2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
American crows (Corvus brachyrhynchos) and northwestern crows (C. caurinus) attack larger common ravens (C. corvus) in 97 percent of interspecific conflicts, scientists from the United States and Canada have found, who analyzed more than two thousand observations of amateur ornithologists. in North America. An article published in The Auk: Ornithological Advances reports that conflicts are higher during the nesting season and most often involve groups rather than individuals.
Interspecies conflicts are not uncommon among social animals. In particular, birds often conflict: they can either defend their territory, or - much more often - fight for food. Another reason for bird conflicts is the search for a suitable habitat during the nesting period: clashes between representatives of the two species can occur during nesting predation.
Benjamin Freeman of the University of British Columbia and Eliot Miller of the Cornell Laboratory of Ornithology decided to study the causes of interspecies conflicts among ravens. They analyzed 2014 cases of attacks between members of the raven genus, which were collected by volunteer observers participating in the eBird project.
Scientists divided the studied birds into two subgroups: the first included American and northwestern crows, and the second - common crows. This division is not accidental: English-speaking bird watchers call the first two species "crows", since they are phenotypically almost indistinguishable and are inferior in size to the reproductively isolated common crow (it, in turn, is called "raven", that is, raven), more resembling a hooded crow (C. cornix). In the Russian-speaking tradition, only the gray and black (C. corone) crows are usually called ravens, and all the species studied in the work are considered ravens.
After analyzing the data, the authors of the work found that American and Northwest crows act as an aggressor in 97 percent of cases of conflicts with common crows. This preponderance existed even despite the fact that the common raven is larger than its offenders in size: scientists also found that the American and northwestern ravens outnumbered the common ravens involved in the conflict in 81 percent of cases.
Distribution of interspecific conflicts in North America: purple indicates cases in which the American and Northwest ravens acted as the aggressors, and orange - those in which the common raven was the aggressor
Scientists also noted that most of the conflicts occur from March to May - that is, during the period of active nesting. The authors explain this by the fact that common ravens are characterized by nest predation, or kleptoparasitism: they prey on other people's nests, especially on the nests of American and Northwest ravens, which defend their homes and food by attacking. Conflicts were observed in another period, in particular - in winter: scientists suggest that this behavior is due to the desire to protect their habitat during the nesting period in advance.
According to scientists, their work shows how important observations made by ordinary observers can be for science: in this work, it was with the help of data provided by amateur bird watchers that it was possible to study the behavior of different species of ravens in North America and to find out the distribution and prerequisites of interspecific conflicts.
Crows are very smart animals, so their cognitive abilities are studied quite often. They, for example, are distinguished by the ability to distribute tasks and make plans for the next day, and also know how to recreate tools from memory.
