Wintering close to home - Amazon Simple Storage Service (S3)
left: ©DUC/Brian Wolitski
Wintering close to home by krista e l l iott
People who live around the lower Great Lakes are keen observers of seasonal changes in the lakes that are the backdrop to their lives. Typically in the cold months people see a frozen, wintry lake and little to no waterfowl.
M
ore and more frequently residents are noticing the opposite happening. In past winters, the lakes have little snow and ice on them and a sizeable amount of ducks and other waterfowl are staying around longer into the winter months. At first glance, this phenomenon seems simply cause-and-effect. Why would a duck bother migrating further south if open water and plenty of food are right beneath its bill? As it turns out, it’s not quite that simple. Migration is a phenomenon still shrouded in mystery. Not all duck species migrate in the same way or follow the same cues. Based on studies performed by scientists at Long Point Waterfowl in Port Rowan, Ont., it is deduced that mallards are particularly responsive to small shifts in winter weather. The left diagram in the figure opposite shows preliminary results from ongoing research conducted by Michael Schummer, PhD with Long Point Waterfowl. It illustrates
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Conservator | summer 2012
the estimated mallard migration patterns averaged from 1950 to 2008.The light green area represents places where you would expect to see fewer mallards (based on consecutive population surveys).The dark green area indicates where you would see more. The right-hand image predicts migration patterns resulting from a winter temperature
Interestingly, not all species respond this way. While mallards may see open water on the Great Lakes and winter there, other species may see the open water and just keep heading south. “We are not certain that all species of ducks have the capacity to adjust migration patterns based on weather cues alone,” says
“Changes in climate may greatly change available food and habit resources but some species may still migrate ‘on schedule’ based on daylight patterns.” – Michael Schummer, PhD
increase of only four degrees Celsius. As illustrated, this small increase would likely result in a larger number of mallards wintering in higher latitudes. Conditions depicted in the right-hand image are similar to those experienced by waterfowl last winter, where an abundance of mallards delayed leaving Lake Erie until late January.
Schummer. “Thus, changes in climate may greatly change available food and habit resources but some species may still migrate ‘on schedule’ based on daylight patterns.” The implications of this pose interesting questions. If the average winter temperature rises by four degrees, resulting in more mallards (and other duck, goose and swan
below: ©DUC/Andrew McLachlan
Right: the left map illustrates estimated mallard migration patterns averaged from 1950 to 2008. The map on the right predicts migration patterns resulting from a winter temperature increase of four degrees Celsius.
species) wintering in the Great Lakes area, how will that affect area resources? Coastal wetlands and associated agricultural fields are also used during the spring, which is a critical time for migrating waterfowl. Will an increase in wintering waterfowl drain these resources, resulting in less food available for spring migrating waterfowl? Or will a broader geographical distribution of wintering waterfowl result in improved overall survival rates for wintering waterfowl? And if certain species of ducks do not migrate as far south as before, how might that affect waterfowl hunter success, recruitment and retention in southern states? The first step is accurately determining how increased winter temperatures will influence overwintering waterfowl populations and then how these birds will impact food resources at northern latitudes. These questions are proving to be very exciting for researchers with Long Point Waterfowl, including its executive director, Scott Petrie, PhD. “Waterfowl researchers and managers need to be aware of the fact that availability and accessibility of food available to water-
fowl staging and wintering on the lower Great Lakes is constantly changing due to the introduction of invasive species like zebra mussels, quagga mussels and phragmites, changing agricultural practices, commodity prices and harvesting practices, increased temperatures and decreased snow and ice cover,” says Petrie. “How this will affect waterfowl populations and migratory patterns remains to be seen, but it is something we will all monitor very closely.” As Canadians, one thing we can always depend upon is the arrival of winter. The ducks depend on this as well. What kind of a winter it is and what impact it has on habitat in the short and long terms remain to be seen. The only thing for certain is there are many researchers out there working hard to make sense of it all. A
The first step is accurately determining how increased winter temperatures will influence overwintering waterfowl populations and then how these birds will impact food resources at northern latitudes.
Conservator | summer 2012
35
Wintering close to home by krista e l l iott
People who live around the lower Great Lakes are keen observers of seasonal changes in the lakes that are the backdrop to their lives. Typically in the cold months people see a frozen, wintry lake and little to no waterfowl.
M
ore and more frequently residents are noticing the opposite happening. In past winters, the lakes have little snow and ice on them and a sizeable amount of ducks and other waterfowl are staying around longer into the winter months. At first glance, this phenomenon seems simply cause-and-effect. Why would a duck bother migrating further south if open water and plenty of food are right beneath its bill? As it turns out, it’s not quite that simple. Migration is a phenomenon still shrouded in mystery. Not all duck species migrate in the same way or follow the same cues. Based on studies performed by scientists at Long Point Waterfowl in Port Rowan, Ont., it is deduced that mallards are particularly responsive to small shifts in winter weather. The left diagram in the figure opposite shows preliminary results from ongoing research conducted by Michael Schummer, PhD with Long Point Waterfowl. It illustrates
34
Conservator | summer 2012
the estimated mallard migration patterns averaged from 1950 to 2008.The light green area represents places where you would expect to see fewer mallards (based on consecutive population surveys).The dark green area indicates where you would see more. The right-hand image predicts migration patterns resulting from a winter temperature
Interestingly, not all species respond this way. While mallards may see open water on the Great Lakes and winter there, other species may see the open water and just keep heading south. “We are not certain that all species of ducks have the capacity to adjust migration patterns based on weather cues alone,” says
“Changes in climate may greatly change available food and habit resources but some species may still migrate ‘on schedule’ based on daylight patterns.” – Michael Schummer, PhD
increase of only four degrees Celsius. As illustrated, this small increase would likely result in a larger number of mallards wintering in higher latitudes. Conditions depicted in the right-hand image are similar to those experienced by waterfowl last winter, where an abundance of mallards delayed leaving Lake Erie until late January.
Schummer. “Thus, changes in climate may greatly change available food and habit resources but some species may still migrate ‘on schedule’ based on daylight patterns.” The implications of this pose interesting questions. If the average winter temperature rises by four degrees, resulting in more mallards (and other duck, goose and swan
below: ©DUC/Andrew McLachlan
Right: the left map illustrates estimated mallard migration patterns averaged from 1950 to 2008. The map on the right predicts migration patterns resulting from a winter temperature increase of four degrees Celsius.
species) wintering in the Great Lakes area, how will that affect area resources? Coastal wetlands and associated agricultural fields are also used during the spring, which is a critical time for migrating waterfowl. Will an increase in wintering waterfowl drain these resources, resulting in less food available for spring migrating waterfowl? Or will a broader geographical distribution of wintering waterfowl result in improved overall survival rates for wintering waterfowl? And if certain species of ducks do not migrate as far south as before, how might that affect waterfowl hunter success, recruitment and retention in southern states? The first step is accurately determining how increased winter temperatures will influence overwintering waterfowl populations and then how these birds will impact food resources at northern latitudes. These questions are proving to be very exciting for researchers with Long Point Waterfowl, including its executive director, Scott Petrie, PhD. “Waterfowl researchers and managers need to be aware of the fact that availability and accessibility of food available to water-
fowl staging and wintering on the lower Great Lakes is constantly changing due to the introduction of invasive species like zebra mussels, quagga mussels and phragmites, changing agricultural practices, commodity prices and harvesting practices, increased temperatures and decreased snow and ice cover,” says Petrie. “How this will affect waterfowl populations and migratory patterns remains to be seen, but it is something we will all monitor very closely.” As Canadians, one thing we can always depend upon is the arrival of winter. The ducks depend on this as well. What kind of a winter it is and what impact it has on habitat in the short and long terms remain to be seen. The only thing for certain is there are many researchers out there working hard to make sense of it all. A
The first step is accurately determining how increased winter temperatures will influence overwintering waterfowl populations and then how these birds will impact food resources at northern latitudes.
Conservator | summer 2012
35
