18 January 2012

Review: Dragonflies and Damselflies of the East

If you live in the eastern United States or Canada, be sure to pick up a copy of Dragonflies and Damselflies of the East by Dennis Paulson. This book is a must for any odonata enthusiast.

It covers 336 species in 538 pages. Some of these are the same species Paulson covered in his earlier release, Dragonflies and Damselflies of the West. If you own that book, you may want to pick up the eastern guide anyway; Paulson notes in his preface that in the two years or so since the western guide was published he has learned so much that some material in the eastern guide will "modify, perhaps even contradict" the previous book.

That caveat reflects how rapidly our understanding of Odonata distribution, ecology, and identification is evolving. Putting together a field guide to any taxa is a daunting task, much less authoring one on a moving target like Odonata. Paulson has pulled together reams of data from many sources to make this book an essential step forward from the first broad field guide to Odonata, Dunkle's Dragonflies through Binoculars, published in 2000. And of course, unlike Dunkle, it contains damselflies -- a huge and exciting plus.

Field use

Although it is in a standard roughly 8.5 by 5.5 inch field-guide size, it will weigh down your field pack by 2 pounds, 5 ounces. The type size doesn't seem smaller than other field guides, but it is very dense -- a lot of text with characters spaced very closely. For those of us in middle age, it can be difficult to wade through, especially in the field.

There are two aspects of the layout that could make field use a bit frustrating from some people.  Although we strongly prefer photo/illustration, text, and maps for each species to be all together (as they are in this book) rather than separated into plates and text (as they are in Dunkle), the variable amount of material for each species in this book means a species account could start anywhere on a page. You have to scan each page for the name of the species you are looking for. This layout is unavoidable given the amount of material in the book; thoroughness won out over user-friendly.

Second, the species are arranged in taxonomic order. In most lists of Odonata (including the Checklist of North American Odonata1), the species are listed in alphabetical order within each genus. Perhaps for most folks, who don't know the scientific names of many odonates in the first place, this will start them out on the right foot: learning the correct order and relationships. For those of us who know just enough Latin to be dangerous, it just sends us to the index. Putting together a quickie index to paste inside the back cover to guide you to your most frequently-used genera/species will be helpful.

Introductory and background material

A good introduction reviews Odonata natural history and anatomy with many great photos adding to the text.  Paulson writes clear prose that is easy-to-read without dumbing down, technical and accurate without being pedantic, and which shows his enthusiasm and wonder for odonates. The detailed macro anatomy photos in this section will be extremely helpful to complement the text describing each species, as will the three-page glossary in the back of the book.

Other overview material includes odonate threats and conservation; and finding, photographing, identifying, and collecting Odonata. Paulson outlines the important elements of identification, emphasizing the many pitfalls of trying to ID odes in the field or from photos, and he provides a good section on the hows and whys of collecting voucher specimens.

Species accounts

As one would expect, the majority of the book contains the species accounts. Each species is given similar attention, whether it's widespread and common, or limited in range. Topics for each include identification, similar species, natural history, habitat, flight season, distribution, and a range map. There are typically at least two photos in each account, usually one of each sex but also sometimes various color forms, young individuals, or regional variants.

One of the best features of the book are the illustrations which show differences between similar species' features such as male appendages or female subgenital plates. These usually follow the group of species accounts that they illustrate (pond damsels, common clubtails), but sometimes occur within the species accounts (e.g., some male Aeshna hamules and appendages). We find illustrations like this essential to ID, providing you have the insect in hand (we'd love to have these illustrations included in a small booklet for the field). These are some of the largest and most helpful we've seen, especially helpful since while the photographs of each species are very nice, most cannot adequately portray these key features. Note, however, that the illlustrations are all simple, clear line drawings and depict structural differences. Thus, no page of thoracic patterns of darners, or color patterns of the last few abdominal sections of bluets or dancers. The line drawings are only labeled with common names; scientific names would have been a valuable inclusion, and it seems like space is adequate.

While we haven't read each one, the text for the accounts seems more than adequate. Regional differences are noted if needed. The "Comments" section is often the most interesting, providing information on taxonomic quandaries, distribution mysteries, and/or knotty identification problems. It's worth it to read the introductory material for each genera as well as the accounts of all similar species when you're attacking an ID to get a complete picture. For instance, the account for Slender Baskettail (Epitheca costalis) mentions the intermediate/hybrid individuals (with Common Baskettail, E. cynosura) in the upper Midwest, but this is not brought up in the cynosura account -- even though that account notes it is the most common baskettail in the east with which all others should be compared.

The range maps are not color-coded to indicate early or late flight seasons. That was a nice touch in Dunkle's book, but would have added another layer of complexity to an already complicated task. Constructing range maps for a large region is fraught with pitfalls. These are based on a wide variety of sources and include data through the year 2010. But with a taxa like Odonata where our knowledge of distribution is so dynamic, they should be used, as Paulson notes, to "give a good idea of the known or expected distribution." He provides a further caveat that some records on which the maps are based are old, and some species may now be absent for parts of their former range.

At this particular scale, some range margins need to be taken with a grain of salt. For instance, Flag-tailed Spinyleg (Dromogomphus spoliatus) was first found by us in Michigan in Wayne Co., and has since been found in Monroe and Lenawee counties, all in extreme southeastern Michigan. The range map seems overly generous for the state. We had Michigan's first Band-winged Dragonlets (Erythrodiplax umbrata) in 2007. The record is in Odonata Central, and was published within months, but the range falls short of Michigan (nor is there a dot indicating a vagrant record). And although it was axed from the MOS database -- but not from Odonata Central -- years ago as an error, the Alpena County Russet-tipped Clubtail (Stylurus plagiatus) is shown on its map. It's just not possible for an author to keep up with all of this, and the range maps are surprisingly detailed given the amount of fragmented source data. They are a great jumping off point...and let the errata compilation begin!

In fact, the Princeton University Press web site includes a link to references used in both the eastern and western guides. It only includes papers published through 2007, but will be added to and become a valuable go-to site for serious users wanting updates.

This guide is also available in a Kindle edition. We'd be interested in hearing from people who have this on a Kindle Fire or other color e-reader. How does it look and function?

Our job as reviewers is to critique. Many of our comments are nit-picky, and probably won't be too important to the average user of the book. Though we have critiqued, we are not critical of this absolutely essential book. Get it, study it, and be ready for ode season 2012!


1Paulson, D. R., and S. W. Dunkle. 2011. A Checklist of North American Odonata, Including English Name, Etymology, Type Locality and Distribution. 2011 Edition. Originally published as Occasional Paper No. 56, Slater Museum of Natural History, University of Puget Sound, June 1999; completely revised March 2009; updated February 2011.

30 November 2011

Honduras: the odes of Pico Bonito

We made another trip south this past holiday weekend (November 24-28, 2011). This year we visited Honduras and stayed at The Lodge at Pico Bonito (15.6929, -86.9022) near La Ceiba.

Travel to the location was easy. We flew into San Pedro Sula, then one has two options to arrive at the lodge: fly to La Ceiba or drive 2.5 hours via car. We chose the latter since this gave us a chance to see a bit more of the country. The highway was in amazing condition compared with other roads in Central America, but we soon determined why this was the case. Heading east from the airport, we soon encountered oil palm plantations which have taken over vast areas of land and large variety of issues. We then drove past immense areas of fruit production (bananas and pineapple). Upon arriving in El Pino, we turned onto a nondescript road leading through secondary growth forests and cacao plantations. When the forest became thicker, we knew we were close since the lodge is at the edge of Pico Bonito National Park.

The Lodge at Pico Bonito includes several buildings (lodge, restaurant/bar, cabins) and an outdoor pool. The grounds and gardens between the cabins are a mix of manicured lawn, flower beds, and an old cacao plantation.

These gardens were good areas to find young individuals of a variety of species.



Digiscoped female skimmer (Orthemis sp.).

The porch of our cabin (#2) provided the location of our favorite ode observation.



Megaloprepus caerulatus - our favorite ode in the world.

Megaloprepus caerulatus - close up of wing tips.

The property is situated along a ridge between two rivers (Rio Coloradito to the west and Rio Corinto to the east). These clear, swift-flowing mountain rivers didn't provide much in the way of odonata observations, but they were quite beautiful. The only species observed next to a river was one female Band-winged Dragonlet (Erythrodiplax umbrata). Perhaps this was due to the time of year?

Rio Coloradito.


Rio Corinto.

Each afternoon we took a walk to the Butterfly House since the trail went through an old cacao plantation with a couple of open areas. The clearing between the larval house and the adult houses was a good area to look for odes and leps.

The ubiquitous dragonlet Band-winged Dragonlet (Erythrodiplax umbrata).


Pin-tailed Pondhawk (Erythemis plebeja).

Erythrodiplax fervida. She looks like
she is about to do a swan dive.



On our last full day (11/27/11), we hired one of the lodge's guides Elmer Escoto for a morning bird walk. We went to a new trail created west of the Rio Coloradito. The area on the left side of the photo below.


We crossed a small stream in the forest that had a few patches of sunlight. That's all we needed to pull out the net and find a couple more species of odes. We turned our bird guide into a Honduran dragonhunter.

Our guide Elmer Escoto caught the rubyspot for us.


Hetaerina capitalis.

There were also several Argias present. These appeared to be of the Argia oculatus complex, type B.


Finally, that afternoon (11/27/11) we witnessed the large dragonfly movement that the Lodge's naturalist James Adams had mentioned to us when we arrived. On our walk to the Butterfly House, we spied 1000s, if not 10s of 1000s, of odes flying in an easterly direction. Here's a distant photo (click on it to view large...all the small specs are dragonflies):



...and a digiscoped shot through my binoculars:


This flight continued nonstop throughout the afternoon. Anytime we looked up through the trees, the numbers continued. We're not sure how many species were involved, how many days this continued, or the reason for the movement.

List of species observed and locations during our brief visit:
1. Hetaerina capitalis = small forest stream west of Rio Coloradito
2. Megaloprepus caerulatus = cabin #2
3. Argia oculata complex, type B = small forest stream west of Rio Coloradito
4. Telebasis sp. = small forest stream west of Rio Coloradito
5. Black Pondhawk (Erythemis attala) = Butterfly House vicinity
6. Pin-tailed Pondhawk (E. plebeja) = Butterfly House vicinity
7. Great Pondhawk (E. vesiculosa) = the Lodge's gardens
8. Erythrodiplax fervida = Butterfly House vicinity
9. Band-winged Dragonlet (E. umbrata) = any open area
10. Roseate Skimmer (Orthemis ferruginea) = Butterfly House vicinity

10 November 2011

Updated Late Dates 2011

The mild November weather allowed us to check on a special species in Michigan. Great Spreadwing (Archilestes grandis) has only been found in Livonia through the years. Julie saw individuals again a month or so ago, and had noted goldfish swimming in one of the small pools of the creek. (this may not bode well for the odonata species).

On November 6, we waited until the frost thawed and then headed to THE location. Within a minute I found a male Eastern Forktail (Ischnura verticalis) which marks a new late date.


Julie noted that she now saw a bluegill in the same pool that had goldfish previously, and the location where the A. grandis were easiest to find in past years. (uh oh) I walked further down the creek towards I-275 between the newer buildings. In the first sunlit, sheltered location I flushed a coupled pair of Great Spreadwings! Soon after I saw a solo male and either the same or another coupled pair. This marks the new late date for Michigan by 1 day.


These may be the last species the two of us see in Michigan this season, barring Autumn Meadowhawks (Sympetrum vicinum).

06 November 2011

Last Odes of the 2011 Season in southeastern MI

While walking around campus at my workplace in Farmington Hills, Oakland County, MI, during lunch hour on October 24, 2011, I found 3 of the last dragonfly species of the season.

3+ Familiar Bluet (Enallagma civile)
1 Common Green Darner (Anax junius)
4+ Autumn Meadowhawks (Sympetrum vicinum)

Over the following days I kept an eye out for these since the late dates for specimens was approaching.

On October 31, I was able to find a female Eastern Forktail (Ischnura verticalis) for what I believe is a new late date for a MI voucher. The previous late date in the MOS database was an individual I had on 10/07/07.
This image is of a female I found in Monroe County earlier in October:


On November 2, I found one female and one male Familiar Bluet (E. civile)! This, too, is what I believe to be the latest date for a MI voucher. The previous late date in the MOS database was an individual I had on 10/19/10. Here is the male:


Today is one of the truly nice days remaining for this year. We'll head out to look for the last possibilities of flying damsels around here.

19 October 2011

Aeshna ID: Canada versus Green-striped

In our quest for Canada Darner (Aeshna canadensis) in Wayne County, we have come up with a number of locations and specimens of the similar Green-striped Darner (A. verticalis). While there is a historical and possible photo record for Canada (CADA) for the county, we've had no luck finding this species over the last ten years. We've only found one Green-striped (GSDA), in 2003, prior to this year, when we found many.

Most field guides present differentiating these two species as fairly straightforward. We've found ID more problematic, although we are hampered by a lack of live CADA material to work with. This post will go over these two species, and (necessarily) feature the variability of GSDA that would complicate field ID.

Here are the characteristics typically cited to separate the two species.

Field characteristics

Color of thoracic stripes: Usually blue in CADA, green in GSDA. However, male CADA often have stripes that are greenish ventrally or sometimes all green. Meanwhile, the rear stripe in male GSDA is sometimes blue-green dorsally.

Dot on thorax: CADA usually have a yellow dot between the two thoracic stripes. This feature is also sometimes present on GSDA. We have found it present at least half the time in our area.

Male Green-striped Darner. Rear thoracic stripe partly blue,
spot between stripes present. Livingston Co., MI

Male Green-striped Darner with very bluish stripes and thoracic
spot absent. Wayne Co., MI

CADA females come in a green-striped form, and some female GSDA are blue (rarely). Cold individuals of either species can be dull and confusing. Many guides agree that green females are probably impossible to tell apart without close examination in the hand.

Female Green-striped Darner with bluish and green abdominal spots;
thoracic spot absent. Wayne Co., MI

Female Green-striped Darner with bluish abdominal spots;
thoracic spot present. Note that both females are missing cerci,
which presents another problem (see below). Wayne Co., MI

Shape of thoracic stripes: Front stripe is supposed to be deeply notched in CADA, not so deeply notched in GSDA. The dorsal "flag" (the part of the front stripe that runs along the base of the wing) of CADA narrows, often becomes wider in GSDA, as is evident in the photos above.

This Aeshna has a "flag"that narrows, which could indicate
Canada, but the thoracic stripes are greenish, as in
Green-striped. We were unable to collect this one to verify
identity. Livingston Co., MI

Males, spot on abdominal segment 1: Usually only slightly pinched in CADA, deeply notched or bifurcated in GSDA. I've added this feature per Reuven's comment below. Here is a composite of GSDAs showing variability, with a red arrow in the first photo pointing out s1.


Certainly variable, but often distinctly "bi-lobed." I hestitate to link to online photos since I don't know if they are always correctly identified, but here are some shots that I believe are of genuine CADA showing s1.

Minnesota, s1 nearly entire.
Montana, s1 notched.
Ontario, s1 notched.
Presumed Montana, s1 deeply notched. This photo, by the way, is worth viewing original size, as there is the head of a hymenopteran latched on to one of the darner's legs!

While apparently variable in both species, this could be reliable, especially in combination with other features.

Face: Black band across the labrum in CADA, brownish edge in GSDA.

Canada Darner, black labrum.

Green-striped Darner, brownish labrum.
This seems like it also might be reliable, but we have not looked at enough CADA to be sure. One thing we've noticed about this feature, at least in GSDA, is the variability of facial markings. Many have random botches and spots. We wonder how prevalent this is in CADA, and if it muddies the diagnosis of labrum color. This photo of a putative CADA, also shows a weird blotchy face. Here are just a few GSDA faces.


In-hand characteristics

We have had more success examining these two species in the hand under very close magnification, but the keys and characteristics can be puzzling without experience or comparative material. Here are some of our experiences.

Males

In males, the shape of the cerci are similar in both species. However, as most keys note, the top margin of the superior claspers of male CADA have tiny teeth; these are absent in GSDA. These usually cannot be seen in the field or a photograph, but are said to detectable by running a finger across the cerci. I'm not sure this would be a slam-dunk even for Helen Keller. These teeth are very tiny.

Arrow pointing to teeth on top margin of CADA male cerci.
Crawford Co., MI

What we have found to be most obvious (once you know what you are looking at) are the "anteromedial process of each anterior hamule," or an aspect of the naughty bits. They are, in much more simple language, pointed in toward the rear in CADA and pointed at each other in GSDA. First, let's look at the diagram from DONA*. The red arrows show these bits, and the orientation is such that the top of the diagram is the direction of the heads of the dragonflies:

And to put this in some context, here is what it looks like. We used a Dino-Lite Digital Microscope to take these photos.

Male CADA, arrow pointing to rightmost anteromedial process. Note that in CADA, these
two paired structures look like open gates, pointing to the head of the insect.
Male GSDA, arrow pointing to rightmost anteromedial process. Note that in GSDA, these
two paired structures look like closed gates, with the tips pointing to each other.

These things are very tiny and hard to see! But if you can get the right look, they are diagnostic.

By the way, although it is not pictured or mentioned consistently in all keys, both species have a little tubercle or bump on the top of abdominal segment 10. It's visible in the photo above of the male CADA cerci.

Females

Most authors acknowledge that green-colored females of these two species can't be separated in the field, or with photos. DONA's key points us to the structure of the ridge of the genital valves, and provides us with this diagram:

These two look pretty similar. The shape of the cerci is different -- but they are often broken off. We haven't caught any candidates that still had their cerci. Those being absent, we weren't sure, even with the little arrows, precisely what structure we were supposed to be examining (in the hand, they have a lot of little ridges and flanges going on in those parts). Another diagram is helpful:

This shows that the genital valves in question are the things that the little hair-like styli come from. Once we saw that, we knew what we had to look at. The key notes that in CADA, the basal third of these valves has a weakly developed ridge, which is well developed in GSDA. We must admit, looking at a single specimen we were still uncertain. It looked kind of like either one of them. For what it's worth, here is a GSDA, with the contrast tweaked to show the ridge.


This winter, I'll try to pull out some specimens at the University of Michigan Museum of Zoology Insect Division and take a look at further material. Even better, maybe I can convince Mark O'Brien to take some digital photos. Even better than that, maybe next year the Urban Dragon Hunters can find some Canada Darners of our own.

*Needham, J.G., M.J. Westfall, Jr. and M.L. May. 2000. Dragonflies of North America, revised edition. Gainesville: Scientific Publishers. The granddaddy of Odonata keys.