Nutritional ecology of dimorphic herbivores: digestion and passage rates in Nubian ibex.

We compared forage digestion and passage rates among three groups of Nubian ibex (Capra ibex nubiana) - mature males, non-lactating females, and lactating females - to test hypotheses relating intraspecific digestive ability to body mass and reproduction costs. We hypothesized that large males (60 kg) would exhibit longer forage retention times and more complete digestion of fermentable cell walls than adult females (23 kg). We tested these predictions by measuring digestion and retention of a grass hay and an alfalfa hay, forages that exhibited contrasting rates and extents of cell wall digestion.

Testing values of crested porcupine habitats by experimental food patches.

We established depletable, artificial food patches in three habitats used by Indian crested porcupines (Hystrix indica) in a desert biome, and measured the number of food items remaining (i.e., "giving up density"=GUD) following nightly foraging bouts.