Getting a Copy of Animal Behavior: An Evolutionary Approach 10th Edition
The textbook by John R. Krebs and Nicholas B. Davies is the standard graduate-level reference for ethology courses. The 10th edition came out around 2017 and covers game theory in mating systems, optimal foraging models, signal detection theory, and kin selection with updated empirical examples. Finding a legitimate copy usually comes down to checking your university library hold system first, then looking at the publisher or academic resellers if you need your own physical book. When people search for this title they are usually students who need it for a class and want something fast. The honest answer is that the 10th edition is still under copyright, so pirated PDFs circulate on torrent sites and random file hosts, but those carry malware risk, broken pages, and no access to the online resources the publisher bundles. If you just need to read the material, your university library likely has an electronic reserve link through platforms like VitalSource or CourseReserves, which gives you a time-limited reading copy for a semester at no extra cost. That is the route I usually suggest because it actually includes the chapter quizzes and the image bank. I ran into a specific issue last year when a student was using a scanned PDF from a sketchy site for my seminar. The figures on optimal foraging models were compressed to the point where the isodar graphs were unreadable, and page numbering didn't match the citation style the professor required. They lost two days trying to locate the correct figures in the printed version. The fix was straightforward: I had them check the library's EBSCO or ProQuest e-book license, which pulls the publisher's official ePub with proper vector images. It takes about three minutes to log in with campus credentials and the chapters load correctly on any device.
Some programs use an older edition. Before you spend money or time looking for the 10th, verify with your syllabus which edition your instructor actually requires. The 9th edition covers the same core frameworks, but the sections on sexual selection have revisions and the kinship chapters include newer work from the Hamilton rule literature. Mixing up editions causes confusion when the page references in lecture slides don't line up with what you are reading. If you buy the physical copy, used copies run between forty and eighty dollars on major marketplaces, while the new retail price sits closer to two hundred dollars. The eBook license from the publisher runs around one hundred and twenty dollars, which is steep for a single semester. A few professors allow students to share a single institutional license, so check with your department before buying anything outright. The content itself is dense. Krebs and Davies assume you are comfortable with basic calculus and have taken an introductory statistics course. The derivations in the optimal foraging chapters move quickly. I remember grading papers where students cited the marginal value theorem incorrectly because they skimmed the math without working through the example problems. The book does not walk you through every algebra step, and that is a known gap. You will get more out of it if you keep a notebook and redo the derivations alongside the text.
One thing beginners consistently miss is that the game theory chapters are not just about animal conflicts. The same repeated Prisoner's Dilemma framework applies to human negotiation studies, cooperative breeding models, and even some economic behavior papers. The book treats these as applications, but the underlying logic is identical. If you understand the ESS concept properly, you can apply it across disciplines without relearning the math. The downside of this textbook is that it is very theory-heavy. If you want a descriptive field guide to species behaviors, you will be frustrated. It is meant for analytical students who want to build models, not for casual readers looking for anecdotes about animal intelligence. For that audience, Robert Sapolsky's work or David Attenborough's field notes serve better. The Krebs and Davies volume is not a beginner text, and it should not be bought as one. There is also the issue of rapid change in the field. The 10th edition is several years old now, and some of the case studies on bird song learning and predator recognition have been updated or contested in recent literature. The foundational models remain sound, but if you are citing this for a thesis, you should pair it with at least a few current journal articles to make sure your references reflect the latest findings.
Get the Full Details
If your university does not provide electronic access and you cannot afford the retail price, the next best route is to request an interlibrary loan. Most academic libraries will pull a copy from a neighboring institution within five to ten business days. It is slower than having the book in hand, but it is free and legal, and the physical copy will have the full resolution images your professor expects. Check your course reading list first. Sometimes the instructor uses specific chapters rather than the entire volume, and the library may only need to acquire those sections through a course reserve. That cuts down wait time significantly and reduces the licensing burden on the institution. The 10th edition remains the go-to reference for graduate-level animal behavior courses because it balances mathematical rigor with empirical coverage better than competing texts. Just make sure you are accessing it through a legitimate channel so you get the complete, correct version with the figures intact.
