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.