How Many 'Painters' Capture the Evening Glow of Ulsan Taehwagang?

Ulsan City and Biodiversity Center: "74,800 Rooks This Year"

Photographed Rook Flocks from Five Nests Between January 17 and February 26

World's First Use of Program Counting Individuals in Photos

How many rook flocks paint the winter sunset of Ulsan Taehwagang with a fantastic picture?

Ulsan City and the Ulsan Biodiversity Center announced on the 28th that the number of rook individuals visiting Taehwagang in winter was identified as a maximum of 74,810 and a minimum of 47,220 through five surveys conducted from January 17 to February 26.

According to the trend of decreasing rook numbers visiting Taehwagang, Ulsan City and the Center conducted the survey using a program that counts individuals from photos after consulting experts.

Example of a photo used for estimating the number of rook populations. [Image source=Ulsan City]

A monitoring agent investigating the number of rook populations.

Thirteen people, including Ulsan City's winter migratory bird monitoring personnel and photographers, formed four teams to conduct the survey.

The survey method involved taking photos every 5 seconds at dawn when the rooks leave their nests at the grassy field of Samho Migratory Bird Park in Nam-gu, Ulsan, and the soccer field in Taehwa-dong, Jung-gu, and then counting the number of rooks in the photos using the program.

The survey results showed 74,810 individuals on January 17 and 73,112 on January 24. Additionally, 50,496 on February 7, 47,220 on February 17, and 49,392 on February 26 were recorded.

Dr. Kim Seongsu (ornithologist), who surveys the number of rooks in Taehwagang every year, explained, “The data from January and February are trustworthy as they are scientifically derived through photos and computer programs.”

Dr. Kim said, “This survey produced results by choosing a method not attempted anywhere else in the world because Ulsan City has exceptional interest and affection for rooks.”

An official from Ulsan City said, “Although the survey method differs from that conducted by the National Institute of Biological Resources under the Ministry of Environment, so the numbers may vary, this confirmed that Ulsan Taehwagang is the largest rook wintering site nationwide. When the rooks arrive in November this year, we will base our efforts on this survey experience.”

The National Institute of Biological Resources under the Ministry of Environment conducts a simultaneous winter migratory bird survey once a month by visually observing the time when rooks return to their nests at Taehwagang. This survey recorded 89,320 rooks visiting Taehwagang in 2022 and 70,448 in 2023.