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"crows"
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A murder of crows
Crows are some of the smartest animals on the planet. They can remember peoples faces and warn each other of danger. Some crows even know how to use simple tools. These fascinating facts and more are waiting to be discovered by readers.
Book
Neurons selective to the number of visual items in the corvid songbird endbrain
It is unknown whether anatomical specializations in the endbrains of different vertebrates determine the neuronal code to represent numerical quantity. Therefore, we recorded single-neuron activity from the endbrain of crows trained to judge the number of items in displays. Many neurons were tuned for numerosities irrespective of the physical appearance of the items, and their activity correlated with performance outcome. Comparison of both behavioral and neuronal representations of numerosity revealed that the data are best described by a logarithmically compressed scaling of numerical information, as postulated by the WeberâFechner law. The behavioral and neuronal numerosity representations in the crow reflect surprisingly well those found in the primate association cortex. This finding suggests that distantly related vertebrates with independently developed endbrains adopted similar neuronal solutions to process quantity.
Significance Birds are known for their advanced numerical competence, although a six-layered neocortex that is thought to enable primates with the highest levels of cognition is lacking in birds. We recorded neuronal activity from an endbrain association area termed nidopallium caudolaterale (NCL) in crows that discriminated the number of items in displays. NCL neurons were tuned to preferred numerosities. Neuronal discharges were relevant for the crowsâ correct performance. Both the neuronal and the behavioral tuning functions were best described on a logarithmic number line, just as predicted by the psychophysical WeberâFecher Law. Our data suggests that this way of coding numerical information has evolved based on convergent evolution as a superior solution to a common computational problem.
Journal Article
Crick, crack, crow!
An American crow leaves his large extended family and flies to the nearby farm, where he finds lots of fun and trouble. Includes facts about crows.
Book
Discovery of species-wide tool use in the Hawaiian crow
A species-wide study shows that the Hawaiian crow
Corvus hawaiiensis
is a highly proficient tool user, creating opportunities for comparative studies with tool-using New Caledonian crows and other corvids.
Tool use in a second tropical crow species
Birds in the crow family are renowned for their cognitive abilities. The New Caledonian crow
Corvus moneduloides
is well known for its ability to make and use foraging tools. Christian Rutz
et al
. show that it is not some lone outlier—it is now joined by another species from the Pacific, the Hawaiian crow
Corvus hawaiiensis
, better known by its indigenous Hawaiian name 'Alalā. These birds naturally develop tool-using skills when young, and proficient tool use is a species-wide capacity. The authors can say this with confidence as the 'Alalā is extinct in the wild, and they were able to test 104 of the 109 surviving members of the species at the time, all in captivity. The research suggests that the technological skills of tropical crows might be fostered by rather unusual ecological circumstances found on remote islands, such as reduced competition for embedded prey and low predation risk. The discovery of a second tool-using crow species opens up exciting opportunities for comparative studies on animal tool use.
Only a handful of bird species are known to use foraging tools in the wild
1
. Amongst them, the New Caledonian crow (
Corvus moneduloides
) stands out with its sophisticated tool-making skills
2
,
3
. Despite considerable speculation, the evolutionary origins of this species’ remarkable tool behaviour remain largely unknown, not least because no naturally tool-using congeners have yet been identified that would enable informative comparisons
4
. Here we show that another tropical corvid, the ‘Alalā (
C. hawaiiensis
; Hawaiian crow), is a highly dexterous tool user. Although the ‘Alalā became extinct in the wild in the early 2000s, and currently survives only in captivity
5
, at least two lines of evidence suggest that tool use is part of the species’ natural behavioural repertoire: juveniles develop functional tool use without training, or social input from adults; and proficient tool use is a species-wide capacity. ‘Alalā and New Caledonian crows evolved in similar environments on remote tropical islands, yet are only distantly related
6
, suggesting that their technical abilities arose convergently. This supports the idea that avian foraging tool use is facilitated by ecological conditions typical of islands, such as reduced competition for embedded prey and low predation risk
4
,
7
. Our discovery creates exciting opportunities for comparative research on multiple tool-using and non-tool-using corvid species. Such work will in turn pave the way for replicated cross-taxonomic comparisons with the primate lineage, enabling valuable insights into the evolutionary origins of tool-using behaviour.
Journal Article
As the crow flies
Rhyming text describes the noisy, funny, and sometimes annoying behavior of crows.
Book
The genomic landscape underlying phenotypic integrity in the face of gene flow in crows
The importance, extent, and mode of interspecific gene flow for the evolution of species has long been debated. Characterization of genomic differentiation in a classic example of hybridization between all-black carrion crows and gray-coated hooded crows identified genome-wide introgression extending far beyond the morphological hybrid zone. Gene expression divergence was concentrated in pigmentation genes expressed in gray versus black feather follicles. Only a small number of narrow genomic islands exhibited resistance to gene flow. One prominent genomic region (<2 megabases) harbored 81 of all 82 fixed differences (of 8.4 million single-nucleotide polymorphisms in total) linking genes involved in pigmentation and in visual perception–a genomic signal reflecting color-mediated prezygotic isolation. Thus, localized genomic selection can cause marked heterogeneity in introgression landscapes while maintaining phenotypic divergence.
Journal Article
Ka : Dar Oakley in the ruin of Ymr
\"Dar Oakley -- the first Crow in all of Crow history with a name of his own -- was born two thousand years ago. He tells the story of his impossible lives and deaths to a man who has learned his language in this exquisite novel which unravels like a fireside fable, by award-winning author John Crowley. In Ka we see how young Dar Oakley went down into the human underworld long before Julius Caesar came into the Celtic lands, and there got hold of the immortality meant for humans; how he sailed West to America with the Irish monks searching for the Paradise of the Saints; how again and again he went down into the lands of the dead and returned. All these beings inhabit Ka, the realm of Crows, and dwell also in Ymr, the realm where -- as Dar Oakley learns -- what humans think is so, really is so, even though we could have so much more\"-- Provided by publisher.
Book
Nestling telomere shortening, but not telomere length, reflects developmental stress and predicts survival in wild birds
Developmental stressors often have long-term fitness consequences, but linking offspring traits to fitness prospects has remained a challenge. Telomere length predicts mortality in adult birds, and may provide a link between developmental conditions and fitness prospects. Here, we examine the effects of manipulated brood size on growth, telomere dynamics and post-fledging survival in free-living jackdaws. Nestlings in enlarged broods achieved lower mass and lost 21% more telomere repeats relative to nestlings in reduced broods, showing that developmental stress accelerates telomere shortening. Adult telomere length was positively correlated with their telomere length as nestling (r = 0.83). Thus, an advantage of long telomeres in nestlings is carried through to adulthood. Nestling telomere shortening predicted post-fledging survival and recruitment independent of manipulation and fledgling mass. This effect was strong, with a threefold difference in recruitment probability over the telomere shortening range. By contrast, absolute telomere length was neither affected by brood size manipulation nor related to survival. We conclude that telomere loss, but not absolute telomere length, links developmental conditions to subsequent survival and suggest that telomere shortening may provide a key to unravelling the physiological causes of developmental effects on fitness.
Journal Article
COALITIONAL FIGHTING REVEALS SOCIAL ORDER IN AMERICAN CROWS
We report a fight involving multiple American Crows attacking and nearly killing a single crow. Our observation suggests that the social structure of crow societies is maintained at both an individual and group level.
Journal Article