James D. Roth, John D. Marshall, Dennis L. Murray, David M. Nickerson, and Todd D. Steury. 2007. Geographical gradients in diet affect population dynamics of Canada lynx. Ecology 88:2736–2743.

Appendix D. Seasonal and annual variability in stable isotope ratios of snowshoe hare and red squirrel hair samples from Clearwater National Forest, Idaho, USA.

FIG. D1. Open symbols (mean ± SE) reflect diet during spring molt, and closed symbols reflect diet during fall molt. Seasonal and annual variation in both δ15N and δ13C occurred for red squirrels (n = 32), but not hares (n = 23). For squirrels, there was a significant interaction between season and year in δ13C (F1,26 = 16.3, P < 0.001), but no main effects (season F1,26 = 0.85, P = 0.36; year F1,26 = 2.86, P = 0.11). For squirrel δ15N, there was no effect of season (F1,26 = 1.17, P = 0.29) but there was an effect of year (F1,26 = 5.18, P = 0.031) and there was an interaction between season and year (F1,26 = 6.38, P = 0.018). For hares, there were no differences between seasons or years in δ13C (season F1,20 = 0.03, P = 0.86; year F1,20 = 0.17, P = 0.69) or δ15N (season F1,20 = 2.13, P = 0.16; year F1,20 = 1.93, P = 0.18).