<p>Anthropogenic disturbances pose significant threats to breeding habitats of birds, even from activities perceived as eco-friendly, such as casual birding. This study examined the negative impact of casual birdwatching and photography on the nesting patterns of a shorebird species, the Kentish plover (<i>Anarhynchus alexandrinus</i>), in South Korea. Field surveys were conducted in the Mangyeong estuary during the breeding seasons of 2020 and 2021. In 2020, the site remained undisturbed, with no human presence other than researchers and field managers, coinciding with active breeding by Kentish plovers. However, in 2021, increased casual birding activity coincided with the substantial unselecting of the site as a nesting habitat by the plovers. The number of nests in 2021 markedly declined compared to 2020. Our findings suggest that human disturbance can negatively affect Kentish plover breeding, but the influence of other factors should be comprehensively investigated in future studies. In light of this likely negative effect, a precautionary approach would involve effective management strategies, including protection, and clear guidelines to mitigate the impact of recreational activities on vulnerable bird populations.</p>