Taylor S. Daily, C. E. González, L. Harveson, W. Conway, Froylán Hernández
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Survival estimates of desert bighorn sheep were compared amongst resident, hard-released, and soft-released individuals throughout the study. In winter 2017–2018, we radio-collared and released 30 resident (8 M, 22 F) and 70 within-state-translocated (36 M, 34 F) desert bighorn to BGWMA. Of the 70 translocated individuals, 28 (12 M, 16 F) were hard released (i.e., released immediately onto the landscape) and 42 (24 M, 18 F) were soft released (i.e., released into an enclosure before onto the landscape). Resident desert bighorn had the highest probability of survival over time (Ŝ = 0.83), followed by hard-released (Ŝ = 0.67) and then soft-released (Ŝ = 0.54) individuals. To date, 26 mortalities (13 M, 13 F) were recorded. Of those mortalities, 4 were residents (15%), 6 were hard released (23%), and 16 were soft released (62%). The soft release is thought to be a better strategy for translocating large mammals; however, in this study, it did not improve survival. Survival is potentially influenced by acclimation time and individual exit strategy from the soft-release pen, which should be managed for future restoration efforts. Incorporating a flushing-method exit strategy would aid in removing soft-released individuals from the high-fenced pen simultaneously and may increase survival estimates. This could potentially allow individuals to form larger groups when exiting the enclosure and entering the new habitat. The soft-release method is also more costly to implement, which could be challenging for wildlife managers.","PeriodicalId":49364,"journal":{"name":"Western North American Naturalist","volume":"15 1","pages":"94 - 106"},"PeriodicalIF":0.5000,"publicationDate":"2022-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"Comparing Survival and Cause-Specific Mortality of Different Translocation Release Methods for Desert Bighorn Sheep\",\"authors\":\"Taylor S. Daily, C. E. González, L. Harveson, W. Conway, Froylán Hernández\",\"doi\":\"10.3398/064.082.0109\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Abstract. Historically, desert bighorn sheep (Ovis canadensis mexicana) were prevalent throughout the Trans-Pecos region of Texas. However, they were extirpated by the 1960s due to unregulated hunting, habitat loss, predation, and disease transmission from livestock. Restoration efforts have been successfully conducted by the Texas Parks and Wildlife Department to increase population numbers of resident (i.e., animals that currently populate a region of interest) desert bighorn sheep at Black Gap Wildlife Management Area (BGWMA) through the use of translocations. Because there is a lack of knowledge on alternative release methods for large mammal translocations, our goals were to monitor cause-specific mortality and postrelease survival of desert bighorn sheep translocated during 2017. Survival estimates of desert bighorn sheep were compared amongst resident, hard-released, and soft-released individuals throughout the study. In winter 2017–2018, we radio-collared and released 30 resident (8 M, 22 F) and 70 within-state-translocated (36 M, 34 F) desert bighorn to BGWMA. 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Incorporating a flushing-method exit strategy would aid in removing soft-released individuals from the high-fenced pen simultaneously and may increase survival estimates. This could potentially allow individuals to form larger groups when exiting the enclosure and entering the new habitat. 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引用次数: 1
摘要
摘要历史上,沙漠大角羊(Ovis canadensis mexicana)在德克萨斯州的跨佩科斯地区很普遍。然而,到20世纪60年代,由于不受管制的狩猎、栖息地丧失、捕食和牲畜传播疾病,它们灭绝了。德克萨斯州公园和野生动物部门已经成功地进行了恢复工作,通过使用迁移来增加黑峡野生动物管理区(BGWMA)的居民(即目前居住在感兴趣地区的动物)沙漠大角羊的数量。由于缺乏关于大型哺乳动物易位的替代释放方法的知识,我们的目标是监测2017年易位的沙漠大角羊的病因特异性死亡率和释放后存活率。在整个研究过程中,比较了沙漠大角羊的生存估计,硬放养和软放养的个体。在2017-2018年冬季,我们通过无线电圈定并释放了30只居民(8米,22华氏度)和70只州内迁移(36米,34华氏度)的沙漠大角羚到BGWMA。在70个迁移个体中,28个(12 M, 16 F)被硬释放(即立即释放到景观中),42个(24 M, 18 F)被软释放(即在进入景观之前释放到围栏中)。随着时间的推移,居住的沙漠大角羚的存活率最高(Ŝ = 0.83),其次是硬放生(Ŝ = 0.67),然后是软放生(Ŝ = 0.54)。迄今为止,记录了26例死亡(13例男、13例女)。在这些死亡中,4人是居民(15%),6人是硬释放(23%),16人是软释放(62%)。软释放被认为是转移大型哺乳动物的更好策略;然而,在这项研究中,它并没有提高生存率。适应时间和个体退出软放养圈的策略可能会影响它们的生存,这些因素应该在未来的恢复工作中加以管理。采用冲洗法退出策略有助于同时将软放生个体从高围栏围栏中移走,并可能增加生存估计。这可能会让个体在离开围栏进入新栖息地时形成更大的群体。软放生方法的实施成本也更高,这对野生动物管理者来说可能是一个挑战。
Comparing Survival and Cause-Specific Mortality of Different Translocation Release Methods for Desert Bighorn Sheep
Abstract. Historically, desert bighorn sheep (Ovis canadensis mexicana) were prevalent throughout the Trans-Pecos region of Texas. However, they were extirpated by the 1960s due to unregulated hunting, habitat loss, predation, and disease transmission from livestock. Restoration efforts have been successfully conducted by the Texas Parks and Wildlife Department to increase population numbers of resident (i.e., animals that currently populate a region of interest) desert bighorn sheep at Black Gap Wildlife Management Area (BGWMA) through the use of translocations. Because there is a lack of knowledge on alternative release methods for large mammal translocations, our goals were to monitor cause-specific mortality and postrelease survival of desert bighorn sheep translocated during 2017. Survival estimates of desert bighorn sheep were compared amongst resident, hard-released, and soft-released individuals throughout the study. In winter 2017–2018, we radio-collared and released 30 resident (8 M, 22 F) and 70 within-state-translocated (36 M, 34 F) desert bighorn to BGWMA. Of the 70 translocated individuals, 28 (12 M, 16 F) were hard released (i.e., released immediately onto the landscape) and 42 (24 M, 18 F) were soft released (i.e., released into an enclosure before onto the landscape). Resident desert bighorn had the highest probability of survival over time (Ŝ = 0.83), followed by hard-released (Ŝ = 0.67) and then soft-released (Ŝ = 0.54) individuals. To date, 26 mortalities (13 M, 13 F) were recorded. Of those mortalities, 4 were residents (15%), 6 were hard released (23%), and 16 were soft released (62%). The soft release is thought to be a better strategy for translocating large mammals; however, in this study, it did not improve survival. Survival is potentially influenced by acclimation time and individual exit strategy from the soft-release pen, which should be managed for future restoration efforts. Incorporating a flushing-method exit strategy would aid in removing soft-released individuals from the high-fenced pen simultaneously and may increase survival estimates. This could potentially allow individuals to form larger groups when exiting the enclosure and entering the new habitat. The soft-release method is also more costly to implement, which could be challenging for wildlife managers.
期刊介绍:
The Western North American Naturalist places neither restriction nor preference on manuscripts within the disciplines of the biological sciences. Each issue treats diverse taxa from the perspectives of various disciplines (e.g., ecology, population dynamics, behavior, systematics, anatomy, and physiology).