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1.
Fluctuations of bird abundances in the Midwest region of the United States have been attributed to such factors as landscape change, habitat fragmentation, depredation, and supplemental feeding. However, no attempt has been made to estimate the collective role of landowner activities that may influence birds across a landscape. To investigate how landowners might influence birds when the majority (> 90%) of land is privately owned, we surveyed all 1694 private domestic landowners living on three breeding bird survey routes (120 km) that represent a continuum of rural-to-urban landscapes in Southeastern Michigan from October through December 2000. Our survey was designed to investigate (1) the proportion of landowners involved in bird feeding, providing bird houses, planting or maintaining vegetation for birds, gardening, landscaping, applying fertilizer, and applying pesticides or herbicides; (2) whether differences existed between urban, suburban, and rural landowner activities; and (3) whether landowners that carried out a given activity were sociodemographically different from those who did not. Of the 968 respondents (58.5% response rate), 912 (94%) carried out at least one of the activities on their land and the average landowner carried out 3.7 activities. A total of 65.6% fed birds, 45.7% provided bird houses, 54.6% planted or maintained vegetation for birds, 72.7% gardened, 72.3% landscaped, 49.3% applied fertilizer, and 25.2% applied pesticides or herbicides. Significant differences existed between the landscapes, with rural landowners having more bird houses and applying pesticides or herbicides in greater frequency. Similarly, urban landowners had a greater density of bird feeders and houses, but planted or maintained vegetation in the lowest frequency. Participation in activities varied by demographic factors, such as age, gender, and occupation. Scaling each activity to all landowners, including nonrespondents, across all landscapes indicates that between 14% and 82% of landowners may be engaged in a particular activity, with application of pesticides or herbicides having the least potential involvement (13.9%–55.4%) and gardening having the greatest potential involvement (40.1%–81.6%). Taken collectively, our results indicate that landowners are both intentionally and unintentionally engaged in a wide range of activities that are likely to influence bird populations. 相似文献
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Abstract: To assess the completeness of a floristic or faunal inventory, one may use the ratio of the observed number of species to the "true number" of species ( C ). If the inventory is complete , C = 1. The estimate of the true number can be obtained from accumulation curves, nonparametric methods, or other techniques. We devised a simple method for computing confidence intervals (CI) for C and for evaluating the null hypothesis that the inventory is complete. The method is based on the assumptions that an estimate of the variance of the true number of species is known and that the distribution of the estimator of the true number of species is approximately normal. We applied our method to bird inventories in the Balsas Basin of Mexico. The completeness index for subtransects were lower (84.0, 85.4, and 89.9%) than for the whole transect (91.6%) (all significantly different from 100%). Thus, these particular inventories were incomplete at 2 spatial resolutions. Our method of estimating CI for C can be used to estimate species richness obtained from databases of different sites or to test the null hypothesis that an inventory derived from a database is complete. 相似文献
4.
A. P. Galanina 《Russian Journal of Ecology》2008,39(6):418-424
The population density and relative abundance of some bird species reach the highest values in the communities of habitats with a high degree of anthropogenic transformation. The species diversity of birds shows an inverse correlation with the index of anthropogenic impact (in grades) calculated with regard to a number of parameters. Relevant correlations change periodically, with the correlation coefficient reaching the highest values in the nesting period and decreasing to a minimum during the flight period. 相似文献
5.
V. A. Kolbin 《Russian Journal of Ecology》2008,39(6):398-404
To reveal the effect of forest fires on the avifauna of the Northern Amur Region, bird assemblages of primary dark conifer-deciduous forests, wild rosemary larch forests, and secondary larch-birch forests have been studied in the Komsomol’skii and Norskii nature reserves. It has been shown that the replacement of primary dark conifer-deciduous forests by secondary forests is accompanied by a significant decrease in bird population density, with some species being lost and the composition of the dominant species group being changed. On the other hand, fires lead to increasing patchiness of the environment, which can sometimes provide for an increase in biological diversity. 相似文献
6.
Abstract: The traditional environmental Kuznets curve (EKC) hypothesis postulates that environmental degradation follows an inverted U-shaped relationship with gross domestic product (GDP) per capita. We tested the EKC hypothesis with bird populations in 5 different habitats as environmental quality indicators. Because birds are considered environmental goods, for them the EKC hypothesis would instead be associated with a U-shaped relationship between bird populations and GDP per capita. In keeping with the literature, we included other variables in the analysis—namely, human population density and time index variables (the latter variable captured the impact of persistent and exogenous climate and/or policy changes on bird populations over time). Using data from 9 Canadian provinces gathered over 37 years, we used a generalized least-squares regression for each bird habitat type, which accounted for the panel structure of the data, the cross-sectional dependence across provinces in the residuals, heteroskedasticity, and fixed- or random-effect specifications of the models. We found evidence that supports the EKC hypothesis for 3 of the 5 bird population habitat types. In addition, the relationship between human population density and the different bird populations varied, which emphasizes the complex nature of the impact that human populations have on the environment. The relationship between the time-index variable and the different bird populations also varied, which indicates there are other persistent and significant influences on bird populations over time. Overall our EKC results were consistent with those found for threatened bird species, indicating that economic prosperity does indeed act to benefit some bird populations. 相似文献
7.
Kumar V Rani S Malik S Trivedi AK Schwabl I Helm B Gwinner E 《Die Naturwissenschaften》2007,94(8):693-696
Daytime light intensity can affect the photoperiodic regulation of the reproductive cycle in birds. The actual way by which
light intensity information is transduced is, however, unknown. We postulate that transduction of the light intensity information
is mediated by changes in the pattern of melatonin secretion. This study, therefore, investigated the effects of high and
low daytime light intensities on the daily melatonin rhythm of Afro-tropical stonechats (Saxicola torquata axillaris) in which seasonal changes in daytime light intensity act as a zeitgeber of the circannual rhythms controlling annual reproduction
and molt. Stonechats were subjected to light conditions simulated as closely as possible to native conditions near the equator.
Photoperiod was held constant at 12.25 h of light and 11.75 h of darkness per day. At intervals of 2.5 to 3.5 weeks, daytime
light intensity was changed from bright (12,000 lux at one and 2,000 lux at the other perch) to dim (1,600 lux at one and
250 lux at the other perch) and back to the original bright light. Daily plasma melatonin profiles showed that they were linked
with changes in daytime light intensity: Nighttime peak and total nocturnal levels were altered when transitions between light
conditions were made, and these changes were significant when light intensity was changed from dim to bright. We suggest that
daytime light intensity could affect seasonal timing via changes in melatonin profiles.
Professor Dr. E. Gwinner died on 07 September 2004. 相似文献
8.
目的研究飞机尾翼结构采用芳纶纤维复合材料的抗鸟撞性能。方法根据芳纶纤维夹芯和芳纶纤维层合板两种飞机尾翼前缘构型,分别建立有限元模型进行仿真计算,分析两种构型鸟撞后的损伤和变形,并对两种构型进行抗鸟撞性能研究试验。结果芳纶夹芯前缘构型前缘凹陷,前梁没有破裂;芳纶层合板前缘构型前缘破裂,前梁有破损。试验结果与仿真分析结果高度吻合。结论芳纶夹芯前缘构型比芳纶层合板前缘构型具有更好的抗鸟撞性能。芳纶纤维层合板构型会造成前缘蒙皮变形过大,前梁腹板破损,导致飞机鸟撞后维修成本较高。 相似文献
9.
广东汕头海岸湿地鸟类群落与多样性的研究 总被引:2,自引:2,他引:2
对广东汕头海岸湿地的鸟类资源进行了调查,共记录鸟类100种,隶属15日31科,其中古北界鸟类43种,东洋界鸟类45种,广布种鸟类12种。区系组成呈南北鸟类混杂分布,鸟类的多样性表现出明显季节性。该湿地有国家二级重点保护鸟类10种,中日候鸟保护协定名录中的鸟类43种。5个湿地样区主要鸟类种类和数量的调查结果表明,汕头海岸湿地是水鸟类重要的越冬栖息场,鸟类群落多样性指数以三屿围和六合围两个样区较高,分别为3.2306和3.2283;濠江口的多样性指数较低,为1.98l。群落多样性指数的高低主要受物种数量和各物种数量均匀度的影响。文章还提出了对鸟类资源保护和管理的建议。 相似文献
10.
Glyphosate has become the most commonly used herbicide worldwide and is reputedly environmentally benign, nontoxic, and safe for use near wildlife and humans. However, studies indicate its toxicity is underestimated and its persistence in the environment is greater than once thought. Its actions as a neurotoxin and endocrine disruptor indicate its potential to act in similar ways to persistent organic pollutants such as the organochlorines dichlorodiphenyltrichloroethane (DDT) and dioxin. Exposure to glyphosate and glyphosate‐based herbicides for both wildlife and people is likely to be chronic and at sublethal levels, with multiple and ongoing exposure events occurring in urban and agricultural landscapes. Despite this, there has been little research on the impact of glyphosate on wildlife populations, and existing studies appear in the agricultural, toxicology, and water‐chemistry literature that may have limited visibility among wildlife biologists. These studies clearly demonstrate a link between chronic exposure and neurotoxicity, endocrine disruption, cell damage, and immune suppression. There is a strong case for the recognition of glyphosate as an emerging organic contaminant and substantial potential exists for collaborative research among ecologists, toxicologists, and chemists to quantify the impact of glyphosate on wildlife and to evaluate the role of biosentinel species in a preemptive move to mitigate downstream impacts on people. There is scope to develop a decision framework to aid the choice of species to biomonitor and analysis methods based on the target contaminant, spatial and temporal extent of contamination, and perceived risk. Birds in particular offer considerable potential in this role because they span agricultural and urban environments, coastal, inland, and wetland ecosystems where glyphosate residues are known to be present. 相似文献