Along Beijing’s major thoroughfares such as Chang’an and Qianmen, it’s not uncommon to spot flocks of crows in the early evening. These crows tend to rest on buildings and in trees through the night, and fly away in groups in the morning. Many curious locals and visitors have pondered where the crows come from and how there are so many.

For ages, and throughout a variety of cultures, crows have been stigmatized as a bird of bad luck. They are commonly seen as pests, and find few admirers. In rural areas, they destroy crops in the fields and fruit in the orchards, and in the cities, they disturb residents, especially in winter. When night falls, most crows perch on porches and rooftops, breaking the silence with their bothersome cawing. Scavengers of rotten meat by nature, the birds are adept at spreading disease, and their excrement in bulk can be utterly devastating.

Over the past few years, I’ve investigated the origins of these crows. In Beijing’s suburban areas, there are plenty of fields and wetlands – the ideal home for these birds. They scavenge for food and water during the day and like to spend the night in urban areas because it is warmer, and trash along the roadsides provides ideal late night snacks.

Guo Geng, a specialist in wild animal protection, believes that the rise in crow numbers is related to environmental issues. “Crows are natural city sweepers,” he explains. “Rats, harmful insects, and spoilage are their food – making them a fascinating link on the urban food chain.” It goes without saying that large flocks of crows are extremely troublesome city dwellers, so their infestation becomes a major concern for many metropolitan residents around the world.

Actually, crows are quite intelligent compared to other species. One of their characteristics is strict, lifelong monogamy in mating. Child-raising is a shared responsibility for both genders, which follow the rules of regurgitation-feeding. They even look after their elderly.

Overseas scientific research shows that the sensory ability of the crows is on a par with some primates, ranking them the most intelligent of avian species – even smarter than talking parrots.