Highlights
1.Twenty one H13 subtype avian influenza viruses were isolated from 50016 samples in migratory birds during 2017 to 2024 in Shandong Province, China
2.The H13 viruses were mainly harbored by shorebirds (gulls) and exhibited considerable genetic diversity
3.Extensive gene segment reassortment between H13/H16 like viruses and other subtypes were observed