Meeting Report

Prepared by David Case, D.J. Case & Associates Thursday, November 26, 2001

Black Duck AHM Working Group
Quebec, QC
November 15, 2001

List of participants:

8:30 Welcome and Introductions

Dave Case opened the meeting by reviewing the agenda. Dave commented that this was an important meeting in the development of a potential AHM process for Black Ducks. He pointed out that the Working Group needs to keep in mind that the Group is going to start making decisions that are hard to undo later in the process. In effect, we have to make decisions as though we are "doing" AHM even though the Group has not committed to that yet.

Mike Conroy raised the questions of whether we include other people on the mailing list who are interested. The Working Group agreed to include others on the black duck mailing list. Contact Chris Fonnesbeck(chrisf@fonnesbeck.net) to get on the mailing list.

8:45 Review of June BDAHM meeting items and current focus of technical group - Mike Conroy

Several revisions to the black duck models were described in detail during the June meeting. Notable, the Eastern Mallard Model has now been directly incorporated into the Black Duck AHM model, making it essentially a two-species model. This has major implications for management which will be addressed more fully as studies proceed.

Mike reviewed several items from June meeting - series of points/questions for Mike's Team to work on through the end of the project, which is June 2003.

The 16 models involve combinations of factors that are reasonable explanations for variation in black duck populations: 4 combinations of production models - Mallard Competition (none) and habitat effects (none), together with 4 combinations of survival model, winter habitat (none) and compensation (none), for 16 total models.

Mike then described more detailed work on model behavior and the implications for constraints on harvest management that have been conducted since the last meeting.

Models were investigated with 26 scenarios, representing combinations of constraints on black duck harvest and mallard harvest (24 scenarios), together with 2 scenarios in the absence of harvest to investigate the equilibrium behavior of black duck populations with no harvest.

The 26 scenarios were combined with 17 models (16 model combinations, plus a model based on AIC averaging across the 16 models).

The decision variable was harvest rate, not regulation packages (this was decided at the June meeting). All models had a density-dependent "restriction" on population growth, via a density-dependent reproduction function.

Question from Fred: why does there seem to be relatively little effect of mallard harvest even under the mallard hypotheses?

Answer from Mike: This needs further checking. It is possible that the mallard effect on black ducks only occurs at relatively low levels of mallard harvest, and that in most situations both black duck and mallard populations rapidly grow beyond these ranges.

There are so many factors operating at once that I have developed graphs to try to examine the effects of factors visually. Standard statistical analyses seem to be of relatively little value.

Brian Collins: we need to look carefully at how we are putting the mallard compensation into the model if doesn't appear to be doing what we think it should.

Break

Mike continued to review different scenarios. There seemed to be a problem with scenarios 18 and 24 showing some effect of mallard competition when there isn't any in the model. This will require further checking.

A question arose about scenario 24: Why are seasons more "liberal" if you allow some harvest ("no closed") at higher black duck populations? Seems like it should be the opposite.

Group may now want to consider simplification: eliminating some of the models.

Questions/Comments

• Mike has some concerns about habitat measurements used in models.
• There is a lot to digest, difficult to digest/hard to follow in brief presentation.
• Steve Wendt: you have to be careful of "believing" what the models are saying, habitat for example . . .
• Brian: in simulations, do model weights change over time? Also finds "1" and "0" confusing - maybe change them to letters that mean something.

Discussed where to go from here communications-wise; report will be on the web site.

What does Mike need input on?

• As we move into spatial models, something will have to give because it gets so complex. Mike thinks we should remove the habitat issue from the alternative models reducing it from 16 to 4 models. What about eliminating them?
• Fred would want to see some sensitivity analysis - how might all of these other conclusions changes if habitat were to change significantly.

Lunch

Spatial AHM

Update on Delineation

Jerry-wanted to know the derivation of the three populations, similar to what was done for the two populations presented in June.

Fred-concern about boundaries between populations. Don't follow along the political boundaries on which hunting seasons are set.

Jerry-why 3 versus 2 units? Mike: I heard it pretty clearly at last meeting here that the group, particularly the Canadians, wanted to look at the potential of using 3 populations.

Mike said that he could change boundaries if there was a need to, it would be no problem. However, that decision needs to made pretty soon. There may be a potential problem in movement results. Will check to see if the northern and southern Atlantic Flyway labels could possibly have been reversed in the analyses.

The group discussed the need to take a look at increasing numbers of black ducks wintering in Atlantic provinces (approx. 20,000 and increasing)

Break

Production Modeling

Spatial Modeling

Wrap-up

Mike Conroy provided a summary/overview of the University of Georgia Project:

• Working AHM model by end of 2002
• Preliminary report early 2003
• Final report June 2003

Basically looking at having some form of working single and multiple population models. Adding to what he has presented here today.

Dave Case asked what input the UGA team needs from the Working Group to complete its work?

Discussion followed on:

Leave habitat in models or not?

Group agreed to have Mike drop the breeding and winter habitat models, thus leaving 4 models.

Change boundaries of breeding/harvest areas in Canada or leave them as recommended?

Group agreed to leave them as is.

Are there things we're doing that may make AHM unpalatable to stakeholders?

Delineation of north-south division in Atlantic flyway-should the delineation be the same for eastern mallards and black ducks?

Issue of packages: Mike is not sure regulations packages are part of end product from UGA, not a deliverable. This group or some part of this group has to be involved and get feedback from people on those packages. This needs to be brought up at the next meeting as a key agenda item.

How does AHM for Black Ducks become operational?

Mike said AHM becomes operational when the 2 federal agencies take over and start to use it. That is not going to happen if the states/provinces are not supportive. The Group of Seven needs to make a recommendation to each respective country.

Paul Castelli commented that one of most critical elements to this is continuing communications. Specifically, Mike's continued participation at Flyway meetings.

The Working Group agreed that a summary of AHM for Black Ducks to date for technical audiences would be useful to have. Dave Case and Mike Conroy will work on one.

Dave Case brought up the question of who needs to be reached that we are not reaching?

Suggestions included:

• Keep going to the flyway meetings.
• Take technical presentations to Northeast, Midwest, and SE meetings along with TWS annual meeting.
• Also need to be reaching Canadian counterparts.
• Continue with communications efforts in general.

Next Meeting

The next meeting of the Black Duck AHM Working Group will be held June 11-13 (full-day meetings on all 3 days) somewhere in NJ. Travel days are June10 and 14. Paul Castelli will work on potential locations in NJ and communicate via the list serve with the Working Group.

5:45 pm Meeting Adjourned

The group continued to meet to discuss the NAWMP population objective for Black Ducks.

Followup subsequent to meeting:

• An error was discovered in the Scenario 18 and Scenario 24 files, which resulted in an apparent mallard effect even under models in which mallards had no effect on black ducks. These scenarios have now been rerun and incorporated into the revised presentation.
• Double checking of our distribution and derivation analyses confirm the estimated movement rates in the presentation. Breeding/ harvest area boundaries, and the distribution of banding stations/ recovery locations within stratum, may still be an issue, however.

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Last updated 05 December 2008