Pack rats (Neotoma) are resourceful rodents found across North and Central America. Their diet is highly adapted to the specific environment they inhabit. Although generally classified as herbivores, their ability to consume a vast array of plant species and other matter makes them highly successful. This dietary flexibility, coupled with their unique behavior of collecting and storing items, allows Neotoma species to thrive from arid deserts to high-elevation woodlands.
The Core Diet: Primary Plant Matter
The foundation of the pack rat’s diet consists of readily available plant material. This includes foliage, stems, seeds, nuts, and fruits gathered within their home range. They often prefer soft and easily digestible vegetation, such as the leaves of aspen, willow, and various shrubs.
Seeds and nuts provide a significant portion of their energy, offering concentrated sources of fat and protein. Examples include the seeds of Douglas-fir, gooseberries, and juniper berries. Pack rats favor the leaves and twigs of herbs and trees over grass. They also strip bark for consumption, which provides fiber and nutrients when other food sources are scarce.
Specialized Diets and Regional Adaptations
The specific plants consumed shift dramatically depending on the local ecosystem. In the arid Southwest, species like the white-throated woodrat (Neotoma albigula) rely heavily on succulent plants such as prickly pear and cholla cactus. Consuming these water-rich plants helps them obtain necessary moisture where standing water is unavailable.
Pack rats have evolved specialized methods to manage plant toxins found in regional flora. For instance, some consume juniper, a plant containing defensive chemicals. Their gut microbiome helps break down and detoxify these compounds, allowing them to utilize food sources poisonous to many other animals. Bushy-tailed woodrats (Neotoma cinerea) commonly feed on the twigs and needles of coniferous trees like Douglas-fir and Engelmann spruce.
Beyond Plants: Opportunistic Feeding
While plant matter forms the bulk of their diet, pack rats are opportunistic omnivores that consume almost anything available. This flexibility extends to non-vegetable items, including small insects and snails. They may also scavenge on animal bones or carrion for a boost of protein and minerals.
They are quick to exploit new food sources, particularly near human settlements. Pack rats feed on pet food left outdoors or stored human food if they gain access to a structure. This opportunistic behavior, including consuming garden vegetables and discarded scraps, underscores their success in varied environments.
Food Storage and Middens
A defining characteristic of the pack rat is their practice of hoarding food and other materials in a complex structure known as a midden. This elaborate construction serves multiple purposes, functioning as a fortified nest, a shelter from predators, and a secure larder for stored provisions. They meticulously collect food items like seeds and dried vegetation, stockpiling them for use during lean times, such as winter or periods of drought.
Middens are often large, conical piles of sticks, twigs, and debris. The pack rat’s highly concentrated urine is repeatedly deposited onto the pile. In arid climates, this urine crystallizes as it dries, creating a hard, cement-like matrix called “amberat” that encases and preserves the contents for thousands of years.