Wolf (3) presented measurements of humerus, ulna, carpus, femur, tibiotarsus, tarsometatarsus. Cassin's Sparrow has relatively long legs compared to other sparrows in the genus Peucaea.
Mean testis size: 4.99 g (n = 12; mean body mass of sampled birds = 18.2 g) (27). Testis size is relatively small compared to body size, the smallest testis/body ratio of 19 North American sparrows. Four species with smallest ratios were all in xeric grasslands (27).