Corvidae

Corvidae is a cosmopolitan family of passerine birds that includes crows, ravens, rooks, magpies, and jays, among others, totaling 139 species. The genus Corvus, with 50 species, comprises over a third of this family. Corvids are known for their remarkable intelligence, showing self-awareness and tool-making abilities, comparable in brain-to-body mass ratio to non-human great apes and cetaceans.

These medium to large birds have strong feet and bills, occurring worldwide except in the southern tip of South America and polar regions. Most species thrive in tropical regions, with a few in Africa and Australasia. Corvids are primarily sedentary, though they may migrate in search of food, forming large flocks in the fall.

Crows often have overlapping breeding territories, allowing for increased local population density compared to ravens. While it was suggested that human development might lead to higher nest predation by crows and magpies, studies show that these species do not significantly impact smaller bird populations compared to other factors like habitat destruction.

Corvids, such as jackdaws, exhibit strong social hierarchies and often display mutual aid within their communities. Young corvids engage in social play, participating in games like “king of the mountain” and manipulating sticks, which aid in their survival skills. Mate selection is complex, involving tests of aerobatic skills.

While some corvids, like blue jays, can be aggressive, most exhibit an omnivorous diet that includes invertebrates, fruits, and human food. They often form foraging flocks in winter and can prey on agricultural pests.

Corvids are territorial, with some species nesting communally. They typically have strong, often lifelong bonds, building large nests together. Female corvids usually lay 3 to 10 eggs, which they incubate with the help of the male. Parental care varies, including bi-parental and cooperative breeding, where relatives assist in raising young.