Predicting the Accessibility of Upland Land Units Relative to the Density and Distribution of Breeding Duck Pairs (The Thunderstorm Map)

The primary factor limiting duck populations in the PPR is the success that hens have in making a nest and incubating it until the ducklings hatch. Most of the threats of nest loss are realized by ducks that nest in uplands, and are also the most numerous of the prairie ducks. In the early 1990’s, the HAPET office began the development of a tool that would assist resource managers identify upland habitats that are positioned in high wetland landscapes and are accessible to large numbers of breeding hens. An accessibility model was developed that utilized the duck pair–wetland regression models developed from Four Square Mile Survey data, and integrated the distance that hens of upland nesting ducks commonly travel from their territory to a nest site.

The modeling was conducted for the 5 most common upland nesters, mallard, northern pintail,
Blue-winged teal, gadwall, and northern shoveler, and here is how it works: a 40 acre landscape
Unit (in this example in Benson County, North Dakota) is identified, the potential breeding pairs
For each of the duck species is summed relative to the travel distance represented by a white
Ring. The pair values are converted to a density value, summed, and presented as duck pairs
per square mile that have access to the central landscape unit. The model then moves to the adjacent cell and the process is repeated. This processes is completed for the entire region and grouped into 7 categories for display. The color scheme that was selected resembles the color representation of a weather service severe thunderstorm radar image and the duck pair modeling map has become
known as the “thunderstorm map”. The thunderstorm map been used extensively as a landscape prioritization tool for targeting upland management practices to benefit breeding waterfowl.