DOI: 10.5061/dryad.p4h15
title: Data from: Extreme precipitation variability, forage quality and large herbivore diet selection in arid environments

description: Nutritional ecology forms the interface between environmental variability
 and large herbivore behaviour, life history characteristics, and
 population dynamics. Forage conditions in arid and semi-arid regions are
 driven by unpredictable spatial and temporal patterns in rainfall. Diet
 selection by herbivores should be directed towards overcoming the most
 pressing nutritional limitation (i.e. energy, protein [nitrogen, N],
 moisture) within the constraints imposed by temporal and spatial
 variability in forage conditions. We investigated the influence of
 precipitation-induced shifts in forage nutritional quality and subsequent
 large herbivore responses across widely varying precipitation conditions
 in an arid environment. Specifically, we assessed seasonal changes in diet
 breadth and forage selection of adult female desert bighorn sheep Ovis
 canadensis mexicana in relation to potential nutritional limitations in
 forage N, moisture and energy content (as proxied by dry matter
 digestibility, DMD). Succulents were consistently high in moisture but low
 in N and grasses were low in N and moisture until the wet period. Nitrogen
 and moisture content of shrubs and forbs varied among seasons and climatic
 periods, whereas trees had consistently high N and moderate moisture
 levels. Shrubs, trees and succulents composed most of the seasonal sheep
 diets but had little variation in DMD. Across all seasons during drought
 and during summer with average precipitation, forages selected by sheep
 were higher in N and moisture than that of available forage. Differences
 in DMD between sheep diets and available forage were minor. Diet breadth
 was lowest during drought and increased with precipitation, reflecting a
 reliance on few key forage species during drought. Overall, forage
 selection was more strongly associated with N and moisture content than
 energy content. Our study demonstrates that unlike north-temperate
 ungulates which are generally reported to be energy-limited, N and
 moisture may be more nutritionally limiting for desert ungulates than
 digestible energy.
description: Niche breadth
 dataLevins niche breadth
 data for desert bighorn sheep. Levins niche breadth was calculated from
 individual fecal pellet groups collected from female desert bighorn sheep.
 Individual levins indices were then averaged for each year, season and
 climate period. See Cain et al. 2017 for more details.LevinsNicheBreadth.csvForage sample nutritional contentNutritional content data for forage available to desert bighorn sheep on the Cabeza Prieta National Wildlife Refuge. N = nitrogen, DMD = calculated dry matter digestibility, NDF = neutral detergent fiber, ADF = acid detergent fiber, ADL = acid detergent lignin, and Moisture = moisture content. See Cain et al 2017 for more details.NutDataAll.csvMean nutritional content and forage selectionNutritional content data of forage plants and selection indices (Jacobs D) averaged by season, year and climate period. See Cain et al. 2017 for more details.Av_NutCont_JacD.csvweighted means_nutcontent_dietvsavailWeighted mean nitrogen, DMD, NDF, ADF, ADL and moisture content comparing forage available to desert bighorn sheep and diet. See Cain et al. 2017 for ore details.