Fig. 2
From: Mining morphometrics and age from past survey photographs
Calibration graphs of 11 linear mixed-effects models, showing the relationship between age, calculated from molar exams, and each of the 11 tusk to body size ratios, calculated from images, including a natural cubic spline (d.f. = 3) and individuals as random effects: (1) tusk length to body length, 2) tusk length to body height, 3) tusk length to foot diameter, 4) tusk length to head height, 5) tusk length to head girth, 6) tusk length to tusk diameter, 7) tusk diameter to body length, 8) tusk diameter to body height, 9) tusk diameter to foot diameter, 10) tusk diameter to head height, and 11) tusk diameter to head girth. Thick lines represent models with significant p values < 0.05. Each age class represented by different coloured backgrounds: 1) young adults from 15 to 25 years in orange, 1) adults from 25 to 35 years in blue, and 3) prime adults from 35 to 55 years in green. The current recommended age for sustainably hunting males based on local protocol depicted by grey dashed line. n = 11 individuals