Step-selection functions to infer active search behavior
Of the four carnivore species, none made movements such that they
encountered parturient mule deer (within a 200-meter proximity) in the
first 30 days post parturition more often than the random movements
generated in the step-selection function (Figure 3a; Figure 4a; Tables
S1–S2) suggesting they were not actively searching for mule deer
neonates. We documented no GPS-collared cougars or bobcats within 200
meters of a GPS-collared mule deer at the time a simultaneous fix was
taken during the 30 days following parturition so models could not be
fit for these species. For elk, only two carnivore species exhibited
movements that positioned them in proximity of elk post-parturition more
often than did hypothetical movements, cougars (βelk
presence = 0.94, P = 0.001; Figure 3b; Table S3) and bears,
although for bears the result was marginally significant
(βelk presence = 0.30, P = 0.059; Figure 3b;
Table S3). Sex-specific analysis revealed that male bears were more
likely to encounter elk than expected by chance (βelk
presence = 0.56, P = 0.004, N = 7 bears; Figure 4b; Table
S4) while there was no evidence supporting this effect for female bears
(βelk presence = -0.45, P = 0.24, N = 4
bears; Figure 4b, Table S4). Projecting model predictions onto the
landscape spatially and overlaying GPS locations of post-parturient
female elk in the 30 days post birth further revealed similarities
between areas used by neonatal elk and areas selected for by male bears
and cougars as documented by the high degree of spatial overlap (Figure
5a,c). Female bears, however, generally did not select for areas that
overlapped with elk neonates (Figure 5b), suggesting their space use
decisions were driven more heavily by other resources that were
unrelated to elk.