Low pathogenic avian influenza viruses circulate in wild birds but are occasionally transmitted to other species, including poultry, mammals, and humans. To date, infections with low pathogenic avian influenza viruses of HA subtype 6, HA subtype 7, HA subtype 9, and HA subtype 10 among humans have been reported. However, the epidemiology, genetics, and ecology of low pathogenic avian influenza viruses have not been fully understood thus far. Therefore, persistent surveillance of low pathogenic avian influenza virus infections in wild birds and other species is needed. Here, we found a low pathogenic avian influenza virus of the subtype H13N2 (abbreviated as WH42) in black-tailed gulls in China. All gene sequences of this H13N2 virus were determined and used for subsequent analysis. Phylogenetic analysis of the HA gene and NA gene indicated that WH42 was derived from the Eurasian lineage. We analyzed the timing of the reassortment events and found that WH42 was a reassortant whose genes were transferred from avian influenza viruses circulating in Asia, Europe, and North America. Additionally, WH42 possessed several molecular markers associated with mammalian virulence and mammalian transmissibility. Interestingly, we also found low but detectable hemagglutination inhibition antibodies against H13N2 low pathogenic avian influenza virus in serum samples collected from chickens. Taken together, our findings show that the H13 virus may have been introduced into poultry and that sustainable surveillance in gulls and poultry is required.