A presentation by Patrick Gaskin

• 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

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

• 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

• 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”

• 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

• Female Mallard

• 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

• 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

• 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

• 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

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

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

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

• 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

• 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

• 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

• Compounded by the introduction of captiveraised 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

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

• Restore waterfowl populations to their
1970’s (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

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

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• 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

American Black Duck Trends of Breeding
Pairs since 1990

• 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

• 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

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

More recently the priority has been on the relation between:
• Variation in recruitment rates and landscape configuration
• Habitat productivity
• The presence of the Mallard

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

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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• No solid evidence of major decreases in quality or quantity of breeding habitat for Black Ducks since the late 1980’s
– 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

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