They migrate to the park every year. The species is classified as endangered by the International Union for Conservation of Nature (IUCN).
There are 219 species of birds in the park, mainly water birds, including more than 100 migratory species and species listed as endangered like the spoon-billed sandpiper, pelican, gull, and red-headed heron.
A flock of royal spoonbills search for food near a mangrove forest.
Every year, from November to April, Xuan Thuy National Park is home to tens of thousands of birds migrating southward.
Migrating to Vietnam, the royal spoonbills look for food in estuaries. Their food includes small fishes and other aquatic creatures.
This species is also found in North Korea, southern Japan and the eastern coast of China.
Xuan Thuy National Park has the largest population of royal spoonbills in Vietnam. Their maximum number for a year is 74.
The spoonbills choose this area to migrate to but do not nest here.
Ornithologists have also spotted some spoonbills in provinces like Thai Binh (northern Vietnam), Ha Tinh (central region), Dong Nai and Dong Thap (southern Vietnam).
According to conservation organization Birdlife International and the Hong Kong Bird Supervision Association, in 2011 there were 2,340 adult royal spoonbills in the world.
In addition to the spoonbills, the mangrove forest is also a shelter for many other migrating birds, many endangered and needing to be protected.