In the presence of clinical signs of disorders of the gastrointestinal tract, apteriosis and alopecia, excessive growth of microorganisms was established from the intestinal contents of birds. The article presents data on the dynamics of biofilm-forming microorganisms, Salmonella typhimurium and Candida albicans, identified in diseases of the digestive system of Psittaciformes. With a decrease in the compensatory mechanisms of mucocilliary clearance and colonization resistance of the organism due to the representation of quorum-sensing signaling molecules, an excessive growth of pathogenic microorganisms is observed. Population immobilization of the architectonics of a mature three-dimensional biofilm is mediated by intensive cell proliferation and the synthesis of exocellular molecules of the intercellular matrix. The orderliness and compactness of the multicellular heteromorphic structure of polyspecies biofilms depend on the degree of differentiation of the adhesive basal layer of a dense network of blastoconidia, hyphal and pseudohyphal forms, and gram-negative bacteria. Depending on the microorganisms' cultivation time, a gradual increase in the absolute optical density values of the tested specimens was established. When cultured for 18, 24, 48, 72, 96, 120, and 144 hours, the intensity of biofilm formation ranged from ≥0.1 to ≥0.4. © 2025, Unique Scientific Publishers. All rights reserved.