Chang et al. • ALTITUDINAL CHANGES OF 5 15 N AND 8 ,3 C IN MONTANE BIRDS 37 
12 
10 
8 
6 
4 
2 
0 
h 
h- 
h 
< 
L 
11 re 
S 13 C = 0.14 x Alt + 6.98 ( R 2 = 0.01, P = 0 
GLM; F 6 , 9 = 0.69, P = 0.66 
.78) 
8 13 C = 0.65 x Alt - 24.76 (R 2 = 0.43, P < 0.001) 
0.5 
1.5 
2.5 
0.5 
1.5 
2.5 
12 
10 
8 
6 
4 
2 
0 
Japanese White-eye 
(B) 
-20 
(E) 
Kfl 
"o -22 
o' 
o - 24 ‘ 
CO 
To -26 
(2) (4) W 
S 15 N = -3.39 x Alt + 9.84 (R 2 = 0.30, P = 0.10) 
5 13 C = 0.49 x Alt - 24.60 (R 2 = 0.15, P = 0.27) 
Kruskal-Wallis test; H 2 = 3.68, P = 0.16 
-28 
Kruskal-Wallis test; H 2 = 2.46, P = 0.29 
0.5 
1.5 
2.5 
0.5 
1.5 
2.5 
Taiwan Yuhina 
FIG. 2. Change in 5 I5 N and 8 I3 C values of feathers of herbivorous birds with altitude in Taroko National Park, Taiwan. 
Results of all species combined are shown in A and D. Results of individual species are shown in B, C, E and F. Stable 
isotope values of all individuals of each species collected at the same sites are expressed as means ± SE. Numbers of 
feathers used for isotope analyses for each species at different sites are in parentheses. Numbers of feathers used for isotope 
analyses for all species combined correspond to those of each species at different sites. One-way ANOVA results are also 
presented. Asterisks indicate significant differences (P < 0.05) between sites. 
Altitudinal Pattern and Site Comparison in 
S I3 C Values .—Feather 8 I3 C values exhibited 
varying relationships to altitude among guilds 
and among species (Figs. 2-4). These values for 
both herbivores (Fig. 2D) and omnivores 
(Fig. 3E) decreased significantly with increasing 
altitude. Feather 5 I3 C values for insectivores had 
no significant relationship to altitude (Fig. 4F). 
When analyzed by species, Grey-cheeked Fulvet- 
tas (Fig. 3F), Rufous-capped Babblers (Fig. 41), 
and White-browed Bush Robins (Fig. 4J) had 
significant increases in feather 5 13 C values with 
increasing altitude. However, Grey-hooded Ful- 
vettas (Fig. 3H) had significant decreases in 
feather 8 13 C values with increasing altitude. The 
R 2 of the four species varied between 0.14 and 
0.35. The relationship for the other five species 
between feather 8 I3 C values and altitude did not 
reach significance (P > 0.05) (Figs. 2E, F; 3G; 
4G, H). 
Feather 8 13 C values were significantly different 
between some, but not all, sites for all three guilds 
(Figs. 2D, 3E, 4F). When analyzed by species, 
8 l3 C values were significantly different between 
some, but not all, sites for Grey-cheeked Fulvettas 
(Fig. 3F), Steere’s Liocichla (Fig. 3G), Grey- 
hooded Fulvettas (Fig. 3H), Rufous-capped Bab¬ 
blers (Fig. 41), and White-browed Bush Robins 
