particles, lanes have been observed in more realistic systems where crowding effects are at play [@Farrell2012; @Schaller2010; @Schaller2011polar; @Kohler2011]. In our model, transversal (band) and longitudinal (lane) swarming patterns coexist in the MC regime. As we discuss below, we provide evidences that the pattern-selection process is controlled by the persistence of the particles, and propose a mechanism to explain why lanes generically appear in systems with excluded volume interactions. At high persistence and alignment, the heterogeneous structure of the system is dominated by the presence of bands (see Fig. \[fig:PhD\] (d)). By decreasing $\text{Pe}$, band structures become rarer while lanes continuously take over to finally dominate the low-$\text{Pe}$ regime (see Fig. \[fig:PhD\] (e,f) and supplementary movies [@SM]). In order to favor the formation of such structures and analyze their relative statistical weight as as a function of $\text{Pe}$, we simulate the model in a rectangular box $L_x=5L_y$. We postpone this discussion to section \[sec:cluster\].

Flocking {#sec:flock}
========

We focus now on the emergence of spontaneous polar order (flocking) as the normalized coupling strength $\text{g}$ increases. In this section we provide the details about the location (and nature) of the flocking transition (in red in Fig. \[fig:PhD\] (a)).

We characterize the 