- Sep 2024
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academic.oup.com academic.oup.com
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However, because crows and ravens co-occur across the vast majority of North America, rigorous comparisons of habitat use may be challenging to undertake. Both crows and ravens have increased in population size and distributional extent within the last century as a result of land use changes and diminishing persecution from humans
Another reason for the crows behavior towards the ravens could very well be a simple “winner takes all” scenario, in which the stronger of the two groups beats out the other as a means of securing their increasingly dwindling territory, food sources, mating spots, and other environmental factors.
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We found strong seasonality overall in crow attacks on ravens. The majority of instances of American Crows attacking ravens took place between March and May (Figures 2–4), which corresponds to the breeding season of crows in most places in North America
This may provide some insight behind why this aggressive behavior takes place. It could be both territorial as well as pre-emotive protection of their mates as well as their young(?). It could also be an increase in aggressive behavior due to the increased agitation in the mature crows, perhaps frustration?
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Aggressive interactions between crows and ravens in North America were highly asymmetrical; crows were the aggressor in nearly all (∼98%; 1,964 of 2,014) contests between these congeners.
This portion sums up the findings of the study rather well, and emphasizes the understanding that crows (both larger in size and highly complex social creatures) acted as the aggressors in majority of the cases, leading us to believe that they are the more dominant species when it comes to conflicts.
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1) the aggressors outnumbered the target of aggression (“strength in numbers”), (2) equal numbers of aggressors and targets of aggression (“fair fight”), and (3) the targets of aggression outnumbered the aggressor (“outnumbered”). We were able to assign observations to 1 of these 3 categories in 1,704 of the 2,014 instances (852 observations that noted the precise numbers of crows and ravens involved in the interaction, and 852 additional observations that described a flock of crows and a solitary raven involved in the interaction).
This breakdown of classical aggression tactics I believe helped mitigate the lack of individual-specific behaviors being observed. I also think it highlights the fact that within the crow social circle there are both hierarchies as well as the fascinating (albeit strange) existence of clique-like behavior and tag-teaming to agitate or attack other birds.
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y interspecific aggression between crows and ravens. To counteract this small sample size problem, we turned to citizen science. Specifically, we compiled a data table of aggressive interactions between crows and ravens from eBird. eBird is a citizen science program to which participants contribute bird abundance and distribution data by uploading checklists of species that they have observed at a specific location at a particular date and time
The fact that they managed to outsource their information to get a much more accurate comparison I feel helps strengthen the study overall. Being able to compare a larger sample sizes behavior over a longer period of time allows a better grasp over what is “normal” behavior and what can be classified as “aggression” towards other species.
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