Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, Minnesota, United States of America.
PLoS One. 2010 Aug 12;5(8):e12114. doi: 10.1371/journal.pone.0012114.
Wildlife populations are difficult to monitor directly because of costs and logistical challenges associated with collecting informative abundance data from live animals. By contrast, data on harvested individuals (e.g., age and sex) are often readily available. Increasingly, integrated population models are used for natural resource management because they synthesize various relevant data into a single analysis.
METHODOLOGY/PRINCIPAL FINDINGS: We investigated the performance of integrated population models applied to black bears (Ursus americanus) in Minnesota, USA. Models were constructed using sex-specific age-at-harvest matrices (1980-2008), data on hunting effort and natural food supplies (which affects hunting success), and statewide mark-recapture estimates of abundance (1991, 1997, 2002). We compared this approach to Downing reconstruction, a commonly used population monitoring method that utilizes only age-at-harvest data. We first conducted a large-scale simulation study, in which our integrated models provided more accurate estimates of population trends than did Downing reconstruction. Estimates of trends were robust to various forms of model misspecification, including incorrectly specified cub and yearling survival parameters, age-related reporting biases in harvest data, and unmodeled temporal variability in survival and harvest rates. When applied to actual data on Minnesota black bears, the model predicted that harvest rates were negatively correlated with food availability and positively correlated with hunting effort, consistent with independent telemetry data. With no direct data on fertility, the model also correctly predicted 2-point cycles in cub production. Model-derived estimates of abundance for the most recent years provided a reasonable match to an empirical population estimate obtained after modeling efforts were completed.
CONCLUSIONS/SIGNIFICANCE: Integrated population modeling provided a reasonable framework for synthesizing age-at-harvest data, periodic large-scale abundance estimates, and measured covariates thought to affect harvest rates of black bears in Minnesota. Collection and analysis of these data appear to form the basis of a robust and viable population monitoring program.
由于从活体动物收集有意义的数量数据相关的成本和后勤挑战，野生动物种群很难直接监测。相比之下，关于被捕猎个体的数据（例如年龄和性别）通常很容易获得。由于它们将各种相关数据综合到单个分析中，因此越来越多的综合种群模型被用于自然资源管理。
方法/主要发现：我们研究了应用于美国明尼苏达州黑熊（Ursus americanus）的综合种群模型的性能。模型使用性别特定的年龄捕获矩阵（1980-2008 年）、关于狩猎努力和自然食物供应的数据（影响狩猎成功率）以及全州范围内的标记重捕数量估计（1991 年、1997 年、2002 年）构建。我们将这种方法与Downing 重建进行了比较，Downing 重建是一种常用的种群监测方法，仅使用年龄捕获数据。我们首先进行了一项大规模的模拟研究，结果表明，我们的综合模型比 Downing 重建提供了更准确的种群趋势估计。趋势估计对各种形式的模型误设都具有稳健性，包括不正确指定幼崽和一岁龄动物的存活率参数、在猎捕数据中与年龄相关的报告偏差以及未建模的生存和猎捕率的时间变化。当应用于明尼苏达州黑熊的实际数据时，该模型预测猎捕率与食物供应呈负相关，与狩猎努力呈正相关，这与独立的遥测数据一致。由于没有关于繁殖力的直接数据，该模型还正确预测了幼崽数量的 2 点周期。最近几年的模型衍生出的数量估计值与完成建模工作后获得的经验种群估计值相当吻合。
结论/意义：综合种群模型为综合年龄捕获数据、周期性的大规模数量估计以及测量被认为会影响明尼苏达州黑熊猎捕率的协变量提供了一个合理的框架。收集和分析这些数据似乎构成了一个稳健且可行的种群监测计划的基础。
