WWG_AllocationIssues
To: LMVJV Waterfowl Working Group
From: John Tirpak
Date: 1 October 2008
Re: Issues and concerns with individual habitat sources
At the meeting in Dumas, we identified a suite of issues associated with our inability to
either assess or predict the DEDs associated with a particular habitat source (naturally
flooded, public managed, and private managed lands) in any given year. These issues
speak directly to the gaps in our knowledge, our technical limitations, and the natural
variability of our system. Now that we have identified and documented these
imperfections in our information, it is time to ask the harder questions:
1. How much uncertainty and variability is associated with each of these issues?
2. How much uncertainty and variability am I comfortable operating under?
3. What are the consequences of being wrong?
By examining these questions for each of the issues below, we will be able to identify
those pieces of information that are critically holding us back and which pieces of
information are valuable but not vital to the efficacy our management decisions.
Documenting the assumptions that answer these questions and the logic behind those
assumptions for each of these issues will allow us to progress further and faster than we
have to this point.
I. Natural Flooded Habitats: Independent of managed lands
A. Frequency (reliability)
1. Issue
a The extent of natural floods exhibit wide interannual variation
2. Critical question
a How frequently does a site need to flood before we are comfortable
relying on it as a source of waterfowl foraging habitat?
b How can we utilize available information (e.g., DU’s Waterfowl Habitat
Monitoring Program) to identify this flood frequency?
3. Assumptions
a
B. Depth
1. Issue
a Dabbling duck foraging is limited to a specific range of water depths.
2. Critical questions
a Within what range of water depths are food resources available to
dabbling ducks? Minimum? Maximum?
b What percent of naturally flooded habitats are within this range at any
given point in time?
c Can we assess depth from satellite imagery or by some other method?
3. Assumptions
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WWG_AllocationIssues
C. Duration
1. Issue
a The length of time a site is flooded affects its availability to waterfowl.
2. Critical questions
a How long does a site need to be flooded to ensure it is available to a duck?
b Can we assess flood duration from satellite imagery or by some other
means? What does data from one scene represent temporally?
3. Assumptions
a
D. Quality (what’s under the flood; DED value)
1. Issue
a Natural floods occur over many different habitat types that vary in their
quality as waterfowl foraging habitat.
2. Critical questions
a How can we account for this variation in our estimation of DEDs provided
by naturally flooded habitats?
b What is an appropriate DED value for an acre of naturally flooded land?
195 DEDs?
3. Assumptions
a
E. Scale
1. Issues:
a The number of acres actually under water affects foraging habitat
availability.
b The scale at which one looks at the impact of naturally flooded habitats
affects whether the impacts are viewed as positive or negative.
2. Critical questions
a Are quantitative assessments of naturally flooded habitats from Landsat
imagery accurate?
b How do we account for the variable effects of natural flooding at local vs.
system-wide scales? Do we need to account for the “lost” foraging
opportunities in our assessment of natural flood habitat? Do we need to
calculate a net gain in DEDs by explicitly considering losses?
3. Assumptions
a
II. Private Managed Lands – There is a large diversity of private managed lands that
provide waterfowl foraging habitat: MIP, MOP, WRP, duck clubs. The issues and
concerns identified below are relevant to all, but the specific assumptions regarding
these issues are unique for each.
A. Reliability between years (short-term)
1. Issues
a The management intensity on private lands is not constant.
b Most of the private lands capacity for waterfowl foraging habitat is not
formally protected through easement or similar agreement.
2. Questions:
a How much does private land management vary from year-to-year?
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b
Can we predict the intensity of private land management from known
factors (e.g., duck population size, diesel prices, private land type, etc.)?
c What are the transition probabilities of waterfowl foraging habitat on
private land to non-habitat? Other private land types? Other habitat
sources?
d How can we account for these sources of variability when allocating
foraging habitat objectives to private lands? Do we use a minimum DED
value? Minimum acreages? Average? Other?
3. Assumptions
a
B. State change over time (long-term)
1. Issues
a The value of waterfowl foraging habitat on private land tracks changes in
agricultural practices (e.g., shifts in agricultural crops and improvements
in harvesting efficiency).
b Availability and funding of federal programs significantly impact the
ability of private lands to serve as waterfowl foraging habitat.
2. Critical questions:
a How does the uncertainty associated with the long-term ability of private
lands to provide waterfowl foraging habitat affect the allocation decisions
we make today?
3. Assumptions
a
C. Sanctuary
1. Issues
a Disturbance on private lands prevents waterfowl from accessing available
forage.
b Disturbance on private lands creates habitat sinks – attractive habitats with
unsustainable mortality.
c Disturbance on private lands forces waterfowl to feed at night, which is an
additional physiological cost for acquiring food resources.
2. Critical questions:
a How can we estimate the effect of disturbance on waterfowl? Is there an
effect at the population level?
b How can we account for disturbance on private lands when making
allocation decisions? Do we discount available forage on non-sanctuary
habitats?
3. Assumptions
a
D. Habitat quality
1. Issue
a Standard DED values may not be applicable to private lands if they were
not initially estimated from private land samples.
2. Critical questions
a Is the use of standard DEDs/ha values for a specific habitat type on both
public and private lands reasonable?
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3. Assumptions
a
E. Lack of accountability
1. Issues
a It is difficult (if not impossible) to spatially document waterfowl foraging
habitat provided on private managed lands
2. Critical question
a How closely does waterfowl foraging habitat on private managed lands
need to be monitored before it can be included in our allocation decisions?
b How do we handle current inability to quantify WRP contributions?
Private duck clubs? etc.? Can we rely on subsamples?
3. Assumptions
a
III. Public Managed Lands
A. Capability vs. Performance
1. Issues
a Actual performance will never equal capability.
2. Critical question
a How much does performance vary from year to year?
b How can we account for this variability in our allocation decisions?
3. Assumptions
a
B. Sanctuary (same as for private managed lands)
1. Issues
a Disturbance on public managed lands prevents waterfowl from accessing
available forage.
b Disturbance on private managed lands creates habitat sinks – attractive
habitats with unsustainable mortality.
c Disturbance on private managed lands forces waterfowl to feed at night,
which is an additional physiological cost for acquiring food resources.
2. Critical questions:
a How can we estimate the effect of disturbance on waterfowl? Is there an
effect at the population level?
b How can we account for disturbance on public managed lands when
making allocation decisions? Do we discount available forage on nonsanctuary habitats?
3. Assumptions
a
C. Habitat quality (same as for private managed lands)
1. Issue
a Standard DED values may not be applicable to private managed lands if
they were not initially estimated from private managed land samples.
2. Critical questions
a Is the use of standard DEDs/ha values for a specific habitat type on both
public and private managed lands reasonable?
3. Assumptions
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