[Odonata-l] Sonoma Co. excitement

[Kathy &/or Dave Biggs]

Hi all,

I was out doing the weekly 1 hr. survey of my backyard pond and had a 
few exciting moments:

First, a gorgeous female Pacific Spiketail (Cordulegaster dorsalis) flew 
in and was capturing prey right next to the pond. I took several images 
of her, but haven't downloaded the camera yet to see if they came out at 
all. I believe that she is the first 'for-certain' report of the year 
for California.

Then, I noticed fairly large damselfly wings floating among the 
marestail. I used a net to fish it out. It was a female Exclamation 
Damsel (Zoniagrion exclamationis), and although I see that she was a 
mature (dark) female, I couldn't see the last half of her abdomen. Odd I 
thought! So I brought her in to scan (haven't done so yet) and wondered 
where her back half had gone....I didn't have to wonder long.

Because we're supposed to record Guarding and Ovipositing, I focused in 
on a pair of Pacific Forktails (Ischnura cervula) in tandem as they flew 
down to the water level. I was amazed to see the female seemingly 
crawling down the stem until she was mostly submerged. Odd I thought and 
brought my binocs to them to be further amazed to see the male let go 
and abandon her there! Then I saw what was happening. A large darner 
nymph (probably Rhionaeschna multicolor) had grabbed her and was pulling 
her under and eating her!! Now I suspect that was what was happening or 
had happened to the Exclamation female! So, I timed the nymph, and he 
pretty much ate all of the forktail, letting her wings float up to the 
surface, in 4 mins.

I've had very very few dragonflies emerge this year, even though all 
winter long I found meadowhawk and forktail nymph plentiful. What I 
suspect is happening is that, since I'm using mosquito dunks (BTi), the 
only food the Ode nymphs have is each other, and it's the darners who 
are coming out on top of the food chain!

But there was still one more interesting event that had occurred just 
prior to this, a male Pacific Forktail (I cervula) had grabbed the lone 
male Western Forktail (I. perparva) and was busy thrashing it about, I 
assume he was trying to get 'her' to mate. When I looked through the 
binocs, I saw that he had not grabbed the other forktail by the 
prothorax, but by the top of the thorax, between the wings! He finally 
gave up, ~ 5mins later! I'm at a loss for whether he was 'confused' in 
mating or if he was just trying to keep the other male, even if a 
different species, from mating!

For the record, the species on the pond during the hour:
Vivid Dancer Argia vivida - 1 males
Pacific Forktail Ischnura cervula - 2 males and one doomed female
Western Forktail O. perparva - 1 harassed male and 2 ovipositing mature 
females
Exclamation Damsel Zoniagrion exclamationis - 1 dying female, 5 males
*Pacific Spiketail Cordulegaster dorsalis - 1 feeding female
Cardinal Meadowhawk - 5 males, 2 females inc. i ovipositing pair
and
Blue-eyed Darner Rhionaeschna multicolor - one feeding nymph!

Some census days are better than others!

Cheers!!
Kathy

-- 
California Dragonflies	       http://www.sonic.net/dragonfly
Southwest Dragonflies		    http://southwestdragonflies.net/
Bigsnest Wildlife Pond	       http://www.bigsnestpond.net/
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Kathy and Dave Biggs	         bigsnest at sonic.net      707-823-2911
308 Bloomfield Rd.               Sebastopol, CA  95472 
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dba Azalea Creek Publishing      azalea at sonic.net   fax: 707-823-2911
http://www.sonic.net/~bigsnest/azaleacreekpublishing/ 
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