ecology

Multiple Megarhyssa males

/ Ted C. MacRae / 9 Comments

Today while hiking at Hilda Young Conservation Area (north-central Jefferson County, Missouri), I encountered a declining sugar maple (Acer saccharum) with lots of woodboring insect holes in the trunk. As I approached I noticed numerous giant ichneumon wasps in the genus Megarhyssa flying about the trunk and resting on its surface. Giant ichneumons belong to the family Ichneumonidae and are, as the name suggests, the largest members of the family in North America. Interestingly, all of the wasps that I initially saw were males. I have never seen male giant ichneumon wasps before, and certainly not in such numbers, so this was quite exciting. We have two species of giant ichneumons here in Missouri—M. atrata and M. macrurus, the females of which I have seen only rarely, but I couldn’t immediately decide which of these two species the males represented. I looked up higher on the trunk, and there I saw a female M. macrurus in the act of oviposition, so I decided that the males must also represent this species. However, one of the males was smaller and differently colored than the others, having more brown than black on the body and the wings clear with a well developed spot on the costal margin. The other males were noticeably larger and had more black than brown on the body and the wings smoky with only a narrow spot on the costal margin. After a little bit of digging, I know believe that the smaller male is also M. macrurus—the same species as the ovipositing female, while the larger males all represent the larger species M. atrata.

Megarhyssa macrurus (male) | Hilda Young Conservation Area, Jefferson Co., Missouri

Megarhyssa macrurus (male) | Hilda Young Conservation Area, Jefferson Co., Missouri

Megarhyssa atrata (male) | Hilda Young Conservation Area, Jefferson Co., Missouri

Megarhyssa atrata (male) | Hilda Young Conservation Area, Jefferson Co., Missouri

As I watched the males that had landed on the trunk of the tree, I observed both the M. macrurus male and one of the M. atrata males to bend their abdomen forward beneath their body rub the tip of the abdomen against the bark, a behavior called “tergal stroking”, and at times inserted the tip of the abdomen into cracks in the bark in an almost prehensile-looking manner. These behaviors belong to a suite of behaviors exhibited by male Megarhyssa aggregations. Previously thought to be function in early insemination of as-yet-unemerged females, the precise function of these behaviors remains unknown but seems somehow related to enabling sex discrimination of emerging wasps and/or increasing the rate at which virgin females are encountered (Matthews et al. 1979).

All species of Megarhyssa parasitize the woodboring larvae of Pigeon horntails (Tremex columba) (order Hymenoptera, family Siricidae), which the females reach by inserting their long, thin ovipositor deep into the wood where the horntail larvae live. Multiple species of giant ichneumons occurring in the same area at the same time and utilizing the same resource seems to violate a basic ecological concept; the competitive exclusion principle, which states that two species competing for the same resource cannot coexist at constant population values because one species will always eventually outcompete the other. In the case of Megarhyssa, it seems that size differences between the species allow them to share a common resource (horntail larvae), as females of the larger M. atrata have longer ovipositors than the smaller M. macrurus, thus allowing them to penetrate deeper into the wood to parasitize horntail larvae that M. macrurus females cannot reach. By the same token, M. macrurus females tend to parasitize horntail larvae tunnel at shallower depths and that tend not to be utilized by M. atrata females.

REFERENCE:

Matthews, R. W., J. R. Matthews & O. Crankshaw. 1979. Aggregation in male parasitic wasps of the genus Megarhyssa: I. Sexual discrimination, tergal stroking behavior, and description of associated anal structures behavior. The Florida Entomologist 62(1):3–8 [pdf].

© Ted C. MacRae 2015

Brazil Bugs #15 – Formiga-membracídeos mutualismo

/ Ted C. MacRae / 50 Comments

Of the several insect groups that I most wanted to see and photograph during my trip to Brazil a few weeks ago, treehoppers were near the top of the list.  To say that treehoppers are diverse in the Neotropics is certainly an understatement – South America boasts an extraordinary number of bizarre and beautiful forms that still, to this day, leave evolutionary biologists scratching their heads.  The development of this amazing diversity is a relatively recent phenomenon (thinking geological scale here), as there are no known membracid fossils prior to Oligo-Miocene Dominican and Mexican amber – well after the early Cretaceous breakup of Gondwanaland split the globe into the “Old” and “New” Worlds.  With its origins apparently in South America, numerous groups continued to spring forth – each with more ridiculous pronotal modifications than the last and giving rise to the dazzling diversity of forms we see today.  Even North America got in the evolutionary act, benefiting from northern dispersal from South America’s richly developing fauna via temporary land bridges or island stepping stones that have existed at various times during the current era and giving rise to the almost exclusively Nearctic tribe Smiliini (whose species are largely associated with the continent’s eastern hardwood forests).  Only the subfamily Centrotinae, with its relatively unadorned pronotum, managed to successfully disperse to the Old World, where it remains the sole representative taxon in that hemisphere.  With a few notable exceptions, treehoppers have virtually no economic importance whatsoever, yet they enjoy relatively active study by taxonomists, evolutionists, and ecologists alike – due almost completely to the bizarreness of their forms and unique mutualistic/subsocial behaviors.

I did manage to find a few species of treehoppers during the trip (a very primitive species being featured in Answer to ID Challenge #4 – Aetalion reticulatum), and of those that I did find the nymphs in this ant-tended aggregation on a small tree in the rural outskirts of Campinas (São Paulo State) were perhaps the most striking in coloration and form.  Most were jet black, although a few exhibited fair amounts of reddish coloration, and all exhibited sharply defined white bands of wax and long erect processes on the pronotum, mesonotum, and abdomen.  I’ve seen a fair number of treehopper nymphs, but I did not recognize these as something I had seen before, and given the incomplete state of immature taxomony I feared an identification might not be possible.  Still (and I know this is probably beginning to sound like a broken record), I gave it the old college try.

I usually like to start simple and get more creative if the results aren’t satisfactory, so I went to my old friend Flickr and simply typed “Membracidae” as my search term.  Predictably, pages and pages of results appeared, and I began scanning through them to see if any contained nymphs at all resembling what I had.  After just a few pages, I encountered this photo with very similar-looking nymphs, and although no identification beyond family was indicated for the photo, I recognized the lone adult sitting with the nymphs as a member of the tribe Aconophorini – a diverse group distinguished from other treehoppers by their long, forward-projecting pronotal horn.  Luck was with me, because I happen to have a copy of the relatively recent revision of this tribe by Dietrich and Deitz (1991).  Scanning through the work, I learned that the tribe is comprised of 51 species assigned to three genera: Guayaquila (22 spp.), Calloconophora (16 spp.), and Aconophora (13 spp.).  The latter two genera can immediately be dismissed, as ant-interactions have not been recorded for any of the species in those two genera – clearly the individuals that I photographed were being tended by ants.  Further, the long, laterally directed apical processes of the pronotal horn, two pairs of abdominal spines, and other features also agree with the characters given for nymphs of the genus Guayaquila.  In looking at the species included in the genus, a drawing of a nymph that looked strikingly similar to mine was found in the species treatment for G. gracilicornis.  While that species is recorded only from Central America and northern South America, it was noted that nymphs of this species closely resemble those of the much more widely distributed G. xiphias, differing by their generally paler coloration.  My individuals are anything but pale, and reading through the description of the late-instar nymph of the latter species found every character in agreement.  A quick search of the species in Google Images was all that was needed to confirm the ID (at least to my satisfaction). 

In a study of aggregations of G. xiphias on the shrub Didymopanax vinosum (Araliaceae) in southeastern Brazil, Del-Claro and Oliveira (1999) found an astounding 21 species of associated ant species – a far greater diversity than that reported for any other ant-treehopper system.  The most frequently encountered ant species were Ectatomma edentatum, Camponotus rufipes, C. crassus, and C. renggeri, and after perusing the images of these four species at AntWeb I’m inclined to believe that the ants in these photos represent Camponotus crassus (although I am less confident of this ID than the treehoppers – corrections welcome!).  The authors noted turnover of ant species throughout the day in a significant portion of the treehopper aggregations that they observed, which they suggest probably reflects distinct humidity and temperature tolerances among the different ant species and that might serve to reduce interspecific competition among ants at treehopper aggregations.  Since treehopper predation and parasitism in the absence of ant mutualists can be severe, the development of multispecies associations by G. xiphias results in nearly “round-the-clock” protection that can greatly enhance their survival.

Update 3/3/11, 9:45 a.m.:  My thanks to Chris Dietrich at the Illinois Natural History Survey, who provided me in an email exchange some clarifying comments on the origins and subsequent dispersal of the family.  The first paragraph has been slightly modified to reflect those comments.

REFERENCES:

Del-Claro, K. and P. S. Oliveira. 1999. Ant-Homoptera interactions in a Neotropicai savanna: The honeydew-producing treehopper, Guayaquila xiphias (Membracidae), and its associated ant fauna on Didymopanax vinosum (Araliaceae). Biotropica 31(1):135–144.

Dietrich, C. H. and L. L. Deitz.  1991.  Revision of the Neotropical treehopper tribe Aconophorini (Homoptera: Membracidae).  North Carolina Agricultural Research Service Technical Bulletin 293, 134 pp.

Copyright © Ted C. MacRae 2011

3rd Blogoversary, 7 New Blogs, & AIF #10

/ Ted C. MacRae / 26 Comments

Today happens to be BitB’s 3rd blogoversary.  I won’t bore you with an attempt at witty, insightful introspection on what it means to have reached this modest milestone.  BitB is still what it started out as – tales from my life-long, entomocentric, natural history learning experience.  I’ve enjoyed these past three years immensely, learned far more than I would have initially imagined, and deeply appreciate the support and encouragement I’ve received from an admireably erudite readership.

Rather than talk on about myself, however, I’d like to talk about others.  I’m always on the lookout for new blogs – those that seem interesting make the blogroll, and if I find their content compelling enough they make my RSS feed list.  A few rise to the top due to their superior photography, insightful writing, or close alignment with my own interests – these I like to feature from time to time by name in an occasional post such as this one.  Following is the latest crop of new sites (or at least new to me) that have piqued my interest:

Crooked Beak Workshop is written by coleopterist Delbert la Rue, Research Associate at the Entomology Research Museum, University of California, Riverside.  I can forgive his primary interest in Pleocomidae (rain beetles) and other scarabaeoid taxa due to his strong side interests in Cicindelidae (tiger beetles), Buprestidae (jewel beetles), and ecology of sand dune ecosystems.  Posts occur irregularly, but when they do appear they are good old-fashioned hardcore coleopteran taxonomy and desert southwest ecology – what could be better?

Field Notes is a herpetology website by Bryan D. Hughes.  “Spectacular” does not even begin to describe his photographs, focused heavily on the marvelous diversity of venomous snakes and other reptiles in the desert southwest (and the occasional desert arachnid as well).  Bryan hopes his pictures and information will help homeowners who choose to live in areas harboring native wildlife become interested in it rather than kill it due to fear and myth – I hope he succeeds!

Gardening with Binoculars is a fairly new site by my good friend and fellow WGNSS member Anne McCormack.  Anne is a true “naturalist’s naturalist,” with solid knowledge that spans the breadth of Missouri’s flora and fauna – both vertebrate and invertebrate.  In GWB, Anne uses this knowledge and her considerable writing talents to weave informative and entertaining tales of her experiences with wildlife in a small native plant garden.  I can almost hear the campfire crackling in the background!

Natural History Museum Beetle blog is a new blog by Beulah Garner, one of the curators of Coleoptera in the Entomology department at The Natural History Museum in London (I am sooo jealous!).  With only two posts under her belt so far, it might be premature to give the site such quick praise; however, I couldn’t resist – the 2nd post had photos of tiger beetles!  Regardless, working amongst more than 9 million insects (did I mention I’m jealous?) should provide plenty of fodder for future posts.

The Atavism is written by David Winter, a PhD student in evolutionary genetics in New Zealand.  Wide ranging in his interests, it is his  series that has captured my interest (and while “spineless” across much of the blogosphere means squishy marine animals, David’s spinelessness is more to my liking – i.e., arthropod-heavy).  Moreover, in true academic fashion, David usually finds an unusual angle from which to discuss his subjects.

The Prairie Ecologist. Chris Helzer is an ecologist for The Nature Conservancy in Nebraska whose writings demonstrate deep, intimate understanding of the prairie landscape and its myriad biotic interactions, as well as the passion that many of us here in the heartland feel when looking out on its vast expanses.  As if that wasn’t enough, Chris is also one of the rare bloggers who combines his well-crafted writing with truly spectacular photography – he’s the total package!

The Sam Wells Bug Page is written by – you guessed it – Sam Wells.  This is a straight up entomology site, featuring a diversity of insects from that wonderful state called California.  You won’t find these insects anywhere else on the web, and though it is (to my liking) heavy on the beetles, a variety of other insect groups are featured as well.  What’s more, each post almost always contains fabulous photos of that remarkable California landscape.  Each post is a little mini-collecting trip – I get a little homesick for the Sierra Nevada every time I read!

One final note – Heath Blackmon at Coleopterists Corner has posted the tenth edition of An Inordinate Fondness.  This was Heath’s first blog carnival hosting gig (could there have been any more appropriate?), but you wouldn’t know it by looking – 14 coleocontributions artfully presented, each with a teaser photo and just enough text to invite further clicking.  Head on over to AIF #10 and enjoy elytral ecstasy at its finest (and don’t forget to tip the waiter!).

Copyright © Ted C. MacRae 2010

Flaming the debate

/ Ted C. MacRae / 14 Comments

Eastern redcedar encroaching loess hilltop prairie, a critically imperiled natural community in Missouri.

ResearchBlogging.orgAs my interest in prairie insects has increased over the past few years, so has my interest in their conservation. Many insects are restricted to prairies through dependence upon prairie plants or their unique physical and trophic characteristics. Thus, preservation of not only prairie plants but their insect associates as well is a major goal of conservationists.  The task is daunting – for example only ~1% of tallgrass prairie remains in the central U.S., the rest long ago converted to agriculture or otherwise irreparably altered.  Prairies are dynamic natural communities that rely upon disturbance – this need to “disturb to preserve” creates an oxymoronic conundrum for restoration ecologists that is made even more difficult by the fragmented nature of today’s prairie landscape.  The situation here in Missouri is even more difficult, as nearly all of our grassland preserves (tallgrass prairie, sand prairie, loess hilltop prairie and glades) are exceedingly small and highly disjunct relicts not connected as parts of larger systems.

In recent years, prescribed burning has become the management tactic of choice for restoring and maintaining grassland preserves.  There are good reasons for this – not only are increased floral diversity and reversal of woody encroachment well-documented responses to fire, but burning is also highly cost-effective (a critical consideration in today’s climate of shrinking public budgets).  As the use of prescribed burning on grassland preserves has become widely adopted, however, concerns about the impacts of fire on invertebrate populations have been raised.  The subject is now an area of intense research, but studies are hampered by the limited availability of large, long-unburned tracts of native prairie, and no scientific consensus has yet emerged.  Regrettably, the debate has polarized into “pro-” and “anti-fire” camps that seem unable to communicate with each other constructively.  This is unfortunate, since both ends of the spectrum offer ideas that could be used to achieve the goal of preserving prairie remnants while mitigating concerns about invertebrate impacts.  I have previously expressed my own views on the subject, a position that I suspect some might mistakenly characterize as “anti-fire.”  While I do support the use of prescribed burning, I do not support its use with no consideration of other prairie management strategies such as haying and light grazing (not to be confused with the heavy, abusive, unmanaged kind of grazing that has degraded so much of our landscape).  All of these tools (as well as parcels that receive no management at all) have potential value in prairie management and should be considered.

Those interested in potential fire impacts on prairie invertebrates will be interested in this latest salvo by Scott Swengel and colleagues, who used metadata analysis to correlate declines of prairie butterflies in the Midwest with the widespread adoption of prescribed burning as a management tactic.  The authors present convincing evidence that tallgrass prairie butterfly populations are not co-evolved with fire regimes currently used for prairie management, although their conclusions will no doubt be challenged.  Nevertheless, until a firmer scientific consensus can be achieved, prudence should dictate some measure of caution in the use of fire as an exclusive prairie management tactic.

Dear Colleagues:

We are pleased to announce a new article by Scott Swengel, Dennis Schlicht, Frank Olsen, and Ann Swengel, based on long-term data that has just been published online,  Declines of prairie butterflies in the midwestern USA.  This paper is available free from Springer Open Choice at http://www.springerlink.com/content/l732444592662434/fulltext.pdf or by going to the Journal of  Insect Conservation Online First section and scanning through the articles in ascending number order until getting to articles posted 13 August 2010.

The trends of tallgrass prairie skippers shown here, although disastrous, underestimate the decline in Iowa and Minnesota for several reasons:

  1. In statistical testing we only include sites with adequate data for testing, which eliminates many sites from inclusion that had 100% declines of a specialist we know about.
  2. Nearly all sites with long time series were the top sites to begin with, which are likely to take a longer time to show large declines than medium or low-quality sites.
  3. Recent government sponsored surveys not included here show another round of huge declines for Poweshiek Skipperling in Iowa and Minnesota.
  4. Some species went undetectable by the late 1980s and early 1990s, so didn’t register as a presence when the study began.  Hence, they cannot show a decline since then.

Some good news is that conservation based on existing knowledge of specialists’ management responses gets far better results (as shown by Regal Fritillaries and Karner Blues in Wisconsin than typical management.  So declines like this are not inevitable.

The Ecological Interpretations and Conservation Conclusion section of Discussion contain some of our new insights explaining the observed about land-use effects on prairies and butterflies.

Scott Swengel

My thanks to Scott Swengel for giving me permission to reprint his introduction.

REFERENCE:

Swengel, S. R., D. Schlicht, F. Olsen & A. B. Swengel. 2010. Declines of prairie butterflies in the midwestern USA Journal of Insect Conservation: DOI 10.1007/s10841-010-9323-1.

Copyright © Ted C. MacRae 2010

A wiley wasp

/ myrmecos / 7 Comments

[The following is an invited post by Alex Wild of Myrmecos blog]

Little did Ted know that giving me the keys to his beetle blog meant I’d be able  to use his own soapbox to convince everyone that Hymenoptera (the ants, bees, and wasps) are just waaaayyyyy cooler than Coleoptera.

Exhibit A:

Leucopsis sp. ovipositing into a solitary bee nest

Meet Leucospis. This colorful insect, about a centimeter in length, is a parasite of wood-nesting bees and wasps. In this photo she is drilling down through a leafcutter bee nest to lay her egg in one of the bee’s sealed cells. There, her larva will consume the developing bee.

Leucospid wasps aren’t terribly common, so I was rather surprised to see this one on my front porch in downtown Urbana.

The joys of ecological restoration

/ jtrager / 11 Comments

Indian paintbrush and lousewort now dominate patches of SNR

I moved to Missouri in the summer of 1988, having experienced 8 years of generous support of my family’s livelihood by my research on the infamous imported fire ants of the US Southeast, and their relatives in South America. When I arrived in the Midwest, I  hoped to land a job as an insect taxonomist in a university or museum, a goal of mine since before entering college. But this dream was one that even before moving to Missouri was dimming, and then receded ever further from the realm of possibility for me (and for traditionally trained taxonomists, generally), once here. So, I began to re-think what I might do with my work life. It would be something, I hoped, that would make some use of all the course work (mostly in entomology and botany) and research (on ant systematics) I had done during my 24 years (!) of getting educated and four additional years as a post-doc. As or more important, whatever job I ended up in would somehow have to allow me to share my life-long love of nature with others.

A museum drawer of ant specimens mounted for taxonomic study, the ants no doubt frustrated by the years of inattention they have received as I have tended to the duties of my day job.

Early in my residence in eastern Missouri, I made the acquaintance of the naturalist at a 2500-acre (1000-hectare) nature reserve outside of St. Louis. Shaw Arboretum, as it was then known, is country cousin to the world-renowned Missouri Botanical Garden, and is named after the Garden’s founder Henry Shaw. Long story short, in the summer of 1990 the naturalist mentioned to me that he would soon retire, the position would become available, and that I ought to apply. So I applied, and was hired as the arboretum’s naturalist in January 1991.

A dolomite glade plant endemic to a few counties in eastern Missouri, this leatherflower was established at SNR in the 1930s, but expanded exponentially after prescribed fire was introduced in the 1990s. Here, an ant characteristic of glades and dry prairies forages on the flower.

When I came on board, the “Arboretum” had mostly ceased to be an arboretum (a formal collection of trees for display, breeding and research), and most folks seemed unable to either pronounce or define the word. Indeed we learned, through a public survey, that the strange name and the stone wall in the front actually dissuaded people unfamiliar with it from entering! Yes, there were a few patches of exotic trees scattered around the property, especially in the conifer collection near the front entrance know as the “Pinetum”, but ever since the Garden had decided around 1930 that it would not, afterall move all of its horticultural operations to this then very rural site (the original intent of its purchase), formal arboretum and botanical garden type activities had been few and far between, and the site began gradually reverting from abandoned farmland to a wilder sort of place, as well as a haven for native biota. Thus, on its 75th anniversary in the year 2000, Shaw Arboretum was renamed Shaw Nature Reserve.

Colony-founding queen bumblebees are the primary actors in loosening pollen with ultrasound from shootingstar anthers, and distributing it about the plant population.

Around that time, my title changed too, to “Restoration Biologist”. The job is multifaceted; presenting public programs and classes on various aspects of the site’s natural history, writing and reviewing articles, acting as liaison to the vigorous regional group of academic ecologists who use the site for research and teaching, a very intermittent personal research program on ants resulting in sporadic publications, and last but certainly not least, ecological restoration.

Ecological restoration, in the broad sense, consists of  two primary practices:

  • Restoration of a natural community to structure and species composition presumed characteristic of an  ;;earlier condition (however arbitrary or ill-defined).
  • Reconstruction of regional, native-like habitats, de novo, using locally acquired native plant propagules in the appropriate settings of soil, hydrology,  slope aspect and climate.

Both  require essentially perpetual, follow-up maintenance, including invasive species control, mowing, haying, grazing, selective timber removal, species richness enhancements, and prescribed burning. All of these have many variations and nuances in application, and there can be impassioned arguments about their implementation in the literature, at conferences, and in forums and blogs on ecological restoration, native plants, butterflies, beetles, etc..

An ecologically conservative lily ally of undisturbed moist soil habitats now thrives in prairie plantings at the Reserve.

Attitudes about ecological restoration vary, among practitioners, among sociologists and philosophers, and in the general public. One broad attitudinal schism lies along the lines of  whether ecological restoration activities are some sort of primitivist, grand-scale gardening, or do they represent ecologically valid landscape conservation? Another question some pose is to what extent we should interfere with “natural successsion”? Be this as it may be, most people with functioning sensory perception agree the results can be very beautiful. The loveliness of the mosaic of colors in the herb layer of a spring woodland is inarguable, especially so after it has had its woody stem density reduced, and had the leaf litter burned off, to allow more light, rain and seeds to the soil surface — even where there is genuine concern about damage to invertebrate assemblages residing in forest duff. A waving meadow of grasses and flowers in a tallgrass prairie planting, intended to replace just a few of the tens of millions of acres of this ecosystem that have succumbed to the plow, has its own grand beauty, though its per-square-meter species density of plant species remains less than half that of a native prairie remnant and it is dominated mainly by habitat-generalist insect species rather than prairie specialists, even after 30 or more years.

A self-introduced grassland ant forages among a thriving, human-introduced population of this wet prairie gentian.

The smaller, daily rewards of restoration, to the practicing ecological restorationist and to those who visit his or her work, are many. Over 20 years, in the opened-up woods, restored glades and prairie and wetland plantings at SNR, I repeatedly have enjoyed the “sudden appearance” and increase in populations of ant species (of course) that I never observed during my early years of working at SNR (then scouring it for purposes of preparing an annotated ant list). The feeling I get upon discovering that a grouping of shooting star, royal catchfly, bunch flower or bottle gentian plants, are in bloom at a site where I spread their seeds five, seven, or even ten years earlier is a bit like that one feels when a child is born. The spontaneous colonization of SNR grassland plantings by prairie ragged orchid never fails to amaze me. Bird, or frog, or katydid and cricket songs in a former crop field or pasture, as the “restored” vegetation fills in and matures, is as pleasing to my ear as it is to my soul.

A few days ago (in early July), the director of the Reserve came to my office asking if I had noticed a purply pink, “possibly orchid” flower growing on a section of a berm (planted with native vegetation) in our 32-acre wetland complex. I had not been in the area recently, but headed right out to see what it was. Joyously, and not a little surprised, I learned that seeds of the purple fringeless orchid, sowed at a location nearby 17 years previously, had washed to this site, taken root, and as terrestrial orchids are wont to do, flowered after so many years!

The black-legged greater meadow katydid thrives in low areas and near bodies of water in SNR

The prairie ragged orchid began to appear in old fields and prairie plantings where prescribed burning occurs at SNR. It has not been seen in fields maintained exclusively by mowing or haying.

The purple fringeless orchid surprised the restorationist and St. Louis area botanists by flowering in the SNR wetland area 17 years after the original sowing.

Copyright © James Trager 2010

Add to FacebookAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to TwitterAdd to TechnoratiAdd to Yahoo BuzzAdd to Newsvine

Email to a friend

Taum Sauk Mountain – Missouri’s High Point

/ Ted C. MacRae / 10 Comments

Although spring is now well underway in the middlin’ latitudes of Missouri, it was only a few short weeks ago that winter was still with us.  For my last winter hike of the season, I returned to perhaps my favorite stretch of my favorite trail in all of Missouri – the Mina Sauk portion of the Taum Sauk Trail on Taum Sauk Mountain.  Located in the rugged St. Francois Mountains (the “epicenter” of the Ozark Highlands), Taum Sauk Mountain is Missouri’s highest peak.  I say “peak” with a bit of reservation – at 1,772 feet it hardly compares with the high peaks of the Rocky Mountains or even the much mellower Appalachians (and certainly not with those of my beloved Sierra Nevada).  Nevertheless, unlike the remainder of the Ozark Highlands, the St. Francois Mountains are true mountains initially formed through a series of volcanic events occurring well over a billion years ago.  They, and the rest of the Ozark Highlands, have been shaped to their current form by repeated cycles of uplift and subsequent erosion.  

During their Precambrian prime, the St. Francois Mountains reached heights of 15,000 feet (the “ancient” Appalachians, in the meantime, were still just a twinkle in Mother Earth’s eye).  Rain and wind and the vastness of time have reduced them to nubs, leaving only the most ancient of volcanic rocks as testament to their former glory.  Although most of what is now the Ozark Highlands was inundated repeatedly later in the Palaeozoic (laying down the sediments that were then uplifted and “carved” to their current shape), the highest peaks of the St. Francois Mountains may be among the few areas in the United States never to have been completely submerged under those ancient seas.  Standing atop Taum Sauk Mountain, it is tempting to visualize today’s craggy terrain as a fossil of that ancient landscape – the peaks representing the former islands of rhyolite, their slopes barren and lifeless in stark contrast with the exploding diversity of bizarre life forms appearing in the tropical waters that surrounded them.

The sterile, volcanic rocks of the St. Francois Mountains support an abundance of open, rocky glades – especially on their peaks and southern and western slopes – that are home to a number of plants and animals more typically found in the tallgrass prairies further west.  Indian grass (Sorghastrum nutans) and little bluestem (Schizachyrium scoparium) thrive in clumps between the large, pink boulders that are strewn across the landscape and which provide shelter and sunning spots for animals ranging from the charismatic eastern collared lizard (Crotaphytus collaris) to the smaller but no less beautiful splendid tiger beetle (Cicindela splendida).  The surrounding forest is historically an open woodland with a rich, herbaceous understory and widely-spaced, drought-tolerant trees such as shagbark hickory (Carya ovata), post oak (Quercus stellata), and blackjack oak (Quercus marilandica).  These woodlands and glades are a fire-mediated landscape dependent upon periodic burns to maintain their vegetative character.

A trail begins at “High Point”, marking the summit of Taum Sauk Mountain and the highest point in Missouri.  A granite slab next to the summit rock documents the elevation at 1,772.68 feet MSL (Mean Sea Level).  The Mina Sauk Falls Trail, a rugged three-mile loop that joins the Taum Sauk Section of the Ozark Trail, leads to the tallest wet-weather waterfall in Missouri, Mina Sauk Falls.  During periods of high water flow, water gushes over the edge and drops 132 feet over a series of rocky ledges.  Water was flowing lightly during my late winter visit; nevertheless, looking out from above the falls (see photo above) offers one of the most spectacular vistas available in Missouri.  A rather difficult hike down the side of the mountain to the bottom of the falls is also well worth the effort, although clear views of the entire falls are difficult to find in the dense, moist forest below (it was here that I photographed the spectacular Ozark Witch Hazel).

A second unique geological feature lies about a mile farther down the Ozark Trail – Devil’s Toll Gate.  The rocks stand 30 feet high on either side of this eight-foot-wide, 50-foot-long fissure.  The gap probably began as a vertical fracture in the rock that has been enlarged by subsequent weathering. Over time the fissure will continue to widen, as the rocks on either side lose height.

Returning to High Point at the end of the hike, I noticed that the summit was a little higher than when I started my hike – whether this was through additional uplift of the underlying mountain or a depositional event I cannot say.  Nevertheless, I estimated Missouri’s new highest elevation to be approximately 1,773.01 feet MSL!

Copyright © Ted C. MacRae 2010

Add to FacebookAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to TwitterAdd to TechnoratiAdd to Yahoo BuzzAdd to Newsvine

Email to a friend

Habitat Partitionining in Tiger Beetles

/ Ted C. MacRae / 28 Comments
Cicindela willistoni estancia

Cicindela willistoni estancia. Photo by David Melius.

ResearchBlogging.orgThe latest issue of CICINDELA (December 2009, vol. 41, no. 4) contains an interesting paper by David A. Melius titled, “Post-monsoonal Cicindela of the Laguna del Perro region of New Mexico.” This paper continues a theme that I have touched on a few times in recent posts regarding the partioning of resources by multiple species of tiger beetles utilzing the same habitat. The author reports on the results of two visits to the Laguna del Perro salt lake region of New Mexico (Torrance County) in July 2009, during which time he recorded a total of eight tiger beetle species in the area. As in many other parts of the arid west, tiger beetles in this region are highly dependent upon summer monsoonal rains to trigger adult emergence (Pearson et al. 2006), resulting in multiple species occupying a given habitat during the relatively short post-monsoonal period. However, according to the competitive exclusion principle (Hardin 1960), two species cannot stably coexist in the same habitat and compete for the same resources—one of the two competitors will always overcome the other unless resources are partitioned to avoid competition.

Cicindela willistoni estancia

Cicindela willistoni estancia. Photo by David Melius.

Tiger beetles that occupy the the same habitats employ a variety of mechanisms for avoiding direct competition. One of these is partitioning the environment into different “microhabitats.” One of the earliest reports of this was by noted American ecologist Victor Shelford, who reported that adult tiger beetles on the southern shores of Lake Michigan occupied different habitats from water’s edge to oak forest floor (Shelford 1907). Similarly, Choate (2003) found three sympatric species of tiger beetles in a coastal mudflat region in South Carolina, each of which utilized a different portion of the salt marsh. I myself have noted multiple species occupying the same habitat in Oklahoma’s Salt Plains National Wildlife Refuge, on a coastal salt marsh in Florida, and in the White River Hills of southwestern Missouri.

In the present study, the author noted distinct preferences among the eight species for different microhabitats within and adjacent to the salt flats, including 1) thick, wet mud immediately adjacent to the water, 2) damp, soft sand 10-20 m from the water and devoid of vegetation, and 3) dry to damp sand further away from the water with salt-tolerant plants. Nearby roadside habitats were also noted as an additional microhabitat. The species found and their preferred niches were:

  • Cicindela fulgida rumppii, exclusively in vegetated dry sand areas around the salt flats.
  • Cicindela (Cicindelidia) nigrocoerulea, mostly 10-20m from the water’s edge, a few also in roadside habitat.
  • Cicindela (Cicindelidia) punctulata chihuahuae, exclusively in roadside habitats.
  • Cicindela (Cicindelidia) willistoni estancia, mostly along the water’s edge.
  • Cylindera terricola cinctipennis, exclusively in dry grassy areas away from the water.
  • Ellipsoptera nevadica, exclusively along the water’s edge.
  • Eunota togata fascinans, unvegetated areas near and 10-20m from the water’s edge.
  • Habroscelimorpha circumpicta johnsoni, limited to roadside habitats and vegetated dry sand areas around the salt flats.

These microhabitat partitions can be visualized below. Note that although eight total species were collected, only 2-4 occur within each particular microhabitat and that all eight species were limited to just 1 or 2 microhabitats, resulting in unique species-guilds for each.

Some differences were also noted in species present during the different trips, suggesting that species occurring within the same microhabitat are also utilizing differences in temporal occurrence to further minimize competition. Differences in size among the different species were noted as well – for example, of the four species occurring in the vegetated, dry-damp sand microhabitat, Cylindera terricola is notably smaller and Habroscelimorpha circumpicta notably larger than the others. Since mandible length of adult tiger beetles is highly correlated with preferred prey size (Pearson et al. 2006), this likely results in utilization of different prey, further partioning resources within the different microhabitats.

I thank David A. Melius (Albequerque, New Mexico) for allowing me to include his stunning photographs of Cicindela willistoni estancia in this post.

REFERENCES:

Choate, P. M., Jr. 2003. A Field Guide and Identification Manual for Florida and Eastern U.S. Tiger Beetles.  University Press of Florida, Gainesville, 224 pp.

Hardin, G. 1960. The competitive exclusion Principle. Science 131:1292-1297.

Melius, D. A. 2009. Post-monsoonal Cicindela of the Laguna del Perro region of New Mexico. CICINDELA 41(4):81-89.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

Shelford, V. E. 1907. Preliminary note on the distribution of tiger beetles (Cicindela) and its relation to plant succession. Biological Bulletin of the Marine Biological Laboratory at Woods Hole 14:9-14.

Copyright © Ted C. MacRae 2009

Add to FacebookAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to TwitterAdd to TechnoratiAdd to Yahoo BuzzAdd to Newsvine

Email to a friend