* Browse: This is their primary food source in winter. Browse refers to the twigs, buds, and leaves of shrubs and trees. Some common browse species include:
* Conifers: Ponderosa pine, Douglas fir, juniper, and spruce
* Deciduous trees and shrubs: Willow, aspen, maple, and oak
* Forbs: These are non-woody plants, and while less abundant in winter, mule deer will eat their leaves, stems, and roots when available.
* Grasses: Dried grasses are a secondary food source, especially when browse is scarce.
* Lichens and Mosses: These are low-nutrient sources, but mule deer will consume them when other options are limited.
* Bark: In dire situations, mule deer may strip bark from trees, but this is usually a last resort.
How they adapt to winter:
* Rumen: Their four-chambered stomach allows them to digest tough, fibrous winter foods.
* Fat reserves: They build up fat reserves in the fall to help them survive the winter.
* Migration: Some populations migrate to lower elevations where food is more readily available.
Important factors influencing winter diet:
* Snow depth: Deep snow limits access to browse, forcing deer to rely on lower-quality food sources.
* Climate: Harsh winters with prolonged periods of cold and snow can make food scarce.
* Habitat: Areas with diverse vegetation offer more options for winter forage.
Overall, mule deer have evolved remarkable adaptations to survive harsh winter conditions, but their survival depends on having access to sufficient and nutritious food sources.