Table 1.

Results of the linear-mixed effects models to test for changes in food availability (cumulative log₁₀ DBH) in 22 plots between four survey periods in K-30, K-15 and K-14. Means ± 95% confidence intervals (CI₉₅ = 1.96 × s.e.) and t-values of fixed effects (survey periods) are presented. Significant values at the 5% level are in italics and marked with an asterisk. The baseline year to test for changes in food availability over time is 1989 for (a,b), and 1996 for (c,d). We included the sampling period as the fixed effect, and vegetation plot identity as a random effect. We summarize model results using the ANOVA function in the R package ‘car’ [48], which calculates p-values for the predictor variable using Wald tests, and calculated R² for the model by dividing the sum of squares for the sampling period divided by the residual sum of squares. RC, red colobus; YL, young leaves, ML, mature leaves (data from [47]; however, R² and p-values represent novel analyses).

food abundance (cumulative logDBH)	intercept (mean ± CI95)	t	2000 (mean ± CI95)	t	2006 (mean ± CI95)	t	2013 (mean ± CI95)	t	R2	F-statistic (d.f. = 3,63)
(a) all trees	111.7 ± 13.7	16.66*	–1.9 ± 5.1	–0.72	7.3 ± 5.1	2.83*	12.4 ± 5.1	4.78*	0.393	13.03*
(b) RC food species	46.6 ± 9.7	9.44*	1.1 ± 3.3	0.65	5.4 ± 3.3	3.20*	8.6 ± 3.3	5.09*	0.346	11.10*
(c) RC food species weighted by protein : fibre of YL	46.4 ± 7.6	12.03*	0.0 ± 2.8	0.01	2.0 ± 2.8	1.39	3.2 ± 2.8	2.21*	0.102	2.38 (p = 0.078)
(d) RC food species weighted by protein : fibre of ML	30.8 ± 5.9	10.27*	1.6 ± 1.9	1.70	4.5 ± 1.9	4.68*	6.9 ± 1.9	7.12*	0.487	19.93*