4.3 Food choice
Previous studies have shown that
primates are selective about the types and components of their food,
including the selection of plant species and food portions (Zhou et al.,
2018). This selectivity is influenced by factors, such as the quality
and quantity of food (e.g., nutrients, cellulose, mineral elements,
secondary toxicants, and food availability) and water content (Zhou et
al., 2021). The findings of this study were consistent with previous
studies, and the Encheng François’ langur had obvious food selectivity.
However, food selection is not strictly based on the number of plants in
the habitat. In this study, 72.99% of the total foraging records of the
François’ langurs consisted of 23 plant species. They used 68 of the 150
plant species marked by the vegetation surveys in the overall foraging
record, which accounted for 89.04% of the total foraging record. The
top 10 tree species in the vegetation survey included Pittosporum
pulchrum and Vitex kwangsiensis, which accounted for more than
2% of the total foraging records. This was similar to the findings of
other studies. In the Van Long Nature Reserve in Vietnam, the 10 most
commonly consumed plants by Trachypithecus delacouri accounted
for 82% of the total foraging records (Workman, 2010). In Madhupur,
Bangladesh, the caped langur (Trachypithecus pileatus (Blyth,
1843)) feeds on only 35 species of trees and vines during the year (John
et al., 2001). In Sri Lanka, long-tailed langurs used a total of 43
plant species, of which 70% of their food consisted of 10 species, none
of which were dominant species (Newton, 1992). In the Kuala Lumpur area,
45% of the diet of the black-crowned langur consists of five plant
species, which make up only 9.6% of the forest tree species (Bennett,
1983). François’ langurs and white-headed langurs showed selectivity in
the plant species they ate, and the 10 plants that were most consumed
accounted for 51%–90% of the food composition (Zhou & Huang, 2021).
In summary, François’ langurs
living in the ECNNR have similar feeding behaviors to other primates,
their choice of food is independent of the number of plant species in
the habitat, and the most common tree species in the habitat are only
consumed in a small amount.
Overall, we found the François’ langurs in the fragmented limestone
forest in southwest China had a similar feeding ecology to other
François’ langurs in distinct habitats. However, there were also some
differences. The langurs in this study ate a higher number of food
species throughout the year when compared with other species, maintained
a high level of food diversity, and ate more vines. These François’
langurs might have a slightly different feeding strategy than the other
François’ langur populations, although we suspect that these dietary
differences are mainly due to environmental conditions. We concluded
that François’ langurs exhibit a flexible feeding strategy, and thus
they are an ecological generalist that inhabits fragmented limestone
forests. Further research is needed to better understand the langurs’
feeding ecology, especially in southwest China.
CRediT authorship contribution
statement
Qi-Hai Zhou and Peng-Lai Fan conceived the ideas and designed
methodology; Wei Yao, Jia-Xin Zhao, Rong Huang, Wen-Hua Li collected the
data; Wei Yao and Cheng-Ming Huang analysed the data and wrote the
manuscript. All authors contributed critically to the draft and gave
final approval for publication.