Posts Tagged ‘hemi-marsh’

Wildlife watching “Wildlife Watching” sign

November 24, 2016

There is a “Wildlife Watching” sign located along the boardwalk at Huntley Meadows Park, near the observation tower overlooking the central wetland area.

Notice the Autumn Meadowhawk dragonfly (Sympetrum vicinum) perching on the signage. This individual is a male, as indicated by the bright red coloration of his abdomen and by his terminal appendages.

Regular readers of my photoblog know I love a good head-tilt! Doesn’t this guy look jaunty?

Autumn Meadowhawks like to rest on sunlit surfaces like the sign (and boardwalk) in order to absorb thermal energy.

Hey folks, you’re looking the wrong way — there’s a big dragonfly behind you!

The hemi-marsh at Huntley Meadows Park is a good habitat for many species of odonates, including Autumn Meadowhawk.

I spent about 30 minutes watching the sign, waiting for the dragonfly to land at different places on the sign. During that time, several people passed the sign but no one noticed the dragonfly. As the sign says, “Take time to look carefully” when you visit a wildlife watching park.

Editor’s Note: 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 the hemi-marsh at Huntley Meadows Park, and for many good friends with whom I share the experience. Happy Thanksgiving!

Copyright © 2016 Walter Sanford. All rights reserved.

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Snowy scenes along the Hike-Bike Trail

February 7, 2016

The “exposure triangle” has three corners: 1) Aperture; 2) Shutter Speed; and 3) ISO (light sensitivity). When shooting in “Program” mode and Auto ISO, all three corners of the exposure triangle are wildcards set by the camera. In “Aperture Priority” mode and Auto ISO, the user selects the aperture (lens opening) and the camera selects the shutter speed and ISO. In “Shutter Priority” mode and Auto ISO, the user selects the shutter speed and the camera selects the aperture (lens opening) and ISO. Finally, in “Manual” mode the user selects all three settings in the exposure triangle.

All of the photos in this post were shot in “Aperture Priority” mode at ISO 100. That leaves one corner of the exposure triangle for the camera to set: Shutter Speed. At an aperture of f/4 and ISO 100, the camera is set for a relatively wide lens opening and maximum light sensitivity. Ice and snow are very reflective surfaces, so it’s no surprise the camera selected fast shutter speeds to limit the amount of light received by the camera sensor. One upside of this combination of settings: Camera shake was virtually a non-factor!

The following gallery of photos shows views along the Hike-Bike Trail at Huntley Meadows Park, a little more than a week after the “Blizzard of 2016.”

The view along the Hike-Bike Trail at Huntley Meadows Park, Fairfax County, Virginia USA.

4mm (25mm, 35mm equivalent) | f/4 | 1/2000s | ISO 100 | -1 ev

Notice that exposure compensation (ev) was used for most of the photos. In “Aperture Priority” mode at a fixed ISO, exposure compensation affects shutter speed: negative exposure values (ev) make the shutter speed faster, further reducing the amount of light received by the camera sensor; positive exposure values make the shutter speed slower, increasing the amount of light received.

Looking downstream along a creek that crosses the Hike-Bike Trail.

Looking downstream along a creek that crosses the Hike-Bike Trail at Huntley Meadows Park, Fairfax County, Virginia USA.

4mm | f/4 | 1/1000s | ISO 100 | -1 ev

Approaching the observation platform at the terminus of the Hike-Bike Trail. Notice the chromatic aberration in the tree tops at the upper-right corner of the photo.

Looking toward the observation platform at the terminus of the Hike-Bike Trail, Huntley Meadows Park, Fairfax County, Virginia USA.

4mm | f/4 | 1/1600s | ISO 100 | -1 ev

Looking toward the observation platform.

Approaching the observation platform at the terminus of the Hike-Bike Trail, Huntley Meadows Park, Fairfax County, Virginia USA.

4mm | f/4 | 1/1300s | ISO 100 | 0 ev

The central wetland area, as viewed from the observation platform. Notice the observation tower is faintly visible at the far side of the wetlands.

The central wetland area, as viewed from the observation platform at the terminus of the Hike-Bike Trail, Huntley Meadows Park, Fairfax County, Virginia USA.

4mm | f/4 | 1/2000s | ISO 100 | -1 ev

A vernal pool located near the terminus of the Hike-Bike Trail. The pool is mostly covered by ice and snow and somewhat difficult to see in the following photo.

A vernal pool located near the terminus of the Hike-Bike Trail at Huntley Meadows Park, Fairfax County, Virginia USA.

4mm | f/4 | 1/2000s | ISO 100 | -1 ev

A view of the “Mystery Pool.”

A view of the "Mystery Pool," Huntley Meadows Park, Fairfax County, Virginia USA.

4mm | f/4 | 1/1600s | ISO 100 | -1 ev

Heading toward the parking lot at the beginning of the Hike-Bike Trail.

The view along the Hike-Bike Trail at Huntley Meadows Park, Fairfax County, Virginia USA.

4mm | f/4 | 1/500s | ISO 100 | 0 ev

Related Resource: The exposure triangle and exposure compensation.

Copyright © 2016 Walter Sanford. All rights reserved.

The Final Four

October 12, 2015

March Madness was six months late this year. Huh? On the same day I discovered a male Roseate Skimmer dragonfly (Orthemis ferruginea) at Huntley Meadows Park, I witnessed what could be described as an orgy of odonate mating. Common Whitetails, Great Blue Skimmers, and Twelve-spotted Skimmers — if it were flying then it was mating and mating frequently!

The following gallery of photos features several Twelve-spotted Skimmer dragonflies (Libellula pulchella). All of these individuals are mature males, as indicated by their coloration and terminal appendages. The scratch marks on their abdomen shows they have mated many times.

As it turns out, these were the last Twelve-spotted Skimmers I saw during 2015. I was as close to these guys as I’ve ever been to Twelve-spotted Skimmers  — I think they were simply too tired to care! Please look at the full-size version of each photo in order to appreciate what it’s like to be up close and personal with a male Twelve-spotted Skimmer dragonfly.

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature male.

23 SEP 2015 | HMP | Twelve-spotted Skimmer (male)

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature male.

23 SEP 2015 | HMP | Twelve-spotted Skimmer (male)

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature male.

23 SEP 2015 | HMP | Twelve-spotted Skimmer (male)

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature male.

23 SEP 2015 | HMP | Twelve-spotted Skimmer (male)

Copyright © 2015 Walter Sanford. All rights reserved.

You look Familiar.

October 4, 2015

Do I know you? You look familiar. Like a Familiar Bluet damselfly (Enallagma civile), that is.

A Familiar Bluet damselfly (Enallagma civile) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Familiar Bluet (male)

This individual is a male, as indicated by its coloration and terminal appendages.

A Familiar Bluet damselfly (Enallagma civile) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Familiar Bluet (male)

Many American Bluets, members of the Pond Damsels Family of damselflies, can be difficult to identify, especially in the field. There are many species of bluets, most of them are blue, and many of them look similar. That being said, identification of bluet damselflies is relatively simple at Huntley Meadows Park. (Yay, another reason to love the park!)

The fact of the matter is you’re unlikely to see more than one or two of the blue bluets on the Friends of Huntley Meadows Park Odonata species list of damselflies, especially if you never venture beyond the boardwalk: Familiar Bluet (Enallagma civile); and Stream Bluet (Enallagma exsulans).

The two species look somewhat similar, but similar is not the same, as illustrated by the following composite image: Stream Bluet damselfly (spotted on 24 June 2015); Familiar Bluet damselfly (spotted on 23 September 2015). How many differences can you see?

A Stream Bluet damselfly (Enallagma exsulans) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

Composite image: Stream Bluet (male) versus Familiar Bluet (male).

Both species tend to be habitat specialists rather than habitat generalists: Familiar Bluet is the only blue bluet you’re likely to see in the central wetland area at Huntley Meadows Park; Stream Bluet is more likely to be found along some of the streams that flow through the park, such as Barnyard Run.

And then there’s the matter of timing, as shown by the Dragonflies of Loudoun calendar of adult flight periods for damselflies: 23 September is still prime time for Familiar Bluets; prime time for Stream Bluets ends in August. So if you see a beautiful blue damselfly at Huntley Meadows during September/October, then it’s almost certainly a male Familiar Bluet.

Now that you’re familiar with the who, what, where, and when of Familiar Bluets, why don’t you go find one before they’re gone? Look for them on aquatic vegetation close to the water.

Copyright © 2015 Walter Sanford. All rights reserved.

Fatal injuries?

October 2, 2015

After several years of dragonfly hunting, I’ve seen two dragonflies with three wings rather than four: in one case, I can only speculate how the injury occurred; in the other case, I witnessed the injury firsthand.

Can dragonflies survive with three wings? The answer is yes and no: if they can fly, they can survive; if they can’t fly, they can’t survive.

If they can’t fly, they’ll starve because they only eat prey they catch while flying. Source Credit: 14 Fun Facts About Dragonflies, by Sarah Zielinski, Smithsonian.com.

On the same day I discovered a male Roseate Skimmer dragonfly (Orthemis ferruginea) at Huntley Meadows Park, I heard a loud splash in a pool of water behind me. I turned around quickly and noticed a dragonfly struggling to free itself from the surface of the water. After a few seconds, the dragonfly escaped from the water and flew briefly before landing on the ground near the place where I was standing. I was able to shoot four photos before the dragonlfy flew away.

Turns out that individual was an old, injured female Great Blue Skimmer dragonfly (Libellula vibrans). One of her wings was broken near its base; I don’t know how the injury occurred. She was able to fly, but flight was labored at best.

A Great Blue Skimmer dragonfly (Libellula vibrans) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an old, injured female.

23 SEP 2015 | HMP | Great Blue Skimmer (old female, injured)

Two years earlier, I was photographing dragonflies along the boardwalk in the central wetland area. One male Great Blue Skimmer dragonfly in particular caught my attention: he repeatedly engaged one or more Common Green Darner dragonflies (Anax junius) in brief aerial dogfights. I vividly remember thinking, “Dude, you must have a death wish — those darners can be vicious predators!” Almost immediately afterward, a darner sheared off one of the male Great Blue Skimmer’s wings just like a buzzsaw and looped around for the kill shot. The skimmer dove for cover in vegetation overhanging the boardwalk (shown below) and his life was spared. I shot one poor-quality photo of the injured male Great Blue Skimmer; he flew away when I tried to move closer.

An injured dragonfly, possibly a male Great Blue Skimmer (Libellula vibrans), spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual lost a wing during a fight with a male Common Green Darner dragonfly (Anax junius).

04 SEP 2013 | HMP | Great Blue Skimmer (male, injured)

Did the female Great Blue Skimmer meet the same fate as the male? Who knows? I know there were lots of Common Green Darners hawking invisible airborne insects over a meadow near the location where I spotted the injured female. And I know Common Green Darners feed voraciously in order to store energy for migration. Perhaps both skimmers were attacked as a potential food source.

Copyright © 2015 Walter Sanford. All rights reserved.

Electrofishing for Northern Snakehead

September 28, 2015

Northern Snakehead (Channa argus) is an exotic species of fish (non-native) that threatens to disrupt the marshland ecosystem at Huntley Meadows Park, Fairfax County, Virginia USA.

I think that it is safe to say they are here to stay, after seeing the numbers of fish we removed from the wetland this past summer [2014]. We have to accept that they are here, but we will do our best to manage the populations and keep their influence on our delicate ecosystem as small as possible. Source Credit: David M. Lawlor, Natural Resource Manager, Huntley Meadows Park. Staff Manages Snakehead Threat At Huntley Meadows Park.

On 25 September 2015, Dave Lawlor (shown below, far right) collaborated with a team of staff members from the Fairfax County Department of Public Works and Environmental Services to electrofish for Northern Snakehead in the central wetland area at the park.

Electrofishing for Northern Snakehead (Channa argus) in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA.

Electrofishing for Northern Snakehead at Huntley Meadows Park.

The process seemed to be all about teamwork: every member performed a role, beginning with the “electroshockers” (see close-up, shown below) working closely with the “herders” and “dip-netters,” and ending with the “collectors.” [Editor’s Note: Words in quotes are my unofficial terms for each of the roles on the electrofishing team.]

Electrofishing for Northern Snakehead (Channa argus) in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA.

Electrofishing for Northern Snakehead at Huntley Meadows Park.

The following photo shows a relatively large Northern Snakehead netted near the berm. Approximately 25 snakeheads were culled from the wetlands, including several measuring at least 18 inches (18″) in length! The entrails will be examined to collect data about the diet of these predatory fish.

A Northern Snakehead (Channa argus) netted in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA.

A Northern Snakehead netted in the central wetland area.

The next photo shows Dave Lawlor (shown left) working closely with one of two “electroshockers” in search of snakeheads hunkered down for cover underneath a fallen log.

Electrofishing for Northern Snakehead (Channa argus) in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA.

Electrofishing for Northern Snakehead at Huntley Meadows Park.

Coincidentally, an artificial fishing lure was observed along the shoreline not far from the location of the preceding photo. Fishing is not permitted at Huntley Meadows Park. If you see anyone fishing illegally, please call the HMP Visitor Center at 703-768-2525.

An artificial fishing lure spotted at Huntley Meadows Park, Fairfax County, Virginia USA.

An artificial fishing lure.

Related Resources:

Editor’s Note: Mike Powell and I were fortunate to be in the right place when the electrofishing team arrived at the central wetland area; with permission from Dave Lawlor, we enjoyed the extraordinary opportunity to photograph this interesting event. See Mike’s excellent blog post: Snakeheads at Huntley Meadows Park.

Copyright © 2015 Walter Sanford. All rights reserved.

Roseate Skimmer dragonfly (male)

September 26, 2015

Breaking news: I discovered a new species of dragonfly at Huntley Meadows Park — a Roseate Skimmer dragonfly (Orthemis ferruginea). This is the first official record of Orthemis ferruginea in Fairfax County, Virginia.

Actually, I discovered this species last year but was unable to shoot a photo to prove I wasn’t hallucinating pink dragonflies! On 10 September 2014, I spotted a male Roseate Skimmer that made one patrol around a pool near an old beaver lodge (one that overlapped the boardwalk that goes through the central wetland area), landed for one second (no kidding) and flew upstream along Barnyard Run; I never saw it again. This year, I have photographic proof.

This individual is a male, as indicated by its coloration and terminal appendages.

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

Dig that crazy metallic purple face!

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

After one spotting, I was willing to dismiss the 2014 Roseate as a transient species; after two spottings, I’m beginning to wonder whether there’s a small reproducing population at Huntley Meadows Park. Perhaps I’m guilty of wishful thinking, but some of the marks on the dragonfly’s abdomen look like scratches from mating.

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

Look to the left…

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

Look to the right. Stand up, sit down, fight, fight, fight! Huh? I repurposed a cheer for my old high school football team since it seems to appropriately describe the male Roseate’s aggressive behavior whenever males of other species invaded his space.

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

Roseate Skimmers are common at tropical latitudes; they are uncommon to rare in the middle latitudes.

These have been working their way north but they are rare … in our area.  I have a record at the National Arboretum in Washington, D.C. in 1998, and two were found in Howard County, Maryland in 1999. Source Credit: Richard Orr, renowned expert on odonates of the mid-Atlantic region of the United States.

I’ve never seen a Roseate Skimmer but am aware of three (3) previous records for Virginia. Source Credit: Steven M. Roble, Ph.D., Staff Zoologist, Virginia Department of Conservation and Recreation, Division of Natural Heritage.

Related Resource: Roseate Skimmer (Othemis ferruginea) spotted in Henrico County, Virginia by Allen Bryan.

Copyright © 2015 Walter Sanford. All rights reserved.

Seeing the beauty in a common dragonfly

September 6, 2015
A Common Whitetail dragonfly (Plathemis lydia) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

21 AUG 2015 | Huntley Meadows Park | Common Whitetail (female)

The preceding photograph shows a Common Whitetail dragonfly (Plathemis lydia) spotted during a photowalk at Huntley Meadows Park. This individual is a female, as indicated by her coloration, pattern of wing spots, and terminal appendages.

As its common name suggests Common Whitetail dragonflies are seen commonly, seemingly everywhere, including places far from water. Some dragonflies are habitat specialists; Common Whitetails are habitat generalists. It’s easy to look at something so common and not see its beauty. Although Common Whitetails are subtly beautiful, they are beautiful nonetheless.

Copyright © 2015 Walter Sanford. All rights reserved.

HMP needs some Needham’s!

July 20, 2015

“Don’t it always seem to go that you don’t know what you got ’til it’s gone?” Source Credit: Big Yellow Taxi, Joni Mitchell.

Huntley Meadows Park (HMP), located in Fairfax County, Virginia USA, used to have a big breeding population of Needham’s Skimmer dragonflies (Libellula needhami). 2013 and 2014, not so much. We’re talking about spotting one or two individuals per year.

Is it a coincidence that the past two winters have been unusually cold in the mid-Atlantic states? Same question asked another way: Is there a reason Needham’s larvae would be less likely than other species of dragonflies to survive harsh winters? For example, Blue Dasher dragonflies (Pachydiplax longipennis) seem to be as abundant as ever. I consulted the experts of the Northeast Odonata Facebook group for answers to my questions.

Problem is I don’t think anyone knows the requirements that a breeding population of Needham’s needs to flourish. There could be other factors at play besides cold winters. Source Credit: Ed Lam, author and illustrator of Damselflies of the Northeast.

Alas, the virtual disappearance of Needham’s Skimmer from Huntley Meadows remains a puzzling mystery.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

05 JUL 2015 | Huntley Meadows Park | Needham’s Skimmer (female)

This individual is a female, as indicated by its terminal appendages. She is perching on a Tick Seed (Coreopsis grandiflora) flower dead-head.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

05 JUL 2015 | Huntley Meadows Park | Needham’s Skimmer (female)

This is only the second Needham’s Skimmer dragonfly that the author has spotted during 2015, both females. The first female is featured in another post that includes an annotated image illustrating several key field markers that may be used to identify Needham’s Skimmers.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

05 JUL 2015 | Huntley Meadows Park | Needham’s Skimmer (female)

Back in the good old days, Needham’s Skimmers were seen frequently everywhere in the central wetland area.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

24 JUN 2012 | Huntley Meadows Park | Needham’s Skimmer (male)

This individual is a male, as indicated by its reddish-orange coloration and the terminal appendages at the tip of its abdomen.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

24 JUN 2012 | Huntley Meadows Park | Needham’s Skimmer (male)

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

24 JUN 2012 | Huntley Meadows Park | Needham’s Skimmer (male)

Copyright © 2015 Walter Sanford. All rights reserved.

Common Sanddragon terminal appendages

June 26, 2015

Common Sanddragon (Progomphus obscurus) is a member of the Clubtail Family of dragonflies that is spotted during June and July in mid-Atlantic United States like Virginia. Common Sanddragons are habitat specialists that prefer sandy woodland streams, so don’t look for them in wetland areas like the hemi-marsh at Huntley Meadows Park.

Male and female Common Sandragons look similar, especially their coloration. Terminal appendages may be used to differentiate males from females.

Female dragonflies have a pair of cerci (superior appendages) that have little or no function. (See a full-size version of the following image, without annotation.)

A Common Sanddragon dragonfly (Progomphus obscurus) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

17 JUN 2015 | Huntley Meadows Park | Common Sanddragon (female)

Male dragonflies have three terminal appendages, collectively called “claspers,” that are used to grab and hold female dragonflies during mating: an upper pair of cerci (“superior appendages”) and a lower unpaired epiproct (“inferior appendage”).

A Common Sanddragon dragonfly (Progomphus obscurus) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

20 JUN 2014 | Huntley Meadows Park | Common Sanddragon (male)

Look closely at the full-size version of the following composite image contrasting the terminal appendages of a male and female Common Sanddragon dragonfly. One look at the individual with the distinctive large yellow cerci and you know which one is the male!

A Common Sanddragon dragonfly (Progomphus obscurus) spotted at Wickford Park, Fairfax County, Virginia USA. This individual is a male.

Composite image: male (background photo); female (inset photo).

The preceding male Common Sanddragon dragonfly was spotted on 26 June 2014 at Wickford Park. The female shown in the inset photo is the same one spotted on 17 June 2015 at Huntley Meadows Park.

Related Resources: Digital Dragonflies, presenting high-resolution digital scans of living dragonflies.

  • Genus Progomphus | Progomphus obscurus | Common Sanddragon | female | top view
  • Genus Progomphus | Progomphus obscurus | Common Sanddragon | male | top view
  • Genus Progomphus | Progomphus obscurus | Common Sanddragon | male | side view

Copyright © 2015 Walter Sanford. All rights reserved.


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