Mortality of radio-tagged pheasants on the Waterloo Wildlife Area
Mortality of radio-tagged pheasants on the Waterloo Wildlife Area
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滑铁卢野生动物区无线电标记野鸡的死亡率
DOI：
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发表时间：
1973
期刊：
影响因子：
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通讯作者：
C. Pils
中科院分区：
文献类型：
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作者：
Robert T. Dumke;C. Pils
I 1968-1971 年调查的目的是确定母雉鸡死亡的具体原因，并按季节和年度评估其相对重要性。威斯康星州之前的研究对季节性和年度死亡率进行了全面评估，但仅对单个死亡率因素的重要性进行了初步了解。无线电遥测技术使观察者能够与个体鸟类保持日常联系，并以最短的延迟到达死亡现场。实地研究是在滑铁卢野生动物区进行的，这是一个位于道奇县和杰斐逊县、占地 16,000 英亩的国有和私人土地综合体。秋季和春季夜间照明和冬季诱捕方法捕获了 244 只野鸡，用于安装无线电设备。获得滑铁卢雉鸡种群的性别和年龄比数据，以确定年度和季节性死亡率，以便与放射性标记样本计算的死亡率进行比较。对人群和配备无线电设备的样本之间的平均跌倒死亡率进行比较显示出良好的一致性。母鸡死亡率在人群中平均每年为 73.9%，在无线电群组中每年平均死亡率为 79.7%。然而，对母鸡群体和无线电标记群体之间秋季到春季和春季到秋季的平均死亡率的比较显示出明显的分歧。虽然总体人口的秋季至春季死亡率相对较低（35.3%），但放射性标记样本的损失率却相对较高（57.8%）。春季到秋季损失的情况则相反，人口死亡率为 57.5%，而配备发射机的部分死亡率为 44.8%。研究发现，与可比较的人口估计相比，放射性标记样本的季节性死亡率与威斯康星州先前的研究结果更加一致。通过使用 5 天死亡率（表示为瞬时死亡率）计算 6 个季节性周期的死亡率，为放射性标记样本制定了年度死亡率模式。积雪和筑巢期的重要性分别排名第一和第二，5 天损失率分别为 3.7% 和 2. 7%。它们合计占年度死亡率的 50.9%，其中 35.9% 发生在积雪期间，15.0% 发生在筑巢期间。狩猎季节5天死亡率的重要性排名第三。但适用于最大的年度人口水平，因此占年度死亡率的 31.6%。育雏期和育雏期后对年死亡率影响不大。研究发现，捕食是全年最重要的死亡因素，也是育雏期、育雏后和冬末期间唯一确定的死亡原因。捕食占所有分类死亡的 80.8%。枪击死亡仅限于狩猎期间，占所有损失的 7.4%。同样，割草死亡率也仅限于筑巢期，占 5.3%。高速公路交通事故、猎犬和冬季天气造成的损失分别占年死亡率的 2.1%。在捕食损失中，46 例（60.5%）归因于哺乳动物和捕食者，19 例（25.0%）归因于鸟类捕食者，11 例（14.5%）未分类。在哺乳动物捕食类别中，在可能进行物种指定的 20 个案例中，有 16 个案例（80%）涉及狐狸。在19起鸟类捕食损失中，红尾鹰和大角鸮分别有2起和6起。备案的 11 起案件中，猛禽的种类尚未确定。从入冬到初春，每只狐狸的母鸡数量从 8 只变为 14 只。冬季狐狸的大量收获导致秋季到春季捕食者与猎物的比例异常下降。冬季红尾鹰和大角鸮的比例分别为1：37和1：49，春季为1：20和1：28。秋季至春季期间，狐狸对母鸡的捕食率为每天 1.38 只。积雪期占年度死亡率的最大部分，并且发现冬季天气的严重程度是秋季到春季死亡率年度波动的主要决定因素。在一年中的所有季节中，在有记录的哺乳动物和鸟类捕食的夜间，风速、云量和降水量平均高于年平均值的总和。在筑巢活动的任何阶段，母鸡的脆弱性都没有增加。本研究的范围并未提供对人口调节的评估；尽管如此，捕食似乎是滑铁卢野鸡数量的限制因素。这种怀疑得到了滑铁卢栖息地开发计划（Frank 和 Woehler 1969）缺乏成功的支持，该计划未能使雉鸡密度相对于区域人口趋势出现可测量的增加。滑铁卢实施的栖息地改善措施显然无法有效抵消捕食对雉鸡种群密度的限制。滑铁卢野生动物区无线电标记野鸡的死亡率
I The objective of this investigation from 1968-1971 was to identify specific causes of hen pheasant mortality and to assess their relative importance on a seasonal and annual basis. Previous research in Wisconsin has provided a comprehensive evaluation of seasonal and annual mortality rates but only a glimpse of the importance of the individual mortality factors. Radio telemetry allowed the observer to maintain daily contact with individual birds and to get to the scene of death with a minimum of delay. Field research was conducted at the Waterloo Wildlife Area, a 16,000-acre complex of stateowned and private lands located in Dodge and Jefferson counties. Fall and spring nightlighting and winter trapping were used to capture 244 pheasants for radio-equipping. Sex and age ratio data were obtained on the Waterloo pheasant population to determine annual and seasonal mortality rates for comparison with death rates computed for the radio-tagged sample. A comparison of mean fallto-fall mortality rates between the population and the radioequipped sample revealed favorable agreement. Hen mortality averaged 73.9 percent per year for the population and 79.7 percent per year for the radioed cohort. However , a comparison of mean fall-to-spring and spring-to-fall mortality rates between the hen population and the radio-tagged cohort revealed distinct disagreement. Whereas the population at large realized a r el a ti v ely low fall-to-spring death rate ( 35.3% ), the radiotagged sample experienced a comparatively high rate of loss ( 57.8% ) . The reverse was true for spring-to-fall loss where the population mortality rate was 57.5 percent compared with 44.8 percent for the transmitterequipped segment. The seasonal mortality rates for the radiotagged sample were found to be more consistent with previous research findings in Wisconsin than the comparable population estimates. An annual pattern of mortality was developed for the radiotagged sample by computing mortality rates for 6 seasonal periods using 5-day mortality rates (expressed as instantaneous rates ). Snow cover and nesting periods ranked first and second, respectively, in importance with 5-day loss rates of 3.7 and 2. 7 percent. Combined, they aCcounted for 50.9 percent of annual mortality, 35.9 percent occurring during snow cover and 15.0 percent during nesting. The 5-day mortality rate during the hunting season ranked third in importance. but applied to the largest annual population level and therefore accounted for 31.6 percent of annual mortality. The periods of brood-rearing and post brood-rearing were of little consequence in terms of annual mortality. Predation was found to be the most important mortality factor throughout the year and was the only identified cause-of-death during the brood-rearing, post brood-rearing and late winter periods. Predation accounted for 80.8 percent of all classified deaths. Gunshot deaths were restricted to the hunting period and totalled 7.4 percent of all losses. Likewise, hay-mowing mortalities were confined to the nesting period and tallied 5.3 percent. Losses to highway tJ:affic, hunting dogs, and winter weather each accounted for 2.1 percent of annual mortality. Among losses to predation , 46 (60.5% ) were attributed to m a mmalia n predators, 19 (25.0% ) to avian predators and 11 (14.5% ) were unclassified. Within the category of mammalian predation, the fox was implicated in 16 ( 80%) of the 20 cases where species designation was possible. Among the 19 losses to avian predation, the red-tailed hawk and the great horned owl were incriminated in 2 and 6 cases, respectively. The species of raptor was undetermined in 11 cases on file. The number of hens per fox changed from 8 to 14 from the onset of winter to the beginning of spring. The heavy harvest of fox during the winter caused the unusual decrease in the predator-prey ratio from fall to spring. Red-tailed hawks and great horned owls were represented in a proportion of 1 : 37 and 1:49, respectively, in winter and 1 : 20 and 1 : 28 in spring. The exploitation rate of hen pheasants by fox was found to be 1.38 birds per day during the fall-to-spring period. The period of snow cover accounted for the largest fraction of annual mortality, and the severity of winter weather was found to be the principal determinate of annual fluctuations in fall-to-spring mortality. During all seasons of the year, wind velocity, cloud cover and precipitation averaged higher during nights of recorded mammalian and avian predation than the combined yearly averages. The vulnerability of the hen did not increase during any phase of nesting activity. The scope of this study did not provide for an evaluation of population regulation; nonetheless it seemed likely that predation was the limiting factor of pheasant abundance at Waterloo. This suspicion was supported by the lack of success of a habitat development program at Waterloo (Frank and Woehler 1969 ) to produce a measurable increase in pheasant density relative to regional population trends . Habitat improvements applied at Waterloo were apparently ineffectual in offsetting the limitations placed on pheasant population density by predation. MORTALITY OF RADIO-TAGGED PHEASANTS ON THE WATERLOO WILD·LIFE AREA