Emily Downing

Completing the Puzzle for Pacific Flyway Waterbird Habitat Conservation

As the weather warms and days grow longer each spring, the Northern pintails of the Pacific Flyway stretch their wings and heed their names. Leaving their wintering grounds in the rice fields of California’s Central Valley, the pintails fly north to take advantage of the wet meadows in the Southern Oregon-Northeastern California (SONEC) region that ranchers are starting to flood with snowmelt and the first pulse of irrigation water. These hay meadows and irrigated pastures—that have been managed by ranch families for generations—provide sheet-water habitat with an abundance of seeds and invertebrates that allow the pintails to fuel up when they arrive in SONEC each March. Here, the birds build the energy reserves they’ll need for their journey to their nesting grounds in the prairie pothole region of southern Alberta or in the wetlands along Alaska’s coastline.

If you want to look at waterfowl in any specific spot, you can’t do it because there are very few resident ducks that just stay in one spot. They move all over the place. You have to connect locations.

Mike Casazza, USGS
Photo by Leslie Morris.

The breeding season is short and intense, with the hens building nests, incubating eggs, hatching ducklings, and raising their broods; all while subject to mortality or nest depredation by predators. In the prairies of Canada, in particular, the hens that lay eggs early in the season tend to raise more young because their broods have access to productive seasonal and semi-permanent wetlands that will dry out over the course of the summer. Good body condition upon arrival is key to laying eggs early, so the better access the pintails have to food in SONEC in the early spring, the better their reproductive success on the breeding grounds.

By the time the summer days trend shorter and fall is in the air, the adult pintails and their young of the year are ready to reverse course. In early September, they begin arriving in the Klamath Basin to rest and refuel on one of the few places water still exists in a hot, dry late-summer landscape: the Klamath Basin National Wildlife Refuge Complex and associated private properties that support wetlands through the refuge’s Walking Wetlands program. After a short period of feeding and resting, the onset of winter triggers birds to make another movement: back to the rice fields of the Central Valley, where farmers are wrapping up their fall harvest and flooding their fields to break down the remaining rice straw over the course of the late fall and early winter months.

“It’s almost a perfect match with the timing of the fall migration of waterfowl,” said Luke Matthews, the Wildlife Programs Manager for the California Rice Commission. 

Although agriculture has historically been the biggest driver of wetland loss, rice cultivation now supports crucial agricultural wetland habitats in the Pacific Flyway and provides open space around expanding urban centers. Matthews points to the winter habitat provided by rice farming as critical to sustaining waterbird populations in the Central Valley. State, federal, and private wetland complexes in the area provide habitat, too, but in places like the Sacramento Valley, where wetlands are now a small fraction of their historic extent due to urban expansion and other land-use changes, it’s the surrounding agricultural land that provides birds with critical habitat buffers—and the ample food source provided by the rice harvest leftovers.

“Without rice, we couldn’t sustain the bird numbers on state and federal land alone,” he said.

Ducks feed on a flooded rice field in California’s Central Valley. Photo by Jim Morris.

“The Central Valley has a finite amount of waterfowl food resources and if more birds are getting into the Central Valley earlier than they have because of essentially dry habitats in the Klamath Basin, it’s going to put additional pressure on those food resources and it’s going to increase the conservation challenges we already have in the Central Valley,” he said. “These landscapes are tied at the hip. Unless we see conditions improve in the Klamath Basin, we can see birds get to the valley earlier than we used to.”

But that habitat, and the habitat elsewhere in the Pacific Flyway, is contingent on water in the system. If, for instance, there isn’t water in the habitat in the Klamath Basin, which lies on both Klamath Basin National Wildlife Refuge (NWR) Complex and surrounding agricultural land, a bird will skip over that landscape and wind up in the Central Valley earlier than expected. And that, said Mark Petrie, the Director of Conservation Planning in Ducks Unlimited’s Western Region, could present a problem for the Central Valley rice farmers and other land managers. 

Caroline Brady, the Waterfowl Programs Supervisor for the California Waterfowl Association (CWA), said earlier arrival times to wintering grounds ends up being a problem for the birds, too.

“A lot of birds overfly the Basin now that there’s less water and less habitat and end up here in lower body condition,” she said. “The lack of water directly affects the timing of migration.”

When one of the habitats along this migration route isn’t functioning like it should, there’s a host of other problems that can arise, too. This summer’s botulism outbreak on Lower Klamath NWR due to low water is a good example of that, killing more than 60,000 molting mallards, pintails, and other ducks that would have otherwise eventually ended up in the Central Valley. If, for instance, the wintering habitat and food sources provided by agriculture like rice farming in the Central Valley disappears, it will directly impact how and when birds show up in SONEC come springtime—and how many make it at all. 

Waterfowl need water to be successful. You won’t get high population counts if you don’t have water in the right places at the right time.

Caroline Brady, California Waterfowl Association

Collectively, the Central Valley Joint Venture and the Intermountain West Joint Venture have conducted some of the most sophisticated non-breeding waterfowl conservation planning in North America for the Central Valley, Klamath Basin, and SONEC regions. However, in between each region lies a disconnect in that same planning. The impacts of landscape change in one region are not incorporated into the plans of the other regions; that is, land and water managers operate without the full picture of impacts, risks, vulnerabilities, and opportunities throughout the migratory network. Given the immense and growing challenges associated with providing adequate habitat for waterfowl in these water-limited and intensively managed landscapes—and the inherent water and habitat dynamics associated with periodic drought—managers and habitat conservation practitioners in these areas must increasingly look to collaborative conservation as the way to preserve the Pacific Flyway’s waterfowl habitat and populations. 

Images from the USGS show seasonal pintail movements within the Pacific Flyway. Courtesy of Desmond Mackell.

In the Central Valley, the relationship between waterbird conservation organizations like CWA and rice farmers is long-standing and constantly working to protect both habitat and agricultural land. Paul Buttner, the Manager of Environmental Affairs at the California Rice Commission, said this kind of relationship didn’t happen overnight. It took a lot of trust-building within the rice industry and with outside partners like CWA, Ducks Unlimited, Point Blue Conservation Science, The Nature Conservancy, and Audubon to bring people to the table for meaningful dialogue about the most important issues for each group.

“It can be challenging to get a good number of growers from the rice industry in the room and have these conversations,” he said. “The important thing is to develop those relationships and, in an incremental way, get people involved in programs with new partners that they haven’t worked with previously.”

Local collaboration like this is an important first step, but it is the extension of this collaboration throughout the Pacific Flyway’s boundaries that is critical in maintaining habitat for each stage of the bird’s life cycle. Land managers and scientists like Mike Derrico, who is the biologist for the Sacramento NWR Complex, agree.

“You need to provide space to develop partnerships and get people to sit at the table and really realize that it’s a landscape issue,” Derrico said. “That takes time.”

Derrico and John Vradenburg, who is Derrico’s counterpart in the Klamath Basin NWR Complex, are very much aware of the importance of flyway-scale collaboration in localized decision-making. The duo have worked together from the beginnings of both of their careers at Russell Lakes State Wildlife Area in Colorado’s San Luis Valley. They said they’ve done their best to bring their good relationship to management decisions in each of their respective refuge complexes.

“You need to provide space to develop partnerships and get people to sit at the table and really realize that it’s a landscape issue. That takes time.”

Mike Derrico, USFWS

In the past, when water was more plentiful, they said, this kind of collaboration was common among refuge managers up and down the Pacific Flyway. Due to agency turnover, inter-refuge conversation dried up around the same time as the water did. For solutions to stick, land and water managers along the Flyway must take a leaf out of the notebook of history to bring that kind of collaboration back.

“Breaking up the landscapes as SONEC, Klamath, and Central Valley was detrimental and has led to a lot of problems,” Vradenburg said. “It’s going to move conversations forward much faster when we’re all on the same page.”

Specklebelly geese use an irrigated hay meadow in SONEC in early March.

That doesn’t just mean collaboration between USFWS refuges; it also means collaboration between all water users, private and public land managers alike. Mike Casazza, a research wildlife biologist at the USGS Dixon Field Station in the Central Valley, pointed to the nature of migratory birds and waterfowl as the root need for such cross-boundary collaboration.

“If you want to look at waterfowl in any specific spot, you can’t do it because there are very few resident ducks that just stay in one spot,” he said. “They move all over the place. You have to connect locations.”

And that’s why identifying these locations is key. Desmond Mackell, a master’s student at University of California-Davis, helped Casazza do just that by carrying out a massive bird tagging and monitoring project for his thesis. Their team tagged over 13 species of migratory waterfowl with Global System for Mobile communication (GSM) transmitters, enabling them to track the birds’ movements over the past five years. The results of this study are helping to identify not only the habitats these birds rely on as they move through the migratory network, but also the seasonal timing of the habitat use. In the past, migratory bird science has primarily focused on population sizes of individual species, but ignored the factors that make populations shrink or grow. That’s changing, Mackell said, mainly due to improved technology like the transmitters.

Furthermore, Mackell said, looking at the habitat used by birds is critical in identifying the needs of birds at different phases of their life cycle.

“Migration is a vulnerable time for many of these birds,” he said. “There’s implications at the population scale if we don’t manage birds at all of their life stages”

Brady put it in much simpler terms.

“Waterfowl need water to be successful,” she said. “You won’t get high population counts if you don’t have water in the right places at the right time.”

As water availability decreases with each dry year in the Intermountain West, it’s increasingly important to determine where water exists on the landscape and how those “wet oases” coincide with bird use. Patrick Donnelly, the landscape ecologist for the Intermountain West Joint Venture, has teamed up with Ducks Unlimited biologist Dr. Mark Petrie and Dr. Matt Reiter of Point Blue Conservation Science to monitor the effects of climate and human development on long-term wetland resilience. The study focuses on the changes and causes of wetland availability from 1984 to 2020 in SONEC (including the Klamath Basin) and the Central Valley in order to examine the wetland trends and ecological relationships between these landscapes. 

Wetland resiliency data shows how surface water has changed over time, with yellow depicting decreased surface water, blue depicting increased surface water, and green depicting no change in surface water.

In turn, Donnelly, Petrie, and Reiter hope to pinpoint how seasonal habitats are changing in relationship to each other and how the changing resources they provide influence waterfowl and shorebird breeding, wintering, and migration cycles. This study takes into consideration both public and private lands ephemeral, seasonal, and permanent wetland habitats, as well as the important agricultural water uses linked to wetland resources, from rice cultivation in the Central Valley to flood irrigated hay meadows in SONEC to the flood-fallow rotations used by Klamath Basin farmers.

When combined with the data from Casazza and Mackell’s study, this research could provide land managers with the tools needed to make more effective decisions as it relates to wetland habitat conservation.

“Building a foundation of integrated science is equally important in helping land and water managers meet the needs of waterfowl and people across this one big landscape,” Donnelly said. 

The research will provide natural resource managers a first-ever Pacific Flyway perspective of integrated SONEC and Central Valley wetland ecology. Hopefully, this perspective will encourage the cross-landscape collaboration Vradenburg and Derrico dream of, and the kind of collaboration that could help offset the impacts of habitat threats like urbanization and water scarcity in an increasingly arid West. Connecting ecosystems through science and management collaboration is the first step in combating habitat loss at a local level. And that, Vradenburg said, is critical to saving the Pacific Flyway’s birds.

“If you’re willing to start writing off landscapes, it’s a lot easier to write off the next one and the next one,” he said. “When you’re looking at the entire southern end of the Pacific Flyway hanging by the thread, where are those birds going to go?”

The solutions to the water-related challenges facing Pacific Flyway migratory birds won’t come easy, but the path forward is coming into view—and it’s rooted in collaboration among farmers, ranchers, and wildlife conservationists across one big landscape.

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