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1.
Parent black-legged kittiwakes (Rissa tridactyla) and their dependent chicks respond to food shortages by increasing circulatinglevels of corticosterone. To examine the behavioral significanceof corticosterone release, we experimentally increased levelsof circulating corticosterone in parents and chicks up to thelevels observed during food shortages. We found that corticosterone-implantedchicks begged more frequently than sham-implanted controls.Corticosterone-implanted chicks in broods of two begged morefrequently than singletons. Parent kittiwakes then respondedto the increase in corticosterone levels in their chicks byincreasing chick-feeding rates. However, feeding rates werenot different among corticosterone-implanted chicks in broodsof two and singletons. We also found that corticosterone-implantedparents spent more time away from the nest—perhaps foraging—andless time brooding/guarding chicks than sham-implanted controls.Untreated mates of the corticosterone-implanted bird did notcompensate for the change in their partner's behavior; consequently, chicks were left unattended about 20% of the time compared to1% at the control nests. However, corticosterone-implantedparents did not decrease their chick-feeding rates. Our findingssuggest two functional implications of the increased corticosteronesecretion during food shortages in the black-legged kittiwake:it facilitates begging in chicks, and it affects time allocatedby parents to guarding young at the nest. Thus, release of corticosterone might provide a mechanistic link between physiological condition and behavioral interactions among adults and theiryoung.  相似文献   

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ABSTRACT Recent studies indicate that young seabird chicks exposed to relatively short periods of elevated levels of plasma corticosterone may suffer lifelong cognitive impairment that is detrimental to their survivorship and fitness as adults. We examined the chronic effects of investigator disturbance on the baseline and acute stress‐induced levels of plasma corticosterone of Black‐legged Kittiwake (Rissa tridactyla) chicks in Chiniak Bay, Kodiak Island, Alaska, in 2005. Kittiwake chicks were assigned to one of three disturbance treatments: (1) routine handling, (2) exposure to investigator presence, but not handled, and (3) neither handled nor exposed to investigator presence prior to sampling. At 12–15 d posthatching, blood samples were collected to determine baseline and stress‐induced concentrations of corticosterone. We found no significant differences in baseline or stress‐induced levels of corticosterone among the three disturbance treatments. Our results suggest that Black‐legged Kittiwake chicks do not perceive investigator presence as a stressor. However, investigators studying kittiwakes at other locations should proceed with caution because sampling protocols and environmental conditions may differ, potentially causing chicks to perceive disturbances differently as well.  相似文献   

3.
    
Montane and alpine habitats in Europe remained relatively undisturbed until the beginning of the last century. Today, outdoor recreation activities are a major economic factor in alpine regions. Many tourism areas coincide with winter habitats of shy and endangered species. The Western Capercaillie Tetrao urogallus has suffered from rapid population declines during recent decades over much of its range. In central Europe, many Capercaillie are exposed to intensive human recreation activities in their habitats, which may contribute to this decline. However, little is known about their susceptibility to human recreation activities. This study assessed whether human recreation in winter evokes physiological stress responses in several populations of Capercaillie. During two winters, we sampled 1130 Capercaillie droppings in Germany and Switzerland of populations at various distances from winter recreation activities and measured concentrations of faecal corticosterone metabolites. Capercaillie in relatively dense and homogeneous mountain forests dominated by Norway Spruce Picea abies showed markedly increased stress hormone levels closer to locations with winter recreation activity. However, this physiological response to human recreation was not detectable in forests dominated by various pine species and a heterogeneous structure. Capercaillie may be particularly sensitive to recreation because any factor affecting their fine‐tuned physiological and behavioural adaptations to survive under harsh winter conditions may lead to harmful fitness costs.  相似文献   

4.
    
Undulated Antshrikes (Frederickena unduliger) inhabit dense lowland humid forest understory and, as with other species of antbirds, many aspects of their behavior and ecology are poorly known, especially their breeding biology. We provide the first detailed information about their breeding biology based on three nests monitored in the buffer zone of the Manu National Park, Madre de Dios, Peru, from August to December in 2012 and 2013. Nests (N = 3) were large cups woven to the crossing of two horizontal branches. Eggs were white with purplish hairlines and spots, and all three clutches consisted of two eggs. Both males and females incubated eggs and fed nestlings, but only females incubated eggs at night. Provisioning rates and time spent brooding nestlings did not differ between the sexes. Most aspects of the nesting behavior of Undulated Antshrikes in our study were similar to those reported for other species of antbirds, including placement and composition of nests, clutch size, and provisioning rate. However, incubating behavior and the duration of the nestling period of antbirds appear to be influenced by body mass, with larger species such as Undulated Antshrikes having greater nest attentiveness and longer nestling periods than smaller species. Additional studies of other species of antbirds are needed to better understand factors that might contribute to similarities and differences in the nesting behavior of thamnophilids.  相似文献   

5.
Coloniality is a breeding system that may produce benefits in terms of breeding success, although these advantages could vary according to factors such as colony size or nest position. We studied breeder's age in relation to nest position (peripheral or central) within the colony. In addition, we studied the relationship between breeding success and nest position, controlling for breeder's age, a highly correlated factor, in a White Stork Ciconia ciconia colony over a 7-year period. Our results show that central nests are mainly occupied by adult birds and had lower failure rates. However, controlling for breeder's age, nest position per se did not explain breeding success. The scarce predation and the lack of human disturbance in the study colony could explain the absence of differences in breeding success between different nest positions within the colony.  相似文献   

6.
研究活动(如查巢和视频拍摄)对鸟类巢存活率的影响一直受到关注。近年来的研究虽然已表明这种影响较小, 但以往研究多以开放巢或洞巢鸟类为研究对象, 对营球形巢的鸟类研究较少。为探究研究活动对营球形巢鸟类巢存活率的影响, 本文以营球形巢的红头长尾山雀(Aegithalos concinnus)为研究对象, 利用2011-2018年在河南董寨国家级自然保护区采集的监测数据, 分析了研究者的查巢及视频拍摄活动对其卵期(产卵期及孵卵期)和育雏期的巢日存活率的影响。结果显示, 无论是在卵期(n = 215巢)还是在育雏期(n = 200巢), 红头长尾山雀巢的日存活率与查巢或视频拍摄活动均无显著相关性, 亦不随巢高或巢日龄显著变化。但是, 红头长尾山雀卵期的巢日存活率与产卵日期呈显著的负相关关系, 即产卵日期越晚, 日存活率越低。与此相似, 其育雏期的巢日存活率与雏鸟出壳日期也呈显著的负相关关系, 即出壳日期越晚, 巢的日存活率越低。本研究结果表明, 研究活动不会显著影响营球形巢的红头长尾山雀的巢存活率。尽管如此, 本文仍建议科研人员应注意研究活动可能对研究对象造成的潜在影响, 并尽可能地避免或降低这种影响。  相似文献   

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8.
In the years 1997–2001, I observed 28 broods of the Citrine Wagtail (Motacilla citreola) in the Gulf of Gdask region. First birds arrived at the study area at the end of April. A successful breeding cycle lasted about 1 month and included: 3–4 days of nest building, 1–2 days of a break, 4–6 days of egg laying, 11–12 days of incubation, and 10–13 days of parental care of chicks in the nest. Females started to lay eggs at the beginning of May. The most common clutch-size was 5 eggs. Hatching success was 55.3%. On average, 2.6 chicks hatched in a nest, the final fledging success reached 38.1% and an average 1.8 chicks left the nest. Nests were always on the ground and were situated in tufts or in thick vegetation. Most entrances faced south-east. The mean external diameter of nests was 10.1 cm, the internal diameter, presented as width and length, averaged 6.3 and 6.8 cm, respectively, and the mean depth of cup was 3.9 cm. Eighty-six measured eggs were similar in shape and colour to the eggs of Yellow Wagtail (M. flava). Their mean width was 14.16 mm, and the length 18.40 mm. The growth and plumage development of nestlings is reported. To estimate the nestlings age a multiple regression equation was established with the measurements of highest correlation coefficients, i.e. wing and tarsus length: D=0.12W+0.23T–0.23 (where: D = day of life, W = wing length, T = tarsus length). In the observed nest, both parents participated similarly in feeding the chicks. The average frequency of feeding increased from about 5 per hour on the day of hatching to more than 20 per hour in the last days in the nest. G-test showed statistically significant differences between the male and the female in the distribution of average duration of visit (G=52.3, df=10, P<0.05). During the first few days the female stayed at the nest longer than the male. After 6 days, average duration of a visit in the nest for both parents shortened to several seconds.  相似文献   

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A crucial problem for every organism is how to allocate energy between competing life-history components. The optimal allocation decision is often state-dependent and mediated by hormones. Here, we investigated how age, a major state variable affects individuals'' hormonal response to a standardized stressor: a trait that may reflect allocation between self-maintenance and reproduction. We caught free-living house sparrows and measured their hormonal (corticosterone) response to capture stress in consecutive years. Using a long-term ringing dataset, we determined the age of the birds, and we partitioned the variation into within- and among-individual age components to investigate the effects of plasticity versus selection or gene flow, respectively, on the stress response. We found large among-individual variation in the birds'' hormone profiles, but overall, birds responded less strongly to capture stress as they grew older. These results suggest that stress responsiveness is a plastic trait that may vary within individuals in an adaptive manner, and natural selection may act on the reaction norms producing optimal phenotypic response in the actual environment and life-history stage.  相似文献   

12.
The hormone corticosterone (CORT) is an important component of a bird’s response to environmental stress, but it can also have negative effects. Therefore, birds on migration are hypothesized to have repressed stress responses (migration-modulation hypothesis). In contrast to earlier studies on long-distance migrants, we evaluate this hypothesis in a population containing both migratory and resident individuals. We use a population of partially migratory blue tits (Cyanistes caeruleus) in southern Sweden as a model species. Migrants had higher CORT levels at the time of capture than residents, indicating migratory preparations, adaptation to stressors, higher allostatic load or possibly low social status. Migrants and residents had the same stress response, thus contradicting the migration-modulation hypothesis. We suggest that migrants travelling short distances are more benefited than harmed by retaining the ability to respond to stress.  相似文献   

13.
    
We used radioimmunoassay to determine fecal corticoid concentrations and assess potential stress in 10 endangered whooping cranes (Grus americana) undergoing reintroduction to the wild. Fecal samples were collected shortly after hatching at a captive facility in Maryland, during field training in Wisconsin, and throughout a human‐led migration to Florida. After a 14‐day decline following hatching, fecal corticoid concentrations stabilized at baseline levels for the duration of the captive period, despite exposure to potentially stressful stimuli. Shipment of the cranes to the field training site was correlated with an eight‐ to 34‐fold increase in fecal corticoid concentrations, which returned to baseline levels within 1 week. Increases were positively correlated with age but not body weight at the time of shipping. Fecal corticoid concentrations during the training period increased slightly and exhibited greater variation than levels observed at the captive facility, but were well within expected norms based on previous studies. Fecal corticoid concentrations increased twofold following premigration physical examinations and placement of radiotransmitters, and persisted for up to 4 days before they returned to baseline levels. Though fecal corticoid concentrations and variation during the migration period were similar to training levels, there was an overall decline in fecal corticoid concentrations during the artificial migration. Acute stressors, such as capture, restraint, and severe storms, were associated with stress responses by the cranes that varied in accordance with lasting physical or psychological stimuli. The overall reintroduction process of costume‐rearing, ultralight aircraft habituation, training, and artificial migration was not associated with elevations in fecal corticoid concentrations suggestive of chronic stress. Zoo Biol 24:15–28, 2005. © 2005 Wiley‐Liss, Inc.  相似文献   

14.
目的:观察不同锌水平对体外应激海马神经元金属硫蛋白(MTs)亚型表达的影响。方法:取新生1dWis-tar大鼠海马组织进行体外神经元培养,无血清培养24h后,分别向培养液中加入皮质酮、Zn2+特异鳌合剂TPEN,使二者的最终浓度均为1×10-5mol/L,然后加入不同浓度的ZnSO4溶液,使Zn2+的最终浓度分别为1×10-5mol/L、1×10-4mol/L和2×10-4mol/L,作用24h后检测培养液中IL-6和NO含量,以蛋白印迹法检测细胞MTs含量,以RT-PCR检测细胞MT-1mRNA和MT-3mRNA的表达水平。结果:在海马神经元培养液中加入TPEN后,MTs的表达出现明显降低,皮质酮刺激也未见其表达升高。在补锌组,MTs的含量均明显增加,其中以10-4mol/LZn2+组的表达量最高。海马神经元MT-1mRNA和MT-3mRNA的表达水平在皮质酮应激组和补锌组均出现明显升高。另外,锌缺乏和皮质酮刺激可使海马神经元培养上清中的IL-6和NO水平均出现明显升高。结论:不同锌水平对应激海马神经元金属硫蛋白及其亚型mRNA的表达具有调控作用,缺锌可降低金属硫蛋白的表达,而补锌可增加金属硫蛋白的表达。  相似文献   

15.
    
Free-ranging wild vertebrates need to cope with natural and anthropogenic stressors that cause short and/or long-term behavioural and physiological responses. In areas of high human disturbance, the use of glucocorticoid (GC) hormones as biomarkers to measure stress responses is an increasingly common tool for understanding how animals cope with human disturbance. We conducted a meta-analysis to investigate how human disturbances such as habitat conversion, habitat degradation, and ecotourism influence baseline GC hormones of free-ranging wild vertebrates, and we further test the role of protected areas in reducing the impact of such disturbances on these hormones. A total of 58 studies met the inclusion criteria, providing 152 data points for comparing levels of GC hormones under disturbed and undisturbed conditions. The overall effect size suggests that human disturbance does not cause a consistent increase in levels of GC hormones (Hedges' g = 0.307, 95% CI = −0.062 to 0.677). However, when the data were analysed by disturbance type, living in unprotected areas or in areas with habitat conversion were found to increase GC hormone levels compared to living in protected or undisturbed areas. By contrast, we found no evidence that ecotourism or habitat degradation generates a consistent increase in baseline GC hormone levels. Among taxonomic groups, mammals appeared more sensitive to human disturbance than birds. We advocate the use of GC hormones for inferring major human-caused contributors to the stress levels of free-ranging wild vertebrates – although such information needs to be combined with other measures of stress and interpreted in the context of an organism's life history, behaviour, and history of interactions with human disturbance.  相似文献   

16.
红火蚁Solenopsis invicta Buren工蚁活动能力与蚁群健康、环境条件等密切相关,对蚁群进行干扰会引起工蚁防卫和攻击行为。本文采用标尺插入法对蚁巢进行干扰破坏,测定了工蚁活动性指数,结果显示在相同干扰程度下活动性指数随蚁巢体积增大而增大,相同蚁巢时随着干扰程度增加而活动性指数先迅速增大后基本保持不变。间隔5 min对蚁巢实施连续干扰后工蚁活动性呈明显连续下降趋势,第5次干扰后工蚁的响应活动变得很弱,工蚁活动性指数与干扰时间之间关系符合二次曲线方程。  相似文献   

17.
Paul J. Weldon 《Ibis》2022,164(1):1-12
Human-scent contamination of bird nests and the human-made trails leading to them is suspected to influence nest survival by attracting or deterring predatory mammals. This paper (1) reviews studies in which human-scent contamination was suspected to have biased the survival of real and artificial nests by influencing the behaviour of predatory mammals, (2) summarizes the procedures used in attempts to mitigate human-scent contamination in nest-survival studies, and (3) describes procedures to enhance the design and interpretation of nest-survival experiments. The behaviour of various non-domesticated mammals is confirmed or suspected to be affected by human scent, so similar effects on nest predators are plausible. However, suggestions that human scent affects nest survival by influencing the behaviour of predatory mammals are poorly supported, due to a dearth of appropriately designed experiments. Some studies failed to include measures to reduce human-scent contamination, and the effectiveness of scent-mitigation methods used in other studies has seldom been verified. In addition, volatile compounds arising from soil and vegetation disturbed underfoot by field researchers may have confounded many nest-survival studies. Investigators have routinely inferred human-scent effects from post hoc predation patterns or have simply acknowledged possible human-scent effects among other potential influences of nest fate. Studies are needed of the effects of human scent using uniform methods of scent application and verified methods of scent mitigation, where the fates of different types of nests are examined under a range of field conditions. More fundamentally, studies of naïve and experienced mammals are needed to assess their responses to human scent and clarify its salience in wildlife disturbance.  相似文献   

18.
    
Different forms of outdoor recreation have different spatiotemporal activity patterns that may have interactive or cumulative effects on wildlife through human disturbance, physical habitat change, or both. In western North America, shrub‐steppe habitats near urban areas are popular sites for motorized recreation and nonmotorized recreation and can provide important habitat for protected species, including golden eagles. Our objective was to determine whether recreation use (i.e., number of recreationists) or recreation features (e.g., trails or campsites) predicted golden eagle territory occupancy, egg‐laying, or the probability a breeding attempt resulted in ≥1 offspring (nest survival). We monitored egg‐laying, hatching and fledging success, eagle behavior, and recreation activity within 23 eagle territories near Boise, Idaho, USA. Territories with more off‐road vehicle (ORV) use were less likely to be occupied than territories with less ORV use (β = ?1.6, 85% CI: ?2.8 to ?0.8). At occupied territories, early season pedestrian use (β = ?1.6, 85% CI: ?3.8 to ?0.2) and other nonmotorized use (β = ?3.6, 85% CI: ?10.7 to ?0.3) reduced the probability of egg‐laying. At territories where eagles laid eggs, short, interval‐specific peaks in ORV use were associated with decreased nest survival (β = ?0.5, 85% CI: ?0.8 to ?0.2). Pedestrians, who often arrived near eagle nests via motorized vehicles, were associated with reduced nest attendance (β = ?11.9, 85% CI: ?19.2 to ?4.5), an important predictor of nest survival. Multiple forms of recreation may have cumulative effects on local populations by reducing occupancy at otherwise suitable territories, decreasing breeding attempts, and causing nesting failure. Seasonal no‐stopping zones for motorized vehicles may be an alternative to trail closures for managing disturbance. This study demonstrates the importance of considering human disturbance across different parts of the annual cycle, particularly where multiple forms of recreation have varying spatiotemporal use patterns that create human–wildlife interactions.  相似文献   

19.
慢性应激不同方式对大鼠血清皮质酮的影响   总被引:1,自引:0,他引:1  
目的:比较慢性应激不同方式对生理状态大鼠血清皮质酮水平的影响,研究机体慢性应激反应的整体性适应特征。方法:采用连续4周的适宜游泳、束缚和二者复合的三种应激方式后,测定大鼠血清皮质酮基础含量,分析不同慢性应激方式对皮质酮水平的影响。结果:血清皮质酮水平与对照组比较,复合组无显著性差异;游泳组虽升高但无显著性;束缚组升高有显著性意义。结论:束缚可致大鼠血清皮质酮水平增高;初步认定游泳与束缚复合慢性应激方式可能对机体的整体适应性能具有积极意义。  相似文献   

20.
Disturbance by humans is widely expected to reduce the reproductive fitness of nesting birds if disturbance reduces nest attentiveness, and unattended eggs experience increased risk of predation or exposure to potentially lethal temperature extremes. Yet, relatively few studies have examined the physiological or behavioural mechanisms whereby disturbance influences reproductive fitness, or the extent to which the costs of disturbance may be reduced through habituation. We compared the behavioural responses, egg temperatures and reproductive success of shore-nesting white-fronted plovers Charadrius marginatus to disturbance at two breeding sites experiencing low versus high human recreational activity, respectively. Daytime nest attentiveness decreased with increasing experimental disturbance at both sites, but this relationship differed between sites; for any given level of disturbance, incubating birds at the more disturbed site had greater nest attentiveness. They achieved this through habituation, allowing a closer human approach before leaving the nest, and returning to the nest faster after a disturbance event. Despite lower average daytime nest attentiveness at the more disturbed site, incubation temperatures did not differ significantly between sites. Nest mortality, mostly by natural mammalian and corvid predators, was significantly lower at the site experiencing high recreational activity. However, chick mortality was significantly greater at the more disturbed site, most likely because of predation by domestic dogs. Chick mortality may have been increased by the habitation of chicks, whose escape responses were much reduced at the more disturbed site. Nonetheless, annual fecundity was substantially higher at the more disturbed site, showing that the overall reproductive fitness of wild birds is not always compromised by human disturbance and urbanization.  相似文献   

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