Searching for Skippers on Oregon’s Wild Southwest Coast
The Southern Oregon coast is a wild place. Situated at the convergence of the Coast Range and the Klamath-Siskiyous, this corner of the state is widely regarded as one of the country’s biodiversity hotspots. Puffin-dotted sea stacks and agate beaches quickly give way to a tangle of madrone, hemlock, and oak marching upward into thick fog. Black bears, cougars, elk, and bobcats roam the wooded slopes. Hundreds of streams cut through the mountainous terrain, providing habitat to salmonids and rare salamanders. The incredible diversity of habitats in this region supports an array of invertebrate species as well, from the green sideband snail (Monadenia fidelis flava) to the diminutive mardon skipper (Polites mardon).
Mardon skippers are small, stout butterflies with tawny brown bodies and wings. They have crooked antennae and black eyes that seem large for their body size. Skippers get their name from the way they move: in a rapid skipping pattern across the open prairies and grasslands where they are found. Like many prairie-obligate species in the Pacific Northwest, mardon skipper populations are thought to be in decline, primarily due to loss and degradation of habitat. These skippers use native grasses as host plants for their young, and adults sip nectar from a variety of flowering plants, from fuzzy cat’s ear lilies to purple camas and slender cinquefoil. Mardon skippers are found in fragmented populations across Washington, Oregon, and northern California. In Oregon, they are known from the southern Cascades and the southern coast. Adults are usually on the wing from May through July.
Although previously listed as a federal candidate species under the Endangered Species Act, concentrated survey and conservation efforts, and the discovery of new populations led to its removal in the fall of 2012. Xerces has worked on mardon skipper conservation for many years, collaborating with biologists from the Forest Service, Bureau of Land Management, US Fish and Wildlife Service, and many others to document new sites and monitor existing populations. For the last four years in particular, Xerces has worked with the Interagency Special Status/Sensitive Species Program (ISSSSP) to monitor four of the largest known mardon skipper populations in Oregon and Washington—what we call our sentinel sites. These sentinel sites are surveyed multiple times a season using a method called distance sampling. By analyzing the data from this monitoring effort, we can get population estimates that give us a sense of how the species’ largest populations are doing. While this is helpful for monitoring big picture trends, it is important to keep an eye on smaller satellite populations as well.
With this in mind, Xerces worked with the Coos Bay Bureau of Land Management earlier this summer to revisit some of the known populations on the southern Oregon coast and search for new populations in adjacent meadows. Our crew focused on the Hunter Creek area, where a couple small populations were first discovered by lepidopterist Dana Ross in 2008. As we hiked to our field sites, huge trees and fern-lined creeks gave way to sunny open meadows with bright yellow swaths of monkeyflowers, buttercup, and golden iris. Old Native American trails wind throughout this region, and occasionally we would encounter signs of homesteaders who once made their homes here. More than once we startled a mother grouse with her young, and one afternoon we paused to watch a young black bear saunter through the forest, aware of but seemingly indifferent to our presence. Bear signs were everywhere—huge piles of berry-laced scat, rough claw markings on trees, enormous footprints along the creeks.
As we moved from meadow to meadow, searching for the elusive mardon skipper, we noted all the other butterfly species on the wing. Freshly emerged greenish-blues were everywhere, darting along flower patches and chasing each other in the sunlight. Ochre ringlets performed their jerky dances through the meadows and fritillaries flitted along the meadow edges. Every now and then, we would see a pale swallowtail high along the treeline or a brilliant yellow sulphur blazing through at top speed. Butterflies aside, the habitats here are a botanist’s dream. The clashing of two ecoregions has led to amazingly complex and unique plant associations. Jeffrey pines and knobcone firs rub shoulders with western hemlock and Douglas-fir. Oaks and fragrant azaleas dot the open meadows. Madrones and manzanita course through everything, leaving rubber rabbitbrush, bunchgrasses, and a colorful assembly of flowering forbs in their wake.
Cool weather and occasional waves of coastal fog kept us on our toes this year, but we were still able to confirm that mardon skippers continue to use one of their known meadow habitats. We also found a few mardon skippers in an area that had not been surveyed before. Given the mosaic of open meadows in this area, and the availability of host and nectar plants at several of them, it is possible that mardon skippers are more widespread here than previously known. This is good news for mardon skippers, and for those of us who continue to work on their conservation.
Written by Candace Fallon, Senior Endangered Species Conservation Biologist, Public Lands Lead