Restoration of bighorn sheep metapopulations in and near 15 national parks: Conservation of severely fragmented species; Volume II, Synopsis of research findings

Singer, Francis J.; Gudorf, Michelle A.

doi:10.3133/ofr99105

Cited by 9 publications

(14 citation statements)

References 8 publications

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“…Domestic cattle occur year-round on, or adjacent to, all desert bighorn sheep ranges in New Mexico, including the Sierra Ladron. Presence of cattle has been negatively correlated with success of bighorn sheep translocations (Singer et al 1999). This generally is assumed to result from direct competition or possibly disease (Albrechtsen and Reese 1970, Gallizioli 1977, Onderka et al 1988, Bissonette and Steinkamp 1996.…”

Section: Discussionmentioning

confidence: 99%

“…Despite successes in translocating desert and Rocky Mountain bighorn sheep, translocations continue to fail. The specific causes of failures include predation, disease, and dispersal (Rowland and Schmidt 1981, Bailey 1990, Berger and Wehausen 1991, Singer et al 1999. Documentation of mountain lion predation as the proximate cause of translocation failures and declines in extant bighorn sheep populations is a recent phenomenon (Wehausen 1996, Ross et al 1997, Hayes et al 2000, Rominger and Weisenberger 2000, Kamler et al 2002.…”

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confidence: 99%

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The Influence of Mountain Lion Predation on Bighorn Sheep Translocations

Rominger¹,

Whitlaw²,

Weybright³

et al. 2004

Journal of Wildlife Management

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We studied the effects of mountain lion (Puma concolor) predation on 2 translocated populations of bighorn sheep (Ovis canadensis) in New Mexico, USA. During 1993, 32 Rocky Mountain bighorn sheep (O. c. canadensis) were translocated to Wheeler Peak Wilderness Area in northern New Mexico, and during 1992–1993, 31 desert bighorn sheep (O. c. mexicana) were translocated to Sierra Ladron in central New Mexico. We monitored both populations from release through 2000 using fixed‐wing aircraft and ground and/or helicopter surveys. We determined cause of mortality for radiomarked individuals (n = 26) and calculated survival rates, cause‐specific mortality rates, exponential growth rates, and lamb:ewe ratios. The post‐lambing population estimates in 2000 were 180 in Wheeler Peak and 21 in Sierra Ladron. Annual adult survival was higher (P < 0.005) in the Wheeler Peak population (0.955) than in the Sierra Ladron population (0.784). Annual lamb:ewe ratios also were higher (P < 0.001) in the Wheeler Peak population (66.7 vs. 29.8). Mean annual exponential growth rate (r) in the Wheeler Peak population was 0.25 compared to −0.01 for the Sierra Ladron population. Predation by mountain lions was the primary proximate cause (75%) of 16 known‐cause mortalities of radiomarked bighorn sheep in the Sierra Ladron population, while we did not document any predation in Wheeler Peak. The annual cause‐specific mortality rates due to mountain lion predation in Sierra Ladron were 0.13 for males, 0.09 for females, and 0.11 for all adult bighorn sheep. Mountain lion predation may have limited the Sierra Ladron bighorn sheep population and could be imposing a destabilizing inverse density‐dependent mortality. Mountain lions preyed on domestic cattle in the Sierra Ladron area and throughout desert bighorn sheep habitat in New Mexico; we therefore hypothesize that cattle “subsidized” the diets of mountain lions (i.e., reduced or eliminated natural starvation). The ultimate cause of mortality for these desert bighorn sheep may be related to subsidized mountain lion populations that do not appear to decline following native ungulate population decreases. In addition, the encroachment of woody vegetation may increase the hunting success of ambush predators like mountain lions. High mountain lion predation may require mitigation for the successful restoration of bighorn sheep.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

The Influence of Mountain Lion Predation on Bighorn Sheep Translocations

Rominger¹,

Whitlaw²,

Weybright³

et al. 2004

Journal of Wildlife Management

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“…Lewis (1998) also suggested further developing the model to identify habitats where prescribed burning might be used to improve bighorn sheep habitat. Prescribed burning was suggested to improve habitat prior to future releases of sheep in Mesa Verde NP and Dinosaur NM (Singer & Gudorf 1999). Very limited suitable habitat was available to sheep in Mesa Verde NP (4.9 km 2 ) and horizontal visibility was the most limiting factor, reducing the area of suitable habitat by nearly 600 km 2 .…”

Section: Discussionmentioning

confidence: 99%

“…Areas investigated included seven National Parks (Table 1), some area of surrounding federal and private lands, Black Canyon of the Gunnison National Park (NP) and Mesa Verde NP, Colorado, and Theodore Roosevelt NP, North Dakota. More detailed descriptions of these areas and the bighorn sheep habitat assessments is presented by Singer and Gudorf (1999).…”

Section: Study Areamentioning

confidence: 99%

Test of a Modified Habitat Suitability Model for Bighorn Sheep

Zeigenfuss

Singer

Gudorf

2000

Restoration Ecology

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Translocation of bighorn sheep (Ovis canadensis) is time, labor, and cost intensive and, therefore, high levels of success are desirable. We tested a widely used habitat suitability model against translocation success and then modified it to include additional factors which improved its usefulness in predicting appropriate translocation sites. The modified Smith habitat suitability model for bighorn sheep was 64% accurate in predicting success or failure of 32 translocations of bighorn sheep into the Rocky Mountains, Colorado Plateau desert, and prairie‐badlands of six states. We had sheep location data for 13 populations, and the modified habitat model predicted the areas used by bighorn sheep with greater than 90% accuracy in eight populations, greater than 55% accuracy in four populations, and less than 55% accuracy in one population. Translocations were more successful when sheep were placed into discrete habitat patches containing a high proportion of lambing period habitat (>10% of suitable habitat, p = 0.05), where animals had a migratory tendency ( p = 0.02), no contact with domestic sheep ( p = 0.02), or greater distance to domestic sheep (>23 km, p = 0.02). Rate of population growth was best predicted by area of lambing period habitat, potential area of winter range, and distance to domestic sheep. We retested the model using these refined criteria and the refined model then predicted success or failure of these 32 translocated populations with 82% accuracy.

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“…We determined population size in 1997 (the most recent year of data for all herds) from 24 translocated populations of bighorn sheep (Table 1). We estimated population sizes from annual helicopter counts, corrected for animals missed by means of either (1) mark-recapture (Neal et al 1993), (2) population reconstruction, or (3) Idaho sightability corrections (Bodie et al 1995;Singer & Gudorf 1999;. We calculated average lambda ( ) for the most recent 10 years for each population with the formula ϭ N t ϩ 1 / N t , where t is time in years and N is population size.…”

Section: Persistence Population Growth and Patch Sizementioning

confidence: 99%

Role of Patch Size, Disease, and Movement in Rapid Extinction of Bighorn Sheep

Singer¹,

Zeigenfuss²,

Spicer³

2001

Conservation Biology

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The controversy (Berger 1990(Berger , 1999Wehausen 1999) over rapid extinction in bighorn sheep ( Ovis canadensis ) has focused on population size alone as a correlate to persistence time. We report on the persistence and population performance of 24 translocated populations of bighorn sheep. Persistence in these sheep was strongly correlated with larger patch sizes, greater distance to domestic sheep, higher population growth rates, and migratory movements, as well as to larger population sizes. Persistence was also positively correlated with larger average home-range size ( p ϭ 0.058, n ϭ 10 translocated populations) and home-range size of rams ( p ϭ 0.087, n ϭ 8 translocated populations). Greater home-range size and dispersal rates of bighorn sheep were positively correlated to larger patches. We conclude that patch size and thus habitat carrying capacity, not population size per se, is the primary correlate to both population performance and persistence. Because habitat carrying capacity defines the upper limit to population size, clearly the amount of suitable habitat in a patch is ultimately linked to population size. Larger populations (250 ϩ animals) were more likely to recover rapidly to their pre-epizootic survey number following an epizootic ( p ϭ 0.019), although the proportion of the population dying in the epizootic also influenced the probability of recovery ( p ϭ 0.001). Expensive management efforts to restore or increase bighorn sheep populations should focus on large habitat patches located Ն 23 km from domestic sheep, and less effort should be expended on populations in isolated, small patches of habitat. El Papel del Tamaño del Parche, Enfermedades y Movimientos en la Rápida Extinción del Borrego CimarrónResumen: La controversia (Berger 1990, Wehausen 1999 sobre extinciones rápidas del borrego cimarrón ( Ovis canadiensis ) se ha enfocado solo en los tamaños poblacionales como una correlación con los tiempos de persistencia. Reportamos la persistencia y adaptabilidad de 24 poblaciones translocadas de cimarrones. La persistencia de estos borregos cimarrones estuvo fuertemente correlacionada con parches de tamaño grande, distancias grandes con los borregos domésticos, tasas de crecimiento poblacional elevadas, movimientos migratorios, y con tamaños poblacionales grandes. La persistencia también estuvo positivamente correlacionada con un tamaño de rango de hogar promedio grande ( p ϭ 0.058, n ϭ 10 poblaciones translocadas) y el tamaño del rango de hogar de los cimarrones ( p ϭ 0.087, n ϭ 8 poblaciones translocadas). Un mayor tamaño en el rango de hogar y mayores tasas de dispersión estuvieron positivamente correlacionadas con parches grandes. Por lo tanto concluimos que el tamaño del parche y la capacidad de carga del hábitat, pero no el tamaño poblacional, en sí, es la correlación principal tanto para la adaptabilidad como para la persistencia de la población. Debido a que la capacidad de carga del hábitat define los límites superiores del tamaño poblacional, es claro que la cantidad de hábitat p...

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Restoration of bighorn sheep metapopulations in and near 15 national parks: Conservation of severely fragmented species; Volume II, Synopsis of research findings

Cited by 9 publications

References 8 publications

The Influence of Mountain Lion Predation on Bighorn Sheep Translocations

The Influence of Mountain Lion Predation on Bighorn Sheep Translocations

Test of a Modified Habitat Suitability Model for Bighorn Sheep

Role of Patch Size, Disease, and Movement in Rapid Extinction of Bighorn Sheep

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