The beautiful beaches of the central North Carolina coast, known as the Crystal Coast in tourist brochures, are well known to beachgoers, birdwatchers, and shell hunters. Less well known is a small brown butterfly living amongst the sand dunes which, until last week, had no official name; it has now been formally described in the scientific literature as a full species: Atrytonopsis quinteri. Although newly named, this unassuming animal is not newly discovered. It was first found in 1978, and it had been the focus of my five years of PhD studies—completed with support from a Xerces Society DeWind Award—during which I dubbed it the crystal skipper.
The crystal skipper inhabits a 30-mile stretch of barrier islands, just southwest of Cape Lookout National Seashore. The dunes are a relatively barren landscape and the skipper must search out sources of nectar. However, its caterpillar host plant, seaside little bluestem (Schizachyrium littorale), is the dominant plant behind the primary dune lines, stretching back through the shrubs to the maritime forest.
When I started my PhD at North Carolina State University in 2004, my graduate advisor suggested this little-known butterfly could be a good study species to test questions I had about conservation strategies to reduce the consequences of habitat fragmentation. After an initial field season the following spring, I was hooked.
Despite its global rarity, the crystal skipper is locally abundant. The population strongholds are in two state parks that bookend the butterfly’s range, where thousands of adults fly during the distinct spring and summer broods. These numbers, while seemingly large, are relatively small compared to other rare butterflies. In between the parks, the skipper persists in smaller nature reserves, areas where there is a long setback of houses that supports healthy primary and secondary sand dunes, “empty” lots, and quite notably the unlandscaped yards that are relatively common among the older houses.
Over the course of five years, I used a combination of field and genetic techniques to look at the effects of habitat fragmentation on the crystal skipper, with an eye towards identifying conservation strategies. Before people built roads and houses, only natural barriers such as ocean inlets and maritime forest separated crystal skipper populations. If a hurricane came through and wiped out a population, or one just crashed on its own accord, butterflies from further up or down the coast would eventually fly in and re-colonize an area. Movement also prevented populations from becoming inbred.
But what now? That butterfly naturally wandering down the dune line might turn around when encountering a manicured lawn devoid of dune grasses or a parking lot, could get killed by a passing car, or just run out of energy or overheat when looking for the next patch of dune grasses. In understanding how these issues affected the crystal skipper, I could make recommendations to promote connectivity in a fragmented landscape.
By capturing crystal skippers and then releasing them at the edges of their sand dune habitat and other areas such as parking lots, the beach, housing developments, and maritime forest, I could determine whether skippers would even leave their sand dune habitat. As it turns out, they will fly into parking lot, housing areas, and forest, but infrequently fly out over the beach and ocean. A mark-recapture field study confirmed that crystal skippers would fly for at least 0.25 mile through developed areas; we even found skippers that moved over a mile in just a few days.
Population genetics studies allowed me to infer whether skippers were moving over many miles of urban development, maritime forest, or ocean, and reproducing in populations that they moved to. I found that natural features—maritime forest and ocean inlets—were barriers to dispersal.
The seeming contradiction about whether maritime forest is or is not a barrier reveals the importance of combining studies and also has implications for understanding why the intensity and pattern of urban development does not currently isolate crystal skipper populations. Over short distances, forest might not be a barrier, but within the species’ range there is a ~5 mile stretch with no sand dune habitat for the skippers. This is quite a long distance for a sun-loving, dune-dwelling creature. In more urbanized areas, small habitat patches—stepping stones—of suitable habitat permeate the development. If urbanization intensified to the point where there were no empty housing lots or natural landscaping in backyards, movement of skippers among populations separated by many miles could be very low.
Our findings readily translate to conservation recommendations for the skipper. The current system of state parks and nature reserves provides secure areas of habitat for the crystal skipper hostplant. However, to increase resiliency in the face of storms or other disturbances, there needs to be healthy habitat scattered throughout the range of the species that can support skipper populations and promote connectivity. To this end, local governments and home and business owners can retain native vegetation as landscaping and plant native nectar sources. Additionally, it will be important to control for invasive species, such as beach vitex (Vitex rotundifolia), that can take over sand dunes.
In a way, the formal naming of this butterfly was just science catching up with people. There is already a sense of pride within the local community about “their” species. I’ve been helping to run a three-day class summer class for middle school students that focuses on coastal conservation and includes activities about the crystal skipper. Taking kids out to see a butterfly they’ll find nowhere else in the world really brings home how and why conservation is important, and how local actions can make a difference.
Contributed by Allison Leidner
Allison Leidner studied the crystal skipper while earning a Ph.D. in Zoology from North Carolina State University. She currently is the Program Manager for Education and Communication in the Earth Science Division of NASA’s Science Mission Directorate.