Decades of research from three, multi-year Ducks Unlimited Canada studies (PHJV Assessment Study, 1993–2000 [Howerter et al. 2014]; Pintail Study, 2005–2007 [Devries et al. 2018]; and the Spatial/Temporal Variability Study 2001–2009 [SPATS, Bortolotti et al. 2022]) focused around hen- and nest-level breeding success related to habitat parameters, has culminated in a dataset that is like no other in the wildlife conservation discipline. The datasets focus on the five main dabbling duck species breeding in prairie Canada; mallard (Anas platyrhynchos), gadwall (Mareca strepera), blue-winged teal (Spatula discors), northern shoveler (Spatula clypeata), northern pintail (Anas acuta). These data have allowed us to build the WPM, a computer simulation that predicts the breeding density and breeding success of these species in response to past and future habitat changes in their key breeding landscapes in prairie Canada.
In operation, the WPM inputs breeding pairs by species, habitat availability and other landscape-specific covariates (e.g., breeding location; latitude, longitude) to generate a population of nests which are apportioned among habitats within seasonal periods, and exposed to habitat- and season-specific nest survival rates. Final model output is estimated hatched nests by species, habitat and seasonal period with associated estimates of variation. Thus, in a conservation planning context, the model can estimate the impact of various habitat changes, whether background or conservation-related, affecting the number or species composition of waterfowl pairs present (e.g., wetland loss or restoration), or the distribution and survival of nests (e.g., grassland loss or restoration, increased acreage of winter wheat, etc.). This conservation planning tool allows us to estimate how much habitat is needed, and where, to achieve waterfowl NAWMP population objectives.
In order to include non-game birds in conservation planning, we developed species distribution models for a variety of landbirds, shorebirds, and waterbirds. Most waterbird models predicted probability of occurrence across the PHJV while shorebird and landbird models predicted species density. Models were developed using data during >70,000 surveys from >28,000 unique locations across the PHJV. Species distribution models were used to identify priority areas and set habitat conservation targets for non-game birds.
Overall, the WBF contains about 262.5 million acres of wetlands, or 35% of the total area. For the purposes of conservation planning, waterfowl habitat is defined as open water or wetlands along with their adjacent upland habitat located within 400m. Based on this simplistic definition, 49% of the WBF is considered suitable waterfowl habitat with varying distribution among jurisdictions (Table 1).
As waterfowl are distributed at much lower densities in the WBF than in the prairie pothole region, thus, key waterfowl habitat are identified based on Ducks Unlimited Canada’s Hybrid Wetland Layer (Ducks Unlimited Canada 2010a). This product was derived by merging Canvec and Earth Observation for Sustainable Development earth cover data, and categorizing the landscape into open water, undefined vegetated wetlands and uplands. Waterfowl habitat was then defined as open water and any of the other two habitat classes within 400 metres of the open water boundary.
Current approaches and analyses have focused on guild level grouping of species (i.e., ground, cavity, overwater) to identify broad trends to focus on immediate conservation objectives. There is a need for more species-specific studies given the need to understand changes in community structure (i.e., species composition and abundance) and differing species population trajectories in the WBF, even within guilds.
Several key topics where WBF information gaps will be the priority for future boreal waterfowl modeling studies over the 2021—2025 period include: