Juvenile Trumpeter Swans forage for corn residues. Photo: John Gussman
2022–2023 Season Summary
You can find the OPAS Swan Team's 2022–2023 data-analysis graphics here.
by Laura Davis and Liam Antrim
The 2022–2023 winter was the 12th year of swan monitoring in the lower Dungeness Valley by OPAS-led volunteers. At the end of an unusual season that kept us on our toes, our last overwintering swans left the lower Dungeness Valley to head north at the very beginning of April.
Data from our weekly foraging surveys this season showed an average of 129 Trumpeter Swans, slightly lower than than six of the past seven years. (See Figure 1.) About 60% of observed foraging was east of the Dungeness River and 40% on the west. Corn, grain, and seed dominated November forage, which was observed west of the Olympic Game Farm, along Sequim-Dungeness Way south of Woodcock, and in the Schmuck Road area. Use of pasture grasses and fallow fields picked up in December in fields the length of Schmuck Road, west and east of the river near Woodcock Road, and near the Dungeness Creamery. Daytime use focused from January to season end on pasture grasses or hay fields, as is typical for the late winter; these fields were almost exclusively in the Port Williams Road and Schmuck Road area and east of the Sequim Valley Airport. (See Figure 2.)
Figure 1: Twelve Seasons of Swan-Foraging Counts.
Figure 2: Observed Swan Habitat Usage during Midday Surveys, 2022–23.
Our dawn surveys showed overnight usage at the seven known inland roosting sites, with one addition this season. Swans regularly change locations following changes in forage and water availability, nutritional needs and environmental conditions. Five of eight roosting sites were observed almost daily and others only during our monthly surveys. Highest overnight use occurred at the constructed pond along Woodcock known as Kirner Pond or Gaskell Slough, the hunting club ponds west of the Olympic Game Farm, and the estuary wetlands of Gierin Creek at Graysmarsh. Cat Lake on the Miller Peninsula and a pond south of Bell Hill also were often used by overnighting swans. While distance to preferred forage in agricultural fields can change usage from year to year based on recent plantings, we do see regular use of these two sites every year in spite of their distance from daytime forage. Other sites used by the swans included Roberta's Pond near Three Crabs, a pond southwest of Highway 101 and Agnew, plus new use this season at a constructed irrigation reservoir near Port Williams Road.
From the late October 2022 start of our swan season, we observed strikingly unusual patterns in our local swan counts. We saw a stronger November influx of swans than the team has ever recorded, surging rapidly to a peak count of 201 swans on November 23. About half moved on by the end of November; then our counts picked up again by 20% at the beginning of December and held steady through early February. (See Figure 3.) Other areas in western Washington also experienced this November population surge. We also saw in mid-November more Tundra Swans than usual – eleven swans where we otherwise have counts of only zero to three Tundras during the season. Further, throughout the season, we had a lower percent of juveniles than ever, an anomaly that was also seen elsewhere within the Pacific Flyway and across all sites in WDFW's annual winter survey. Our observations averaging 6% juveniles were one-third of typical. There are a lot of variables at play, and several factors may have contributed to these two observations.
Figure 3: Numbers of Swans Counted during Midday Surveys, 2022–23.
Migrating birds move seasonally partly as a response to environmental conditions. Our early-season high counts of swans were likely due to early freeze-up in the northern portion of the Pacific Flyway that accelerated the southerly migration. The fact that we experienced not only earlier arrivals here but higher counts of both swan species may relate to the migration route. Swan families accustomed to flying over central British Columbia may have averted from the cold inland temperatures and followed the warmer coast. Flying along Vancouver Island or the west side of mainland British Columbia, both Trumpeter and Tundra Swans would cross the Strait of Juan de Fuca to arrive in our Lower Dungeness area. While we are at the southern end of the Trumpeter Swans' range, Tundra typically pass over the east side of Puget Sound on their flight path south to central California overwintering grounds. Although site fidelity is common in the migrational swans, most will have experienced different routes and stopover sites in different years due to variable conditions. Changes to the breeding grounds may also cause swans to explore new migration routes that connect up with established ones, according to Martha Jordan of the Northwest Swan Conservation Society. All along the route of travel and on the overwintering grounds, habitat loss can cause swans to keep moving in search of more favorable conditions.
An adult Tundra Swan on Kirner Pond at dawn, November 2022. Note the flat U-shape between the eyes where the bill meets the head; this area is V-shaped in Trumpeters. Photo: Bob Phreaner
A larger number of total swans returning to ponds also meant more crowding on our local roosting sites. Mid-November, we lost two swans at Kirner Pond to the H5N1 highly pathogenic avian influenza (HPAI). At the same time, we saw more swans overnighting at Kirner Pond than ever before counted, peaking at 200. With concerns of an HPAI outbreak at Kirner Pond, we were relieved to see our area's swan counts decrease and more typical waterfowl densities return by late November. The congested context of a small pond is territory ripe for infection and disease. Limited availability of freshwater habitats in our area may restrict the waterfowl population that can be sustained locally.
A flock of Trumpeter Swans flies over Kirner Road as they leave the roosting site at dawn. Photo: John Gussman
HPAI-infected waterfowl and crowding issues may have motivated some swans to leave our area. We also saw local wind and rain storms kick in after the early-autumn arctic cold front that may have first biased them in our direction. It is a resilient flock that remembers other habitat sites and remains flexible and adaptable.
With regards to local and regional observations of the low percentage of juvenile swans, multiple factors may have been at play. WDFW Waterfowl Section Manager Kyle Spragens noted that the wet, cool spring of 2022 in Alaska's boreal forests delayed nesting on the breeding grounds. Then, in autumn, the sudden early turn to freezing conditions may especially have impacted juvenile swans not ready for migration. It is possible that HPAI also impacted the swans on their breeding groups, however, there is neither qualitative nor quantitative data describing the impacts of HPAI on the Pacific Coast Population (PCP) of swans.
Two juvenile Trumpeter Swans forage for corn residues in the harvested fields in November. Photo: John Gussman
During our 2022–23 season, testing for cause of swan death, illness or injury was limited partly due to concerns about the spread of HPAI. The focus was on retrieving carcasses in a timely manner before predation, and the swan team responded by being observant for impacted birds during regular surveys and beyond. Fortunately, we only had three swans deaths with indications of possible HPAI infection; the two that were tested were positive for H5N1 HPAI.
Lastly, the 2022–23 season brought our team a new observation. During spring, northward migration, swan numbers often increase in the fields around Schmuck and Port Williams roads, and this past season was no exception. What seemed to be different late this winter was the source of midday water. Rather than getting adequate hydration for digestion of forage from wet plants or the water in depressions, we observed swans flying short distances back and forth between a constructed reservoir used to store water for irrigation and the adjacent, farmed fields during the midday. All this movement made locking in flock counts more challenging for our team. We hope next winter brings precipitation more typical to our area to satisfy the needs of our overwintering swans.
Swans and other waterfowl found the midday water they needed in this concrete reservoir. Photo: John Gussman
Warmer weather is forecasted for the winter 2023–24 season associated with El Niño. Compounded with the complexities of last season, it is impossible to speculate what our next winter season will bring. During their northward, spring migration, the swans encountered exceptionally heavy snow cover in British Columbia. Their lives and trials will continue until we see them again.