Complex Dynamics in Ecological Systems and Animal Behavior

This chapter is based on three contributions that illustrate recent progresses focusing mainly on the physics of active matter, on collective behavior of flocks of birds and on models in theoretical ecology. First, M. C. Marchetti discusses how key concepts developed to quantify the behavior of disordered condensed matter systems, from window glass to spin glasses, are impacting the physics of active matter. Second, I. Giardina reviews some of the main experimental findings that have been obtained along the years on natural flocks of birds, and we describe how, starting from experimental data, theoretical descriptions of their collective behavior have been developed. Finally, A. Altieri reviews some of the most used models in theoretical ecology along with appealing reformulations and recent results in terms of diversity, stability and functioning of large well-mixed ecological communities.