A flock of egrets fly over Ninghai Bay in Ningbo, East China's Zhejiang province. [Photo/cnnb.com.cn]

Thousands of migratory birds including ducks, egrets and swans recently arrived in Ninghai Bay, Ningbo, East China's Zhejiang province.

They arrived about a month earlier than usual and in larger numbers than last year, according to an official from Qiangjiao town, Ninghai county.

The changes have been largely attributed to increased environmental conservation efforts by the local authorities in recent years.

Ninghai Bay is situated in the middle of the migration route between East Asia and Australia.

In spring and autumn every year, a large flock of migratory birds will stop at the bay for roughly a week to forage. A few never end up leaving. 

Night patrols are being carried out in the wetlands around Ninghai Bay regularly to protect the visiting birds.

A flock of wild ducks forage near Ninghai Bay in Ningbo, East China's Zhejiang province. [Photo/cnnb.com.cn]