Figures
Figure 1. Example of the 7 morphological spatial pattern analysis categories for the combined young forest, shrubland, and understory habitats. Background indicates absence of young forest, shrubland, and understory vegetation classes. In the foreground, core is interior continuous vegetation classes, edge is the external perimeter of core, fragments are areas too small to contain core area, and margin is continuous vegetation classes that does not fit into any other category. Core openings are background classes found within core areas and perforations are the perimeter of those core openings. See Figure 3 for how these categories influence New England and eastern cottontail habitat suitability.
Figure 2. Map of New England cottontail (NEC; black diamonds) and eastern cottontail (EC; black circles) locations in Connecticut used to produce the maxent outputs. The maxent outputs shown are an average of the three models, average, lower and upper credible interval prevalence values stated in Bischoff et al. (2023), for each species. The cooler colors indicate lower habitat suitability values, and the warmer colors indicate higher habitat suitability values for the representative species. The projections for the state maps are North American Datum 1983 State Plane Connecticut FIPS 0600 (Meters) and the projection for the US map is USA Contiguous Equidistant Conic.
Figure 3. Comparison of New England cottontail (NEC; left column in blue) and eastern cottontail (EC; right column in orange) marginal responses curves to the top 5 contributing predictors in the New England cottontail Maxent model in Connecticut, where the selected predictor was varied while all other predictors were held constant. Each dot or line represents the output of each run in the 10-fold cross validation (10 models for each predictor and species). For the last row of plots, background is area where young forest, shrubland, and understory vegetation classes is absent, core is interior area, edge is the external perimeter of core, fragments are areas too small to contain core area, and margin is continuous area that does not fit into any other category. Core openings are background classes found within core areas and perforations are the perimeter of those core openings.
Figure 4. Plots of the niche overlap and niche dynamics of New England and eastern cottontail in Connecticut across the two principle component analysis (PCA) dimensions including all predictors. In plot a, the blue colored area is the niche stability, or area where eastern cottontail niche overlaps with the New England cottontail niche. The red shaded area represents niche expansion, area where eastern cottontail niche does not include New England cottontail niche, the green shaded area represents niche unfilling, area where New England cottontail niche does not include eastern cottontail niche. The solid lines represent niches within all available environmental conditions, while the dotted lines represent niches within 50% of the available environmental conditions (New England cottontail is green, eastern cottontail is red). The darker shading represents the occurrence density of New England cottontail within its own range. The red arrows represent the shift in niche centroids between New England cottontail and eastern cottontail niche, where the red solid arrow shows the shift in environmental conditions and the dotted red arrow shows the shift in background conditions between the two species’ niches. Plot b includes the percentage of each dimension of the PCA explaining the variation in predictors and the top 7 contributing predictors to the PCA: annual precipitation (precip), regenerating forest (regen), elevation (elev), shrubland (shrub), transitional to forest (trans) and barberry (barb) and mixed invasive understory (mix_inv). The interpretations of the dimensions in plot a correspond to the predictors shown in plot b.
Figure 5. Density plots of niche overlap and niche dynamics for New England cottontail and eastern cottontail across the range of elevation, annual total precipitation, and distance to shrublands in Connecticut. For all plots, the grey shaded area represents the overlapping of the two species’ niches, the red shaded area represents the eastern cottontail range, and the green shaded areas represent the New England cottontail range. The bars at the bottom of the plot represents stability or the area where the eastern cottontail niche overlaps with the New England cottontail niche (blue), unfilling or the area where the New England cottontail niche does not overlap with the eastern cottontail niche (green), and expansion or the area where the eastern cottontail niche does not overlap with the New England cottontail niche (red). The solid lines represent the extent of the species niche across the range of the predictor values and the dotted lines represent the extent of the species niche across 50% of the predictor values. The solid red arrow represents the niche centroid shift in environmental conditions and the dotted red arrows represents the niche centroid shift in background conditions.
Figure 6. Comparison of New England cottontail (NEC) Maxent output (A), morphological spatial pattern analysis output (B), presence of understory species, shrublands, and transitional to forest (C), and eastern cottontail (EC) Maxent output (D) in a specific area of highly suitable New England cottontail habitat in Connecticut. For the Maxent outputs, the warmer colors indicate a higher relative habitat suitability value (RHS) for the species and the cooler colors indicate a lower RHS value for the species. For the morphological spatial pattern analysis, background is the absence of young forest and shrubland vegetation, core is continuous interior young forest and shrubland vegetation, edge is the perimeter of core, fragment is continuous area too small to be core, core opening is background classes found within core, perforation is the perimeter of core openings, and margins are young forest and shrubland vegetation that does not fit into any other classification. Understory indicates the presence of both native and invasive deciduous understory species. Shrublands is a young forest class created through the process of succession (no recent forest disturbance) with vegetation height mostly between 0.5 to 2.5 m and transitional to forest is also created through the process of succession but within a mixture of vegetation height above and below 2.5m.