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30 May 2010 @ 07:59 pm
Hurdman in late May  

The days following my return to work were so busy that I was barely able to take any time for lunch, let alone a full hour to visit Hurdman Park. Once things calmed down, however, I spent a couple of lunch hours there the following week. Migration seemed all but over; I didn't see any migrating warblers or songbirds, and all the breeding birds now seemed to be present. The newest addition was the Least Flycatcher, and I followed his snappy, repetitive "Ch-bek!" until I located him on the branch of a thin tree just below eye level. Since these small flycatchers are easier to hear than to see, I was happy to find him out in the open.

Cedar Waxwings, too, were calling from the treetops, as were Red-eyed and Warbling Vireos, Yellow Warblers, and plenty of American Redstarts. At one point I heard the distinctive high-pitched song of a Blackpoll Warbler, and although I tried to locate him for my year list, he remained elusive. These are the last warblers to pass through Ottawa on their way north, and a sure sign we were now entering the quiet breeding season.


Royal Swan


I saw a large dragonfly zip by in the same area that I heard the Blackpoll Warbler, and watched as he landed on the side of a tree. I was not expecting to see a mosaic darner; these dragonflies, and the common Canada and Lance-tipped Darners in particular, are much more easily found later in the summer. When I checked the Ottawa checklist of odonates, I learned that two species do in fact fly in mid- to late-May: the Harlequin Darner and the Springtime Darner. As with all mosaic darners, the best way to tell these species apart is by the shape of the stripes on the side of the thorax; fortunately my one photo was clear enough to see these stripes and identify this dragonfly as a Springtime Darner - my second new dragonfly in only a couple of days!



Springtime Darner


I really wish I had been able to get closer to this dragonfly, and to get some photos of him from the top, but he flew off just after I took this photo and started to walk to toward him for a better view.

I took the trail through the woods, then followed the paved bike path toward the river. I checked the grassy opening just south of the 417 bridge, and found the two black swans swimming serenely down-river. These are the captive birds owned by the City of Ottawa; every May they release them onto the Rideau River and bring them to an indoor shelter at the end of October. This was the first time this spring I had seen any of the royal swans.



Royal Swan


On my way back to the bus station I encountered a few butterflies, including my first Hobomok and Arctic Skippers of the year, and lots of Common Ringlets which are abundant here.



Common Ringlet


The next day I returned to try and get some better photos of the skippers. I wasn't successful, but I found a couple of other interesting insects instead. The first was a large, Bald-faced Hornet nectaring on some blossoms. It was frighteningly large, and I didn't want to get too close to him in case he was in a surly mood.



Bald-faced Hornet


Named for the large patch of white on the faces of the workers, this insect is not a true hornet, but rather a wasp. It is closely related to the yellow jacket and is found only in North America. Like other wasps, the Bald-faced Hornet will visit flowers for two reasons. They feed on the nectar to obtain energy while hunting, and they prey on the smaller insects that are also attracted to the flowers. This species is very beneficial in gardens, since they are predators of insects that damage plants.

Fortunately, its aggressiveness does not match its fearsome appearance; the workers are usually not as sensitive to disturbance around the nest as some of the other, smaller hornet species, and their tendency to build their paper nests high in trees reduces the likelihood of conflict between humans and the hornet colony.



Bald-faced Hornet


The second insect that caught my eye was a tiny beetle in the vegetation close to the river. It initially appeared bright golden-orange, and seemed to glow against the green leaf. I thought perhaps it was a small lady beetle, but when I got close enough to take a few photos I realized it was nothing of the sort. Upon closer examination it appeared a dull red, with a transparent outer cuticle which looked to me like a protective shell - hence the name "tortoise beetle".



Golden Tortise Beetle (Charidotella sexpunctata)


Although the beetle I photographed doesn't look very interesting, it is a fascinating creature which can change its colour from a brilliant, shiny metallic gold to dull red in a short period of time when stressed. There is a thin layer of moisture between the transparent cuticle and an inner layer of the elytra, and the beetle is able to change colour by controlling the amount of moisture present. The gold colour is produced by an optical illusion resulting from the reflection of light through the layer of liquid. When the insect is stressed, or when it dies, the liquid between the two layers of its shell thins to the point where there is not enough moisture to produce the illusion.

These beetles feed primarily on wild morning glories (also known as field bindweed), which is a common weed in the Ottawa area, so I'll have to watch out for them on future walks. As this particular beetle goes to show, there is often more to the insect world than meets the eye!