The order Tinamiformes is unique to Latin America and is represented by 47 species found from northern Mexico to Tierra del Fuego. Throughout their range they are commonly referred to as "partridge" due to their similarity to Galliformes (partridges, quails, pheasants, etc.) in morphology and behavior. The tinamous, however, are most closely related to the ratites (rheas, ostrich, etc.) being an excellent example of convergent evolution, and in austral South America ecologically replace the Galliformes.
Tinamous are found in a wide range of habitat types including dry and moist tropical forests, grasslands, savannas, and deserts. Where tinamou distributions overlap with galliform distributions they are are mainly forest dwelling species. Furthermore, distributions of several tinamou species often overlap, suggesting complex inter- and intra-taxa ecological segregation among species.
Most species are sexually monomorhic, both the males and females have the same appearance. Females, however are usally considerably larger. The increased size of females is related to the mating system of tinamous which is in most cases polyandrous. In polyandry the female mates with multiple males, sometimes sucessively with one male at a time or with multiple males concurrently, and the male incubates the eggs (depending on the species clutches range from 1 to >12 eggs at a time but usally have 4-7 eggs) and rears the chicks. Subsequently, the female is free to invest a relatively high proportion of energy into egg production, which is increased through increased body size. Additionally, females are likely larger because the threat of being detected by predators while incubating eggs is no longer an issue, which leads to selection for larger body size. This has important implications for population dynamics since theoretically, reproductive output can be higher than polygenous or monogamous systems.
Tinamous are some of the most commonly harvested bird species by subsistence hunters in the New World due to their terrestrial habits and relatively large size (0.43 kg-1.8 kg). Moreover, in regions where there is sport and commercial harvest they are primary targets. Despite the importance of tinamous as game birds, their diversity, extensive distribution, and that a relatively high proportion of species are listed as threatened and endangered, little is known of their biology.
