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Publications:
PHJV Assessment Study

Prairie Habitat Joint Venture (PHJV) Evaluation Program

The Prairie Habitat Joint Venture (PHJV) Assessment was designed to evaluate the cost-effectiveness of PHJV conservation activities.  The objectives were to: (1) test whether waterfowl reproductive success increased in response to the full suite of PHJV upland habitat treatments, (2) assess the effectiveness of individual habitat interventions, and(3) test and improve the model that was used to develop implementation plans.

During the course of the study, vital rate information was collected for 3,214 radiomarked female mallards (Anas platyrhynchos) at 27 sites throughout the parkland biome of Manitoba, Saskatchewan, and Alberta in 1993-2000.  Additionally, we located >19,000 duck nests using traditional search methods.  Nesting success was generally higher in PHJV habitat projects than elsewhere on study sites; however, reproductive success was only weakly correlated with the amount of PHJV habitat interventions when measured at the scale of a study site.

We used information theoretic techniques to contrast hypotheses about the effects of environmental covariates on adult female and duckling survival, nesting effort, and nesting success.  Additionally, we constructed a stage-based matrix projection model of mallard population growth.  Adult female survival had a curvilinear relationship with the proportions of grass and wetland habitats measured at the study-area scale (65 km2), and was negatively related to the ratio of adult/second-year females sampled on a study area.  Duckling survival was positively related to the proportion of seasonal wetlands containing water in July and negatively related to the number of days during which minimum temperatures dropped below 10 C.  Nesting effort was positively related to wetland inundation in July.  Nesting success was positively related to the amount of herbaceous vegetation on the study areas and the total precipitation for the 12-month period prior to the nesting season.

The stage-based projection model constructed using mean vital rates values indicated that populations were declining slightly (λ=0.95).  Variance-stabilized sensitivities indicated that populations were most responsive to variation in vital rates for older birds and that nesting success was the single vital rate to which populations were most sensitive.  Not surprisingly, however, a prospective simulation revealed that the sensitivity to nesting success is likely to decrease at higher levels of nesting success.  While mallard populations were affected by a variety of climactic variables and land uses, efforts to increase populations should focus on improving nesting success rates where they currently are low.

PHJV Assessment Study Publications (PDF)

PHJV Assessment Study Update Archives

• November 2002
• January 2002
• November 1999 (PDF)
• November 1998 (PDF)
• July 1998 (PDF)