Lack of diet partitioning by sex in reintroduced desert bighorn sheep

Fulbright, Timothy E.; Robbins, W. Frank; Hellgren, Eric C.; DeYoung, Randall W.; Humphreys, Ira D.

doi:10.1006/jare.2000.0738

Cited by 11 publications

(5 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Likewise, Bowyer et al (1996) observed that black-tailed deer spatially segregated but exhibited little divergence in use of habitats. Others also have noted a lack of difference in habitat selection or small differences in diet between sexes of ruminants when they were segregated (Conradt 1999;Cransac et al 1998;Fulbright et al 2001). We urge abandonment of a reductionist approach in favor of one that synthesizes factors related to sexual segregation.…”

Section: Discussionmentioning

confidence: 85%

Effects of Foraging Activity on Sexual Segregation in Mule Deer

Bowyer

Kie

2004

Journal of Mammalogy

View full text Add to dashboard Cite

We retrospectively tested whether differences in activity patterns and foraging efficiency by males and females were responsible for sexual segregation in mule deer (Odocoileus hemionus). These deer spatially segregated by sex during the dry season (May-October), which encompassed parturition, and aggregated during the wet season (November-April), which included rut. Activity did not differ among types of social groups of deer (mixed-sex, adult male, or adult female), but was greater during the dry season than in the wet season. Foraging efficiency (percentage of active deer feeding) was greater in mixed-sex groups than in groups of either adult males or adult females during both wet and dry seasons. We rejected the hypothesis that differences in activity or foraging efficiency lead to spatial segregation of the sexes in mule deer; no aspect of that hypothesis will explain why sexes use space or other resources differentially. We propose a new approach that incorporates niche theory and reconciles past difficulties in how best to interpret sexual segregation in ungulates.

show abstract

Section: Discussionmentioning

confidence: 85%

Effects of Foraging Activity on Sexual Segregation in Mule Deer

Bowyer

Kie

2004

Journal of Mammalogy

View full text Add to dashboard Cite

show abstract

“…However, grasses were found in higher proportions seasonally in other studies in Arizona (Hansen and Martin 1973, Dodd and Brady 1988, Morgart 1990, Holt et al 1992) and dominated seasonal diets of bighorn sheep in Nevada (Barrett 1964, Brown et al 1977 and California (Bleich et al 1997). In the Virgin Mountains, Arizona, and Baja California Sur, Mexico, forbs dominated the diets of bighorn sheep (Sanchez 1976, Smith and and in Texas forbs and browse were equally important in bighorn sheep diets (Fulbright et al 2001).…”

Section: Discussionmentioning

confidence: 99%

“…The diet of desert bighorn sheep has been studied in Arizona (Seegmiller and Ohmart 1981, Smith and Krausman 1987, Morgart 1990, Holt et al 1992, California (Welles and Welles 1961, Ginnett and Douglas 1982, Cunningham and Ohmart 1986, Bleich et al 1997, Nevada (Barrett 1964, Yoakum 1964, Brown et al 1977, New Mexico (Sandoval 1979, Watts 1979, Elenowitz 1983, Texas (Brewer 2001, Fulbright et al 2001, Utah (King and Workman 1982), USA, and Sonora and Baja California Sur, Mexico (Sanchez 1976, Tarango 2000. Previous diet studies have been largely descriptive and most are of a relatively short duration (i.e., 2 yr); with a few exceptions (Brown et al 1977, Bleich et al 1997, Etchberger and Krausman 1998 these studies documented temporal and spatial variation in diet of desert bighorn sheep across the desert Southwest.…”

Section: Introductionmentioning

confidence: 99%

Responses of Desert Bighorn Sheep to Removal of Water Sources

Cain

Krausman

Morgart

et al. 2008

Wildlife Monographs

View full text Add to dashboard Cite

In arid regions of the southwestern United States, water is often considered a primary factor limiting distribution and productivity of desert ungulates, including desert bighorn sheep (Ovis canadensis mexicana). Thus, wildlife management agencies and sportsmen's organizations have invested substantial time and resources in the construction and maintenance of water catchments. Although the availability of freestanding water sources is believed to influence many aspects of the ecology of desert bighorn sheep, the efficacy of these water sources has been questioned and has not been examined experimentally. We used a before‐after‐control‐impact study design to determine if removal of water catchments changed diet, characteristics of foraging areas used by female desert bighorn sheep, home‐range size, movement rates, distance to catchments, adult mortality, productivity, or juvenile recruitment in 2 mountain ranges on the Cabeza Prieta National Wildlife Refuge, Arizona, USA. During pretreatment (2002–2003), we ensured that water catchments were available to desert bighorn sheep in both mountain ranges; during posttreatment (2004–2005), we drained all water catchments in the treatment range. We measured diet composition, characteristics of foraging areas, 50% and 95% kernel home ranges, movement rates, and distance to water catchments seasonally from 2002 to 2005. We also estimated adult survival, lamb:female, and yearling:female ratios from 2002 to 2005. We predicted that removal of water catchments would result in 1) increased use of foraging areas with more vegetation cover, more thermal cover, and higher succulent abundance; 2) increased consumption of cacti and other succulents; 3) an increase in home‐range size, movement rates, and distance to nearest catchment; and 4) a decrease in adult survival, productivity, and juvenile recruitment. Removal of water catchments in the treatment range did not result in predicted changes in diet, foraging area selection, home‐range size, movement rates, mortality, productivity, or recruitment. Female desert bighorn sheep did use areas with more thermal cover during the summer after removal of water catchments, but other characteristics of foraging areas used by bighorn sheep and their diet did not change appreciably with removal of water catchments. We did not document changes in home‐range area, movement rates, or distance sheep were from water during hotter months; we only documented changes in home‐range area, movement rates, and distance to water catchments during winter and autumn. There were 10 desert bighorn sheep mortalities in the treatment range and 8 in the control range; 7 mortalities in each mountain range were during pretreatment. Twelve of the 18 total mortalities occurred during summer. Survival rate was lower during pretreatment than posttreatment in both mountain ranges. We did not document increased mortality or a change in lamb:female or yearling:female ratios after removal of water catchments. Home‐range area and movement rates declined with incre...

show abstract

“…We estimated DBS daily nutrient and preformed water intake, and metabolic water production for each season based on diet composition, forage quality, and DMI. We assumed that DBS diets did not differ between sexes [ 86 , 87 ], and thus, female diet compositions measured in this study were also used to calculate male intakes. Early and late summer were the only seasons where we predicted DBS (both sexes) would have a negative daily water balance ( Table 1 ).…”

Section: Resultsmentioning

confidence: 99%

Potential Foraging Decisions by a Desert Ungulate to Balance Water and Nutrient Intake in a Water-Stressed Environment

et al. 2016

View full text Add to dashboard Cite

Arid climates have unpredictable precipitation patterns, and wildlife managers often provide supplemental water to help desert ungulates endure the hottest, driest periods. When surface water is unavailable, the only source of water for ungulates comes from the forage they consume, and they must make resourceful foraging decisions to meet their requirements. We compared two desert bighorn sheep (Ovis canadensis nelsoni) populations in Arizona, USA: a treatment population with supplemental water removed during treatment, and a control population. We examined whether sheep altered their seasonal diets without supplemental water. We calculated water and nutrient intake and metabolic water production from dry matter intake and forage moisture and nitrogen content, to determine whether sheep could meet their seasonal daily water and nutrient requirements solely from forage. Diets of sheep were higher in protein (all seasons) and moisture (autumn and winter) during treatment compared to pretreatment. During treatment, sheep diet composition was similar between the treatment and control populations, which suggests, under the climatic conditions of this study, water removal did not influence sheep diets. We estimated that under drought conditions, without any surface water available (although small ephemeral potholes would contain water after rains), female and male sheep would be unable to meet their daily water requirements in all seasons, except winter, when reproductive females had a nitrogen deficit. We determined that sheep could achieve water and nutrient balances in all seasons by shifting their total diet proportions by 8–55% from lower to higher moisture and nitrogen forage species. We elucidate how seasonal forage quality and foraging decisions by desert ungulates allow them to cope with their xeric and uncertain environment, and suggest that, with the forage conditions observed in our study area during this study period, providing supplemental water during water-stressed periods may not be necessary for desert bighorn sheep.

show abstract

Lack of diet partitioning by sex in reintroduced desert bighorn sheep

Cited by 11 publications

References 14 publications

Effects of Foraging Activity on Sexual Segregation in Mule Deer

Effects of Foraging Activity on Sexual Segregation in Mule Deer

Responses of Desert Bighorn Sheep to Removal of Water Sources

Potential Foraging Decisions by a Desert Ungulate to Balance Water and Nutrient Intake in a Water-Stressed Environment

Contact Info

Product

Resources

About