Lesser Scaup Pair.  Traditionally, lesser scaup (also known as "blue bills") have been one of the most abundant ducks in North America; however, their populations have been spiralling downwards in recent years. (Photo Courtesy of ©Ducks Unlimited Canada / Brian Wolitski)) Lesser Scaup Pair. Traditionally, lesser scaup (also known as "blue bills") have been one of the most abundant ducks in North America; however, their populations have been spiralling downwards in recent years. (Photo Courtesy of ©Ducks Unlimited Canada / Brian Wolitski))

Scouting for Scaup. What factors affect boreal breeding ducks and the number of young they have?

The boreal forest is one of the most important breeding habitats for waterfowl in North America.  Thousands of lakes and wetlands provide critical nesting, breeding, resting (“staging”), and molting habitats for ducks, swans, geese, and other water birds.  However, landscape changes due to development activities and other environmental pressures including climate change may be putting some species and their habitat at risk.  Declines in populations of boreal nesting species, such as scaup and scoters, have been detected in parts of North America.

Female lesser scaup. The  brown female has a white face patch around her bill and a short white wing stripe. .(Basar / Wikimedia:  CC BY-SA 3.0)

Kyla Bas, a Master’s student from the University of Saskatchewan, is working on a project on scaup duckling production.  A species of conservation concern, approximately 68% of lesser scaup breed in the boreal forest –close to 3 million birds.  Although the lesser scaup has the largest population of any species of diving duck in North America, their population has not recovered to meet conservation goals since declining in the mid-1980s.  The causes for this decline remain unknown, but climate change, habitat loss, and landscape changes are suspected factors.  Low productivity (the number of young produced), possibly associated with earlier springs, may account for population declines in the past. 

Male lesser scaup. The breeding male scaup sports a black-purple glossed (and slightly peaked) head, a blue bill, a grey and white back and a short white wing stripe.   (Connor Mah / Wikimedia Commons:  CC BY-SA 3.0)

Linked to the Canadian Wildlife Service’s Yellowknife Study Area project (see Fact Box), Kyla’s research is looking at how the timing of spring green-up and other factors, namely density dependence and predator-prey dynamics, affect breeding ducks –specifically the lesser scaup- and their productivity.  How do the number of breeding ducks in an area (“density”) affect population size and growth? Are there enough resources or is there competition for them?   Are predation rates on lesser scaup ducklings higher? 

“We know the environment is changing,” Kyla said.  “But we don’t know how this is impacting the ability of ducks to produce young.  Are there changes in food webs, suitable habitat, or predator-prey dynamics?  Are these ducks being limited by the sharing of resources?  Local predators usually prefer to prey on small mammals in these habitats. But are changes in local small mammal populations impacting how much predators prey on ducks? Perhaps when there are fewer small mammals to prey on, predators will switch to preying on ducks, causing their local population to decrease.” 

Lesser scaup hen and her ducklings. The young leave their down-lined nest within a day of hatching and head to the water, where they are tended by the female but feed themselves.  (Photo courtesy of ©Ducks Unlimited Canada/Brian Wolitski)

The project will include two spring surveys to count breeding pairs of lesser scaup, two surveys in the summer to count broods, and additional roadside surveys.  As well, Kyla’s research team will put together a picture of the timing of lesser scaup arrival and when spring is occurring, using photographs taken of ice and ice break-up at various time intervals.  The team will also have access to weather station data over the past 30 years and be able to use airport data and satellite imagery.   As well as providing insight into the factors affecting lesser scaup, this information can also bring to light changes in the ecosystem over the last 30 years, including local temperature, snow and ice cover duration, the onset of spring, and the length of the growing period.  Researchers will also learn more about the timing of the spring arrival and nesting of other duck species and their productivity.  

Once completed, the information gained from this research study can then be used to guide conservation actions aimed at mitigating and reversing the decline of lesser scaup.

Lesser Scaup in flight. (Andy Reago & Chrissy McClaren / Wikimedia Commons:  CC BY 2.0)

Scaup Fact Box

  • Lesser scaup breed on inland lakes and marsh ponds in the boreal forest.
  • Scaups nest in a sheltered location on the ground near water, usually among thick vegetation such as sedges and cattails.
  • As soon as their down dries, Lesser scaup checks dive under the water.  They’re too buoyant to stay down for long, but by the time they are 5 to 7 weeks old, they can dive for up to 28 seconds and swim up to about 18 m underwater. 
  • Excellent swimmers and divers, lesser scaup forage mainly by diving underwater and sifting through the bottom mud for invertebrates (animals without backbones) such as clams, as well as seeds and other parts of aquatic plants. 

Yellowknife Study Area Project

  • The Canadian Wildlife Service has been gathering information on the abundance and productivity of migratory birds since 1985.
  • The project involves surveying ponds in a study area bordering Highway #3 between Yellowknife and Behchokǫ̀.
  • The surveys will give researchers a better understanding of population trends for waterfowl and other aquatic birds breeding in the boreal forest.