The survivorship analysis (Cox regression) on the husking
times for all seeds, with family and maximal bite force ascovariates gives similar results. There is a significant difference
in husking time between estrildids and fringillids (P=0.002) as
well as for different maximal bite forces (P=0.000). The
estimated function for husking time is very similar to the one
found for the model II regression on average husking time. The
cumulative hazard function of the survival function estimates
the change of a successful cracking attempt as a function of
time. Fig.·4 shows that the chance that a hemp seed cracks
within a certain amount of time is much higher in the fringillids
than in the estrildids, irrespective of the difference in maximal
bite force.