Nutritional Bottleneck in a Herbivore, the Desert Wood Rat (Neotoma lepida)

  title={Nutritional Bottleneck in a Herbivore, the Desert Wood Rat (Neotoma lepida)},
  author={William H. Karasov},
  journal={Physiological Zoology},
  pages={1351 - 1382}
  • W. Karasov
  • Published 1 November 1989
  • Environmental Science, Biology
  • Physiological Zoology
The nutritional ecology of desert wood rats (Neotoma lepida) was studied at a site in the Mojave Desert that lacked succulents such as cactus, yucca, and agave. During the late fall and early winter, before winter rains, wood rats ate primarily mature leaves and stems ofcreosote bush (Larrea tridentata), whereas after winter rains they ate newly germinating annuals. Wood rats lost body mass during the prerain period and some were visibly emaciated, whereas they suffered no significant mass loss… 
An Oak (Quercus agrifolia) Specialist (Neotoma macrotis) and a Sympatric Generalist (Neotoma lepida) Show Similar Intakes and Digestibilities of Oak
The two species' similar tolerances for oak were probably due to their similar abilities to digest and potentially assimilate the ground oak leaves.
Plant secondary metabolites alter the feeding patterns of a mammalian herbivore (Neotoma lepida)
It is suggested that the immediate and sustained ability to detect and regulate the intake of resin concentrations during each foraging bout provides a behavioral mechanism to regulate blood concentrations of resin and allows desert woodrats to make “wise” foraging decisions.
It is hypothesized that: (1) smaller animals would be more dependent than larger animals on highly digestible food items such as seeds, and (2) smaller dogs and cats will be more selective than large animals forhighly digestible and energy-rich plant parts.
Creosote Bush (Larrea tridentata) Resin Increases Water Demands and Reduces Energy Availability in Desert Woodrats (Neotoma lepida)
The increased water requirement and energy losses of woodrats consuming a diet with resin could have notable ecological consequences.
Woodrat (Neotoma) herbivores maintain nitrogen balance on a low-nitrogen, high-phenolic forage, Juniperus monosperma
The results suggest that absorption and detoxification of juniper secondary compounds may be more important for restricting juniper intake by the generalist than nitrogen imbalance.
Estimating the influence of the thermal environment on activity patterns of the desert woodrat (Neotoma lepida) using temperature chronologies
The results suggest that activity of N. lepida is constrained during the climatically intense summer months, and animals face a trade-off between remaining in the thermal safety of the den vs. emerging to obtain resour- ces.
Using the Specialization Framework to Determine Degree of Dietary Specialization in a Herbivorous Woodrat
Behavior and habitat differences between these woodrat species lead to the categorization of N. stephensi as an obligate juniper specialist with a small range that overlaps that of its preferred food, J. monosperma, and N. lepida as a facultative juniper Specialist with a large range, and only a portion of its distribution containing populations that feed extensively on J. osteos perma.
The role of dietary fiber in dung size of bushy-tailed woodrats, Neotoma cinerea : its potential application to paleoclimatic interpretation
An increase in fiber intake led to a significant increase in dung length and dry dung weight but not dung width or body weight, although the relationship is not clearly understood and needs further evaluation.


Antiherbivore Chemistry of Larrea Tridentata: Effects on Woodrat (Neotoma Lepida) Feeding and Nutrition
The results indicate that creosote resin does deter feeding by desert woodrats, and the antiherbivore mechanism of creosotes resin to desert wood rats is likely one of toxicity and not digestibility reduction.
Energy Assimilation, Nitrogen Requirement, and Diet in Free-Living Antelope Ground Squirrels Ammospermophilus leucurus
  • W. Karasov
  • Environmental Science
    Physiological Zoology
  • 1982
The results suggested that even though free-living small mammals have rates of energy expenditure two to three times basal, their N requirements can be reliably predicted based on laboratory measurements made under more basal conditions.
Woodrats and Cholla: Dependence of a Small Mammal Population on the Density of Cacti
In the deserts of Southern California, stands of jumping cholla cactus (Opuntia bigelovii) are usually inhabited by desert woodrats (Neotoma lepida), and the dependence of woodrat populations on the density of cholla may be attributed to the fact that the cacti provide most resources required by the woodrats.
Habitat Utilization by Neotoma lepida in the Mohave Desert
The desert woodrat has successfully increased its exploitation of these habitats by constructing houses from whatever materials are available in a particular habitat and also by utilizing a wide taxonomic and morphologic spectrum of food plants.
Ontogenetic Changes in Diet, Field Metabolic Rate, and Water Flux in the Herbivorous Lizard Dipsosaurus dorsalis
High mass-specific energy requirements associated with small body size did not impose a physiological limitation precluding herbivory in a lizard as small as hatchling Dipsosaurus, and Ontogenetic shifts in the balance of the diet from carnivory at hatching toward Herbivory at maturation is found among omnivorous species of intermediate adult size.
Energy Utilization and Temperature Regulation by Jackrabbits (Lepus californicus) in the Mojave Desert
Energy expenditure for black-tailed jackrabbits in the Mojave Desert is highest in winter when ambient temperatures were consistently below the zone of thermoneutrality, and during late spring, summer, and early fall energy expenditure is high despite appreciable seasonal and diurnal temperature shifts.
Energy and Nitrogen Budgets of the Free-Living Desert Lizard Sauromalus obesus
Animals lost weight during the year, apparently because succulent vegetation was unavailable after May, and most animals stopped feeding and reduced their activity in June and this estivation apparently prevented even greater weight losses than those observed.
Desert rodent populations: factors affecting abundance, distribution, and genetic structure
Although desert rodents have been the subject of hundreds of studies on a number of levels, it is not yet feasible to make general conclusions as to the relative importance of various factors in determining the abundance, distribution, and genetic structure of populations of desert rodents.
Measuring the Local Distribution of Ribes
Blister rust control, as is well known, consists of the destruction of the alternate hosts, currant and gooseberry plants (Ribes spp.), in and near stands of susceptible five-needle or white pines.
Periods of Nutritional Stress in the Annual Cycles of Endotherms: Fact or Fiction?
The main thesis of this essay is that the diversity and potency of such compensatory mechanisms haveoften been underrated, and hence the frequency and intensity of nutritional stress in free-living animals have often been exaggerated.