Unconformity on Shelf Road

Precambrian granite (about 1.6 billion years old), distinct to the practiced eye from Pikes Peak Granite, sits directly under the Ordovician Manitou Limestone (~ 450 million years ago), which has fossilized scales from jawless fishes. This contact represents over a billion years that’s missing from the geologic record (at this site). That means that the old granite probably had a series of overburdens that may have represented many events, but the evidence has all eroded away, leaving the nearly flat erosional surface, upon which the seafloor sediments accumulated that became the limestone. On Shelf Road you can put your finger on over a billion years of missing time.screen-shot-2017-03-04-at-10-18-49-pm.png



Early and Late Records for El Paso County Butterflies

Here is a list of my personal records for the early and late observations of about 170 butterfly species in El Paso County. I hope that other naturalists will make notes and contact me with new records. Collected specimens are the best way to verify sightings, but photographs usually work.


Butterfly abundance indices, Bear Creek Canyon, El Paso Co., Colorado

Amblyscirtes eos

Introduction and site description:     Butterfly surveys have been used around the world for several decades to determine the ecological health of habitats and to document or measure changes over time. In El Paso County, since F. Martin Brown began his first forays into the hills to document butterfly ranges in the 1930’s, the human population has grown from about 33,000 to over 587,000. In the same time interval, the land area of Colorado Springs proper has increased from about 12 square miles to nearly 300 square miles, and the current human population density of Colorado Springs is about 2027/square mile, and that of El Paso County about 276/sq. mi. (http://www.citydata.com/county/El_Paso_ County-CO.html; U. S. Census Bureau 2000 Report). Although the habitat loss concomitant with development caused many local population extinctions, especially as wetlands were disturbed, the city of Colorado Springs today is bordered by abundant preserved public lands, and it is probable that most butterfly populations in the areas around the city are little changed in the wake of this extensive development. Strongly restricted species, however, may now have fewer refugia and may occur in depressed populations. Regional extinctions may have gone undetected. Continue reading “Butterfly abundance indices, Bear Creek Canyon, El Paso Co., Colorado”

Earliest Spring Butterflies

Obviously, it’s not spring yet, but with the last few warm days, the butterfly species that hibernate as adults (most butterflies hibernate as pupae, larvae or even eggs) are feeling springtime in the air. Today in Bear Creek I found two species, the earliest date ever for the anglewing, and the second earliest date for the mourning cloak (Eric Eaton saw a mourning cloak in town on the 6th!). These species emerge from the pupa in August, September, October or even November, and then find safe refuge in deep grass clumps or under bark until spring. But 75°F feels a lot like spring to us, and to butterflies as well. the top is the mourning cloak (Nymphalis antiopa) and the bottom the zephyr anglewing (Polygonia zephyrus).


Historic Star Ranch

I grew up at Star Ranch, a Young Life summer camp dedicated to saving teenagers’ souls. The Ranch, previously a tuberculosis sanitarium, functioned as an evangelical camp from 1949 until the mid 1970’s, when it was sold to International Students, Inc., which served a similar purpose except directed at foreign exchange students who were far from home and vulnerable. The property fell into decline, was divided into two halves, and finally bought by Nichols and Comito for a gated community development that they called “Historic Star Ranch.” Here are a few photos of the Ranch, before and after.

First, the “house” in which I grew up. The downstairs is the Dining Hall, which fed about 150 people every meal. For several years, we lived in the upstairs, but only the right half. Later, we got the whole upper story. And, below, after Nichols and Comito prepared the grounds for Historic Star Ranch.

Star Ranch


“The Lodge,” as we knew it, had two huge rooms, one a recreation room for ping pong and pool, and the other a “library” for meetings. Then and now. In the bottom photo, the Lodge footprint is in the middle ground, right. The rock pile on the left is the rubble, awaiting the bulldozer.anzgx


The only historic aspect of this is the destruction of every detail that characterized Star Ranch. The only detail they were unable to destroy was this tiny grave, protected by State law, with a flat headstone that seems to read, “Daughter of G. and Ida Louma / Adopted dau. of S. & Phebe Briggs. / Died / Oct. 1, 1872 / Aged 7 Years / She being dead, yet spiritual.”DSC_0007.jpg

This old shed stood next to the head stone, and they had trouble destroying it without disturbing the grave site.DSC_0002.jpg

When Nichols and Comito finished bulldozing every structure on the Ranch grounds, except this stone shed, they invited my sister and me to come up to reminisce about our lives at the Ranch. They showed us the rubble fields where the main buildings once stood. They asked about our lives there. It was the single most insensitive act I’ve experienced, to ask people to identify the ruins of their home. “So, where exactly was your home?”

Forest thinning

My goodness, I’ve been going back through my old data sets from the 2006 and 2007 season when we studied the effects of forest thinning on many aspects of the ecology, including the invertebrates, which, to me, suggests moths. Look at these graphs, for example. Each of them considers a single group, or genus, of moths as they respond to thinning across the years. The leftmost points are from the control stand–never thinned. The next point, moving right, is a collection made from a stand thinned the previous year. The highest points are collections made four years after the thinning. And the last point, way off to the right, is a collection made sixteen years after thinning. Look at the pattern.screen-shot-2017-01-09-at-8-16-10-pm




Can you see the trend in all of these groups? The upshot is that they all show reduced numbers after one year of thinning, then they all show increasing numbers after four years. Then, by sixteen years after thinning, the numbers fall to near the original set. The bottom graph shows the overall biodiversity of ALL moths in this study. But the wonder of wonders is that, while the biodiversity is about the same after sixteen years, the community has greatly changed. That is, many of the original species are gone, but have been replaced by a new set. So biodiversity is not affected, but the community structure is very, very different. All this to be published in the next year. One of my 2017 goals. Questions? Ask.

Butterfly and Moth Biodiversity

Do you have any idea how many moth species live in the Pikes Peak Region? Take a guess. A hundred? A thousand? Ten thousand? Well, it turns out, if you have data like I have, a reasonable estimate can be made. I used the Clench equation, taken from Harry K. Clench’s paper* on estimating butterfly biodiversity on reserves. It is useful after a few years (or hours) of data points are available. If you want the answer, you can skip the math and go to the case study, below. But in case you’re interested…

The equation shows that the eventual number of species (Se) in a locality can be estimated as a function of a constant, K, and the number of hours spent in the field (N).


As K approaches zero, N + K approaches N, and Se = S. In this equation, S represents the number of species taken at any given time and N represents the number of years (or hours) afield. Simplified, the equation looks like this:


Data that show a positive curve will not apply, of course. This can result if the first expedition is poor but the second is extraordinary. But as more data accumulate, a negative curve is generated, and any two points roughly on the curve can be used to estimate the asymptote, which is equivalent to Se.

Let us assume that after two years, 62 species have been cataloged (2, 62), and that after an additional 2 years, a total of 81 have been recorded (4, 81). Using these to create a system of equations allows us to calculate K, and then Se, as follows.

2Se = (2)(62) + 62K

4Se = (4)(81) + 81K

multiplying the first equation by –2 yields this pair:

– 4Se = –248 – 124K

4Se =   324 + 81K

eliminating the Se term,

0 = 76 – 43K

– 76 = –43K

K = 1.77

Substituting into the original equation yields an estimate of

Se = 124 + 110 = 234 species


screen-shot-2017-01-14-at-1-20-43-pm*Clench, H. K. 1979 How to make regional lists of butterflies: some thoughts. Journ. Lepid Soc 33(4) 216-231