The present publication is designed to arrange diverse areas of environmental biology in a coherent manner. The publication includes Light and Temperature, Environmental Factors, Seasonality in Vertebrates, Environment and Reproduction, Seasonality Mares, Cyclic Changes, The Influence of Light on Ovulation in Birds, Influence of Temperature, Influence of Radiation, Effects of Chemicals, Influence of Environment in Birds, Influence of Environment in Mammals, Influence of Environment in Lower Vertebrates, Influence of Environment in Invertebrates. The subject matter, both as regards the arrangement of chapters as well as contents is designed to meet the requirement of the student in several Indian universities.