Extreme cold snaps are threatening lives of birds in northeastern China's Heilongjiang Province, and local zoologists called for actions from local residents to help birds survive the current harsh winter days.

Xu Qing, an associate professor with the school of wild animal resources under the Northeast Forestry University in Harbin, said approximately 30 species of birds winter in the provincial capital every year. Some of them live on cereals and weed seeds, and others on insects in tree barks.

"Continuous heavy snowfalls covered food for birds. And it's extremely cold this winter. It's hard for birds to survive it," said Zhao Xianbo, head of the wild animal rescue station under the municipal forestry bureau.

"If a sparrow has no food to eat for two or three consecutive days, it will probably die," Zhao added.

This winter saw an obvious decrease in the number of birds in Harbin, according to local residents. Some of them even saw birds die in flocks, but no official number of the deaths is available now.

Zoologists suggested local residents help clear accumulated snow from woods, gardens and lawns and set up some feeding places there for birds.

Heilongjiang is famous for its coldness in winter. This winter has seen temperature fall to a record of minus 40 degree Celsius in the northern part of the province.