The chapter introduces the theoretical development of understanding how territorial behavior influences habitat distribution in birds. The authors, Stephen Dewitt Fretwell and Henry L. Lucas, Jr., aim to clarify and resolve conflicting views on the role of territorial behavior in species dispersal. They present a theoretical framework that defines key concepts such as ideal free distribution and Allee-type ideal free distribution. The chapter outlines three hypotheses regarding the impact of territorial behavior on habitat distribution: the density assessment hypothesis, the density limiting hypothesis, and the spacing hypothesis. These hypotheses are derived from broader considerations of factors affecting habitat distribution, including overcrowding and evolutionary optima. The authors plan to test these hypotheses through field observations and provide sample studies in subsequent papers.The chapter introduces the theoretical development of understanding how territorial behavior influences habitat distribution in birds. The authors, Stephen Dewitt Fretwell and Henry L. Lucas, Jr., aim to clarify and resolve conflicting views on the role of territorial behavior in species dispersal. They present a theoretical framework that defines key concepts such as ideal free distribution and Allee-type ideal free distribution. The chapter outlines three hypotheses regarding the impact of territorial behavior on habitat distribution: the density assessment hypothesis, the density limiting hypothesis, and the spacing hypothesis. These hypotheses are derived from broader considerations of factors affecting habitat distribution, including overcrowding and evolutionary optima. The authors plan to test these hypotheses through field observations and provide sample studies in subsequent papers.