Monday, October 12, 2009

Dragoning

--- Pacific spiketail devouring a wasp or similar insect
as detected by the yellow & black parts dropping from its mouth. ---

Dragoning is to dragonfly watching as birding is to bird watching. Frogs were hard to find round here in September, but the Dipper ponds were buzzing with swimming and flying insects. So a-dragoning I did go.

The amphibious frogs, toads and newts spend their larval days in the water, and spend some or much of their adult life on land. Dragonflies and damselflies spend their larval days in ponds, gobbling up other pond critters, and then they metamorphize into swift predators of the air. Both the amphibians and aquatic insects return to water to breed.

--- Dragonfly wing position on left;
damselfly wing position (hard to see as they are held against the abdomen) on right. ---

Dragonflies and damselflies together as a group are the Odonata order of insects, commonly referred to as the odes. The basic way to tell the difference is that the dragonflies, which are usually larger and stronger fliers, hold their wings out flat from their body like airplane wings when they are resting. Damselflies, which are usually smaller and frequently rest on the ground or vegetation, hold their wings folded against their sides like a closed fan or above their body in an erect 'V' when they are resting.

--- Odes mating in the "wheel" position.
The male (above) is gripping the female behind her head with special appendages on the tip of his abdomen. With the tip of her curled abdomen, the female is picking up sperm from a special segment on the forward part of the male's abdomen. ---

I am curious whether the 3 summer ponds at the Dipper Ranch support different odes. Based on my rudimentary knowledge of ode biology, my guess is that the following conditions affect the type and number of odes at each pond throughout the summer: size of pond at time of survey and change since the beginning of summer; amount of open water surface; whether water is moving or still; absolute and relative amount of submergent, emergent, floating and pond edge vegetation; and amount and variation of insolation.

Factors which can be highly variable at the time of each survey and thus influence which dragonfly or damselfly species are seen at any one moment are: air temperature, wind speed, time of day and lateness in the summer season. I expect the number of ode species I see to increase as I gain experience with dragoning.

Here is my initial prediction on ode populations and results from my first dragoning adventures in the last hot days in September. Below, you will find a brief description of the general conditions of each pond, my predictions and then photos of odes seen at that pond with a summary of habitat preferences for each species as provided in Kathy Biggs' field guide. These are preliminary identifications as I am dragoning novice.

The Woods Pond is shallow (1-2" deep) throughout the summer and its surface is about 80% covered by emergent vegetation, mostly cattails and cyperus. In September, water was slowly trickling out of the earthen bank at its head, spreading through the small pond and draining downhill through its outlet, although there were periods of no outflow in midsummer. I would expect the Woods Pond to have fewer total numbers of odes, lower diversity, and to support species that like slow moving water. In addition to the species shown below, a large bluish darner was seen.

--- Pacific spiketail, Cordulegaster dorsalis deserticola, hillsides, small wooded streams. ---

--- Vivid dancer, Argia vividia, seeps, streams.
The triangular shapes on the abdominal segments along with the pinched stripe on the thorax help identify this species among the many blue dancers.
Dancers hold their wings above their abdomen which helps distinguish them from the bluets which hold them alongside their abdomen. ---

The Plum Pond is a small pond in bright sun. It starts the summer with 1/2 open water and 1/2 dense cattail stand. By September, the cattail thicket is surrounded by narrow band of water covered by azolla and smartweed. No above ground inflow is evident and there is currently no outflow. My guess is that the depth is up to one foot in late summer, and the combination of sun, plants and water results in lots of odes and lots of different species. In addition to the species shown below, I saw a species of forktail damselfly and the wheeling odes shown above at the Plum Pond, but I could not identify them.

--- Common green darner, Anax junius, fields & waterways.
I don't know what the black thread is beneath its abdomen. ---

--- One of the all-blue mosiac darners, Aeshna or Rhionaeschna species. ---

--- Common whitetail, Libellula lydia, marshes, streams. ---

The Mallard Pond is a medium-sized pond surrounded by tall trees. It looks several feet deep. It has a small island covered with several small trees and rose thickets. The pond and island edges are crowded with cattails, overhanging tree limbs, and the long dam face is bare earth. Even by the end of the summer, as much as 75% of the water surface is open with patches of floating vegetation. I suspect the pond is slowly fed in the summer by underground springs and there was no outflow in September. With these varied conditions, I expect the Mallard Pond to have more odes and a greater diversity of species, but the general closed margins might mean more damselflies and less dragonflies (the later being stronger fliers and perhaps preferring to have nearby grasslands for hunting).

--- Probably the blue-eyed darner, Rhionaeschna mulitcolor, ponds, lakes, slow streams. ---

--- Striped meadowhawk, Sympetrum pallipes, ponds and lakes.
The four velvety spots where the wings meet the body are distinct. ---

--- Western forktail, Ischnura perparva, weedy ponds. ---

--- Desert firetail, Telebasis salva, shallow water with algae scum.
Only all red California damselfly in Biggs' field guide---

After a preliminary set of late summer odes surveys, I found:
  • The Woods Pond had 3 species of odes, with only one of those being a damselfly, matching my expectations of lower numbers and diversity.
  • The Plum Pond had 5 species of odes, with two of those being a damselfly. I was surprised that the sun power didn't provide more odes, but it could have been the weather on the day I surveyed or my inexperience.
  • The Mallard Pond had 4 species of odes of which 2 species were damselflies, a lower ode diversity and damselfly balance than I predicted.
These are very preliminary results, and I plan to go dragoning again next spring and summer.

--- Flying odes are hard to photograph.
One gets dizzy following them with binoculars or camera. ------

See also:

Kathy Biggs' California Dragonflies and Damselflies website with links to her excellent field guides

--- One of the blue darners.
They sometimes turned to face the camera when the focusing mechanism whirred ---

3 comments:

  1. So awesome! Love the photography and the self-taught air of curious exploration!

    I think the blurred pic is actually really 'artsy' - you could probably take a bunch like them and sell them at a pricey gallery! (maybe?)

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  2. Hi, Cindy, I stumbled across your blog the other day and was immediately hooked. I couldn't resist searching for "dragonfly", as it's always interesting to learn what's on the wing in different parts of the world. With reference to your "black thread" comment in one of the photos, those are the the rear legs, which fold up under the thorax when the insect is in flight. Regards, Graeme

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  3. Thanks for the explanation on the flying dragon legs, Graeme. I look forward to seeing the dragonflies and damselflies return again this spring. I visited your blogsite in your part of the world and your pond cleaning adventures are quite amusing along with your local expressions. I hope you've had some refreshing rain by now.

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