The population of game ducks at the eastern lake contains a higher percentage of nonadult game ducks than the population at the western lake contains. Adult female game ducks outnumber nonadult female game ducks in the eastern lake's population. The population of game ducks at the western lake contains a lower percentage of adult males than the population at the eastern lake contains. The total number of male game ducks is higher in the eastern lake's population than in the western lake's population.
A population of game ducks at a western lake contains 55 males to every 45 females, while a population of game ducks at an eastern lake contains 65 males for every 35 females. Among those ducks that have not yet bred there are only slightly more males than females, but among older ducks the number of males greatly exceeds the number of females. Because there are appreciably more males among adult ducks than among young ducks, we can infer that the greater the disparity in overall sex ratios, the greater the percentage of older male ducks in the population.
Which one of the following can be inferred from the passage?