Conservation of the American Black Duck

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Conservation of the American Black Duck

• A presentation by Patrick Gaskin

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American Black Duck

• Large dabbling duck of the North East
• A species of special concern
• Combined conservation efforts between the US and
  Canada may have the numbers on the rise

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Background Information

• Order- Anseriformes
• Family- Anatidae
• Sub-family- Anatinae
• Tribe- Anatini
• Anas rubripes
• Other names
• Canard noir (French) Andande sombrio americano
  (Spanish)

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Description

• Body is a dark blackish brown
• Head and neck are lighter
• Legs and feet are red
• White linings under wings
• Blue speculum is not bordered by white
• Similar to female Mallard and Mottled Duck at a
  distance
• Immature are similar to adults
• Underparts more heavily streaked

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Description continued

• Size 54-59 cm (21-23 in)
• Wingspan 88-95 cm (35-37 in)
• Weight 720-1640g (25.42-57.89 oz)
• Population about ½ million
• Voice is a raspy quack

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Differences among the genders

• Male is slightly larger
• Bill colors differ
• Male has a yellow bill
• Female has a green bill often with black mottling
• Males legs are a brighter red than female

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Similar species

• Female Mallard

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Eclipse Male Mallard
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Mottled Duck
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Mallard/Black Duck hybrid male
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Range

• Breeds Eastern Canada and the North East US
• Winters Southern Canada to the Gulf Coast, as
  far west as Iowa
• SE refuges especially
• in TN and AL
• Most migrate along the Atlantic Flyway
• but about 1/3 use the Mississippi Flyway

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Habitat

• Breeds in a variety of wetland habitats
• Salt marshes, beaver ponds, river islands and
  boreal bogs
• Often prefers wooded habitats (boreal forests and
  parkland ecotones)
• Nest typically in upland locations
• Winters in salt water along coasts, but also in a
  variety of freshwater areas inland

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Other info

• Diet is diverse
• Higher in animal protein than many other dabblers
• Mussels, snails, and gizzard shad
• Also grains and seeds as other dabblers
• Filter feeds at surface and also tips up in
  shallow water

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Other info continued

• Nest in vegetation in upland locations (boreal
  forest and parkland ecotones)
• Nest is lined with down
• 1-17 eggs in clutch, typically 9-10 on average

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What happened?

• Populations declined in the mid-20th century
• Several factors have contributed to the decline

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Reasons for population decline

• Loss of habitat (both breeding and non-breeding
  areas)
• Over-harvesting by hunters
• Interbreeding with the Mallard
• Competitive disadvantages to Mallard
• Mallards may take over some breeding spots

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What is being done?

• Initially population counts and surveys
• Essential to measure the scale of the problem
  before proceeding with any management options

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The Findings

• American Black Duck wintering populations have
  been declining since 1955
• This led to pressure to prohibit hunting of this
  duck
• US government decreased the daily bag limit for
  this species in 1983
• Canadian government followed suit in 1984
• Further tightened the harvest limits in 1989 and
  1990
• Current daily bag limit in KY is 1 Black Duck

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This didnt accomplish all that was hoped for

• Despite these measures, the Black Duck remains a
  source of concern due to
• Hunting pressure
• Some hunters mistake Black Ducks for female
  Mallards, or ignore possession limits
• Habitat loss and degradation
• Competition and hybridization with the Mallard
• However, since 1989, the average number of
  American Black Ducks killed by hunters has
  decreased by 26 in Canada, and by 44 in the US

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Habitat loss and degradation

• Mid Atlantic coastal areas have been affected by
  ditch building
• To control mosquito populations
• Coastal lagoon and housing developments
• Clearing and logging
• Losses of forested wetlands decreases suitable
  breeding habitats
• Environmental contamination by pollutants
• Formerly affected by DDT and lead poisoning
• DDT banned by US in 1971, and lead shot banned
  twenty years later

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Interbreeding with Mallards

• Compounded by the introduction of captive-raised
  Mallards into Black Duck breeding ranges
• Since 1940, 1.7 million game-farm Mallards have
  been released in American Black Duck ranges
• Not only leads to increases in hybridization, but
  also to increases in competition for breeding
  sites
• Leads to diluted stock of Black Ducks
• Decline of American Black Duck as a distinct
  species

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NAWMP

• In 1986, the US and Canada joined forces to
  institute the North American Waterfowl Management
  Plan (NAWMP)
• Mexico signed on in 1988

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Main goal of NAWMP

• Restore waterfowl populations to their 1970s
  (1970-1979) winter levels
• The urgency of restoring the Black Duck led the
  NAWMP to set up the Black Duck Joint Venture
  (BDJV)
• Between the US, Canada, and Mexico

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Black Duck Joint Venture mandate

• Facilitate and coordinate the gathering of
  information
• Improve our knowledge of the species
• Guide conservation and manage most decisions

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Three programs were established under the
venture

• Survey program
• Banding program
• Research program

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Survey Program

• The survey data has been analyzed to determine
  population trends and changes
• Birds are counted from aircraft
• Count all pairs and lone males in a breeding
  habitat
• The numbers are expressed as breeding pairs

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American Black Duck Trends of Breeding Pairs
since 1990
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Banding Program

• Coordinated by the Atlantic Flyway Eastern
  Cooperative Banding Agreement under the BDJV
• Determine the relative distribution of kills and
  sport harvest rates
• Used to calculate the survival rates for the
  populations sampled
• These can be done using program ESTIMATE or
  others

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Research Program

• Identify the causes for Black Duck population
  declines
• Identify factors that may help the species to
  recover
• Attempt to determine the relative importance of
  the factors influencing American Black Duck
  numbers and population dynamics

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At the beginning of the program

• Research efforts focused on measuring annual
  American Black Duck productivity compared to that
  of Mallards

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More recently the priority has been on the
relation between

• Variation in recruitment rates and landscape
  configuration
• Habitat productivity
• The presence of the Mallard

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• The current focus of the program is on Adaptive
  Harvest Management related studies

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Adaptive Harvest Management (AHM)

• Seeks to reach a long-term harvest objective
• Decisions being annual harvest regulations (quota)

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Tasks of AHM

• Using the analyses completed under previous work
  orders, develop a model set for use in adaptive
  optimization
• Emphasis devoted to initiating a very simple AHM
  model
• Exploring the consequences of finer vs. coarser
  resolution in objective, decision space and state
  space, and of alternative model weightings

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• Working with BDJV and other stakeholders, develop
  and incorporate objective functions
• Formulation of a suitable objective function is
  critical
• A matter for resolution among managers and policy
  makers
• Concept of sustainability is at the core of
  most natural resource management

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• Working with BDJV and other stakeholders, develop
  alternatives
• Joint Black Duck-Mallard objective
• Joint consideration of harvest regulations for
  each species
• Restrictive for both species
• Liberal for both species
• Restrictive for one, liberal for the other

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• Definition of state space and resolution of
  monitoring efforts
• Important state variables to consider
• Estimates of breeding (wintering, or both) Black
  Duck populations
• Estimate of breeding habitat conditions
• Estimates of breeding Mallard populations

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• Evaluate the potential impacts of model
  resolution and management scale on optimal
  decision making, with respect to gain in
  objective value, vs. costs Evaluate the potential
  impacts of model resolution and management scale
  on optimal decision making, with
• Reconfigure models to allow for multiple
  populations and stratified objectives and
  decision making
• Evaluate the consequences of spatial
  stratification on
• The ability to meet resource objectives
• The tradeoffs in terms of complexity and costs of
  finer vs. coarser scale management

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• Depending on the results of 1-5, develop a
  working adaptive management protocol for Black
  Ducks
• Possible joint Black Duck-Mallard protocol
• Recommend one or more forms for the objective
  function
• Recommend sets of decision alternatives
• Develop a working model set and optimization
  procedure
• Recommend the scale and intensity at which
  relevant state variables and other parameters
  should be measured

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Conclusions

• Combined conservation efforts of the US and
  Canada may have numbers on the rise
• The BDJV graph showing breeding pair distribution
  trends shows a higher population of breeding
  pairs since 1994
• Populations still experience rising and falling
  trends, but they remain higher than the low
  population count of 1994
• The steady decline in breeding pairs from
  1990-1994 looks to be halted

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• No solid evidence of major decreases in quality
  or quantity of breeding habitat for Black Ducks
  since the late 1980s
• Except in specific areas, such as those disrupted
  by hydroelectric projects
• An increase in beaver populations may be helping
  to create more wetland breeding habitat
• Populations are currently steady
• But only about ½ as many Black Ducks as there
  were in the early 1950s
• Still face problems with Mallard competition and
  hybridization
• Adaptive harvest management techniques could be
  employed to ease the hunting pressure on American
  Black Ducks, while working to control Mallard
  populations in areas shared by the two species

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Sources

• Canadian Wildlife Service (CWS), Quebec Region
  www.lavoieverte.qc.ec.gc.ca/faune/sauvagine/html/h
  istoric.html
• Cornell Lab of Ornithology
• www.birds.cornell.edu
• Hinterland Whos Who
• www.hww.ca.com
• Black Duck Adaptive Management Working Group
• http//coopunit.forestry.uga.edu/blackduck/overvi
  ew.html