29 July 2010

Two new species for the Rouge River watershed

In a previous post, I mentioned the three major rivers in Wayne Co., and the degraded nature of the Rouge River. By one recent estimate*, over 90% of the Rouge is ecologically impaired. So it was exciting to find two woodland stream specialists in the watershed recently.

Streams running through woods, at least accessible ones, aren't terribly easy to find anywhere in the county. I spend a lot of quality time with Google Earth looking for decent ones. The best is the little no-name creek that flows into the Huron at Lower Huron Metropark, the only location where we've found Arrowhead Spiketail (Cordulegaster obliqua). A few weeks ago, I was scouring the new updated images on Google Earth, and came across a little creek that I had written off in the past, flowing through the northwestern corner of Maybury State Park, itself in the extreme northwestern part of the county. I later found out it has the unflattering name "Sump Drain" and it's a tributary of Johnson Creek, discussed in the previous post. Stylurus and I decided to check it out.

It was quite easy to get to, and when we reached a point where it crossed under the trail, Stylurus went in on a deer trail for a closer look. Immediately he saw a spiketail, and moment later an emerald! This was astounding and I rushed to join him (brushing against plenty of wood nettle in the process). We both saw each species cruising the stretch we were standing by, but it was twisty and overgrown. We went across the trail to the other side, where it was much more open, with less undergrown. The little creek was still sinuous, and had deadfall over it in places, but it was easier to get around. Every few minutes, a spiketail or emerald would pass by on patrol. Despite being half-blind in one eye due to an infection, Stylurus was the one who caught a male of each species: Arrowhead Spiketail and Mocha Emerald (Somatochlora linearis, the only species of this genus we've had in the county). Stylurus was happy to point out I won the prize for "most missed swings in one day."

Arrowhead Spiketail. We were surprised to see
so many, as it is getting late in the season for them.

Mocha Emeralds aren't much to look at, aside from the eyes.
Which aren't much to look at in this particular shot.

We returned with Mark O'Brien the next weekend. When we get together with Mark, it involves a lot of just standing around and jawing. And as much as I love urban dragon hunting, having a chance to get out in the field with Mark is even better, if a little less productive!

We saw no spiketails. Apparently the bunch we had the previous weekend were the last of the season. There were quite a few emeralds, however, and Mark was determined to land one to have a look.

We also saw one Fawn Darner (Boyeria vinosa), as their season is just beginning. The deadfall became more dense as we walked south, so we didn't go too much farther than we had the first week. The good water quality was indicated by the presence of Mottled Sculpin (Cottus bairdii), a fish of well-oxygenated water.

Then we wandered out to a clearing, where we saw several darners flying around. We caught a couple, and got very close to some others. Far as we could tell, they were all Lance-tipped Darners (Aeshna constricta), one of the most common species around here.

We'll be visiting this location again to see if any other darners show up, and to explore a couple of nearby ponds.

*Rising, C. M., et al. 2010. An ecological assessment of Great Lakes tributaries in the Michigan Peninsulas. Journal of Great Lakes Research, in press. DOI:10.1016/j.jglr.2010.04.008.

23 July 2010

There's a spinyleg on the Johnson

There are three major rivers here in Wayne Co., MI. The Detroit River forms the eastern border, and also the border between the U.S. and Canada. The Huron River enters from the west then flows south where it forms the southeastern border of the county before it empties into Lake Erie. The Rouge River, a tributary of the Detroit River, goes through my hometown and my place of work; I live in its watershed, I support research and protection of the Rouge, and it's the river I consider "my" home river. Unfortunately, it is also the most impaired of the three rivers. While it has come a long way in the last 30 years, it is still troubled by extremely variable flow rates, sedimentation, and pollution.Not surprisingly, most of the interesting species of lotic odes we find in the county are not in the Rouge watershed. Even the primary tributaries such as Tonquish, Fellows, and Johnson creeks suffer from the same problems as the main branches.

The Johnson, however, has the most potential for interesting odes. It is spring-fed along much of its length, and one of only three coldwater creeks in southeast Michigan. Brown trout are stocked here (although not many overwinter) and the state endangered Redside Dace are also found in the Johnson. We've had trouble finding many interesting odes over the years, though. Ever-growing development has increased sedimentation and temperatures in the creek. A lot of it is on private property.

One place with easy access is Fish Hatchery Park in Northville.

View Larger Map

It was the site of the first federal fish hatchery, which operated from 1880-1957 (it was established 6 years earlier but under state control). Here's an old postcard from "back in the day."

There is a short trail along the creek that has some pretty stretches, like the one below, but there are steep, eroded hillsides and outfalls from residential areas. Our lack of luck has meant we have not visited here often at all, and not in several years.

At the park, Johnson Creek runs by the only remaining fish pond. We dropped by a couple of weeks ago and wandered over. I saw three brown trout in the creek, and Stylurus saw a big dragonfly zoom by and perch on some overhanging vegetation. We both got great looks -- it was a Black-shouldered Spinyleg (Dromogomphus spinosus) -- a new county record! Standing on the side of the creek and looking at it only 12 feet away through binoculars, the spines on the legs looked like tree branches.

Stylurus hopped in the creek. This was not going to be an easy swing, as the insect could easily see the approach, and branches were in the way. Indeed, a voucher was not to be had this day. Or the next weekend, when we saw one patrolling that quickly retreated to the trees. Or the weekend after that, when we didn't see one at all. Thus, the record remains unofficial. You know where we'll be this weekend...

16 July 2010

Stylurus shows up on another blog

Check out Stylurus looking up odes on a credit card and posing for American Gothic here.

06 July 2010

Identifying Odonata from photographs

We are getting lots more emails these days asking us to identify photographs of damselflies and dragonflies. First let me say that we are thrilled that more people are getting interested in Odonata, and we are happy to help nurture that curiosity. These are still the salad days of odonatology -- we have an enormous amount to learn about the distribution and ecology of these insects. Because their life cycles include both aquatic and upland portions, and since many species are habitat specialists, Odonata are very important indicator species of the health of ecosystems.

Accurate, quantifiable data on Odonata abundance and distribution are invaluable, and it's easy for citizen scientists to make substantial contributions!

In one big long-winded post, we're going to tackle the issues surrounding how to do this regarding photo ID and official records, with a Midwestern-centric focus.

Identifying Odonata from photographs
We disappoint (or piss off) some people when we do not positively identify to species many of the photos that are sent us. There are many pitfalls to identifying odes from photos. We're not being fussy -- these pitfalls should not be taken lightly. Here are a few.
  • Many species can only be identified by close examination in the hand. Honest. We are not making this up. Some examples of genera that fall into this category are many damselflies, especially spreadwings (Lestes) and bluets (Enallagma); the blue darners (Aeshna); many clubtails, especially the dull Gomphus; some emeralds (Somatochlora) and many baskettails (Epitheca); and most meadowhawks (Sympetrum).

    Typically, in-hand ID involves the shape and configuration of the male's claspers and/or hamules; the female's ovipositor, subgenital plates, and/or mesothoracic plates; wing veination; or subtle markings. Or combination of some or all of the above.

    Even when these characteristics are clearly defined, many non-experts still find it difficult, or impossible, to get a positive ID. After nine years of experience, we have a good understanding of ode anatomy and have examined many hundreds of individuals. Yet we can still spend a hour with an ode under a microscope with technical manuals spread out on the table and be stumped.

    There are a slew of cases that illustrate these hazards. Some are garden-variety similar species. Then there is the really weird stuff. Some we hope to cover in detail in separate posts, but a here is an overview.

    • Hybrids and uncertain taxonomy. While not restricted to these genera, the best examples of hybrid, intergrade, or uncertain taxonomy in common species of this are are among the Epithecas and Sympetrums.

      Four species of Epitheca -- cynosura (Common Baskettail), costalis (Slender [Stripe-winged] Baskettail), semiaquea (Mantled Baskettail), and petechialis (Spot-winged Baskettail) pose serious ID challenges in the eastern U.S. Nick Donnelly works on a number of confounding taxonomic challenges, and said this about these species [1]: "Each of these species has proven to be somewhat variable at a single locality and much more so over a wide range. The variability is such that occasional specimens are not easily determined to species." Slender Baskettail was added to the Michigan checklist based on specimens deposited as Common Baskettail in the UMMZ [2]. We added Slender to the Wayne Co. list after collecting a series of baskettails in 2006. Since then we have submitted more specimens to Nick -- it turns out that most baskettails in this area are intermediate between Slender and Common. There is no way humanly possible to discern this with a photograph. And not enough have been collected to determine the geographic range of intergrades, or where different proportions of each species or intergrades occur. Therefore, in this region, this species complex cannot be identified from photographs. Period.

      The problem is similar, perhaps worse, with several common species of meadowhawks. Intergrades and taxonomic murkiness occur in various species nation- and worldwide. In this area they are Sympetrum rubicundulum (Ruby), S. internum (Cherry-faced), and S. obtrusum (White-faced). All sorts of morphological variations occur, especially in the male genitalia. In theory, Ruby and Cherry-faced have red faces, and White-faced are white. Even if this held true, immature individuals present a long continuum of color as they mature. Our collections indicate that in southern Michigan, individuals that closely match the morphology of Cherry-faced are very rare. What appear to be, in the field, Ruby and White-faced are both common, with White-faced tending to stick to wetlands more closely than Ruby. However, a large number of putative Ruby Meadowhawks (or, meadowhawks with reddish faces) have puzzling genitalia that indicate intergrades with Cherry-faced or (probably more likely in southern Michigan, at least) White-faced. We are just starting to look at the morphology of Sympetrums with white faces. We'll get back with you on that. However, Donnelly has been working on this since at least 1991 [3], so don't expect answers soon. By the way, DNA analysis has not even helped clear up this mess -- indicating species differentiation is still taking place. Ergo, we don't feel confident that this species complex can be identified from photographs. Period.

      There is also taxonomic uncertainly in a bunch of the river cruisers (Macromia), and hybrid Enallagma, Gomphus, and Leucorrhinia have also been found.

    • Aberrant individuals. Beyond the range of normal variation discussed below is the issue of truly abberant individuals. In northern Michigan, I (Nannothemis) once caught what I thought was a Variable Darner (A. interrupta) or Mottled Darner (Aeshna clepsydra) based on the thoracic pattern. When I got it home, I saw that the opposite side of the thorax was that of a Canada Darner (A. canadensis). An examination of the claspers and other features verified that it was the latter species [4]. Had I photographed the weird side, the ID would have been incorrect. We don't know how common these types of abnormalities are but they are not without precedent.

  • Inexperience with individual variation. A lot of beginners are not aware that male and female odes are often have different colors or patterns. Many female damselflies have multiple color morphs, sometimes including one "androgenic" morph that looks like a male. Many Aeshna females come in two or three colors, such as green and yellow-striped female Lance-tipped Darners (Aeshna constricta) and blue-striped Shadow Darners (A. umbrosa -- although this may be a separate subspecies). And both males and females go through color changes (in both body and wings, for species with colored wings) between emergence and sexual maturity, a process that takes place over days up to a week or more. Old individuals of some species, especially males, develop a waxy bloom (called pruinescence) on the body and occasionally wings that obscures other patterns. Some odes are a different color when they are cold, or when they are mating.

    There can also be regional differences, often in wing patterns. This is true in those pesky Sympetrum, where some species have a lot of color in their wings in the west, but none in the east. The wing bands of Widow Skimmers (Libellula luctuosa) are paler in the west, but there is range-wide individual variation. The wings of Prince Baskettails (Epitheca princeps) can be heavily or lightly marked.

    While many more experienced ode watchers can correctly identify many variable species, a big problem with photos that are incorrectly identified is that in this digital age they get posted online, perpetuating wrong IDs (see below).

  • The Internet.  There are an increasing number of good field guides to Odonata being published. However, it requires consultation of more than one to provide enough photos or plates of reliable identification characteristics to help with an ID.

    The majority of people we know don't own an array of ode field guides. Instead, they turn to the Internet to find photos that "match" their own. This is really hazardous! Without proper, verified identification a species name gets attached to a misidentified photo, another person comes along and finds a "match" and misidentifies their photo and sticks it on their web site, and viola! Misidentifications go viral. Too often even when the bad ID is discovered, people don't correct their mistakes online. We have contacted owners of popular web sites and pointed out some off-base IDs. We're thanked, and the correction never gets made to the site. When we identify a cryptic species in one of our own photos, it generally means we've netted it and confirmed the ID in the hand after taking the picture.
The bottom line is that there are species that can be confidently ID'd from an appropriate photo, and a slew of them that cannot. We are just as interested in positive ID's as anybody else -- a favorite quote is by Linneaus: "If you do not know the names of things, the knowledge of them is lost too." But we also accept that we see and photograph Odonata that cannot be named if we did not have an opportunity to examine them in-hand.

Identifying Odonata in the hand
A lot of the newer Odonata guides provide a few pages summarizing the in-hand features of confusing groups -- such as a page of "bluet butts" that illustrate the last several abdominal sections and claspers of the males of each species of Enallagma. A photocopy or scan of these cheat sheets tucked in your field gear enable you to make a giant leap forward in ode identification. You will, of course, need an insect net, and probably a 10x hand lens (although many binoculars can be used backwards for this task). While there will still be some species that require a very close look with technical manuals as reference, using a variety of cheat sheets in the field will allow the positive ID of a ton of commonly-encountered odes. And you'll become familiar with Odonata anatomy, which will increase your field ID skills as well.

A few words about how sensitive odes are to handling: they are not. Butterfly wings can be easily damaged in a net or by being handled. Odes (except for newly emerged individuals) are tough as nails. You can hold them by the wings and look them over without damaging them. If you need to hold onto a few until you get back to the car to consult more books, you can tuck them into glassine envelopes with their wings folded over their backs and tote them around for quite awhile. So long as the envelopes are carried in a hard-sided container to prevent crushing, the odes will be fine and can be examined and released without harm.

No, they don't sting. The big ones can bite, but it's just a mild pinch.

Don't want to carry a net? Then don't expect to correctly identify all the odes you see.

Official records require vouchers
We started out saying that we have a lot to learn about Odonata distribution. We live in Wayne County, Michigan, outside Detroit. It is (and always has been) the most populous county in the state, and is also the most developed. Prior to 1995, there were fewer than 50 species recorded for the county, only 32 verified by specimens. Since 2001 -- in this heavily urban county -- we have nearly doubled the number of species for the county (including several species new to the state) and re-verified nearly all the historical species. If we can do that here, what can you do around your home?

Most states that keep track of their Odonata do so out of their department of wildlife or natural resources, a state university, or museum. For a species to be "official," a voucher specimen needs to be submitted to the appropriate organization. In Michigan, this is the Michigan Odonata Survey. Requiring voucher specimens is pretty standard with insects, owing to the difficulty in identifications and taxonomic status of so many species, outlined above. Further, most states don't have well-developed Odonata study programs -- so there isn't a cadre of professionals and amateurs with the expertise to form committees to "judge" sight and photo records. The MOS, for example, was started by the University of Michigan Museum of Zoology (UMMZ) Insect Division's former collections manager Mark O'Brien. [As of late 2019, it is now managed by us, the Urban Dragon Hunters; see the website for more information.]

The golden rule of the scientific method is that studies should be objective, verifiable, and repeatable. Vouchers help to satisfy that rule in a way sight records and most photos cannot.

Read the collecting policy of the Dragonfly Society of the America for more details.

When to collect a voucher specimen
  • State and county records. These are required in Michigan. They are the most solid evidence of distribution, so if you collect anything, collect these new records (see below for which species are needed).
  • New locations. In a county with limited habitat, areas under restoration (or development), or more than one watershed, voucher specimens can help delineate habitat requirements, dispersal over time, extirpations, etc.
  • Unusual or aberrant specimens.
  • Early or late flight dates. Very useful to establish ecological parameters. For species where there is sufficient historical data, it can help shed light on the effects of global climate change (or dispute it, for deniers out there). For those without enough historical data, we may as well start now.

The value of vouchers
Aside from documenting current distribution, vouchers can help clarify or define species limits and taxonomy; be used in toxicology, genetic, and biochemical studies; and track species composition over time. An excellent overview, The role of voucher specimens in validating faunistic and ecological research, was published by the Biological Survey of Canada. Please read it.

We hope this provides the backstory to our reluctance to always positively ID photos, and our frequent encouragement of catching odes to identify them and, if needed, voucher them.

[1] Donnelly, N. 2006. Rediscovery of Intergrade Epitheca in Southern Indiana. Argia 18(2):12-13.

[2] O'Brien, M. 2004. Epitheca costalis (Stripe-winged Baskettail) in Michigan: Update.
Williamsonia 8(3):1-2.
[3] Donnelly, T.W. 1991. Current problems in Sympetrum and Libellula (a.k.a. Plathemis).
Argia 3(4): 8-12.

[4] Craves, J. 2005. Canada Darner with an unusual thorax pattern.
Williamsonia 9(1):1.

05 July 2010

Spring Migration of Southern Species?

This year (2010) seems to have quite a flurry of southerly species in southeast Michigan. Some may successfully breed in Michigan, while other individuals may be migrants.

Citrine Forktail
(Ischnura hastata) numbers have varied year-to-year since we first found them in the state in 2002. So far this season, we've only observed them at Banotai Park (formerly Sherwood Park) in Sumpter Township, Wayne County.

Comet Darner (Anax longipes) was a rarity in years past, but we've seen multiple individuals each year recently. My first of 2010 was a male observed in Farmington Hills on May 28th. Here is a female I found at Robert H. Long Park in Commerce Township on June 28th:

Swamp Darner (Epiaeschna heros) is more common some years than others. The beginning of this season brought many individuals to several locations in the area. The first observed was in our Dearborn yard on May 27th. Here is a male found in a stalled subdivision (due to the economy?) on June 11th:

Great Blue Skimmer (Libellula vibrans) is a species we are finding throughout Wayne County in proper habitat (wooded ponds) almost every year since we obtained the first voucher for the state in 2005. On July 24th, we found a male in Sumpter Township, Wayne County for our first this year:

Spot-winged Glider (Pantala hymenaea) appeared early this year and we collected a new early date voucher for MI on May 30th. Here is a female at Humbug Marsh, Detroit River International Wildlife Refuge:

Carolina Saddlebags (Tramea carolina) are also variable in numbers year-to-year. This is another good year and I saw 2 males on May 27th in Farmington Hills. We've seen a number of individuals at several sites early in the season. On June 10th, I found this male at the Novi Wetlands mitigation site at the south end of Lakeshore Park:

Others?: I'm sure there are many more species and records of note such as the Red Saddlebags (Tramea onusta) found in Port Perry, Ontario on July 6th and reported on the Great Lakes Odes listserv. I'd encourage others to get out in the field and help fill in the gaps for Michigan. Some of the species noted above are missing on the county lists of SE MI. Check out the MOS database.

04 July 2010

New vouchers for Oakland County

2010 is turning out to be a great year for insects. Nannothemis and I haven't seen such a good season for dragonflies in SE MI in years. The diversity and abundance of individuals is exceptional.

Here are accounts of three species newly vouchered for Oakland County.

1. Azure Bluet (Enallagma aspersum)
One of the parks visited during my lunch hours is Robert H. Long Park in Commerce Township, Oakland County, Michigan. On June 4th, I found several individuals northeast of the covered bridge in the swampy area before the woodlot. It's surprising to me that this species hadn't been noticed previously, since I have visited the park for at least 7 years or that it hadn't been collected for the county.

Here's a shot of a male:

Here's a shot of a female:

2. Swamp Darner (Epiaeschna heros)
This has been a good year for the presence of Swamp Darners in SE MI as we have noted them in several areas and multiple individuals at some locations. For some reason this species was missing on the list for Oakland County. On June 11th, I visited a soon-to-be subdivision in Novi that bordered mature woods and found a male patrolling the edge.

A close-up of this large species:

...and a shot showing the habitat in the background:

3. Blue-fronted Dancer (Argia apicalis)
I've been surveying insects and birds around the campus at work in Farmington Hills as a baseline. We now have a Sustainability Initiative and will plan to improve the landscaping and water areas. Currently, we have the stark, industrial landscaping that was typical of years past. On June 17th, I found a female trapped in a covered walkway. Without thinking much about this fairly common species, I plucked her from the window and released her to the great outdoors. However, while checking my list and database I learned this species was still missing for the county.

Then on June 25th, my boss and a co-worker joined me for a lunchtime walkabout and we found a few individuals. They said they'd catch one for me by hand. I warned them that the dancers are quite skittish and difficult to nab, but they tried anyway. (a video should have been taken) I ended up going to my car for the net while they "staked out" a male. Once again, I should have taken a photo. (How many engineers does it take to catch a dancer?)