Avian migration is a challenging journey that is subject to sudden storms, vast bodies of water and the risk of losing direction.

Climate change has made this situation worse, especially with record-low temperatures in northern China this winter.

In early November, a snowstorm struck more than 100 Oriental white storks in Changchun, the capital of Northeast China's Jilin province, during their southward migration. The birds are classified as first-level protected animals in China.

As the storm passed, most of the storks continued their journey, except for 11 birds who were too exhausted to fly on.

On Nov 16, staff members from the local forestry and grassland bureau transported these birds to the Qilihai wetland in Tianjin, where they joined others migrating to the area. The 11 storks are in good condition in their natural habitat, the bureau said.

Oriental white storks usually leave their breeding grounds in Northeast China for the warmer south in September or October, returning north in spring.

By Nov 24, about half the migratory birds in China had completed their journeys and reached coastal areas in eastern and southern parts of the country for the winter, the National Forestry and Grassland Administration said.

At that time, cranes and storks were experiencing a second migratory peak, the administration added.

The China Meteorological Administration said the increasing frequency of extreme weather events, rising sea levels, disappearing wetlands, and record temperatures are having adverse effects on avian migration.

Severe drought, wind and temperature drops, and wildfires that force birds to alter their routes are contributing to migratory difficulties.

Without the ability to replenish their energy and rest in areas along their route, birds may struggle to reach their habitats safely, the administration said.

In late summer 2020, wildfires and an early snowstorm are thought to have played a major role in causing a huge number of deaths among migratory birds throughout the west of the United States.

An essay published in the journal Geo-Health in 2021 said a laboratory report showed that the birds were severely emaciated.