Eibl-Eibesfeldt's Ethology, the Biology of Behavior (second edition, 1975; in English) is a masterpiece in describing and summarizing classical ethology. That work, literally, gave me life. No better work exists still to this day on classical ethology (the ethology that correctly uses ALL the terminology of ethology and uses it all in the best ways). If you want to learn the biology of behavior (behavior per se), this is your best source (especially the first half of this book, esp. pp. 1 - 215). I will forever remember Prof. Dr. Irenaus Eibl-Eibesfeldt very fondly and with the greatest admiration and greatest respect. A bit more on E-E's Ethology, The Biology of Behavior: from this you learn how a real behavior pattern is recognized through and by discovery AND, by the way, you will SEE that ethology DOES NOT LEAD ONE TO THINK LESS ABOUT LEARNING OR see/find less learning, but actually the very opposite: you see more learning and more types of learning. This is very, very contrary to some ignorant definitions of ethology given nowadays.
I believe there is no way you could read Eibl-Eibesfeldt's Ethology, the Biology of Behavior, and fail to be filled with admiration and with the hope engendered by imagining the promise of classical ethology, and want to bring the "life" back -- the empirical nature and the quality of which nowadays is NEVER matched.