Archive for the ‘Canon 580EX Speedlite’ Category

Milkweed seed pod

December 12, 2017

A solitary milkweed seed pod was spotted during a photowalk along Easy Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. According to Drew Chaney, a.k.a., “plantmandrew,” it is either swamp milkweed or butterfly weed, more likely the latter.

Since it was a windy day, I used a shutter speed of 1/1000s in order stop the motion of the silky seeds blowing in the wind. I also used an external flash unit and -2 ev exposure compensation for the first photo.

16 NOV 2017 | Occoquan Bay NWR | milkweed seed pod

I used the same shutter speed for the last photo, but turned off the flash and reset exposure compensation for 0 ev.

16 NOV 2017 | Occoquan Bay NWR | milkweed seed pod

Although I like both photos, this may be one of those rare times when I prefer the no-flash image. Which one do you prefer?

Copyright © 2017 Walter Sanford. All rights reserved.

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Urban Heat Island

December 10, 2017

On 01 December 2017 I didn’t see any Autumn Meadowhawk dragonflies (Sympetrum vicinum) during a photowalk along Easy Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

In contrast, I saw several Autumn Meadowhawks perched on man-made structures such as a concrete curb in the blacktop parking lot at the refuge. All of the dragonflies were perched on vertical surfaces that received more direct insolation than horizontal surfaces. The parking area seems to be an urban heat island microclimate that exists within a larger natural area.

Male 1

The first individual is a male, as indicated by his terminal appendages. Although the male is missing one of four wings, he was able to fly well enough to move to three different perches along the curb.

01 DEC 2017 | Occoquan Bay NWR | Autumn Meadowhawk (male, injured)

01 DEC 2017 | Occoquan Bay NWR | Autumn Meadowhawk (male, injured)

01 DEC 2017 | Occoquan Bay NWR | Autumn Meadowhawk (male, injured)

Male 2

The next male has a full set of four wings; his wings are tattered slightly, as expected toward the end of dragonfly season.

The last photo shows the male grooming and excreting at the same time.

Related Resources

Copyright © 2017 Walter Sanford. All rights reserved.

“Winter Meadowhawk” dragonflies

December 8, 2017

The season called “winter” is defined two ways: atmospheric scientists, including meteorologists and climatologists, define winter as the three-month period from December to February; astronomers define winter as the time period that begins on the December Solstice (12/21) and ends on the March Equinox (03/21), although the actual dates for these events may vary slightly.

Several Autumn Meadowhawk dragonflies (Sympetrum vicinum) were spotted on the first day of climatological winter at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. Therefore I think it is appropriate to call them “Winter Meadowhawks.”

The last two photos show the same male, perching on different surfaces. My guess is he was looking for a good source of thermal energy on a cool, windy day.

The Sun is always low in the sky during winter, even at its maximum altitude. Indirect incoming solar radiation (insolation) is less intense than direct insolation. The last photo shows the male dragonfly perched on a south-facing wooden board that is perpendicular to the surface of the Earth, therefore the solar energy received by the board is more intense than the energy received by the ground. This probably explains why the male moved from the ground to the board.

Enrichment

The last photo was taken on 01 December 2017 at 11:33:50 a.m. EST, as shown by the EXIF information for the image. The altitude of the Sun was 28.9° at 11:30 a.m., meaning a ray of sunlight formed an angle of 28.9° with horizontal surfaces such as the ground. At the same time, a ray of sunlight formed an angle of 61.1° with vertical surfaces such as the wooden board shown in the first and last photos. That’s the beauty of mathematics — some simple geometry shows clearly which surface received more intense insolation. Smart dragonflies!

Related Resource: Sun or Moon Altitude/Azimuth Table, U.S. Naval Observatory.

Copyright © 2017 Walter Sanford. All rights reserved.

Cobra Clubtail dragonflies (females)

December 6, 2017

Male and female Cobra Clubtail dragonflies (Gomphurus vastus) are nearly identical in appearance except for their terminal appendages: females have two terminal appendages (cerci); males have three (claspers). Also notice the subtle difference in the shape of their hind wings: female hind wings are rounded; male hind wings are “indented.”

Several female Cobra Clubtails were photographed during the annual mass emergence along the Potomac River at Riverbend Park, Fairfax County, Virginia USA.

The first female, shown above, has a malformed wing.

Notice part of an insect leg on the wooden beam, underneath the female’s abdomen. Is it a leftover from a late-morning snack?

Copyright © 2017 Walter Sanford. All rights reserved.

Incredible!

December 4, 2017

Odonates are aquatic insects. They spend most of their life as larvae that live in water; this stage of their life cycle can last from a few months to a few years. Finally, they emerge from the water and metamorphose into adults in order to reproduce; their offspring return to the water and the cycle begins again.

Careful and/or lucky observers will notice exuviae (sing. exuvia), also known as either “cast skins” or “shed skins,” left behind when odonate larvae emerge. Would you believe this…

metamorphosed into that? (See below.) It’s a miraculous transformation! The adult stage of the odonate life cycle can last from a week-or-so to a month-or-so, depending upon the species.

The first photo shows an exuvia from a Cobra Clubtail dragonfly (Gomphurus vastus), photographed in situ at Riverbend Park, Fairfax County, Virginia USA. All other photos in this gallery show adult male Cobra Clubtails, as indicated by their terminal appendages and “indented” hind wings.

Copyright © 2017 Walter Sanford. All rights reserved.

Reminiscing

December 2, 2017

As I was reminiscing about the annual mass emergence of Cobra Clubtail dragonflies (Gomphurus vastus) along the Potomac River at Riverbend Park, Fairfax County, Virginia USA, I realized there are lots of photos shot in May 2017 that were never edited.

This photo set features a female perching on colorful kayaks in a storage rack near the boat ramp. Both photos are uncropped, that is, they are full-size images (4,000 x 3,000 pixels).

Related Resource: Because it’s fun, a blog post featuring photos of a male Cobra Clubtail (perching on the same kayaks) shot on the same day using my Fujifilm X-T1 digital camera.

Copyright © 2017 Walter Sanford. All rights reserved.

Blister beetle

November 30, 2017

During a photowalk along Easy Road at Occoquan Bay National Wildlife Refuge, I noticed a type of beetle I didn’t recognize so I stopped to shoot a few photos. I consulted the expert members of the BugGuide Facebook group for help in identifying the unknown beetle.

Turns out it’s a member of the Family Meloidae (Blister Beetles). Several BugGuide members identified the insect as a species of “oil beetle” from the Genus Meloe. As its common names suggest, if this insect is disturbed then it releases an oil that can cause skin blisters. It’s as if chiggers and ticks weren’t enough of a nuisance — now I need to watch out for blister beetles too!

Editor’s Note: Thanks to BugGuide Facebook group members Dana Perantie, Brett Marshall, Shaun Delph, and Alonso Abugattas for help in identifying the beetle.

Related Resource: Oil Beetles, a blog post by Alonso Abugattas, Natural Resources Manager for Arlington County Parks, Virginia USA.

Copyright © 2017 Walter Sanford. All rights reserved.

Common Buckeye butterflies

November 28, 2017

(Common) Buckeye butterflies (Junonia coenia) are relatively common at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. I notice them when I’m hunting for dragonflies and damselflies. They’re skittish usually, but if they cooperate I always stop for a few shots.

The Common Buckeye color palette is unusual, yet it just works. Who knew brown butterflies could be so beautiful? Definitely one of my favorites.

Copyright © 2017 Walter Sanford. All rights reserved.

A week later…

November 26, 2017

On 09 November 2017 I visited Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA, looking for late-season odonates before the first hard freeze. Several Autumn Meadowhawk dragonflies (Sympetrum vicinum) were spotted during a photowalk along Easy Road.

I revisited the same place one week later. I saw slightly fewer Autumn Meadowhawks than the week before. Although some dragonflies survived the freezing temperatures, their numbers seemed to be diminished according to my non-scientific survey.

Both individuals featured in this photo set are male, as indicated by their terminal appendages.

I love the palette of fall colors in the first two photos! The two-photo sequence shows how I typically “work a shot.” I start by “getting a shot, any shot” (above) and slowly refine the shot until I am able to get as close as the subject will allow, while looking at the overall composition (below). Remember to check the edges of the photo for leading lines and distracting elements.

The last dragonfly I photographed was perched on the wooden border of a flower bed located near the parking lot.

Related Resources: Five Guys; Thermal energy vampire!

Copyright © 2017 Walter Sanford. All rights reserved.

Happy Thanksgiving!

November 22, 2017

On the traditional day when we give thanks for our many blessings, I am especially thankful for the opportunity to be a frequent and careful observer of the natural beauty of several wildlife parks located in Northern Virginia, and for many good friends with whom I share the experience. Happy Thanksgiving! Now let’s have some turkey…

Signs of Wildlife

Although I have never seen a Wild Turkey (Meleagris gallopavo) at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA, I know they’re there because of several items that were observed at the refuge recently.

A tail feather from a Wild Turkey was photographed in situ along Easy Road. The feather is approximately eleven inches (11″) long from end-to-end.

A wing feather was photographed in situ along Easy Road, near the preceding tail feather. The feather is approximately ten inches (10″) long from end-to-end.

Thanks to Mike Boatwright for confirming my tentative identification of the tail feather and for identifying the wing feather.

Lots of animal scat, possibly from Wild Turkey, was observed along Easy Road near the Wild Turkey feathers shown above.

Did you notice the brown flies on the animal scat? They may be Scathophaga furcata, a species of dung fly. Thanks to Matt Pelikan from the BugGuide Facebook group and Charles Davis from the Capital Naturalist Facebook group for help in identifying the flies!

Related Resource: The Feather Atlas – Flight Feathers of North American Birds, U.S. Fish & Wildlife Service Forensics Laboratory.

Copyright © 2017 Walter Sanford. All rights reserved.


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