Christmas and New Years Office Closure
Colorado Parks and Wildlife offices will be closed on December 24, December 25, December 26 and January 1.
Uncompahgre Fritillary
This high-elevation butterfly is a subspecies of the dingy fritillary.
About This Species
This subspecies occupies only a very narrow range in the San Juan Mountains. It was listed as endangered in 1991. There are around 10 known colonies of UFB; however, given this subspecies occupies remote, alpine habitats, it is possible that more colonies exist that haven't been discovered.
More Information:
Physical Characteristics
The Uncompahgre fritillary (UFB) is a relatively small butterfly with a wingspan of about an inch. The wings are rusty brown and criss-crossed with black bars. Females tend to have lighter colored wings than males. The underside of the forewing is light brown, and the underside of the hind wing has a jagged white bar separating the reddish-brown inner half from the purple-gray outer half.
Range
The UFB is endemic to Colorado, meaning it lives in Colorado and nowhere else on Earth. It’s found only in a narrow range in high alpine sites above 11,800 feet in the San Juan Mountains.
Habitat
The UFB requires habitat on northeastern facing slopes above 11,800 feet that have the correct microclimate and their host plant, snow willow (Salix nivalis).
Diet
UFB caterpillars require snow willow as a host plant. Adults require abundant and diverse nectar sources, including rambling fleabane, onestem fleabane, moss campion, many-flowered phlox, American bistort, old-man-of-the-mountain, Ross’s avens and twinflower sandwort.
Reproduction
UFB have a biennial life cycle, a reproductive cycle that takes two years to complete. Females lay eggs on or adjacent to the host plant, snow willow. Caterpillars go through multiple instar stages, phases of growth and development before they form a chrysalis; each instar stage is separated by a molt, when the caterpillar sheds its exoskeleton. With a longer life cycle than many other butterflies, caterpillars of this subspecies are thought to overwinter twice, once at the first instar stage and again at the fourth instar. This life history strategy results in odd- and even-numbered broods, according to the year they were born. These broods may function largely as distinct populations, meaning butterflies from even- and odd-numbered years rarely breed with one another. However, gene flow (genes from one population making their way into another through interbreeding) between the two broods has been documented, showing that larvae that hatch early in the summer may complete their life cycle in one year.
Threats to Species
When this subspecies was added to the federal endangered species list, overcollection was identified as a key threat; however, this is not likely a major threat today. As an alpine butterfly that requires a very specific microclimate (a small part of an environment where seasonal change is less extreme), climate change is a major threat. Habitat destruction through fire or trampling by humans or cattle also puts this subspecies in danger.