://www.hkbws.org.hk/BBS/images/common/back.gif[/img][/url]
不祥之兆!
一隻游隼對燕鷗的影響有多大?
我覺得很視乎那隻游隼在附近地區逗留多久。
依我觀察,當游隼發現一個取之不竭的食物庫(燕鷗島)後,牠便會重覆地回到該處獵食。
而且牠往往會在島上慢慢進食,並不懼怕燕鷗的滋擾。
這 ... [/quote]

今年在兩個燕鷗島都見過游隼,
據個人觀察,游隼喜歡選擇褐翅燕鷗下手,
而黑枕燕鷗的自衛能力較高,
最少曾見過兩次成功將游隼趕走,
而兩次拍得游隼得手的都是褐翅燕鷗,
上次的照片見《香港鳥類攝照圖鑑》及《燕鷗 海上的精靈》小冊。

[[i] Last edited by BWA at 20/07/2008 01:01 [/i]]

BWA 20/07/2008 00:58

[quote]Original posted by [i]kmike[/i] at 20/07/2008 00:44 [url=http://www.hkbws.org.hk/BBS/redirect.php?goto=findpost&pid=12369&ptid=5477][img]http://www.hkbws.org.hk/BBS/images/common/back.gif[/img][/url]
Amzing series of pix Isaac - well done!
Looks like the tern was colour-ringed ringed in Hk from the leg flags.  
How many yaers has this been done? It wouldbeinteresting to know to give an indicator ... [/quote]

I understand that the last time was around 2004.

cchristina 20/07/2008 20:20

2008.7.18
Eastern Waters of Hong Kong

[img]http://images4.fotop.net/albums2/yinming/raptors/image8O6I0962.jpg[/img]

[img]http://images4.fotop.net/albums2/yinming/raptors/image8O6I0993.jpg[/img]

[img]http://images4.fotop.net/albums2/yinming/raptors/image8O6I1012.jpg[/img]

ajohn 21/07/2008 14:54

[quote]Original posted by [i]BWA[/i] at 20/07/2008 00:58 [url=http://www.hkbws.org.hk/BBS/redirect.php?goto=findpost&pid=12371&ptid=5477][img]http://www.hkbws.org.hk/BBS/images/common/back.gif[/img][/url]


I understand that the last time was around 2004. [/quote]

This is correct - the last birds were ringed/flagged in 2004, meaning that this individual is at least 4 years old. It's a shame the ring could not be recovered to identify the bird for certain.
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