Ducks Pick Ducks

Rand did a big study of how the different US armed forces recruit and promote their general officers, particularly what are the features of each one's culture.  I skimmed it, finding it interesting, with some resonance with the differences in the cultures of the different USDA agencies I once knew.  

I hadn't run across the saying in the title before, but it makes sense.  It explains a lot of patterns in the bureaucracy.  A paragraph:

 “Ducks pick ducks.” We were unable to obtain data on exact compositions and backgrounds of promotion board members in order to compare them with the backgrounds of the candidates they ultimately chose for promotion. But we heard repeatedly from interviewees in each service that there is a tendency for promotion boards to select officers whose career experiences are comparable to their own, and for senior officers to select officers with backgrounds similar to theirs for aide jobs, positions that serve as a signal of O-7 potential to board members and can provide access to powerful networks of G/FOs. We also observed this trend in the SLSE. The notion of “ducks picking ducks” serves to cyclically reinforce service culture by perpetuating the selection of officers who similarly reflect service goals and preferences. As far back as World War II, Morris Janowitz wrote about the propensity of senior military leaders to fill their staff roles (e.g., military assistant or executive officer) with people who could “speak the same language.”582 However, this observation does not mean that the officers who are selected for promotion by similar, more senior officers are necessarily less qualified; it is possible that the “ducks pick ducks” tendency in some cases occurs because well-qualified officers sitting on promotion boards are selecting for other wellqualified officers.