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Blackbird

The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Bruno Faivre – 1st expert on this subject based on the ideXlab platform

  • carotenoid trade off between parasitic resistance and sexual display an experimental study in the Blackbird turdus merula
    Proceedings of The Royal Society B: Biological Sciences, 2008
    Co-Authors: R Baeta, Bruno Faivre, Sebastien Motreuil, Maria Gaillard, Jerome Moreau

    Abstract:

    Many parasites depress the expression of the carotenoid-based colour displays of their hosts, and it has been hypothesized that animals face a trade-off in carotenoid allocation between immune functions and ‘degree of ornamentation’. While numerous correlative studies suggest that parasite infection decreases the intensity of carotenoid-based colour displays, the existence of this trade-off has never been demonstrated experimentally in a host–parasite model. In this study, we used the Blackbird ( Turdus merula ) and Isospora (an intestinal parasite) to assess whether this trade-off does indeed exist. Blackbirds were supplemented with carotenoids while simultaneously being exposed to parasites. Supplemented males circulated more carotenoids in the blood and developed more brightly coloured bills than unsupplemented males. In addition, supplementation slowed down the replication rate of parasites. Supplementation with carotenoids enabled infected birds to maintain their bill coloration, whereas birds that were infected but not supplemented showed reduced bill coloration. At the same time, infection slowed carotenoid assimilation in the blood. Overall, we demonstrated that bill colour reflects a bird9s health, and that only males with a carotenoid-rich diet are capable of coping with costs associated with parasitic infection. Carotenoids are thus traded off between host physiological response to parasites and secondary sexual traits. Further investigations are required to determine the physiological mechanisms that govern this trade-off.

  • sensitive measure of prevalence and parasitaemia of haemosporidia from european Blackbird turdus merula populations value of pcr rflp and quantitative pcr
    Parasitology, 2006
    Co-Authors: Sophie Bentz, Thierry Rigaud, Marco Barroca, F Martinlaurent, Jerome Moreau, Bruno Faivre

    Abstract:

    Haemosporidian parasites are common in birds in which they act as an important selective pressure. While most studies so far have focused on the effect of their prevalence on host life-history traits, no study has measured the effect of parasitaemia. We developed molecular methods to detect, identify and quantify haemosporidia in 2 natural populations of the Blackbird Turdus merula. Three different parasite genotypes were found – 1 Haemoproteus and 2 Plasmodium. A PCR-RFLP screening revealed that only approximately 3% of Blackbirds were free of parasites, compared to the 34% of uninfected birds estimated by blood smear screening. A quantitative PCR (q-PCR) assay revealed a weaker parasitaemia in microscopically undetected parasites compared to microscopically detected ones. Large parasitaemia differences were found between parasite species, suggesting either differing parasite life-histories or host resistance. Parasitaemias were also weaker in male hosts, and in urban habitats, suggesting that both host factors (e.g. immunity) and habitat characteristics (e.g. vector availability) may modulate parasite density. Interestingly, these differences in parasitaemia were comparable to differences in parasite prevalence estimated by smear screening. This suggests that previous results obtained by smear screening should be reinterpreted in terms of parasitaemia instead of parasite prevalence.

  • distribution and abundance patterns of a newly colonizing species in tunisian oases the common Blackbird turdus merula
    Ibis, 2003
    Co-Authors: Slaheddine Selmi, Thierry Boulinier, Bruno Faivre

    Abstract:

    We investigated distribution and abundance patterns of a recently arrived species in the oases of southern Tunisia: the Common Blackbird Turdus merula. In this system, we expected that the vegetation structure and geographical locations of oases would have played an important part in shaping the patterns of oasis occupancy and local abundance. Using data collected at 53 oases during two breeding seasons, we found that Blackbird occurrence in a given oasis depended mainly on its presence at neighbouring oases. However, vegetation structure did not prove to be a relevant predictor of Blackbird occurrence. Within occupied oases, local abundance was associated with vegetation structure, namely with the diversity and abundance of the two lowest vegetation layers: fruit trees and herbaceous plants. The presence of Blackbirds at neighbouring oases was not found to account for local abundance. Overall, our results suggest that the distribution and abundance of this newly colonizing species in the southern Tunisian oasis system are influenced by processes acting at two different spatial scales. Landscape-scale processes (i.e. dispersal and colonization from nearby occupied oases) are likely to play an important role in shaping the pattern of oasis occupancy, whereas local-scale factors seem to be more relevant in determining the abundance of locally established populations.

George M. Linz – 2nd expert on this subject based on the ideXlab platform

  • Comparisons between Blackbird damage to corn and sunflower in
    , 2020
    Co-Authors: Megan E Klosterman, George M. Linz, Anthony A Slowik, H. Jeffrey Homan

    Abstract:

    For sunflower producers in North Dakota, Blackbird (Icterinae) damage is a chronic problem costing millions of dollars annually. Sunflower damage surveys were last completed in the state in 1979e1980. Since the last surveys, corn plantings have increased 6-fold to 1500 � 10 3 ha, whereas sunflower hectarage has declined by >75% to 310 � 10 3 ha. Blackbirds forage on both crops, and this rapid change in North Dakota’s agricultural landscape was a sound inducement for reassessing crop damage. Field surveys are an important step in damage methods development because they are used for measuring efficacy, as well as assessing historical changes in the quality and quantity of damage. During 2009e2010, we conducted damage surveys on corn and sunflower. We surveyed 120 randomly selected 3.2 � 3.2-km plots in North Dakota’s Prairie Pothole Region. This region of numerous wetlands has historically produced the majority of the state’s sunflower crop, in addition to harboring a Blackbird population of 25 million birds. Over the 2-year study, we measured damage in 68 cornfields and 27 sunflower fields. Annual damage averaged 5.0 � 10 3 t (12 kg/ha, US $1.3 million) for corn and 7.2 � 10 3 t (45 kg/ha, US $3.5 million) for sunflower. Percentage damage was significantly greater in sunflower ðx ¼ 2:7%Þ than corn ðx ¼ 0:2%Þ. The lower per-unit cost of producing corn makes it a potential lure crop for managing Blackbird damage to sunflower. However, the two crops should be phenologically synchronized because corn matures earlier than sunflower and becomes less attractive to Blackbirds. Published by Elsevier Ltd.

  • Evaluation of elevated bait trays for attracting Blackbirds (Icteridae) in central
    , 2020
    Co-Authors: North Dakota, George M. Linz, Jamison B. Winter, William J. Bleier

    Abstract:

    Sunflower (Helianthus annuus L.) became an economically important crop in North Dakota in the 1970s, providing a major source of food for post-breeding Blackbirds (Icteridae). Reducing local Blackbird populations with rice grains treated with an avicide is one proposed alternative for reducing sunflower damage. In fall 2007 and 2008, we evaluated the idea of attracting Blackbirds to rice-baited trays attached to wire cages supplied with live Blackbirds. During our observations (1011 h), we saw 3888 birds, consisting of 25 species and 12 families, on the bait trays. Blackbirds made up 90.4% of the bird observations, whereas sparrows (Emberizidae) made up 1.6% of the birds observed. Overall risk to nontarget species appeared minimal. The bait trays, however, attracted a small number of Blackbirds compared to the source population feeding in nearby crop fields. Our results strongly suggest DRC-1339treated rice used on bait trays is unlikely to be a cost-effective method of reducing Blackbird damage to ripening sunflower. Published by Elsevier Ltd.

  • Potential Use of Perennial Sunflower to Reduce Blackbird Damage to Sunflower
    Proceedings of the Vertebrate Pest Conference, 2020
    Co-Authors: George M. Linz, Brent S. Hulke, Michael B. Kantar, Jeffrey Homan, Robert M. Stupar, Donald L. Wyse

    Abstract:

    Author(s): Linz, George; Hulke, Brent; Kantar, Michael; Homan, Jeffrey; Stupar, Robert; Wyse, Donald | Abstract: Wildlife Conservation Sunflower Plots (WCSP) have shown potential to reduce Blackbird (Icteridae) damage in commercial sunflower. Also known as lure, decoy, or trap crops, WCSP are strategically placed food plots that provide an easily available and proximate food source that entices Blackbirds away from valuable commercial crops. By providing an alternative food source, WCSP reduce direct damage to commercial fields, while also lowering indirect costs that producers incur attempting to prevent Blackbird damage. However, cost inefficiencies have deterred widespread use of WCSP. Cost-benefit ratios of using WCSP would be greatly improved if a perennial sunflower were used instead of the annual types currently available. Perennial sunflower would reduce seed cost and planting cost, and perhaps lower opportunity costs, if able to thrive on poorer quality soils. In the near-term, scientists are focused on producing a perennial sunflower sufficiently productive to replace annual WCSP plantings. In 2013, scientists from the University of Minnesota, USDA-Agricultural Research Service, and USDA Wildlife Services National Wildlife Research Center evaluated a test plot of an open-pollinated variety of perennial sunflower resulting from genetic crossing of a domesticated annual species (Helianthus annuus) and a perennial wild species (H. tuberosus). Here, we report on results from the 2013 field test and discuss the outlook for development of perennial sunflower, which would help lessen damage to commercial sunflower when used in WCSP; provide a pesticide-free food source for beneficial insects, such as honey bees; help stabilize highly erodible lands near wetlands; and provide year-round habitat for wildlife. Lastly, we provide an initial strategy for using perennial sunflower to reduce Blackbird damage in commercial sunflower.

William J. Bleier – 3rd expert on this subject based on the ideXlab platform

  • Evaluation of elevated bait trays for attracting Blackbirds (Icteridae) in central
    , 2020
    Co-Authors: North Dakota, George M. Linz, Jamison B. Winter, William J. Bleier

    Abstract:

    Sunflower (Helianthus annuus L.) became an economically important crop in North Dakota in the 1970s, providing a major source of food for post-breeding Blackbirds (Icteridae). Reducing local Blackbird populations with rice grains treated with an avicide is one proposed alternative for reducing sunflower damage. In fall 2007 and 2008, we evaluated the idea of attracting Blackbirds to rice-baited trays attached to wire cages supplied with live Blackbirds. During our observations (1011 h), we saw 3888 birds, consisting of 25 species and 12 families, on the bait trays. Blackbirds made up 90.4% of the bird observations, whereas sparrows (Emberizidae) made up 1.6% of the birds observed. Overall risk to nontarget species appeared minimal. The bait trays, however, attracted a small number of Blackbirds compared to the source population feeding in nearby crop fields. Our results strongly suggest DRC-1339treated rice used on bait trays is unlikely to be a cost-effective method of reducing Blackbird damage to ripening sunflower. Published by Elsevier Ltd.

  • ARE SUNFLOWER FIELDS FOR THE BIRDS
    , 2020
    Co-Authors: Heath M Hagy, George M. Linz, William J. Bleier

    Abstract:

    The northern Great Plains are home to a variety of birds throughout the year, particularly during migration. Migratory species use native and restored grasslands, shelterbelts, and agricultural fields for food and shelter in North Dakota. Blackbirds (Xanthocephalus xanthocephalus) have been documented to cause economically important damage to some crops and thus, are sometimes the target of concerted harassment efforts. Few studies have assembled an inventory of nonBlackbirds using small grain fields during the fall and spring in North Dakota that may be inadvertently affected by Blackbird management. At least 94 nonBlackbird species use crop fields in the spring and fall in North Dakota. Sunflower fields appear to be a particularly important stopover habitat for a variety of migratory birds, with 78 species and 29 species using sunflower in the fall and spring, respectively. We encourage a joint Blackbird management / wildlife habitat system including Wildlife Conservation Sunflower Plots (lure plots) as part of an integrated pest management plan to reduce Blackbird damage to sunflower and provide habitat for nonBlackbirds.

  • Sunflower Growers Use Nonlethal Methods to Manage Blackbird Damage
    , 2013
    Co-Authors: George M. Linz, H. Jeffrey Homan, Scott J. Werner, James C. Carlson, William J. Bleier

    Abstract:

    Blackbird damage to sunflower in the Prairie Pothole Region of North Dakota, South Dakota, and Minnesota is an unyielding challenge to the industry. Large populations of Blackbirds and environmental concerns have driven the direction of research toward nonlethal methods that can be implemented locally. Currently, Wildlife Services field specialists lend propane cannons to growers and spray wetlands with glyphosate to fragment dense cattail stands used by roosting Blackbirds. After researchers demonstrated decoy crops (wildlife conservation sunflower plots), some growers have adapted the basic principles and have started diverting Blackbirds from sunflower, a high value crop, to alternative lesser-value crops, such as corn. USDA and university scientists are developing a perennial sunflower that might significantly lower the costs of planting WCSP. Growers now have access to several desiccants that hasten the crop harvest and thus avoid late-season Blackbird damage. Finally, researchers are closer to developing an effective chemical bird repellent. In this paper, we outline current nonlethal Blackbird management strategies.