Life on the planet depends primarily of the co-dependent relationship between all living creatures. There is no living organism in the universe that can exist in complete exile from other species without somehow interacting with them, would it be on the surface, in the water, or in the air. In addition, the social interactions are also vital for each representative of particular species. This paper aims at gathering information about the interactions of the Common Raven with other bird species. Based on the results of four different studies from scholarly periodicals presented in this work, this paper would show the social aspect of life of Common Raven and underline the specifics of its existence. This paper goes through each study separately, describing the methodology and the research results. It finally concludes with the results of interactional lifestyle of the Common Raven with other bird species.
Study by Bertran, J. and Margalida, A.
According to the previous researches in this field the specie of a Common Raven populates most of the planet. Common Raven is extremely adaptive to mostly any conditions, and always finds a way to nest and feed performing somewhat parasitic and predatory activities to survive. The researchers correlate such a pattern to high cognitive abilities these birds, coupled with their ability to learn from observation and experience. Knowing these facts, Bertran and Margalida (2004) have tried to identify, in their study, the behavioral patterns of the Corvus Corax in correlation to Bearded Vultures (Gypaetus Barbatus), which are both nesting in the same sites. The reason to study their interaction is that the scientists state, “The Bearded Vulture Gypaetus Barbatusis a solitary, osteophagous vulture, which is considered as an endangered species in Europe”. The scientists identified that the two species had different patterns of feeding: the Bearded Vulture always stores the food in visible places, where it can be easily reached, whereas the Common Raven is known to lead a parasitic lifestyle.
The aim of their study was to study the behavior of these two species specifically focusing on the nesting period. For their behavioral observation, the researchers have identified an area of 3750 squared km. The scientists specifically focused on the behaviors which occurred around the nesting sites. Bertran and Margalida (2004) observed 10 specific nesting sites for the presence of any aggressive interactions between the Bearded Vulture and the Common Raven. They have been further analyzing the gathered data using non-parametric statistical tests.
The researchers have recorded the total of 158 aggressive encounters. According to the results, The Common Raven is more likely to initiate interspecific aggressive behavior, having scored 83 attacks (52, 5%), than the Bearded Vulture, with the result of 75 attacks (47, 5%). The scientists also indicate that the attacks did not correlate with the kleoparasitic attacks (attempts to steal storages of food), nevertheless most Raven initiated attacks occurred at the moment when the Vulture was manipulating the prey. Following the research, the scientists conclude that the aggressive interactions between Corus Corax and Gypaetus Barbatusis occur for two main reasons: defense of the nesting site by the Vulture, or attacks related to prey by the Ravens.
Study by Brambilla, M, Rubolini, D., and Guidali, F.
According to the recent data, the population of the Peregrine (Falco Peregrinus) has decreased dramatically in the last few decades. The main cause of this event is the use of organichlorine pesticides in agriculture. Followed by a steep decrease in population of the Peregrine, these birds are on the edge of becoming an endangered species continuing to decrease in number by the day. The scientists believe that the causes for this might be the rock-climbing human intrusion into the nesting areas on the cliffs where these birds nest that “cause of temporary or definitive nest abandonment by Peregrine pairs” (p. 426), and the clash with Raven, which also breeds in these areas. According to the researchers, even though the Peregrines are the dominant species while settling, “Ravens are opportunistic predators, and may represent a potential threat for Peregrine reproduction: in fact, they have been reported as preying on eggs or chicks when parent falcons are away from the nest”.
In their study, Brambilla, Rubolini and Guidali (2004) investigated whether the recreational activity and interaction with Ravens affect the reproduction cycle of the Peregrines in the cliff areas. Their hypothesis was that these two events occurring simultaneously at the same spot would affect the reproduction of Peregrines dramatically. In the course of the study, the researchers analyzed the area of 2100 square kilometers on the altitude between 190 and 2400 meters in the Peregrine breeding sites in the period February through March studying each separate pair carefully and monitoring them until the end of June, along with the occurrences of Raven pairs and the intrusion on the rock climbers. The results had shown 3 types of patterns: the breeding was at the highest level with pairs of the control group pairs; slightly lowered at nesting areas with availability of one of the variables; none of the 5 pairs would bread progeny. This data proves the initial hypothesis, “nest abandonment is more likely to occur at the beginning of the breeding season, during territory settlement and egg laying, in accordance with theories of parental investment”.
Study by Brown, B. T., Truman, D. G., Jones, L., and Sharp, T.
Ravens are amazing creatures, which are not only intelligent, but also brave and insolent enough to coexist with such raptors as Bald Eagle (Haliaeetus Leucocephalus). Brown, Truman, Jones and Sharp (2006) have been studying the winter roost of Bald Eagles. The findings were indicated as anecdotal, indicated that during the winter season the Bald Eagles were noted roosting with Golden Eagles (Aquila Chrysaetos), some other raptors, and Common Raven (Corvus Corax). According to the previous studies on this topic, the Bald Eagles were recorded roosting along other bird species’ areas rarely; thus indicating, “little systematic information on interspecific use of Bald Eagle roosts in available”.
Brown, Truman, Jones, and Sharp (2006) studied a 22 kilometers long area in the southeastern shore of the Great Salt Lake in the Northern Utah. his area featured a rather flat terrain with open farmlands, rarely having trees at disposition, intersecting with rural and suburban areas, electric lines, and industrial sites. The researchers were counting the total of 280 bird’s roosting through binoculars during the period November through March, 2 nights per week. The scientists were recording the number of birds of each species, their proximity to the Eagles. According to the results, the Ravens have been the most numerous in sharing the night winter roosting with Eagles. The Ravens have also been the most proximal birds to the Eagles situating as near as 5 meters.
Study by Tryjanowski, P.
This study indicates that Ravens affect not only the habitat of raptors, but also those of small birds, as well. Tryjanowski (2011) had been working on correlating the proximity of Common Raven nesting and the breeding patterns of small birds in the farmland. The researcher hypothesized that small birds avoid nesting in the areas close to the Common Raven nesting on electric pylons in farmland areas, due to hazard that Ravens would attack the nests of other birds as they breed when Ravens are already feeding their progeny. The data for the research were gathered during the breeding season in the cereal and sugar beets fields in Western Poland with common power lines. The scientist took into consideration the proximity of the nesting of other birds, their breeding, and the interactive behavior of Ravens and other birds in these areas.
The researcher had recorded 27 bird species close to those of Ravens out of 31 species in total, which was statistically insignificant. According to Tryjanowski (2001), “the main factor affecting the number of species was habitat diversity while the presence of ravens and the times of census were not important”. During the censuses, there was marked 984 pairs which bread. Contrary to the hypothesis, such species as Skylark (Alauda Arvensis), Yellow Wagtail (Motacilla Flava), Corn Bunting (Miliaria Calandra), and Yellow Hammer (Emberiza Citrinella) were the most numerous out of those who breed closely to the Raven. In addition, the presence of Raven nesting affected the breeding process of the Skylar in a positive way, which disproves the researcher’s hypothesis.
To conclude based on the recent research in the field of ornithology, this paper has researched the interactions that occur between the species of Common Raven with other raptors and other bird representatives. According to the research above, being extremely adaptive species, the Common Raven co-exists with both vultures and herbivorous birds. Based on the studies, the most striking finding is the fact that the Common Raven acts aggressively with other raptor birds more often than with small birds. Ravens represent the parasitic species that live more harmoniously with the small birds rather than with other raptors due to the need to defend their habitat, progeny and fight for food, which explains their aggressiveness.