908 resultados para bird strike


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The coevolution of parental investment and offspring solicitation is driven by partly different evolutionary interests of genes expressed in parents and their offspring. In species with biparental care, the outcome of this conflict ma!: be influenced by the sexual conflict over parental investment, Models for the resolution of such family conflicts have made so far untested assumptions about genetic variation and covariation in the parental resource provisioning response and the level of offspring solicitation. Using a combination of cross-fostering and begging playback experiments, we show that, in the great tit (Parus major), (i) the begging call intensity of nestlings depends on their common origin, suggesting genetic variation for this begging display, (ii) only mothers respond to begging calls by increased food provisioning, and (iii! the size of the parental response is positively related to the begging call intensity of nestlings in the maternal but not paternal line. This study indicates that genetic covariation, its differential expression in the maternal and paternal lines and/or early environmental and parental effects need to be taken into account when predicting the phenotypic outcome of the conflict over investment between genes expressed in each parent and the offspring. [References: 36]

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1. Parasites might preferentially feed on hosts in good nutritional condition as such hosts provide better resources for the parasites' own growth, survival and reproduction. However, hosts in prime condition are also better able to develop costly immunological or physiological defence mechanisms, which in turn reduce the parasites' reproductive success. The interplay between host condition, host defence and parasite fitness will thus play an important part in the dynamics of host-parasite systems.;2. In a 2 x 2 design, we manipulated both the access to food in great tit Parus major broods and the exposure of the nestlings to hen fleas Ceratophyllus gallinae, a common ectoparasite of hole-breeding birds. We subsequently investigated the role of manipulated host condition, host immunocompetence, and experimentally induced host defence in nestlings on the reproductive success of individual hen flea females.;3. The food supplementation of the nestlings significantly influenced the parasites' reproductive success. Female fleas laid significantly more eggs when feeding on food-supplemented hosts.;4. Previous parasite exposure of the birds affected the reproductive success of fleas. However, the impact of this induced host response on flea reproduction depended on the birds' natural level of immunocompetence, assessed by the phytohaemagglutinin (PHA) skin test. Flea fecundity significantly decreased with increasing PHA response of the nestlings in previously parasite-exposed broods. No relationship between flea fitness and host immunocompetence was, however, found in previously unexposed broods. The PHA response thus correlates with the nestlings' ability to mount immunological or physiological defence mechanisms against hen fleas. No significant interaction effect between early flea exposure and food supplementation on the parasites' reproductive success was found.;5. Our study shows that the reproductive success of hen fleas is linked to the hosts' food supply early in life and their ability to mount induced immunological or physiological defence mechanisms. These interactions between host quality and parasite fitness are likely to influence host preference, host choice and parasite virulence and thus the evolutionary dynamics in host-parasite systems.

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The decision of how far to disperse from the natal territory has profound and long-lasting consequences for young animals, yet the optimal dispersal behavior often depends on environmental factors that are difficult or impossible to assess by inexperienced juveniles. Natural selection thus favors mechanisms that allow the adaptive and flexible adjustment of the offspring's dispersal behavior by their parents via either paternal or maternal effects. Here we show that different dispersal strategies maximize the reproductive success of young great tits (Parus major) originating from a parasite-infested or a parasite-free nest and demonstrate that differential transfer of maternal yolk androgens in response to parasitism can result in a modification of the offspring's dispersal behavior that appears adaptive. It demonstrates that prenatal maternal effects are an important yet so far neglected determinant of natal dispersal and highlights the potential importance of maternal effects in mediating coevolutionary processes in host-parasite systems.

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Tumult and Tragedy: Michigan’s 1913-14 Copper Strike chronicles one of the greatest upheavals in Michigan’s history. The determination, conflict, sorrow, and tragedy of this epic confrontation changed the Copper Country for decades and memories of conflict remain to this day. This traveling exhibit explores the story of this remarkable period in Michigan history.

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Tumult and Tragedy: Michigan’s 1913-14 Copper Strike chronicles one of the greatest upheavals in Michigan’s history. The determination, conflict, sorrow, and tragedy of this epic confrontation changed the Copper Country for decades and memories of conflict remain to this day. This traveling exhibit explores the story of this remarkable period in Michigan history.

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Tumult and Tragedy: Michigan’s 1913-14 Copper Strike chronicles one of the greatest upheavals in Michigan’s history. The determination, conflict, sorrow, and tragedy of this epic confrontation changed the Copper Country for decades and memories of conflict remain to this day. This traveling exhibit explores the story of this remarkable period in Michigan history.

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The purpose of this study is to take a closer look at media response in Finland concerning the 1913-14 Michigan Copper Strike and depict how the strike was presented in the Old Country and its main newspapers. I shall take a closer look at the 1913-14 issues of Työmies (social democrat), Helsingin Sanomat (liberal), and Uusi Suometar (conservative) for ideological views of the strike. Furthermore, and in terms of close reading and cross-referencing, how did these newspapers in Finland see the strike and the strike’s outcome? Editorial notes and letters from the public shall both be included. Special attention will be given to the notions of transnational solidarity between Finnish-American and Finnish labor activists.

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Labor Historian Marc Karson has singled out “labor priest” Peter E. Dietz as one of the strongest proponents for the active implementation of the Catholic Church’s 1890’s labor encyclical Rerum Novarum in the daily practice of American Catholics. Biographer Sister Mary Harrita Fox pointed out that in his work, Dietz “was particularly concerned over the role of the church in the copper strike in Upper Michigan.” This “particular concern” should be noted since the 1913 strike was one of the only disputes where Dietz went out of his way to visit and become actively involved. Why the keen interest? This presentation will review the impetus for the huge effort which brought Peter E. Dietz to the Copper Country and solely to that dispute alone, the resulting visit and report that he made concerning the strike, the important role he believed this visit and stance in the Copper Strike had in the future of the Church’s relationship to the US labor movement. The presentation will look at both what Dietz thought would occur as a result of his 1913 trip to the Keweenaw and what actually happened in this pivotal pre-World War One era event. The paper will put Father Peter E. Dietz and the Catholic Church into the larger frame of how religion has been viewed within the history of the Strike.

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Streams and riparian areas can be intricately connected via physical and biotic interactions that influence habitat conditions and supply resource subsidies between these ecosystems. Streambed characteristics such as the size of substrate particles influence the composition and the abundance of emergent aquatic insects, which can be an important resource for riparian breeding birds. We predict fine sediment abundance in small headwater streams directly affects the composition and number of emergent insects while it may indirectly affect riparian bird assemblages. Streams with abundant fine sediments that embed larger substrates should have lower emergence of large insects such as phemeroptera, Plecoptera and Trichoptera. Streams with lower emergent insect abundance are predicted to support fewer breeding birds and may lack certain bird species that specialize on aquatic insects. This study examined relationships between streambed characteristics, and emergent insects (composition, abundance and biomass), and riparian breeding birds (abundance and richness) along headwater streams of the Otter River Watershed. The stream bed habitats of seven stream reaches were characterized using longitudinal surveys. Malaise traps were deployed to sample emergent aquatic insects. Riparian breeding birds were surveyed using fixed-radius point-counts. Streams differed within a wide range of fine sediment abundances. Total emergent aquatic insect abundance increased as coverage by instream substrates increased in diameter, while bird community was unresponsive to insect or stream features. Knowledge of stream and riparian relationships is important for understanding of food webs in these ecosystems, and it is useful for riparian forest conservation and improving land-use management to reduce sediment pollution in these systems.

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In the Iron Range Strike of 1916, working-class wives picketed alongside their husbands in a conflict-ridden and dangerous setting. Mine deputies abused immigrant women on the picket lines and in their homes, with several disquieting reports receiving statewide attention in Minnesota. Many middle-class reformers in the Twin Cities grew sympathetic to the plight of northern mining families and became controversially involved the labor struggle. Some middleclass women worked alongside working-class wives and radical organizers from the Industrial Workers of the World (IWW). At the center of this gendered analysis is the cross-class cooperation between an upper-middle class woman, Lenora Austin Hamlin, a radical reformer, Elizabeth Gurley Flynn, and the story of a working-class housewife, Mikla Masonovich. This study will ask how authentic, prevalent, and unproblematic their stories of cross-class cohesive action actually were. In answering this, it will address and identify those factors that impeded women’s potential for unity. “Flash in the Pan” argues that as a result of both real and perceived differences, these networks of women remained isolated, inhibiting each from gaining sufficient power to work cohesively, and marginalizing their influence. Drawing upon a variety of sources, including media representations in newspapers, and archives of social, labor and women’s organizations, this regional study lends state-level insight into the larger gender-labor historiography.

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In the autumn of 1913, a small, remote Michigan mining community attracted national attention as miners and management found themselves embroiled in a conflict that would prove no easy victory for either side. The strike came as a shock to management, who, with the help of a nearly perfected paternal system, had come to expect a generally docile and compliant workforce. But what was even more shocking was the involvement of the miners’ wives in the strike effort, and the lengths they went to in order to keep men from crossing the picket line. This paper focuses on that effort, arguing that the women of the Michigan copper country developed strike strategies that were derived from their domestic experience, and justified their involvement through maternal arguments. However, these public actions allowed the management to disregard the respect and courtesy generally given to the domestic sphere as police and private agents perpetrated a number of home invasions in an attempt to break the strike. The involvement of women in male dominated labor disputes (mining, steel productions) has been largely ignored in the literature due to their indirect connection to the company as wives and not workers. This paper seeks to remedy this gap, and gain a better understanding of that indirect relationship. Sources include newspaper articles, private correspondence, public investigation records, and oral histories, found largely in the Michigan Tech Archives and Copper Country Historical Collections, Michigan Technological University, Michigan.

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In May of 1968, workers at the Kingston mine, a branch of the Calumet Division of Universal Oil Products walked off the site in protest of a safety issue involving a man-car. Knowing their contracts were due for negotiation in just a few months, the workers quickly returned, only to find themselves striking yet again just three months later, when negotiations failed. Requesting pay equal to that of the workers at the nearby White Pine mine was unacceptable to the heads of Universal Oil, the corporation which bought the long running Calumet & Hecla just a year earlier in 1968. The strike would last for nine months, ending in a total shutdown of all mining operations on the Keweenaw Peninsula, and bring an economic hardship to the area that would take decades to recover from. The Copper Strike of 1968-1969 is often forgotten, though extremely important to the story of the copper industry in Michigan, as well as to the United States. This paper has not yet been submitted.