34 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 1, March 2011 
FIG. 1. Banding sites in Taroko National Park, Taiwan. Longitude, latitude, and altitude of sampling sites are in 
Table 1. 
passed on to the organisms at higher trophic 
levels, and animals should reflect the altitudinal 
trends of the plants and soils in their local habitats 
(Mannel et al. 2007). 
However, not all animals exhibit altitudinal 
trends of 5 I3 C and 6 I5 N similar to those observed 
in plants and soils. Previous studies on altitudinal 
patterns of isotopic signatures in animals have 
focused on either one species (Graves et al. 2002, 
Yi and Yang 2006) or several species within a 
single feeding guild (e.g., nectarivores or herbi¬ 
vores) (Hobson et al. 2003, Mannel et al. 2007). In 
each case they were primary consumers. The 8 I3 C 
values of animals in some cases become more 
positive with increasing altitude (Graves et al. 
2002, Mannel et al. 2007), while others show no 
altitudinal trends (Graves et al. 2002). Two 
studies show 5 15 N values increase with increasing 
altitude (Hobson et al. 2003, Yi and Yang 2006), 
one study shows no altitudinal trend (Graves et al. 
2002), and the other shows 5 I5 N values decreasing 
with increasing altitude (Mannel et al. 2007). 
More studies should be conducted in other 
ecosystems with animals in a variety of trophic 
levels to expand our understanding of the effect of 
altitude on 8*'C and 5 I5 N of animals. 
We discuss altitudinal patterns of feather 5 13 C 
and 5 15 N values of nine wild passerine species, 
belonging to three feeding guilds (Chen and Chou 
1999, Lin et al. 2003) collected along a large 
altitudinal gradient of ~2,500 m in Taroko 
National Park, Taiwan (Fig. 1, Table 1): 
Herbivores: Japanese White-eye (Zosterops 
japonicus ), Taiwan Yuhina ( Yuhina brunnei- 
ceps); 
Omnivores: Grey-cheeked Fulvetta (Alcippe 
morrisonia ), Steere’s Liocichla ( Liocichla 
steerii), Grey-hooded Fulvetta (A. cinereiceps)', 
and 
Insectivores: Collared Bush Robin ( Tarsiger 
johnstoniae ), Green-backed Tit ( Parus monti- 
colus ), Rufous-capped Babbler ( Stachyris rufi- 
ceps ), White-browed Bush Robin (T. indicus). 
Our first objective was to ascertain if 8 13 C 
values in feathers increased, while 5 I5 N values in 
feathers decreased with increasing altitude for 
each guild and each species. Our second objective 
was to examine year-to-year and/or month-to- 
month fluctuations of 5 13 C and 5 15 N in feathers of 
birds. This would naturally reflect altitude and 
diet inferences. The presence or absence of 
