44 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 1, March 2011 
TABLE 2. Repeated-measures ANOVA for isotopic values of the feathers grown in 2006 and 2007 from the same 
individuals. Significant differences (P < 0.05) are in bold italics. Degrees of freedom are indicated in parentheses (df for 
numerator, df for denominator). Results (1-/?) of the power analysis are presented (a = 0.05). Sample sizes of each species 
are indicated in parentheses by the 
common name 
of each species. 
8 I5 N 
8 I3 C 
Species 
F 
P 
i-p 
F 
P 
i -P 
Herbivores 
Japanese White-eye (2) 
Taiwan Yuhina (9) 
12.25 (1, 1) 
13.1 (1, 9) 
0.18 
0.006 a 
0.05 
13.44 (1, 1) 
0.44 (1, 9) 
0.17 
0.52 
0.05 
Omnivores 
Gray-cheeked Fulvetta (25) 
2.97 (1, 23) 
0.10 
0.36 
3.75 (1, 23) 
0.07 
0.45 
Steere’s Liocichla (13) 
4.9 (1, 13) 
0.045* 
0.00 (1, 13) 
0.96 
0.05 
Grey-hooded Fulvetta (6) 
0.47 (1, 5) 
0.52 
0.07 
0.05 (1,5) 
0.83 
0.10 
Insectivores 
Collared Bush Robin (2) 
26.56 (1, 1) 
0.12 
0.06 
0.66 (1, 1) 
0.57 
0.05 
Rufous-capped Babbler (12) 
4.06 (1, 11) 
0.07 
0.43 
0.37 (1, 11) 
0.55 
0.09 
a Feathers grown in 2007 were significantly higher than those grown in 2006 (Fig. 7). 
sampled may be attributed to individuals of these 
species consuming a variety of insects and/or 
plant matter during the time of molt which, when 
combined, cancel the effect of altitude. Similarly, 
increase/decrease of feather 5 13 C and 8 I5 N values 
with increasing altitude for some species may also 
be due to the combination of foods they choose to 
eat, rather than to any effect of altitude. Detailed 
surveys of the isotopic ratios of foods and 
knowledge of diet-tissue fractionation (Gannes et 
al. 1997) of these birds are both necessary for 
testing these hypotheses. Second, different indi¬ 
viduals of the same species may move freely 
during feather growth between different resource 
patches along a wide range of altitudes to obtain 
their daily food requirements. Foraging over a 
wide altitudinal range may lead to feather 5 I3 C 
and 5 I5 N values that do not to reflect expected 
altitudinal trends. 
Year-to-year arid Within-year Comparison — 
One can examine changes in diet or in feeding 
locations over time by repeatedly comparing 
isotopic values of tissue samples at different time 
intervals, but from the same source (Dalerum and 
Angerbjorn 2005). Feathers are ideal for a 
temporal analysis of feeding locations (Mizutani 
et al. 1990, Hobson and Clark 1992, Thompson 
and Furness 1995) because they can be collected 
continually from the same individual (Ainley et 
al. 2003, Dalerum and Angerbjorn 2005). Our 
results show within-individual variation of feather 
5 I5 N and 5 I3 C values is low both between- and 
TABLE 3. Repeated measures ANOVA for isotopic values of the feathers grown at different times in 2007 from the 
same individuals. Degrees of freedom are in indicated parentheses (df for numerator, df for denominator) Results (1-fl) of 
the power analysis are presented (a = 0.05). Sample sizes of each species are indicated in parentheses by the common name 
8 I5 N 
8 ,3 C 
— 
Species 
F 
P 
i-p 
F 
P 
i-P 
Omnivores 
Gray-cheeked Fulvetta (6) 
Steere’s Liocichla (7) 
Grey-hooded Fulvetta (3) 
2.26 (2, 6) 
5.37 (1, 6) 
0.02 (2, 2) 
0.19 
0.06 
0.98 
0.07 
0.45 
0.05 
1.20 (2, 6) 
4-29 (1,6) 
0.05 (2, 2) 
0.36 
0.08 
0.95 
0.20 
0.37 
0.05 
Insectivores 
Collared Bush Robin (7) 
Green-backed Tit (2) 
Rufous-capped Babbler (2) 
4.44 (1, 5) 
0.66 (1, 1) 
0.24 (1, 1) 
0.09 
0.56 
0.71 
0.33 
0.05 
0.05 
4.08 (1, 5) 
0-12 (1, 1) 
0.13 (1, 1) 
0.10 
0.79 
0.78 
0.30 
0.05 
0.05 
