Category: Science Corner

Open post

Chickaloon Flats: A Hidden Gem on the Kenai National Wildlife Refuge

By John Morton, (retired Kenai Refuge Supervisory Biologist) Within sight of almost half of all Alaskans lies a little-known tidal estuary.  Perched along Turnagain Arm on the northwestern Kenai Peninsula, the 27,000-acre Chickaloon Flats is the only part of the Kenai National Wildlife Refuge that touches marine waters.  It represents 7% of the total estuarine area in Cook Inlet and Prince William Sound, the two water bodies that form the peninsula. As such, it’s a small but important part of the Pacific Flyway for migratory shorebirds and waterfowl.
Yellowlegs and other shorebirds foraging in a tidal pool on Chickaloon Flats.
But how important? Sadie Ulman, before becoming a biologist at Arctic Refuge, did her graduate research on shorebird use of Chickaloon Flats in 2009-2010. The last part of her thesis, which addressed that question, was published recently in the journal Waterbirds.  Sadie documented that 23 of 37 common shorebird species breeding in Alaska use Chickaloon Flats during migration.  With peak daily shorebird population estimates of 23,000 in the spring and 95,000 in the fall, this stopover site hosts a lot of birds for short periods of time. But Sadie took it another step, using stable isotope analysis of feathers to determine where six of those shorebird species spend their winter. Feathers maintain an isotopic signature of what was eaten during the relatively short period of feather growth.  This allows individual shorebirds to be sampled during breeding to estimate the geographic origin of their feather growth during the previous nonbreeding season. A combination of values from three stable isotopes (d2H, d13C, and d15N) are used to infer feather molt origin on a broad geographic scale because predictable spatial patterns of d2H occur in precipitation on a continental scale, and d13C and d15N are then used to further distinguish if the feather was grown in a terrestrial versus marine environment. Sadie used drop nets and decoys to catch (and band) migrating shorebirds that stopped over on Chickaloon Flats, from which she pulled feathers.  What did she find? Greater Yellowlegs using Chickaloon Flats likely molted in southwest Alaska, and Short-billed Dowitchers in southcentral Alaska. Lesser Yellowlegs likely molted in western Alaska and a latitudinal band across Canada, and wintered throughout the Lower 48. Least Sandpipers wintered from Oregon and south in North America but showed an isotopically similar possibility in Ecuador, Colombia, and Venezuela. Long-billed Dowitchers molted primaries across the western U.S. and Canada. Pectoral Sandpipers using Chickaloon Flats likely molted near the Rio de La Plata in southeastern South America! Sadie Ulman looking for shorebirds on the Chickaloon Flats. Amazingly, this tidal wetland, hidden in plain sight from Anchorage (15 miles from Potters Marsh), has significant value as a stopover for many shorebird species breeding in Alaska.  Belugas and brown bears also forage for silver salmon in the Chickaloon River and other parts of the estuary are used as haulouts by harbor seals. The good news is that Chickaloon Flats is conserved within the Kenai Refuge. The bad news is that it’s not protected from natural disasters.  During the 1964 Great Alaskan Earthquake, the entire estuary dropped in elevation and was inundated by mud.  Even today, Chickaloon Flats really does tilt downward to the east and south.  However, as Sadie showed in a 2019 article in Northwest Science, the marsh is slowly recovering.


Open post

Nunivak Island: Home on the Range

By Kyra Neal, Wildlife Biologist, Yukon Delta Refuge

About 30 miles offshore from where the Kuskokwim River meets the Bering Sea, nestled in Shoal Bay, there is a small island village called Mekoryuk, home to around 200 mostly Yup’ik and Cup’ik people. In this place, the mayor is the same person who takes the trash trolley to the transfer station, the city office workers are the same people who teach kindergarten, the reindeer caretaker is the same person who jump started your ATV, and the elders stop by the roadside to share wisdom of their years growing up and to welcome you to their community on Nunivak Island.

Data gap plot on the western side of Nunivak Island in the Bering Sea.

Nunivak Island is also home to 700 muskox and 3,000 reindeer. Grazing has occurred on Nunivak Island for hundreds of years, first by caribou until they were extirpated in the late 1800s and then by introduced reindeer and muskox in the last century.  The condition of their range was evaluated intensively in 1989 with 10 trend plots involving 40 quadrats and two transects for each location.
Kyra Neal pulling fall dandelion near the Mekoryuk sewage lagoon road.

Since 1989, Nunivak Island has become increasingly connected to mainland Alaska with more flights, boating, muskox hunting, and tourism. Consequently, Yukon Delta National Wildlife Refuge partnered with the Natural Resources Conservation Service (NRCS) in 2022 and 2023 to reevaluate the range condition and survey the island and village of Mekoryuk for invasive species at two different spatial scales. One is a fine-tooth comb and the other is more of a broad-stroke brush.


Reindeer at the facility in Mekoryuk
Let’s start with combing the luxurious locks of the tundra. Arriving at each plot via an R-44 helicopter, we applied the same methodology to evaluate range that was used in 1989. Within these 40 20×50 cm quadrats, we estimated ground cover for each species including lichen, shrubs, forbs, grasses, bare ground, rocks, and even scat. In 10 of these quadrats, we measured production by a double sampling clip and weigh method. Changes in ground cover and productivity will tell us how grazing has affected the range. Certain lichens are favorites of reindeer and can be depleted to bare ground exposure when overgrazing occurs. For invasives, we scouted disturbed areas in Mekoryuk by foot and in our monitoring areas, combing the tundra for anything out of place. Roads, barge ports, ATV trails, airstrips were all observed by foot in search of non-native species and plots with a high percentage of bare soil. 

Pulling out our broad-stoke brush, range was surveyed between the established transects. Using NRCS reconnaissance methods, we scored range conditions based on evaluating the amounts of lichen, bare soil, presence of grazing and scat on two acres between transects.  For our invasive species broad brush, we evaluated bare soil vectors for invasive species to get to the interior of the island. We used aerial imagery of ATV trails and disturbed areas to help us identify potential hot spots for introduction of non-native plants to the ecosystem. 

One of our 20×50 cm quadrats used for sampling ground cover to assess the condition of the range.  

What did we uncover? Well, good news and bad news. The good news is there are no invasive species on the Yukon Delta Refuge. The bad news is we did find some fall dandelion on the road leading to the airport and up to the sewage lagoon in Mekoryuk. We removed as much of the fall dandelions as could be done by hand and notified the village council president of our finding. Our range evaluation showed that the western side of Nunivak was heavily grazed, but the rest of the island has high quality grazing range for reindeer to enjoy!

Plot transects laid out by Karin Sonnen and Katie Schmidt (L) while Blaine Spellman collects data (R) on an established transect.  All three work for the Natural Resources Conservation Service.