Collective groups such as bird flocks, fish schools, and insect swarms are systems that regulate their activities without central control.  This unique quality of collective behavior makes collective groups more resilient to failures or removal of any of their parts compared to systems that operate on centralized control.  Thus, there is recent interest in exploiting emergent collective behaviors for decentralized engineering systems, and with this interest, a growing need to understand the structures and precise properties of collective groups, which remains a challenge.

This dissertation addresses some of the open questions in collective behavior by studying two archetypes of collective groups: the disordered swarms and the ordered flocks.  First, we examined how individuals in mating midge swarms (C. riparius) sample the space available to them by using Voronoi tessellation to define different regions of the swarm in a dynamic way.  Next, we conducted field experiments to investigate the response of transit flocks of jackdaw (C. monedula) to impulse perturbations.  Finally, we applied the thermodynamics framework, previously developed to extract an equation of states for insect swarms, to arrive at an empirically-determined equation of states for bird flocks.