نتایج جستجو برای: crow
تعداد نتایج: 1723 فیلتر نتایج به سال:
In many cooperatively breeding societies, helping effort varies greatly among group members, raising the question of why dominant individuals tolerate lazy subordinates. In groups of carrion crows Corvus corone corone, helpers at the nest increase breeders' reproductive success, but chick provisioning is unevenly distributed among non-breeders, with a gradient that ranges from individuals that ...
The hypothesis that spatial-memory specialization affects the size of the hippocampus has become widely accepted among scientists. The hypothesis comes from studies on birds primarily in two families, the Paridae (tits, titmice and chickadees) and the Corvidae (crows, nutcrackers, jays, etc.). Many species in these families store food and rely on spatial memory to relocate the cached items. The...
New Caledonian crows make and use tools, and tool types vary over geographic landscapes. Social learning may explain the variation in tool design, but it is unknown to what degree social learning accounts for the maintenance of these designs. Indeed, little is known about the mechanisms these crows use to obtain information from others, despite the question's importance in understanding whether...
West Nile virus and wild birds West Nile virus (WN) is a virus of wild birds, transmitted from bird to bird primarily by mosquitoes. Native to southern Europe, the Middle East and Africa, the virus arrived in North America in 1999 and spread quickly across the continent. Over 225 species of birds have been reported as infected with WN; some of these species, such as members of the crow family, ...
Although locusts are so destructive to the results of human agricultural industry, and although their presence must be regarded, at least in all cultivated countries, as a calamity of grave and serious import, their presence is, nevertheless, the opportunity of jubilee to various species of the lower creation. First, appears the inevitable crow, with his hop, jump, and caw, surfeiting himself o...
We demonstrate that a photonic lattice with short- and long-range harmonic modulations of the refractive index facilitates formation of flat photonic bands and leads to slow propagation of light. The system can be considered a coupled-resonator optical waveguide (CROW): photonic bands with abnormally small dispersion are created due to the interaction of long-lived states in the cavity regions ...
This work employs Evoked Potential techniques as 19 participants are confronted with sentences that have the potential to produce scalar implicatures, like in Some elephants have trunks. Such an Underinformative utterance is of interest to pragmatists because it can be considered to have two different truth values. It can be considered true when taken at face value but false if one were to trea...
anorexia nervosa Toni-Kim Clarke, Richard C. Crist, Glenn A. Doyle, Amy R.D. Weiss, Harry Brandt, Steve Crawford, Scott Crow, Manfred M. Fichter, Katherine A. Halmi, Craig Johnson, Allan S. Kaplan, Maria La Via, James E. Mitchell, Michael Strober, Alessandro Rotondo, Janet Treasure, D. Blake Woodside, Pamela Keel, Kelly L. Klump, Lisa Lilenfeld, Katherine Plotnicov, Pierre J. Magistretti, Andre...
1. K. R. L. Hall, Curr. Anthropol. 4, 479 (1963). 2. Specific examples of tool use by birds: A. Alcock, Ibid 112, 542 (1970); A. H. Chisholm, ibid. 96, 380 (1954); D. Lack, Sci. Amer. 188, 66 (April 1953); H. B. Lovell, Wilson Bull. 70, 280 (1957); G. C. Milliken and R. I. Bowman, Living Bird 6, 23 (1967); J. van Lawick-Goodall Nature 212, 1468 (1966); and H. van Lawick, Nat. Geogr. Mag. 133, 6...
Much attention has been paid to the impacts of plastics and other debris on marine organisms, but the effects of plastic on terrestrial organisms have been largely ignored. Detrimental effects of terrestrial plastic could be most pronounced in intensively human-modified landscapes (e.g., urban and agricultural areas), which are a source of much anthropogenic debris. Here, we examine the occurre...
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