Photo shows a male great hornbill bringing a berry to his mate while she nests inside a tree hole. (Photo provided by an interviewee)

This month, several wildlife photographers captured rare pictures of a great hornbill, a state-protected wild animal species, sealing up a nest cavity on a tree in Yingjiang County, southwest China's Yunnan Province.

These pictures are of extremely high value in China, compared with text descriptions on how this type of birds seal a tree hole to build a nest.

Yingjiang County is a major habitat of hornbills in China, a species with bright feathers and huge wingspan. When great hornbills fly, the powerful strokes produce a rhythmic thrumming.

The county is home to 710 bird species, where hornbill activities can be observed regularly. A well-organized team is now recording the activities, which consists of journalists, bird-watchers, ornithologists and staff members of local nature reserves. Local farmers have been helping them locate the birds, and offering assistance in logistics.

Yin Yihu is the photographer who recorded how the great hornbill sealed its nest. On March 4, the man, who works for a local media center in Yingjiang, also captured pictures of wreathed hornbill, another family of hornbills under the national second-class protection in China.

Later, together with local wildlife photographers, Yin captured images of three rufous-necked hornbills deep in a forest with an altitude of over 2,000 meters, including two males and one female.

In recent years, China has continuously improved the legal system and management of wildlife protection, further enhanced international cooperation on wildlife protection, vigorously promoted the protection of wildlife habitats, and launched massive in-situ and ex-situ conservation activities for wild plants. As a result, the country has put under protection 90 percent of vegetation forms and terrestrial ecosystems, 65 percent of macrophyte communities, and 85 percent of major wildlife populations. The populations of rare and endangered wildlife species such as giant pandas, crested ibises, Tibetan antelopes, Cycas revoluta and Davidia involucrata have recovered.