A Late Summer Visit to Sweetwater Wetlands

Sweetwater

Sweetwater Wetlands

As promised last week, today’s post will feature a water treatment facility that we have in Tucson.  Like the facility I discussed last week (Gilbert Riparian Preserve – GRP), the Sweetwater Wetlands are part of Tucson’s plan to clean the water Tucsonans flush down their toilets.  Both Sweetwater and the GRP take effluent and turn it into much cleaner water.  However, there are some pretty strong difference between the two sites, and I think that makes for a very different visitor experience.

map of facility

A sign showing a map of the facility

As far as I can tell, the goals of Sweetwater are similar to those at GRP.  However, it’s really obvious that the water treatment goals are more important at Sweetwater than the wildlife or educational goals.  There are some educational signs around the site, but not many.  The wetlands have created habitat for wildlife, but the facility doesn’t celebrate its animal diversity the way GRP does.  Also, there aren’t many interpretive presentations happening at the site unless you schedule a tour or school visit in advance.  The GRP advertises regular bird watching tours, interpretive walks, and events at its observatory.  Sweetwater definitely doesn’t have much of that going on.  After visiting the GRP, it seems a little sad that my city isn’t making better use of Sweetwater as an educational tool.

cattails and algae

Cattails and algae help clean the water

It does help clean water though.  Like the GRP, Sweetwater’s water comes from the wastewater treatment plant.  Unlike the GRP, most of this water isn’t simply treated effluent.  Some of it is, but the majority of the effluent from our wastewater treatment plants is dumped straight into the river and not the wetlands.  Instead, the water at Sweetwater is mostly water used to clean the filters at the treatment plant.  This is water that is too dirty to dump into the river, so it is diverted into Sweetwater instead.  The water at Sweetwater is pretty gross!  The whole site smells musty – and you can smell it from quite a ways away.  I don’t ever touch the water there because I’m a little worried about what will happen to me if I do.

Thankfully, the plants and the sun help clean and/or filter the water at the surface.  A lot of chemicals and contaminants are trapped on the bottom of the ponds as the water slowly flows through the facility.  The water eventually reaches retention basins and filters through the soil into the shallow aquifer 140 feet down, getting cleaner the deeper it goes.  Water from the shallow aquifer is clean enough to be used for landscaping around Tucson.  Sweetwater thus takes really nasty water and recycles it into water that is actually good for something, making it a valuable part of my city’s water treatment resources.

Sweetwater

Sweetwater Wetlands

While the water at Sweetwater might be a little nasty, it really is a great place to see wildlife.  It’s fun being able to see aquatic birds in the city.  Snakes, lizards, and other reptiles abound.  There’s a resident bobcat and there are tons of birds.  In fact, lots of people go to Sweetwater specifically to look for birds.  I am not one of them, in spite of what everyone thinks as I head down the trail with my camera and binoculars.  I’m there for one reason: the dragonflies!

Sweetwater has an astonishingly large population of dragonflies.  There are few areas in Tucson that have the right combination of available water and vegetation necessary to attract large numbers of dragonflies, but Sweetwater most definitely has it!  My recent visit was on a hot, humid day and I’d expected most of the dragonflies to be resting in the shade.  Instead, there were still thousands of dragonflies flying around!  Some species were hiding in the vegetation around the ponds as expected, like the resting blue dasher:

dragonfly duel

A male blue dasher (Pachydiplax longipennis) challenges another male in an effort to drive him away from his perch. The aggressor was largely ignored.

But others were flying:

Tramea lacerata flying

A black saddlebags (Tramea lacerata) male flying over the algae-covered water

or mating:

P. longipennis mating

Blue dashers (Pachydiplax longipennis) mating. The blue male is on top while his female drapes her body beneath him.

… or doing other things that dragonflies normally do.

For the last three years, I have been on a quest to get a good photo of a dragonfly in flight and Sweetwater is an excellent place to pursue this goal.  There are so very many dragonflies I can pretty much point my camera in any direction and find a flying dragonfly.  But photographing them is hard!  You have to get to know their flight patterns, just sit and watch for a while, if you have any hope of getting a decent shot.  You usually have to pan as they fly by.  Focusing is an absolutely nightmare because the dragonfly changes position so rapidly that it’s hard to keep up.  I’ve taken thousands of photos of flying dragonflies at Sweetwater and I’ve gotten a handful that I’m reasonably happy with.  The black saddlebags pictured above is decent.  Could be better, but could be worse.  I’ve got a lot of photos like that.

On this last trip, however, a storm started moving in right when I was about to give up for the day and head home.  It got a little cloudy and cooled off a bit, so more dragonflies started flying.  One of the species that appeared was the gorgeous blue-eyed darner, Rhionaeschna multicolor.  As luck would have it, about 10 of them started flying a few feet from where I was standing, so I decided to snap a few more photos before leaving.  I’m so happy I did!  I got several shots that I was actually happy with, including this one:

Blue eyed darner, Rhionaeschna multicolor, flying

Blue-eyed darner, Rhionaeschna multicolor, flying

… and this one:

Blue eyed darner, Rhionaeschna multicolor, flying

Blue-eyed darner, Rhionaeschna multicolor, flying

I’m happy with both photos because the dragonflies fill up most of the frame and they’re much more in focus than my usual attempts.  But this one, well…  This one made me squeal just a little because I was so incredibly happy to finally get one good shot of a dragonfly in flight:

Blue eyed darner, Rhionaeschna multicolor, flying

Blue-eyed darner, Rhionaeschna multicolor, flying

The whole head is perfectly in focus!  I was beyond thrilled to get this shot.  It’s not the best dragonfly-in-flight shot ever, but I feel like I finally got the shot I’ve been trying for.  And now that I accomplished that photographic goal, I have a new one: getting a good shot of a flying dragonfly where the wings are in focus too!

So, Sweetwater was kinda stinky (as usual) and really hot until the clouds rolled in, but I was very happy I went anyway.  Getting those darner shots was a great way to end a weekend filled with Big Bugs and the Gilbert Riparian Preserve.  As I headed out to my car, I came across one last dragonfly.  I’ll leave you with that:

Libellula saturata

Female flame skimmer, Libellula saturata

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Unless otherwise stated, all text, images, and video are copyright © TheDragonflyWoman.com

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Color Polymorphisms in Dragonflies

In my last post, I talked about the dragonflies that my fiancee and I saw on our recent photographic trip to Sweetwater Wetland in Tucson.  We took a lot of photos of dragonflies and as I went through them, it occurred to me that there is an important topic related to identifying dragonflies that I have not covered so far in my blog: odonate polymorphisms.

If you’re like most people (including me until I’d been an entomology grad student for almost a year), you’re now thinking to yourself, “what is a polymorphism?”  You probably already know more about polymorphisms than you might think!  First, let’s take apart the word to define it.  The root “poly” means many.  Think back to geometry and polygons – a polygon is a shape with many sides.  The root “morph” means shape or form.  So, the word polymorphism effectively means “many forms.”  Form can refer to shapes, colors, sizes, and other characteristics of biological organisms that might vary between stages, sexes, or individuals within the same species.

You probably know about a few species that exhibit polymorphisms already.  Birds are a classic example of sexual dimorphism (di = two, so dimorphic species exhibit two forms): males take one form while females take another.  In birds, the males are often one color while the females are another.  In most cases, the males attract the females, so the males are the more colorful, showy individuals.  In general, the more brightly colored males are healthier and better able to produce strong offspring with a high chance of survival, so females will choose mates that are brightly colored over less colorful males.

Peacock and peahen

Peacock and peahen

As an example, consider peacocks.  Peacock males are VERY showy with their long, elegant tails while the female peahens are much less colorful and have much shorter tails.  Peacocks with the biggest, baddest tails get all the girls while the less showy males have to settle for leftovers (sometimes younger or less healthy females) or simply cheat their way into getting a mate.

Other animals that show dimorphisms are deer and elk.  Again, the males are trying to attract the females and are willing to fight other males for them.  Elk or deer with big racks are generally better able to successfully fight other males.  As in birds, the buck with the biggest rack is likely healthier than the bucks with smaller racks – they have to be getting enough food and other resources to grow those antlers in the first place.  The doe chooses her mate from the available males and usually selects the one that is best able to win fights, the one with the best antlers.  Because the females are not fighting amongst themselves and are not trying to attract the males, a doe doesn’t need antlers.  So, some elk and deer have horns (the males) and others do not (the females).  They are also sexually dimorphic.

Now let’s get back to the dragonflies.  Like in birds, elk, and deer, it is the role of the male dragonflies to attract female dragonflies if they wish to produce offspring.  Thus, male dragonflies are often much more brightly colored than the females and many species are sexually dimorphic.  Take, for example, the blue dashers, or Pachydiplax longipennis.  If you follow my blog, you’ve seen this one before, but here he is again in all of his elegant glory:

Blue dasher (Pachydiplax longipennis) male

Blue dasher (Pachydiplax longipennis) male

Blue dashers are very common mid-sized dragonflies across a big section of the United States, including Arizona.  The males are easy to identify based on their bright green eyes and the bluish coloration of their bodies.  The abdomen is covered in a waxy substance, or prunescence, which can give them a bit of the whitish look you see in the male pictured here.  Blue dashers are perchers, so you’ll commonly find the males sitting on emergent vegetation or on bushes and/or other plants alongside lakes and ponds.  They sit and guard their territories from their perches, waiting for females to come into their areas so they can mate.  In contrast, the females are known to spend a much greater part of their time away from water and only come to the water to mate and lay eggs.  I found this female sitting on a tree branch far from the water:

Blue dasher (Pachydiplax longipennis) female

Blue dasher (Pachydiplax longipennis) female

Can you see how different the female looks compared to the male?  The males are a whitish bluish color while the females are largely black!  The female blue dashers are about the same size and of similar shape compared to the males, but they have very different body colors, making this a dimorphic species.  Female blue dashers are also very easy to identify.  Just look for a black abdomen with yellowish or brownish stripes on each section of the abdomen.  The abdomen tends to be a bit stumpy compared to the male abdomen, so the wings look disproportionately large.  In fact, this is the origin of the species name longipennis, which means “long winged.”

Blue dashers are considered dimorphic because there are two main forms, but they are not exactly sexually dimorphic either.  Odonates are not sexually mature when they molt from nymph to adult and require a period of a few days to complete their maturation.  Immature individuals, including the males, look like the females.  So, the mature males are blueish and the immature males, immature females, and mature females all tend to look like the picture of the female.

Many dragonflies and damselflies follow similar patterns.  Green darners (Anax junius) are actually polymorphic:

Anax junius mating pair

Green darner (Anax junius) pair

As you can see in the photo, the male (the dragonfly in front) is green and blue while the female is green and green-brown.  Immatures of both sexes can have a reddish abdomen and the females can have brown sections on their abdomen.  Sometimes the females even have about the same blue on their abdomens as the males!  Because the green darners have so many different color patterns, they are considered polymorphic.

Not all dragonflies exhibit dimorphism or polymorphism.  Some dragonflies are monomorphic (mono = one) such that all indviduals look about the same, regardless of sex or age.

Next time I’ll post some more photos from the Sweetwater trip and go over how to identify them.  I hope you’ll stay tuned!

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Text and images copyright © 2009 DragonflyWoman.wordpress.com

A Trip to Sweetwater Wetlands

Before I get back to the water bugs, I want to continue my detour for a few posts and talk about some dragonflies I saw yesterday.  I needed to take some dragonfly photos, so my fiancee and I went to a constructed wetland in Tucson called Sweetwater to shoot.  Sweetwater is part of one of the wastewater treatment plants in Tucson and is fed entirely with reclaimed water and secondarily treated wastewater.  It can smell pretty bad at times (it IS made up of treated wastewater after all), but if you can overlook the scent it’s gorgeous and wholly worth a visit.  All those nutrients in the water do wonders for the plant life that grows in the water:

Sweetwater Wetland

Sweetwater Wetland

As you can see, the nutrient-rich water of the wetland is able to support a wide variety of aquatic plants.  Yesterday, the wetlands were full of cattails (the dark green bushy looking things on the right side of the picture), rushes, sedges, and duckweed.  Most of the bright green stuff floating on the water in this picture is duckweed, NOT algae, though there was definitely algae there as well.  The wetland also suports a variety of trees and shrubs and many different species of wildlife.  All those dark spots in the picture are ducks.  I’ve also seen several snakes and lizards, many other birds, and even a bobcat once!  And then there are, of course, the dragonflies.  Thousands of them.  I think Sweetwater is the best place in Tucson to see dragonflies.

We saw several dragonfly species, including green darners (Anax junius), arroyo darners (Aeshna dugesi), blue-eyed darners (Rhionaeshna multicolor),  flame skimmers (Libellula saturata), roseate skimmers (Orthemis ferruginea), blue dashers (Pachydiplax longipennis), Mexican amberwings (Perithemis intensa), variegated meadowhawks (Sympetrum corruptum), and black saddlebags (Tramea lacerata).  We also saw one species of damselfly (though we weren’t really looking hard for the damselflies either – there may have been more), the desert firetail (Telebasis salva).  Most of the dragonflies were flying above the cattails or were resting on them in various positions.  Some were even in the obelisk position, which I have talked about before in another post on dragonflies.

I got some good shots of several different species, which I’ll go over in my next post.  However, I was most thrilled with all of the large flying dragonflies, the darners.  I like taking pictures of flying dragonflies the best because they are the hardest to shoot.  This is the same reason I got interested in dragonflies in the first place – catching dragonflies for my collections for 4-H was the biggest challenge.  I have yet to get a really, really good shot of a flying dragonfly, but I keep at it, and I got some pretty decent shots today.

This is Anax junius, the green darner:

Anax junius mating pair

Anax junius mating pair

This is a mating pair.  The male, the more brightly colored one with the blue abdomen, had just grabbed his mate in preparation for mating, and then they promptly fell out of the tree onto the sidewalk, right next to me!  They sat there in this position for almost a minute while I snapped away with my camera.  Then they flew off to mate and lay eggs.  Anax junius was very abundant at Sweetwater yesterday, so I ended up getting a lot of pictures of them.  They are fliers, so they don’t land very often.  That also makes them fairly hard to photograph – they don’t sit still for very long.  So, most of the photos I got were of these insects flying, and most of them looked like this:

Dragonfly photo

Typical dragonfly flight photo

The little smudge in the photo at the tip of the big blue arrow is the dragonfly!   I took about 90 photos of Anax in flight, and these were the best:

green darner in flight

green darner in flight

green darner in flight

green darner in flight

green darner in flight

green darner in flight

What I particularly liked about these images, aside from the fact that they are actually mostly in focus, is that you can see the legs of the dragonflies folded up underneath their thoraxes.  Having the legs folded up under the body likely helps the dragonflies fly more efficiently.  If they let their legs dangle down underneath them, they are likely to slow the dragonflies down, get snagged on the vegetation when they fly low, and otherwise cause problems.  So, they fly with them tightly folded under their bodies and only stretch them out when they grab food in midair.  It’s fun to be able to see that they do this, but it would be hard to see by observing them directly because they fly so fast and so erratically.  It’s easy to see in the photos.

Like in my post on the species from the dragonfly swarm, you can clearly see from these photos that dragonflies are able to move all four of their wings independently from one another.  For example, in the top photo, you can see that the forewings are both moving down while the hindwings are moving up.  This ability to move their wings independently contributes significantly to the amazing agility that dragonflies exhibit.  If you’ve ever seen dragonflies flying, you know how fast and agile they are.  They can stop in midair, make 180 degree turns, fly backwards, hover, and do all sorts of other things that are nigh impossible for most flying animals.  They dart all over the place, which is why it’s hard to get photos of them in flight.  If you’re dealing with a flier species, such as Anax junius, they are going to be moving constantly too.  Another reason it’s hard to get good photos of dragonflies in flight is the behavior you see in this photo:

green darners in flight

green darners in flight

Dragonflies are highly territorial and protect their territories from other dragonflies that might be trying to steal their access to prime egg laying habitat or other valuable resources.  In flier species, the males typically patrol, or fly within the boundaries of their territories, looking out for females to mate with, food, and males who might want to try to claim the territory for themselves.  In this photo, the dragonfly at the top tried to steal the territory that belonged to the dragonfly on the bottom.  The owner of the territory, the dragonfly on the bottom, successfully chased the would-be thief out away from his territory.  In the photo, the territory holder is returning to his territory to continue patrolling while the loser is flying away to find another spot, hopefully one guarded by a wimpy male.  Because there are usually fewer territories available than dragonflies at a pond, these battles are constantly occurring.  When a male sees another male that might enter his territory, he will immediately change directions and charge the tresspasser in an attempt to protect his territory.  This means that the dragonflies are darting back and forth constantly.  You might track one dragonfly and just be ready to snap a photo when he stops, turns around, and zips off in a completely diferent direction.  It’s very hard to predict where a dragonfly is going to be at any given time, so it is difficult to get good photos of them in flight.

Next time I’ll go over how to identify some of the species that we saw at Sweetwater, then it’s back to the giant water bugs for a while!

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Text and images copyright © 2009 DragonflyWoman.wordpress.com