GAMM for Intra-annual Shift Toward Frugivory
After fitting the GAMM, we noted a temporal shift in frugivory by
plotting the resulting spline (i.e., nonlinear curve) over a color-coded
background representing the seasons (Fig. 2). As a visual representation
of how precipitation also varied interannually, we fitted a spline for
the observed rainfall over the calendar year using precipitation data
from a nearby meteorological station <4km from the study site.
The spline illustrated that frugivory begins in the late spring,
increases substantially over the summer – reaches its peak in the late
summer/early fall – and declines gradually throughout the fall,
eventually near zero in winter and early/mid spring. The 95% credible
intervals emphasize that fruit consumption in summer and fall is
substantially greater than zero, differing from that of winter and
spring, where their credible intervals are much closer to zero
throughout the seasons (Fig. 2). On the other hand, the peak in
frugivory captured in the 95% credible interval in late summer/early
fall shows that the proportion of fecal volume comprised of fruit ranges
between 0.11 and 0.43, with a median estimate of 0.22.