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Lepidoptera of North America 12. Butterflies - 2018 inventories in nine Boulder County open spaces




Chu, Janet, author
C.P. Gillette Museum of Arthropod Diversity, publisher

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This was the fifteenth year butterflies were inventoried on nine select properties within Boulder County Parks and Open Space (BCPOS) lands. The trend for all butterfly species was determined for all surveyed Open Spaces and shows a downward trend of approximately -1.3 Individuals per Research Hour per Year. This trend (R2=0.4) explains 40% of the variation for years 2004 through 2018 which is a decrease of almost 3% /year. This leads to the conclusion that the butterfly population will be significantly diminished over time under present conditions. Our results indicate that most butterfly species are not reproducing successfully enough to keep their population numbers stable within Boulder County. Cabbage Whites (Pieris rapae) and Aphrodite Fritillaries (Speyeria aphrodite) were the most numerous of individual butterflies while Field Crescents (Phyciodes pulchella) represented the widest distribution flying in each of the Open Spaces. These resident butterflies are indicator species, as they are primary for determining if the environment is remaining vital. Of course, the BCPOS properties are influenced by state-wide and national environmental changes. Fourteen volunteers were in the field 70 days completing 175 hours of Research Hours (RH) in 2018 recording data and taking photographs. Often team members hiked somewhat near each member to observe, then experienced members input their sightings into the single day's data. The season's cumulative volunteer hours totaled 500. Of course, those following a transect were usually hiking alone, their numbers available separately, but in 2018 these were counted within the seasonal data.


Cover Illustration: Western Green Hairstreak (Callophrys affinis homoperplexa), Walker Ranch Loop Trail, Boulder Co., Colorado, June 6, 2018, By Dan Fosco.

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Lepidoptera -- North America
Butterflies -- North America
Lepidoptera -- Colorado -- Boulder County


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