mountainbreakfast

Here are graphs showing the 18 most abundant species of butterflies in each summer month or half-month. These are based on 23 years of observations of tens of thousands of butterflies. The y-axis shows the numbers of butterflies noted per hour of observation time. This is a historic record, and I understand that many readers will not know the scientific names of these butterflies, but I am illustrating the three most common above each graph. Nymphalis antiopa, the mourning cloak, hibernates as an adult and flies on the warmest days in February. Celastrina lucia is the tiny spring blue that sometimes congregates at mud spots. Its taxonomy is still uncertain. It is the most common butterfly in the canyon from April through early June. In July, its numbers fall off and it is replaced by a series of brush-footed butterflies that are of medium size and generally orange and black in color. Limenitis weidemeyeri is a large black butterfly with bold white bands across the wings. In July, the silver spots (Speyeria) and a couple of skippers (Poanes and Euphyes) become common.

This amounts to about 26 butterflies per hour.

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This amounts to about 43 butterflies per hour.

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This amounts to about 60 butterflies per hour, but over half of them are the little Spring Azure Blue.

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This amounts to about 58 butterflies per hour.

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Now we’re at about 72 butterflies per hour. Quite a jump from June.

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And all the way up to 76 per hour…

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Then, rather suddenly, back to about 44 butterflies per hour. Clearly, July is butterfly month in the Colorado foothills.

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Or about 55 butterflies per hour.

By September, numbers drop to about 20 butterflies per hour in random habitats. But from late September through October and into November, butterflies can be found in large numbers on rabbitbush, Chrysothamnus nauseosus. On these bushes, I have found 145 butterflies and over 200 day-flying moths in less than a half hour. That’s an average of about 290 butterflies per hour!

Along Nueces Bay in Portland, Texas, the butterfly activity was wonderful yesterday. Check out these guys. In the last photo, the white has his party antennae on. Never noticed that before.

This spring continues to be the warmest I’ve seen, with new early emergence records rolling in each week. Today in Bear Creek I found Erynnis telemachus, the Rocky Mountain duskywing, usually not seen until the second week of April, and Celastrina lucia, the spring azure blue, which usually starts flight around April 5th. Pussy willows in full bloom draw in large numbers of butterflies if you stop and look closely. All of the following are early records in 2017.

Erynnis telemachus, a surprise, especially because another species, E. brizo, usually flies first, and it hasn’t been seen yet.

Celastrina lucia, the spring azure blue.

Pieris rapae, the European cabbage butterfly, an import– in some parts of North America, the most abundant butterfly.

Nymphalis milberti, Milbert’s tortoise shell

Archiearis infans, the Infant moth, photographed in the net and released.

 

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.

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”

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).