An OFNC outing at Petrie Island

Eastern Amberwing

On August 2nd, 2015 I led a dragonfly outing at Petrie Island for the Ottawa Field-Naturalists’ Club. Because I would be leading it on my own, and because the small size of dragonflies and damselflies makes it difficult to point them out to large groups, I decided to limit the group to ten people. Fellow dragon-hunters and Birds Committee members Chris Traynor and Lorraine Elworthy signed up for the outing, as did Jakob Mueller, who led the reptile and amphibian outing at Sheila McKee Park earlier in the year. I recognized Lynne Ovenden from the OFNC; the others were all unknown to me.

I started our outing by talking about the differences between dragonflies and damselflies, as well as the different groups belonging to each family. We would be looking for spreadwing damselflies, which hold their wings out at a 45° angle instead of parallel to their back; emeralds and darners, which are most commonly found flying through the air searching for aerial prey; and skimmers, which tend to hunt from a perch and are usually the most approachable types of dragonflies for photography. As I was speaking, a bright green female Eastern Pondhawk was hunting from a perch in the vegetation, often flying out to snatch an insect from the air. At one point it even landed on one of the group members!

We also found a Blue Dasher and several Eastern Forktails in the vegetation near the parking lot, but none of the specialties I was hoping to see: Orange Bluet, Vesper Bluet, or Fragile Forktail. We made our way along the trail until we reached Crappie Bay, where I was hoping to find some skimmers in the vegetation and perhaps a baskettail flying out over the water. Few insects were around, possibly because it was still early, but I was surprised when I spotted a Racket-tailed Emerald sitting on a leaf in the sunshine. These are early season dragons, and I don’t recall seeing any in August before. This small emerald is one of the most abundant in our region and has bright green eyes and a black abdomen that flares out at the tip. The only other emerald in our area that looks similar to the Racket-tailed Emerald is the American Emerald, whose abdomen does not end in a prominent club, and which has a complete whitish ring at the top of the abdomen instead of an incomplete yellowish ring. The American Emerald also tends to fly earlier in the season. It turned out to be the only emerald of our trip, and although I called the group over to see it, it flew off before everyone could join me.

Racket-tailed Emerald

From there we started up the Muskrat Trail where we started seeing more odes – mostly Autumn Meadowhawks and Eastern Forktails. Then someone pointed out a male Blue Dasher perching on a pink flower. In 2010, Christine Hanrahan recorded the first Blue Dasher in the OFNC circle at the Baxter Conservation Area on the Rideau River. On a visit to Petrie Island in July 2011 I discovered the first known colony in our region. While this species has shown up subsequently at Mud Lake, Shirley’s Bay and Constance Creek, those colonies do not appear to be thriving the way the one at Petrie Island has.

Blue Dasher (click to enlarge)

The males have a blue abdomen with a black tip, a yellow and black thorax, and green eyes. Females are black and yellow and lack the powder-blue pruinosity. Some Blue Dashers have an amber tint to their wings as can be seen in the photos above and below.

Blue Dasher

Then someone in the group pointed out a spreadwing. It quickly vanished, but we found a small inlet where a few more were hunting in the vegetation, perching from the slender stems with their bodies pointing down at an angle. I managed to net two different species for the group, a Northern Spreadwing and a Swamp Spreadwing. While it was clear that the Swamp Spreadwing was the larger damselfly when viewed side by side, they can only be accurately identified by the shape of the male’s claspers.

Swamp Spreadwing

It was warming up by then, so we left the Muskrat Trail (which ends in a dead-end) and went over to the William Holland Trail. Along the way, we noticed a large dragonfly zipping around about ten feet above the ground. I got my binoculars on it in time to identify it as a mosaic darner and see it land on the trunk of a large tree where it was well-camouflaged. Once it landed I was able to get the group on it and identify it as a Canada Darner, probably the most commonly encountered “mosaic darner” (Aeshna species) in our area. The key to identifying these darners is the shape of the first coloured stripe on the thorax. In the Canada Darner, it is deeply notched.

Canada Darner

We didn’t have much luck finding any odes on the Bill Holland Trail at first, though I caught one Stream Bluet, one Skimming Bluet and one Hagen’s Bluet along the way. Overall numbers seemed low compared to my previous visits to Petrie Island, and I was beginning to worry it was turning out to be a boring outing. We stopped to watch a female Monarch attempting to lay eggs in a patch of Swamp Milkweed; it was the first one of the year for me, as well as several others in the group. We also got great views of a female Common Green Darner ovipositing in the shallow water on the river side of the trail, dipping the tip of her abdomen into the emergent vegetation to lay her eggs.

Our luck changed when we came to the small bay near the end of the loop and I observed a brownish butterfly sitting on a tree branch above the trail. It had been a few years since I’d seen a Hackberry Emperor at Petrie Island, and I was thrilled to show it to the group. The Hackberry Emperor is a Petrie Island specialty, as the caterpillars depend on Hackberry trees as host plants, and this is the only spot in Ottawa that I know of where this butterfly can be reliably found. I don’t see them every time I go to Petrie Island, however, so seeing one was a great addition to our insect list!

Hackberry Emperor

We also found several dragonflies in the area, all perching in the vegetation overlooking the water or chasing each other across the bay. This was the most active area of our outing, and we spent a while watching and photographing the dragonflies. We enjoyed watching several Slaty Skimmers, Twelve-spotted Skimmers, Widow Skimmers, and Eastern Amberwings chasing each other from their perches and hunting for food. I was particularly pleased to see the Eastern Amberwings, another Petrie Island specialty; so far this is the only known colony in the OFNC study area (at least on the Ontario side). It is also a relatively new dragonfly on our checklist, having first appeared at Petrie Island in 2012. While flying over the water, they are easily identified by their golden-reddish wings and body.

Eastern Amberwing

We also saw a cooperative Widow Skimmer perching in the grass above the water. These skimmers can be differentiated by the Common Whitetail by the two dark wing patches next to the body and the white spots on the outside. They are common in marshy spots along the Ottawa and Rideau Rivers. Newly emerged Widow Skimmers look quite different, having a yellow abdomen with black stripes and faint dark markings on the wings that will gradually deepen in colour. We didn’t see any for comparison.

Widow Skimmer

Another great find was this Bronze Copper nectaring on the flowers of a Broadleaf Arrowhead plant, which is something I’ve never seen before. This small butterfly is one of the “gossamer-winged” butterflies; it is more closely related to the blues and hairstreaks than it is to the Monarch or fritillaries. Unfortunately it did not stay long enough for the entire group to see.

Bronze Copper

We ended the walk at that point, and slowly made our way back to the parking lot in groups of ones and twos. It was getting hot, and I spent more time taking photos than I did while leading. The Slaty Skimmer is always a favourite subject of mine; one of the largest skimmers in our region, the Slaty Skimmer is found at Morris Island and Petrie Island along the Ottawa River, but not in any of the other bays in between (i.e. Mud Lake and Shirley’s Bay). Males and mature females are easily recognizable by their cobalt blue bodies and dark eyes.

Slaty Skimmer

The meadowhawks were our most abundant dragonfly of the day. Most were freshly emerged individuals, in shades of yellow and brown. Mature males are bright red; they are my favourite ones to photograph, but I didn’t see any. The Autumn Meadowhawk was formerly known as the Yellow-legged Meadowhawk because of its yellow legs. Its yellow or brownish legs (never black) and the limited black markings on its abdomen help to separate this species from other meadowhawks. It is the last dragonfly on the wing in Ottawa, often flying into November.

Autumn Meadowhawk

After the rest of the group left I returned to Crappie Bay and found more dragonflies in the area than there had been when we started. I was happy to find an Eastern Pondhawk to photograph, as I think the blue males are very pretty. Females and immature males, on the other hand, are green, with black markings along the abdomen. It is not uncommon to see intermediate males that appear half-green and half-blue. Both sexes have white appendages at the end of the abdomen and green faces (they are the only skimmer in our area with this combination). While male Blue Dashers superficially resemble the mature male pondhawks, Blue Dashers have white faces, and the last few segments are black.

Eastern Pondhawk

I also noticed a Skimming Bluet perching on the lily pad, which is where I usually find them. Their abdomens are mostly black with thin blue rings, and two blue segments at the end (segments 8 and 9). While the Stream Bluet also has a mostly black abdomen, the proximal blue segment (segment 8) is not entirely blue but has a black triangle at the top.

Skimming Bluet

I was also happy to see two more Eastern Amberwings on the vegetation near the shore. They are very active dragonflies, rarely landing long enough (or close enough) to get some decent photos. When viewed up close, they are distinctive little bugs with unusual proportions: note the large head, the short, stout abdomen, the long yellow legs, and the broad wings that extend halfway down the length of the abdomen. Although they look like over-sized wasps, Eastern Amberwings are members of the skimmer family; that is, they hunt by perching and wait for prey to fly within reach. Like other skimmers, they are often faithful to one perch. If you wait patiently, you may see the same dragonfly return to the same perch again and again after chasing intruders away.

Eastern Amberwing

Although I missed two of the species I was hoping to see (the Orange and Vesper Bluets), and although the dragonfly activity didn’t pick up until late in the morning, it was a fun day with a fun group of people. Altogether we found 17 species:

1. Northern Spreadwing
2. Swamp Spreadwing
3. Hagen’s Bluet
4. Skimming Bluet
5. Stream Bluet
6. Eastern Forktail
7. Canada Darner
8. Common Green Darner
9. Racket-tailed Emerald
10. Blue Dasher
11. Eastern Amberwing
12. Eastern Pondhawk
13. Slaty Skimmer
14. Twelve-spotted Skimmer
15. Widow Skimmer
16. Dot-tailed Whiteface
17. Autumn Meadowhawk

I enjoyed our outing; it’s fun showing other people about the dragonflies I am so passionate about, and it reminded me that I need to get out to Petrie Island more often during the peak of the dragonfly season.

Advertisement