<p>Understanding the factors that shape the functional diversity of bird communities is essential for biodiversity conservation, particularly in agricultural landscapes that are experiencing rapid environmental changes. This study examines the effects of anthropogenic activities, climate, and habitat area on the functional diversity of bird communities within steppe agricultural ecosystems in the northwestern region of the Azov Sea in Ukraine. Utilizing long-term field surveys conducted from 1988 to 2018, along with geospatial modeling, we analyzed bird communities across seven distinct landscape types. Our findings suggest that agricultural expansion and habitat fragmentation, has a more pronounced impact on bird functional diversity than climate or habitat area. The functional diversity indices demonstrate long-term trends, with the majority indicating a decline throughout the study period. Socioeconomic transformations, particularly those associated with industrial and agricultural expansion post-1980s, have significantly contributed to this decline in functional diversity. The functional diversity indices can be categorized into four groups, each of which is sensitive to various aspects of trait-space distribution, species abundance, and niche differentiation. Trends in functional diversity correlate with species richness, while also offering additional insights into community structuring. Principal component analysis identified four independent processes that influence functional diversity, which are associated with habitat area and environmental filtering. It is important to note that an increase in habitat area does not universally lead to an increase in functional diversity; rather, responses differ by ecosystem type due to variations in edge effects, competition, and environmental filtering.</p>