Other Supplementary Material for this manuscript includes the following:

• movie S1 (.avi format). Experimental movie for the gas-like state at frequency f = 20 Hz.
  
• movie S2 (.avi format). Experimental movie for the flocking state at frequency f = 30 Hz.
  
• movie S3 (.avi format). Animation of the experimentally obtained flocking state at frequency f = 30 Hz, where the direction of motion is indicated by the color code.
  
• movie S4 (.avi format). Experimental movie for the vortex state at frequency f = 40 Hz.
  
• movie S5 (.avi format). Animation of the experimentally obtained vortex state at frequency f = 40 Hz, where the direction of motion is indicated by the color code.
  
• movie S6 (.avi format). Experimental movie for the reentrant flocking state at frequency f = 50 Hz.
  
• movie S7 (.avi format). Animation of the experimentally obtained reentrant flocking state at frequency f = 50 Hz, where the direction of motion is indicated by the color code.
  
• movie S8 (.avi format). Experimental movie for the gas-like state at frequency f = 60 Hz.
  
• movie S9 (.avi format). Numerically obtained gas-like state at frequency f = 6 Hz, indicating the direction of motion by the color code.
  
• movie S10 (.avi format). Numerically obtained flocking state at frequency f = 20 Hz, indicating the direction of motion by the color code.
  
• movie S11 (.avi format). Numerically obtained vortex state at frequency f = 47 Hz, indicating the direction of motion by the color code.
  
• movie S12 (.avi format). Numerically obtained reentrant flocking state at frequency f = 88 Hz, indicating the direction of motion by the color code.
  
• movie S13 (.avi format). Numerically obtained vortex state, considering hydrodynamic interactions, at frequency f = 47 Hz, indicating the direction of motion by the color code.