Moose winter diet components from feces and field feeding signs: consistency and variability related to forage availability and nutritional requirements

Diet composition detection of herbivores, relating to feeding strategies, might be influenced by forage availability, geographical variation, and the results of diet estimation also varied in some extent by the different research methods. Therefore, it is difficult to assess how effective various methods of identifying herbivores diet components and their nutritional requirements are. In order to assess the consistency and variability of moose ( Alces alces ) winter diet composition across a large spatial scale, we compared the results of diet analysis from fecal analysis to those of parallel field survey related to forage availability and crude protein requirements during winter from December to March of 2012, 2013, and 2014 in the Greater Khingan Mountains, China. Our results suggested that: (1) the diet components variability between the two methods exist, and the value of species richness index, shannon wiener index and species evenness index in fecal analysis were greater than in field survey; (2) staple foods (birch, willow and aspen) identified from the two methods exhibited the stable consistency; and the percentage of birch was positive relative to forage availability from both methods; (3) quantitative crude protein of staple food items were different between both method, it was much lower than moose nutritional requirement by fecal analysis, and it was match the nutritional requirement of moose during field survey. These findings suggested that the two methods kept variability in detecting quantitative nutritional components, and only diet composition overlap consistency could not be reflected as quantitative nutritional similarity.