Mariton: Annual Butterfly Census

June 30, 2021

by Tim Burris, Preserve Manager.  Photos by Carole Mebus and Marilyn Hessinger, Volunteers.

Photo by Marilyn Hessinger.

A Butterflier verifies identification with the camera. Photo by Marilyn Hessinger.

Mariton held its 31st Annual Butterfly Census on Saturday.  We had a knowledgeable crew of volunteers, and tallied 20 species of butterflies, which is above average.  We tallied 237 individual butterflies: the most we’ve seen in 20 years.

Photo by Carole Mebus

Little Wood Satyr. Photo by Carole Mebus.

There were a few species that were very abundant and drove up the count.  Little Wood Satyrs have been more common this year than many of us can remember.  We counted 68 which is more than double our highest previous count.  I am used to this species becoming less abundant in late June, but I checked a newer butterfly guide, and it shows Little Wood Satyr populations peaking in late June.  They have good habitat at Mariton because they like the edge of woodlands.  We will monitor population numbers for this species in future years to see if this is an ongoing trend or just a blip of circumstances.

Photo by Carole Mebus.

Coral Hairstreaks on Butterfly Weed. Photo by Carole Mebus.

Coral Hairstreaks were another abundant species.  Mariton has lots of Butterfly Weed (Asclepis tuberosa) and this plant’s nectar is like candy for Coral Hairstreaks.  From a distance this small butterfly looks dark gray, but at the right angle the orange dots are remarkable.  This year we counted 22.

Photo by Carole Mebus

Great-spangled Fritillary. Photo by Carole Mebus.

Great-spangled Fritillaries have consistently been a species with high numbers on our counts.  We counted 28 this year but have had as many as 116 in 2001.  This year is below average, but consistent with numbers from the last 10 years.

Some of the other interesting butterflies counted included 19 Little Glassywings, 3 Hoary-edge Skippers, and a Red-banded Hairstreak.

While this count is better than recent years, there is still concern for butterfly populations in our area.  The group has discussed how we can’t be reassured by the high species and individual count this year.  Some of us have been participating in the census for over two decades.  We remember seeing many more butterflies in the meadows and our travels.  Something is affecting butterfly populations, even in protected areas like Mariton, and it is cause for concern.