To test whether there is a significant difference in the time
used to crack hemp seeds between estrildids and fringillids we
performed two analyses: a standardized major axis analysis on
the average husking time per species and a survivorship
analysis on the husking times for all individual seeds. The
model II regression analysis for the ln transformed average
husking time and the inverse of bite force showed a significant
positive correlation for both finches (r=0.978, P=0.000) and
estrildids (r=0.914, P=0.004). However, the slope of the
relationship between average husking time and the inverse of
bite force differed (P=0.033). Husking times were lower for the
fringillids (slope 5.09, 95% CI 4.35–5.96) than for estrildids
(slope 8.56, 95% CI 5.45–5.96) for the same bite force.
Estrildids: husking time=1.43e8.56/bite force (R2=0.835)
Fringillids: husking time=1.83e5.09/bite force (R2=0.956)