The damsels occur around irrigation channels in Shihlin 生活在士林地區灌溉水圳的豆娘

In Shihlin (士林), Taipei, there are some irrigation channels though no paddy fields exit in the area nowadays. Those channels are mostly covered and used as sewers in the city. But near hillside, those channels still exist, though most of them are polluted by domestic wastewater to certain extent. The remaining channels are all aged, built with stones or dirt by old crafts, which provide some plants to grow on the channel bed and wallls/banks, and, therefore, provide damselflies habitats.

士林地區仍有一些灌溉用的水圳，尤其是靠山邊，像是內雙溪、外雙溪、石角、... 等地。這些水圳大都已經很老舊，以舊工法，用土夯或是堆石塊建造，所以水圳的河床上及兩岸上、岸邊都長著草，也就提供了豆娘一個棲地。如果是現在造的，那麼就會拉 PVC 管，而不是開水圳了。

So far, I found the adults of these species living in such habitats.

我發下列現這些豆娘生活在士林地區灌溉水圳：

Calopterygidae 珈蟌科
Matrona cyanoptera Hämäläinen & Yeh, 2000 白痣珈蟌

Euphaeidae 幽蟌科
Euphaea formosa Hagen, 1869 短腹幽蟌

Coenagrionidae 細蟌科
Ischnura senegalensis (Rambur, 1842) 青紋細蟌
Pseudagrion pilidorsum pilidorsum (Brauer, 1868) 弓背細蟌

Platycnemididae 琵蟌科
Copera marginipes (Rambur, 1842) 脛蹼琵蟌
Prodasineura croconota (Ris, 1916) 朱背琵蟌
.
Let me jot down my findings about these species in these irrigation channels.
我歸納一些觀察心得如下：

1. Matrona cyanoptera Hämäläinen & Yeh, 2000 白痣珈蟌
   Only occurs in wider channels with rather fast flowing water at the foot of mountains or on hillside. Dirt banks or rather rich plantation on channel banks, with a certain shad.
   

只出現在較寬，兩岸有較豐富植物，山腳下或是山坡上的水圳。而且要有一定的遮蔭，不必很密。
.

1. Euphaea formosa Hagen, 1869 短腹幽蟌
   Faster flowing water near or on hillside. Don't require rich plantation on channel bed and banks, but there must be some nearby water.

在流速較快的區段，山邊或山腳下，兩岸植被不需要很密或很高，但是水邊必須要有植物(草)。
.

1. Ischnura senegalensis (Rambur, 1842) 青紋細蟌
   Slow flowing water, with plants on the banks, some shade is needed.

流速緩的區域，岸邊有植物，也需要一定的遮蔭。
.

1. Pseudagrion pilidorsum pilidorsum (Brauer, 1868) 弓背細蟌
   Both slow and fast flowing water, some plants on the banks, little demand for shade. Usually co-habit with Copera marginipes during winter, when Taipei is usually cloudy and rainy. But from April to Oct., C. marginipes can hardly be seen in those places with little shade.

流速快慢的區段都見得到，只要岸上或岸邊有一些草，不需要特別的遮蔭。
冬天時因台北經常下雨，且大多為陰天，因此常可以發現弓背細蟌與脛蹼琵蟌混棲，但是約在三、四月到十、十一月，一些沒有良好遮蔭的區段只能見到弓背細蟌。
.

1. Copera marginipes (Rambur, 1842) 脛蹼琵蟌
   As mentioned at pointer 4, it demands more shade in habitats. Preferring slower flowing water.

如上所述，需較佳的遮蔭，也偏好緩慢的流水。
.

1. Prodasineura croconota (Ris, 1916) 朱背琵蟌
   So far, I only found it at 3 locations, it certainly demands more shade but it seems to occur in both slow and fast flowing water channel banks, and in gutter-like narrow channel as well as 3-meter wide one.

到目前為止，只有在三處水圳見過，只能確定朱背琵蟌偏好較佳遮蔭處，水圳寬窄，流速快慢好像影響不大。

Posted on 16 de julho de 2019, 02:48 PM by aru