Randy Smith

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Declining Bluebills Regional Research for a
Continental Problem

• Randy Smith
• Illinois Natural History Survey
• Forbes Biological Station
• Havana, IL

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Bluebills

• Declining Continent Wide
• 89 are Lesser Scaup they drive the population

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Bluebills

• Why worry about scaup here?
• 40 of the continental population migrate through
  or winter in the MS Flyway
• Major staging and wintering sites
• Pool 19
• Great Lakes
• Dramatic declines in some areas
• Illinois River valley

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Possible Reasons for Decline

• Over Harvest
• Migration Changes
• Disease
• Contaminants
• Habitat Quality/Quantity
• Breeding Grounds
• Decreased Productivity

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Reasons for Decline

• Over-harvest?
• Recent historic harvest 6 per day
• Harvest severely restricted since
• Continued population decline
• Scaup remain very abundant
• 3.5 million 3rd or 4th most abundant
• Harvest only a fraction compared to other highly
  abundant species
• Over-harvest Not Likely

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Reasons for Decline

• Migration Changes
• Disease
• Contaminants
• Spring Condition Hypothesis
• Changes in food availability
• Changes in habitat
• quality or quantity

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Disease

• Typically during fall migration
• Most die-offs relatively small
• Trematodes in Minnesota Fall 2007
• Banded Mystery Snail
• Avian Cholera and Botulism
• Not major concerns for scaup
• Disease is not a major factor leading to
  population decline
• Future Concerns
• Faucet Snail in Miss River

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Contaminants

• Diet Shift - Exploiting Zebra Mussels
• Invasive
• Filter feeders
• Concentrate contaminants
• Proliferation coincides with scaup decline

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Contaminants

• Spring Migration
• Heavy Metals
• Cadmium (Cd) MS River Corridor
• Selenium (Se) Great Lakes and MS
• Potentially decrease female fitness
• Breeding ground effects
• No significant effect on breeders
• May cause some birds to not breed
• Causing problems but not driving the decline

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Spring Condition Hypothesis

• Reproductive success has declined because females
  are arriving on the breeding grounds in worse
  condition than in the past.
• Importance of spring migration
• Build reserves to use for reproduction
• Arctic geese as an example

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Spring Condition Hypothesis

• Changes along migration routes
• Habitat changes
• Food supply
• Water quality
• Studies examining these factors
• Diet and food selection
• Habitat use and quality

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Diet and Food Selection

• Collected feeding females during spring
• Swan Lake
• Sampled food availability

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Location of Swan Lake
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Diet and Food Selection

• Scaup 2004
• n 26

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Diet and Food Selection

• 2005
• n 35
• Diet between years
• ?21 29.3
• P lt 0.001

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Diet and Food Selection

• Diet and Food at Collection Sites

?21 4.0, P 0.046
?21 33.9, P lt 0.001
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Diet and Food Selection

• Availability of food
• Soft Bottom Sediments
• High Turbidity
• Force Tactile Location
• Stationary Benthic Foods
• Food Depth
• Deeper than length of scaup bill
• Unavailable

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Diet and Food Selection

• Possible implications for scaup
• Moist-soil seed diets
• Isolated Incident
• Widespread
• Further Investigation
• Other areas intensively
• managed for moist-soil

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• Another diet and food selection study
• Throughout Great Lakes region
• IL, WI, OH, MI
• 6 Study Sites
• 5 Species
• 940 Total Ducks
• 153 Scaup

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Diet and Food Selection

• More evidence of seed consumption
• Seeds appeared in diets at all sites
• Transitioned to more invertebrates at northern
  study sites
• Scaup and ring-necks consumed corn
• Ring-neck diet differed by region
• West primarily seeds
• East primarily invertebrates

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Diet and Food Selection

• Moist-soil habitats may be good for more than
  just dabblers
• Scaup diets quite adaptable
• Unknown how non-traditional diet may affect body
  condition
• Other studies
• Minnesota and Manitoba
• Scaup diets changed from
• 1980s to 2000s

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Habitat Change

• Changes in habitat quality or food availability
• Diet shifts in MB and MN indicate changes in
  forage abundance
• Declines in amphipods habitat quality
• A very important scaup food

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Spring Condition Hypothesis

• Lots of supporting evidence
• Food availability changes
• Water and wetland quality
• Reduced body condition
• on breeding areas
• Later nesting dates
• Are combined effects
• enough to cause declines?

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Breeding Grounds

• Evidence suggests breeding grounds Boreal
  Forest
• Scaup and White-winged scoters
• Different wintering and migration areas
• Same breeding areas
• Ring-necks doing fine in the same area

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• Boreal Nesters
• Scaup and Scoters declining
• Ring-necks increasing
• Figures from DeVink 2007

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Breeding Grounds

• No evidence for migration effects
• Scaup were in good condition
• Compensating upon arrival
• No heavy contaminant burdens
• Whats going on?
• Alternative Hypotheses?

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Breeding Grounds

• Mismatch Hypothesis
• Ring-necks nest earlier better production
• Scaup and scoters nest later
• Have not adjusted nest initiation date with
  increasing temperature
• Invertebrate abundance peaks earlier with
  increased temperature
• Might miss peak duckling food supplies

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Other Research

• Banding!
• Pool 19 during spring migration
• 4,326 scaup banded this year (2008)
• About 6,400 banded over the 3 previous years.
• An additional 1500 banded on the Great Lakes
  Long Point, Lake Erie

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Banding Pictures
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SatelliteTracking

• Pool 19 Scaup Tracker
• 29 Females in 08
• Ducks Unlimited
• bluebill tracker
• Similar study at Long Point, ON (Great Lakes)

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Other Research

• Benefits
• Should provide clues about
• Migration corridors
• Survival
• Harvest
• Allow us to build better models
• Research Needs
• Banding on Boreal breeding grounds

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Questions?
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