Friday, August 1, 2014

Dragonflies at Myles Standish State Forest, Plymouth - 7/27/2014

Eastern Pondhawk
   A surprising and welcome turnout of 13 people for this "Odes" (Dragonfly & Damselfly) walk! Weather plays an important role as one decides to venture out in search these striking insects. Bright sunny skies with warm temperatures and calm/light winds are the ideal conditions to get most these dragons and damsels active. But when does anyone really get these conditions, not often enough, and not today of course! Today's weather was mostly cloudy with a few peeks of sun and moderate wind, then turned to light rain about three hours into the trip. The group was not deterred however, and we made out quite well in finding many of the representative species of the area, no doubt due to all the extra sets of eyes amongst us. Three hours was a nice amount of time as this was most people's first time out.
Calico Pennant
   Myles Standish State Forest in Plymouth is a huge swath of pine barren forest which is dotted with several coastal plain ponds that harbor a unique set of plants and animals. Coastal plain ponds are generally shallow with a sandy substrate and have no inlet or outlet. Water levels in these ponds can vary depending on weather. Most of this habitat in Massachusetts is in SE MA and Cape Cod and the Islands. Doctor's and New Grassy Ponds were two of these of ponds we focused on.

   Although there were not big numbers, the large, flashy species namely Comet Darner, Golden-winged Skimmer and Carolina Saddlebags put in appearances. These ones can be identified fairly easily as they patrol the shoreline of the ponds. The same cannot be said of many of the others though. With birds, some species can only be separated by voice. Ode identification can have challenges like this as well. Given their relative small size, many of the key characteristics such as shape and structure can only be examined effectively in the hand with magnification. Several small damselflies were netted, and with the aid of some field guides, we were able to "key out" various Spreadwings and Bluets.

Swamp Spreadwing
   Several of the damsels & dragonflies were in their teneral state, meaning that they had very recently emerged from the ponds. Typically the larval(nymph) stage crawls out of the water on nearby vegetation or rocks and then starts the process of breaking through their outer "shell", a process called metamorphosis. Once emerged, odes cannot fly well, as their exoskeleton and wings are soft, making them quite vulnerable to predators. This feature can be noticed in the field because their wings have a glassy/shiny look to them.

Calico Pennant
   During our brief time out in the field, were able to witness, at close range, a female Common Whitetail depositing (ovipositing) her eggs into the water at a particular spot. The female of this species, and several others in the ode family, will hover over the water and quickly dip the end of their  abdomen into the water and release eggs. This motion is repeated in rapid succession making this behavior quite noticeable. Other methods of ovipositing include depositing eggs directly into mud or laying them inside vegetation by slicing into stems of plants.
   All in all, a very enjoyable trip and a great excuse to get out and become better acquainted with a different set of organisms!

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