Jennifer A. Blakesley, Mark E. Seamans, Mary M. Conner, Alan B. Franklin, Gary C. White, R. J. Gutiérrez, James E. Hines, James D. Nichols, Thomas E. Munton, Daniel W. H. Shaw, John J. Keane, George N. Steger, Trent L. Mcdonald
ABSTRACT The California spotted owl (Strix occidentalis occidentalis) is the only spotted owl subspecies not listed as threatened or endangered under the United States Endangered Species Act despite petitions to list it as threatened. We conducted a meta-analysis of population data for 4 populations in the southem Cascades and Sierra Nevada, California, USA, from 1990 to 2005 to assist a listing evaluation by the United States Fish and Wildlife Service. Our study areas (from N to S) were on the Lassen National Forest (LAS), Eldorado National Forest (ELD), Sierra National Forest (SIE), and Sequoia and Kings Canyon National Parks (SKC). These study areas represented a broad spectrum of habitat and management conditions in these mountain ranges.
We estimated apparent survival probability, reproductive output, and rate of population change for spotted owls on individual study areas and for all study areas combined (meta-analysis) using model selection or model-averaging based on maximum-likelihood estimation. We followed a formal protocol to conduct this analysis that was similar to other spotted owl meta-analyses. Consistency of field and analytical methods among our studies reduced confounding methodological effects when evaluating results. We used 991 marked spotted owls in the analysis of apparent survival. Apparent survival probability was higher for adult than for subadult owls. There was little difference in apparent survival between male and female owls. Model-averaged mean estimates of apparent survival probability of adult owls varied from 0.811 ± 0.021 for females at LAS to 0.890 ± 0.016 for males at SKC. Apparent survival increased over time for owls of all age classes at LAS and SIE, for adults at ELD, and for second-year subadults and adults at SKC. The meta-analysis of apparent survival, which included only adult owls, confirmed an increasing trend in survival over time. Survival rates were higher for owls on SKC than on the other study areas.
We analyzed data from 1,865 observations of reproductive outcomes for female spotted owls. The proportion of subadult females among all territorial females of known age ranged from 0.00 to 0.25 among study areas and years. The proportion of subadults among female spotted owls was negatively related to reproductive output (no. of young fledged/territorial F owl) for ELD and SIE. Eldorado study area and LAS showed an alternate-year trend in reproductive output, with higher output in even-numbered years. Mean annual reproductive output was 0.988 ± 0.154 for ELD, 0.624 ± 0.140 for LAS, 0.478 ± 0.106 for SIE, and 0.555 ± 0.110 for SKC. Eldorado Study Area exhibited a declining trend and the greatest variation in reproductive output over time, whereas SIE and SKC, which had the lowest reproductive output, had the lowest temporal variation. Meta-analysis confirmed that reproductive output varied among study areas. Reproductive output was highest for adults, followed by secon
加州斑点猫头鹰(Strix occidentalis occidentalis)是唯一未被美国《濒危物种法》列为受威胁或濒危物种的斑点猫头鹰亚种,尽管人们请愿将其列为受威胁物种。我们对1990年至2005年美国加利福尼亚州南喀斯喀特和内华达山脉4个种群的种群数据进行了荟萃分析,以协助美国鱼类和野生动物管理局的清单评估。我们的研究区域(从N到S)分别是拉森国家森林(LAS)、埃尔多拉多国家森林(ELD)、塞拉国家森林(SIE)和红杉和国王峡谷国家公园(SKC)。这些研究区域代表了这些山脉的广泛生境和管理条件。我们使用基于最大似然估计的模型选择或模型平均方法估计了单个研究区域和所有研究区域的斑点猫头鹰的表观存活率、繁殖产量和种群变化率(荟萃分析)。我们遵循一个正式的协议来进行这项分析,这与其他斑点猫头鹰的荟萃分析类似。在我们的研究中,领域和分析方法的一致性减少了评价结果时混淆的方法学效应。我们用991只有标记的斑点猫头鹰进行表观存活率分析。成体猫头鹰的表观存活率高于亚成体猫头鹰。雄性猫头鹰和雌性猫头鹰的明显存活率差别不大。成年猫头鹰表观存活率的模型平均平均值为0.811±0.021 (LAS)和0.890±0.016 (SKC)。随着时间的推移,所有年龄段的猫头鹰在LAS和SIE,在ELD的成年猫头鹰,在SKC的第二年亚成年猫头鹰和成年猫头鹰的表观存活率都有所增加。对只包括成年猫头鹰的表观存活率进行的荟萃分析证实,随着时间的推移,存活率呈上升趋势。在SKC上,猫头鹰的存活率高于其他研究区域。我们分析了1865份对雌性斑点猫头鹰生殖结果的观察数据。亚成年雌鼠占所有已知年龄领地雌鼠的比例在研究区域和年份之间为0.00 ~ 0.25。雌斑猫头鹰的亚成虫比例与繁殖产量呈负相关(0。年幼羽翼/领地猫头鹰)作ELD及SIE用途。埃尔多拉多研究区与LAS的繁殖产量呈隔年趋势,偶数年产量较高。平均年繁殖产量分别为:ELD组0.988±0.154,LAS组0.624±0.140,SIE组0.478±0.106,SKC组0.555±0.110。埃尔多拉多研究区繁殖产量呈下降趋势,且随时间变化最大,而SIE和SKC的繁殖产量最低,其时间变化最小。荟萃分析证实,不同研究区域的生殖产量存在差异。成虫繁殖产量最高,其次是第二年亚成虫,然后是第一年亚成虫。我们用842只标记为亚成体和成体的猫头鹰来估计种群变化率。建模表明Λ t (Λ t是使用重参数化Jolly-Seber估计器[Pradel 1996]估计的有限种群变速率)要么是平稳的(LAS和SIE),要么是初始减少后增加的(ELD和SKC)。ELD的4个研究区域的平均估计Λ t为1.007 (95% CI = 0.952-1.066);LAS为0.973 (95% CI = 0.946-1.001);SIE为0.992 (95% CI = 0.966-1.018);SKC为1.006 (95% CI = 0.947 ~ 1.068)。人口趋势的最佳荟萃分析模型表明,Λ在不同时期有所不同,但各研究区域的趋势相似。我们对已实现人口变化的估计(Δ t;Franklin et al. 2004),我们将其估计为产品1 Λ 3,基于来自单个研究区域的Λ t估计值,不需要估计每个研究区域的年人口规模。趋势是指第一年的人口规模在随后每一年中所占的比例。与它们所基于的λ4相似,这些λk-1在LAS和SIE的研究期间显示出下降的证据。最佳模型表明,雄性和雌性成虫和亚成虫在时间t时的新领地个体数量/时间t - 1时的领地个体数量变化在0.10 ~ 0.31之间,不同地区之间也有类似的变化。我们还根据meta分析的结果进行了种群生存力分析(PVA)。该PVA对ELD和SKC研究区域的效用有限,因为在5-10年内,95%的可信区间是下降或增加的概率[0,1]。当我们将推断限制为7年时,估计SIE下降>10%的概率为0.41 (95% CI = 0.09-0.78);LAS的概率为0.64 (95% CI = 0.27-0.94)。 相比之下,7年内SIE增加10%的估计概率为0.23 (95% CI = 0.01-0.55), LAS增加10%的估计概率为0.10 (95% CI = 0.00-0.34)。为了进行比较,我们模拟了一个假设种群的PVA,其平均值Λ = 1.0,与我们在猫头鹰种群中观察到的时间变化相同。我们的PVA表明,SIE和LAS种群在7年内下降的概率高于增加的概率,但很难确定种群是否处于轻微的逐渐下降状态。我们对4个研究种群的分析和信息库为管理者监控未来管理行动对猫头鹰的影响提供了一个数据丰富的模板。具体来说,我们的数据可以用来评估美国林务局正在实施的斑点猫头鹰管理策略的效果,这些策略旨在降低内华达山脉生态系统中野火的风险。我们的信息也为评估猫头鹰可能被美国鱼类和野生动物管理局列为受威胁物种的状况提供了基线信息。resume El búho加利福尼亚曼查多(Strix occidentalis occidentalis) es la única subespecie de búhos manchados que no estlistada como amenazada o en peligro de extinción en El Acta de e.e.u. para as es en peligro de Extinción a pesar de las pecticies para que sea包括en la lista como una especespecamenazada。Nosotros realizamos un meta-análisis de los datos de la población de de 4个问题,del de瀑布和la内华达山脉,加利福尼亚州,1990年至2005年como ayuda和una evaluación de listado hecha pel美国鱼类和野生动物管理局。Nuestras áreas de estustudio (de norte a sur) estuvieron localizadas en el Bosque Nacional Lassen (LAS), en el Bosque Nacional Eldorado (ELD), en el Bosque Nacional Sierra (SIE), en los Parques Nacionales Sequoia y Kings Canyon (SKC)。Estas áreas de estudio代表了一种放大的光谱模型hábitat,并通过研究条件来确定它们的变化规律,从而确定montañas。我们calculamos la probabilidad de supervivencia aparente el羊皮纸书卷de reproduccion y el: en la tasa de poblacion de los buhos manchados en地区de工厂化个人y对位所有de las地区工厂化combinadas
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