Archive for the ‘education’ Category

Habitat for Tiger Spiketail dragonfly

August 9, 2019

Millions of readers have acquired the secrets of success through The Magic of Thinking Big. Source Credit: Amazon.

One of the secrets of success when scouting good habitat for Tiger Spiketail (Cordulegaster erronea) is “the magic of thinking small,” as in small seep-fed streams in the forest.

What does the right habitat look like?

The following photos were taken during a Tiger hunt with Michael Powell along a small stream in the forest at an undisclosed location in Prince William County, Virginia USA. The photos are shown in sequence as we worked our way downstream from the headwaters. Mike and I have seen a single Tiger Spiketail patrolling this stream on two days during 2019: 01 July; and 06 August.

The first photo shows a seep in the forest at the headwaters of a small stream located along a segment of a marked trail in Prince William County, Virginia. Notice that skunk cabbage (Symplocarpus foetidus) and interrupted fern (Osmunda claytoniana) aren’t associated with this seep.

06 AUG 2019 | PNC. William County, VA | Tiger Spiketail habitat

The next photo is located a short distance downstream from the headwaters, looking back upstream. The stream channel is ~2-3 feet wide and no more than a few inches deep.

06 AUG 2019 | PNC. William County, VA | Tiger Spiketail habitat

A smaller “side seep” (upper-right) is a tributary of the same stream (foreground).

06 AUG 2019 | PNC. William County, VA | Tiger Spiketail habitat

The last photo shows the view looking downstream from a point just below the small side seep. Although the stream seems to disappear near the bright sunlit patch on the forest floor, in fact the stream flows over the first in a series of mini-“waterfalls” that get progressively higher going downstream.

06 AUG 2019 | PNC. William County, VA | Tiger Spiketail habitat

What time of day is best for Tiger hunting?

Based upon field observations by Kevin Munroe, Michael Boatwright, and Mike Powell and me, Tiger Spiketail seems to have two time periods of increased activity that might be site-dependent: 10 a.m. to 12 noon; and 2 p.m. to 4 p.m. Mike Boatwright and I speculate increased activity might be associated with the time of day when a given site receives more sunlight. The Tiger at the site Mike Powell and I visited seems to be a “morning person.”

Do other odonates live in the same habitat?

Mike Powell photographed a Gray Petaltail dragonfly (Tachopteryx thoreyi) along the same stream on 10 July 2019. Now we know with reasonable certainty that Gray Petaltail and Tiger Spiketail can coexist in the same seep(s).

Mike also photographed a Twin-spotted Spiketail dragonfly (Cordulegaster maculata) on 16 April 2019 in a field near the mouth of the stream. Twin-spotted Spiketail larvae probably live in the stream itself, rather than the seeps that feed the stream.

Related Resource: Habitat for Tiger Spiketail dragonfly, featuring GoPro video showing another small stream where Tiger Spiketail has been observed in Northern Virginia.

Copyright © 2019 Walter Sanford. All rights reserved.

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Another Common Sanddragon

July 10, 2019

Common Sanddragon dragonfly (Progomphus obscurus) was spotted by my good friend Mike Powell during a photowalk along a small stream in the forest at an undisclosed location in Prince William County, Virginia USA.

This individual is a male, as indicated by his “indented” hind wings and terminal appendages.

21 JUN 2019 | PNC. William County, VA | Common Sanddragon (male)

It’s possible the subject is the same male we saw a short distance upstream from this location.

21 JUN 2019 | PNC. William County, VA | Common Sanddragon (male)

Adult flight period

According to records for the Commonwealth of Virginia maintained by Dr. Steve Roble, Staff Zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, the adult flight period for P. obscurus is from May 15 to September 19. The species is classified as common. Its habitat is “sandy streams.”

Bear in mind, Dr. Roble’s records are for the entire state, therefore the adult flight period for P. obscurus seems to be longer than it is in reality. The adult flight period for a single site is probably shorter — more likely around two months. For example, according to records for Northern Virginia maintained by Kevin Munroe, former manager of Huntley Meadows Park, the adult flight period for Commom Sanddragon is 29 May to 06 August.

Cut Banks and Sand Point Bars

Here’s a quick lesson on the geomorphology and basic hydrology of meandering streams, as it relates to odonates such as the Common Sanddragon that Mike and I observed along a small stream in the forest.

Streamflow is faster along cut banks and slower along sand point bars. As a result, erosion occurs along cut banks and deposition occurs along sand point bars.

P. obscurus — like the male featured in this post — can be found perching on sand point bars, usually facing the water.

Source Credit: The preceding image is a file from the Wikimedia Commons, United States Geological Survey.

Tech Tips

The first photo is uncropped, that is, full resolution for the Panasonic Lumix DMC-FZ300 superzoom bridge camera (4,000 x 3,000 pixels). Needless to say, I was fairly close to the subject!

The second photo is cropped in order to eliminate some distracting elements near the edges of the image.

Copyright © 2019 Walter Sanford. All rights reserved.

Golden Boy

July 5, 2019

A Needham’s Skimmer dragonfly (Libellula needhami) was spotted at Occoquan Regional Park (ORP), Fairfax County, Virginia USA.

This individual is an immature male, as indicated by his coloration and terminal appendages. The yellowish-red coloration of this specimen could mislead you into thinking it’s a female. Be aware that the same species of dragonfly may appear differently depending upon gender, age, and natural variation.

At this stage in the male’s maturation, his coloration is similar to females of the same species. As a mature male, the front of his thorax and abdomen will be covered by red pruinescence.

Related Resource: Posts Tagged ‘Needham’s Skimmer dragonfly’

Copyright © 2019 Walter Sanford. All rights reserved.

Gray Petaltail dragonfly (male)

July 3, 2019

The following Gray Petaltail dragonfly (Tachopteryx thoreyi) — spotted in a sunny clearing along a small stream in the forest at an undisclosed location in Prince William County, Virginia USA — is a male, as indicated by his “indented” hind wings, and terminal appendages.

14 JUN 2019 | PNC. William County, VA | Gray Petaltail (male)

Actionable Intel

I looked for Gray Petaltail for years without finding one. (Looking for love in all the wrong places?) For habitat-specific odonates such as T. thoreyi, it’s all about location, location, location. I was familiar with the standard guidance in all the field guidebooks regarding ideal habitat for Gray Petaltail, but it wasn’t until I actually saw the right habitat in the wild — and recognized it for what it is — that I began to find Grays in relatively large numbers. Book learning is good (as Jethro would say), but there’s no substitute for real-world experience.

For example, the following photograph shows a forest seep located at Occoquan Regional Park (ORP), Fairfax County, Virginia USA. The plant with broad green leaves is skunk cabbage (Symplocarpus foetidus). This is ideal habitat for T. thoreyi, and in fact, one or more “Grays” were observed along a sunny trail near this location, including a male that landed on my friend Mike Powell.

01 JUN 2019 | ORP | forest seep, with skunk cabbage

The following quote is perhaps the best description of a forest seep that I’ve read.

[Some] small tributaries … have their sources in numerous woodland seeps. While a few of these perennial springs bubble up out of the ground, most arise in moist hillside patches with lots of decaying leaf litter and luxuriant stands of skunk cabbage. Source Credit: White, Harold B., III. Natural History of Delmarva Dragonflies and Damselflies (Cultural Studies of Delaware and the Eastern Shore) (Kindle Locations 1213-1215). University Press Copublishing Division. Kindle Edition.

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.

Dromogomphus spinosus exuvia

June 28, 2019

A dragonfly exuvia was collected by Joe Johnston on 22 May 2019 at Aquia Creek, Stafford County, Virginia USA. This specimen is the cast skin from a Black-shouldered Spinyleg (Dromogomphus spinosus) larva. D. spinosus is a member of Family Gomphidae (Clubtails).

Black-shouldered Spinyleg (Dromogomphus spinosus) | exuvia (dorsal)

At first I thought the exuvia might be a species from the genus Stylurus, based upon the mid-dorsal spine on abdominal segment nine (S9). After careful examination of two excellent photo-illustrated PowerPoint presentations by Kevin Hemeon at NymphFest 2016 (see Related Resources, below), I noticed none of the species in the genus Stylurus have dorsal hooks. That’s when I realized the specimen must be D. spinosus. Eureka!

Related Resources

The following PowerPoint presentations by Kevin Hemeon are available in the “Files” section of the Northeast Odonata Facebook group. Direct links to the documents are provided below.

The Backstory

Joe Johnston is an avid boater and sport fisherman who kindly agreed to be my “Eyes on the Aquia,” always on the lookout for odonate exuvia to share with me. On 22 May 2019 Joe caught a largemouth bass that swam around one of the wooden pilings of a boat dock that extends far into Aquia Creek. The fishing line was snagged on the piling so Joe moved his boat into position to free the fish. That’s when he noticed the exuvia clinging to a piling on the underside of the dock. Good catches, Joe!

Tech Tips

The following equipment was used to shoot the quick-and-dirty handheld macro photograph featured in this post: Fujifilm X-T1 digital camera; and Fujinon XF80mm macro lens plus lens hood. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Actually, back-button focus was used to autofocus the image and adjusted manually as necessary. That’s also a Fujifilm thing. Camera settings: focal length 80mm (120mm, 35mm equivalent); ISO 200; f/9; 1/180s.

Godox XProF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control an off-camera Godox TT685 Thinklite TTL Flash (TT685F) set for radio slave mode. The flash was fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen the image, plus add annotations.

Sometime in the future (probably the odonate “off-season”) I will create higher quality composite images of this exuvia, shown from all viewpoints including the ventral view. As it turns out, the dorsal view is sufficient to identify this species.

Copyright © 2019 Walter Sanford. All rights reserved.

Gray Petaltail dragonfly (male)

May 29, 2019

Several Gray Petaltail dragonflies (Tachopteryx thoreyi) were observed during a photowalk with my good friend Mike Powell along a small forest stream at an undisclosed location in Prince William County, Virginia USA.

21 MAY 2019 | PNC. William County, VA | Gray Petaltail (male)

This individual — spotted in a sunny clearing — is a male, as indicated by his “indented” hind wings, and terminal appendages.

21 MAY 2019 | PNC. William County, VA | Gray Petaltail (male)

Both of the photos featured in this blog post are uncropped, that is, full resolution for the Panasonic Lumix DMC-FZ300 superzoom bridge camera (4,000 x 3,000 pixels). Needless to say, I was fairly close to this cooperative subject!

Copyright © 2019 Walter Sanford. All rights reserved.

DMC-FZ150 versus DMC-FZ300

May 8, 2019

For years, my go-to camera kit for photowalking has been the Panasonic Lumix DMC-FZ150 superzoom digital camera and a Canon 580EX Speedlite. A formula of camera and flash settings that I call “set it and forget it” works most of the time, enabling me to focus on the subject rather than futzing around with camera/flash settings.

My new Panasonic Lumix DMC-FZ300 features some significant upgrades over the DMC-FZ150 such as a touch-screen LCD, built-in WiFi (enabling remote control of the camera using the “Panasonic Image App“), 49 focus points, 4K video, and an intriguing new feature that Panasonic calls “Post Focus.”

The two cameras are similar, but as I say often, similar is not the same. As appealing as the new features of the FZ300 are, the newer camera doesn’t perform like my older FZ150. After limited testing in both the studio and in the field, I have yet to find the new formula for “set it and forget it” using the FZ300. Disappointed and frustrated, I am!

Panasonic Lumix DMC-FZ150

A Springtime Darner dragonfly (Basiaeschna janata) was spotted along Popes Head Creek at Hemlock Overlook Regional Park, Fairfax County, Virginia USA. This individual is a male.

108mm (600mm, 35mm equivalent) | ISO 100 | f/5.2 | 1/800 s | -1 ev

Flash fired, in compulsory flash mode. My external flash unit is set for Manual mode at a power ratio of 1/16, plus or minus one stop. The other settings listed in the photo caption are typical of what I call “set it and forget it,” that is, these settings work for most subjects in most lighting conditions.

The preceding photo was included in my “Top 10 Photos of 2018.” Many, if not most, of the photos in this gallery were taken using the DMC-FZ150 and my “set it and forget it” formula.

Panasonic Lumix DMC-FZ300

A Brown Spiketail dragonfly (Cordulegaster bilineata) was spotted at Occoquan Regional Park, Fairfax County, Virginia USA. This individual is a male.

108mm (600mm, 35mm equivalent) | ISO 100 | f/2.8 | 1/800 s | 1 ev

Flash fired, in compulsory flash mode.

A Common Green Darner dragonfly (Anax junius) was spotted at the North Tract of Patuxent Research Refuge, Anne Arundel County, Maryland USA. This individual is a female.

108mm (600mm, 35mm equivalent) | ISO 100 | f/2.8 | 1/800 s | 0 ev

Flash fired, in compulsory flash mode.

A Harlequin Darner dragonfly (Gomphaeschna furcillata) was spotted at the North Tract of Patuxent Research Refuge, Anne Arundel County, Maryland USA. This individual is a female.

108mm (600mm, 35mm equivalent) | ISO 100 | f/2.8 | 1/800 s | 0 ev

Flash fired, in compulsory flash mode.

What are the take-aways?

I prefer shooting in Shutter Priority mode at relatively fast shutter speeds (using the reciprocal rule) in order to reduce camera shake at longer focal lengths. If the ISO is set for 100 then the exposure triangle tells us that the only variable is aperture (f/stop). Using my “set it and forget it” formula of settings, the FZ150 typically opts for an f/stop of f/5.6 or higher (that is, a smaller lens opening); for some reason the FZ300 always seems to opt for f/2.8.

Problem is, there is too little depth of field at f/2.8! The only way I’m able to shoot serviceable photos using the FZ300 is to compose photos so the entire subject is nearly parallel to the focal plane and to sharpen the images using Adobe Photoshop.

I’m planning to start shooting in Manual mode so that I can set the ISO, aperture, and shutter speed. During limited testing in the studio, it was necessary to use a higher flash power ratio in order to get good exposure. Otherwise, Manual mode is the ultimate in “set it and forget it!”

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.

Brown Spiketail dragonflies

May 6, 2019

Several Brown Spiketail dragonflies (Cordulegaster bilineata) were spotted during a photowalk with my good friend Mike Powell at Occoquan Regional Park, Fairfax County, Virginia USA.

Male

The first individual is a male, as indicated by his “indented” hind wings, and terminal appendages. Notice the epiproct for Brown Spiketail is a wide “plate” that spans both cerci, as shown in the full-size version of the following photo.

The next individual is also male, as indicated by his hamules, located below abdominal segments two and three (S2 and S3).

Female

The last individual is a female, as indicated by her rounded hind wings and terminal appendages.

Credits

Thanks to Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, for confirming my tentative identification of the gender of the first and last individuals.

Phenology

Phenology (noun) is defined as “the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life.”

There is an annual cycle of odonate activity that can be subdivided into three broad categories: Early Season (spring); Mid-season (summer); and Late Season (fall).

Brown Spiketail is an “Early Season” species for locations in the Commonwealth of Virginia. I have noticed that the adult flight period for a given species of odonate in Northern Virginia tends to lag behind Amherst County, where my good friend Mike Boatwright (Mike B) lives, by about one-to-two weeks. When Mike B reported his first sighting of Brown Spiketail on 24 April in Amherst County, I knew it wouldn’t be long until Brown Spiketail would be flying in Fairfax County. Eight (8) days later, Mike Powell and I spotted our first-of-season Brown Spiketail dragonflies. Thanks for the heads-up, Mike B!

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.

Battery Economics 101

April 22, 2019

I bought a package of eight (8) Energizer Ultimate Lithium AA batteries for $13.28 at Loew’s (hardware store) recently. Assuming that’s a typical price point — and it may not be since retail stores are well known for inflating the price of “impulse buy” items placed near the checkout stands — I wondered which type of battery is the better value, primary cells (like the Energizers) or secondary cells (i.e., rechargeable batteries)?

B&H Photo sells an 8-Pack of Panasonic eneloop pro AA Rechargeable NiMH Batteries (1.2V, 2550mAh) for $32.99.

At face value, rechargeable batteries cost ~2.5x more than primary cells. But the secondary cells are rechargeable up to 500 times! In other words, the consumer will recover the extra cost of secondary cells after recharging them only a few times.

External flash units can be real Energy Hogs, especially when shooting at higher flash ratios. So a word to the wise consumer, get a set of rechargeable batteries — they’re worth the extra cost.

Post Addendum

My good friend Mike Powell suggested this blog post should be updated to mention that rechargeable batteries require a charger. I recommend the following combo deal available from B&H Photo: Panasonic Eneloop Pro Rechargeable AA Ni-MH Batteries with Charger (2550mAh, Pack of Four) that sells for $26.30. Done!

Copyright © 2019 Walter Sanford. All rights reserved.

Uhler’s Sundragon (female)

April 19, 2019

A Uhler’s Sundragon (Helocordulia uhleri) was spotted during a photowalk along a mid-size stream at an undisclosed location in Northern Virginia USA.

This individual is a female, as indicated by her rounded hind wings and terminal appendages. All female dragonflies have a pair of cerci (superior appendages) that have little or no function. Both cerci are visible clearly in the full-size version of the following photo.

16 APR 2019 | Northern Virginia | Uhler’s Sundragon (female)

Notice the right hind wing is slightly malformed. It appears the wing failed to inflate completely during emergence. The malformation didn’t impair her ability to fly. Pollen (probably tree pollen) is especially noticeable on the darker parts of the body.

Just the facts, ma’am.

According to records for the Commonwealth of Virginia maintained by Dr. Steve Roble, Staff Zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, the adult flight period for H. uhleri is 29 March to 27 June. The species is classified as common. Its habitat is “streams.”

Bear in mind, Dr. Roble’s records are for the entire state, therefore the adult flight period for H. uhleri seems to be longer than it is in reality. The adult flight period for a single site is probably no more than a month, and more likely around two-to-three weeks. For example, according to records for Northern Virginia maintained by Kevin Munroe, former manager of Huntley Meadows Park, the adult flight period for Uhler’s is 11 April to 05 May.

It’s also worth noting that the window of opportunity to see Uhler’s Sundragon closes rapidly after trees are in full leaf.

Is Uhler’s Sundragon common? I guess the answer to that question depends upon where you live. In Northern Virginia, Kevin Munroe classified H. uhleri as “rare.” In fact, I’m aware of only one location in Northern Virginia where Uhler’s Sundragon can be found with reasonable certainty.

Copyright © 2019 Walter Sanford. All rights reserved.


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