FIGURE 1 Weight recession of young eagles during hacking documented by the two sampling events. Both sexes lost mass in a similar way (female, upper: male, lower). Circles (female) and squares (males) indicate means and vertical bars denote 0.95 confidence intervals.
FIGURE 2 Distributions of urea values of sample 1 (soon after entering hacking) and sample 2 (just before the release from hacking). Sample 1 showed a non-normal distribution (Shapiro-Wills = 0.889, P < 0.001) that changed to a normal distribution in sample 2 (Shapiro-Wills = 0.965, P = 0.246), after more than one month withad libitum food in the hacking facility.
FIGURE 3 Linear regression between standardized hatching date and urea level in sample 1 (soon after entering hacking) and sample 2 (just before the release from hacking). Sample 1 showed a significant relationship with higher urea levels in later hatched birds (r = 0.397, R2 = 0.16, P = 0.010). This relationship disappeared in sample 2 (r = 0.297, R2 = 0.08, P = 0.059), after more than one month with ad libitum food in the hacking facility.