Herbivore food selection overview thread

[creature386]

I made one for carnivores, so I decided to make a thread for herbivores too. I don't know a lot about herbivore food selection, but threads like that are extremely rare, so I decided to make one.
General patterns (large herbivores):

Ecological theory has formulated the objective of feeding strategies as to maximize the capture rate of some nutrient. But large generalist herbivores typically face a limit on how much material they can digest. Thus, their feeding strategy is best considered as aiming to achieve the best nutritional balance within a fixed total bulk of food. The problem of finding the diet which provides the best mix of nutrients can be formulated as a linear program. A property of this "optimization model" is that the contribution of a food to the diet will sometimes vary with the food's content of a particular nutrient and sometimes will not. This might explain why no consistent relations of this kind have been found experimentally. The long-delay learning mechanism is described. If this exists in large generalist herbivores, it would provide a means by which they might pursue optimization of nutrient mix in the diet. It would also account for the very large inter- and intraindividual variability in preference reported. Optimization achieved by this means would be imperfect. First, the necessary sampling of foods would modify the diet in the direction of greater variety than predicted by the linear model. Second, optimization would not act perfectly on all nutrients. If diet selection is dominated by the need to meet nutritional criteria, the response of the diet to availability of particular foods should not be continuous but take the form of a cutoff at very low availability. This implies that as a food becomes rarer in a plant community, grazing pressure on it will increase, at least until the cutoff is reached.

www.jstor.org/discover/10.2307/2460184?uid=3737864&uid=2&uid=4&sid=21102531991273

There is a similar paper on springer, but the link is broken.

Here another paper from JSTOR on the food selection of howler monkeys:

Some theories on the foraging strategies of generalist herbivores suggest that the food choices of such animals are greatly influenced by the quality and antiquality components of potential foods. Many herbivores selectively feed on young rather than mature foliage. It has been hypothesized that young leaves are preferred because they have higher contents of protein and/or lower contents of toxic secondary compounds. These and several other hypotheses were tested with data from a long-term study of the feeding ecology of howler monkeys (Alouatta palliata), using a cost/benefit approach. Samples of young and mature leaves from the same species were analyzed for total protein, cell wall constituents, total phenolics, presence of condensed tannins, and total nonstructural carbohydrates. The results support the hypothesis that more than one factor determine howler leaf choices. The most important factors (relating to food content) appeared to be protein and fiber content, with perhaps some influence from secondary compounds. For howlers and other relatively small mammalian herbivores, the protein: fiber ratio may be a good predictor of leaf choices.

www.jstor.org/discover/10.2307/2460184?uid=3737864&uid=2&uid=4&sid=21102531991273

I may expand this a bit later, when I have some data.