ארכיון יומן של ינואר 2021

ינואר 24, 2021

Tail Waving Damsels

I had circumnavigated the lagoon and photographed every species I found so now what? Still having time on my hands I decided to try and photograph a charismatic little damselfly performing its characteristic tail-waving. Having capable photographic equipment I thought I would use the opportunity presenting itself — the temperature wasn't too hot to be out in the sun but still warm enough for these insects to be active.

It had been documented that the Ancient Greenling Hemiphlebia mirabilis damselfly waves it tail about at times. Originally thought to only be male territorial signalling behavior I found that both sexes perform this display equally.

They usually wave their tails about immediately after landing or when another perches nearby; most of the rest of their time they spend sitting quite still and may only move to catch a passing meal. So to get them doing their dance I walked back and forth along the edge of the swamp and flung my camera in their direction whenever one I disturbed landed again (like most damselflies they don't fly far). It isn't easy to catch this action as they may only do it two or three times and each wave only lasts around a second. Even though my camera focuses fairly quickly on something near its last focus distance it was still not easy to capture this, but using continuous shooting I managed to get some reasonable images. Ideally I would have had the camera level with the little beasts but as they prefer to perch on emergent swamp vegetation below half a metre tall my photos were angled somewhat from above.

Until 2013 coupling had not even been observed (oviposition is unknown to this day) but the male pounces on the wings of the female and holds them closed (so she can't fly), walks up the wings [image 1 and image 2] before curling his abdomen undernath his body and normal damselfly mating follows. The males don't seem to be too exact about selecting a potential mate and I have photographed one on a male Austrolestes leda and even two on the same male Ischnura aurora! As a result of this indiscriminate behavior I think both sexes have evolved the tail curling as it could dislodge an unwanted attachment. [This is my opinion based on many observations however traditionally it is still believed they are waving at each other, which I guess they are sort of doing and saying "don't land here, Mr".]

Observations 67188374, 67188376 and 67188377 illustrate the tail curling behavior that I captured in the late morning on 25th December, 2020. The second of these shows the full sequence of the tail-flick in chronological order.

פורסם ב ינואר 24, 2021 11:17 לפנה"צ על־ידי reiner reiner | 1 comment | הוספת תגובה