The noun prey is an uncountable noun, it has no plural form. The noun prey is a word for one person or thing, or many people or things.
The possessive form of the noun prey is prey's.
Examples:
The bear dug at the prey's burrow in search of a meal. (singular)
When the swindler was arrested, all the his prey's moneyhad been spent on luxuries. (plural)
Singular possessive: secretary's Plural: secretaries Plural possessive: secretaries'
The plural is relatives. The plural possessive is relatives'.
The plural is lads. The plural possessive is lads'.
The plural form is Mexicans. The plural possessive is Mexicans'.
The plural form is echoes. The plural possessive is echoes'.
The plural form is suffixes. The plural possessive is suffixes'.
The plural form is stepsisters. The plural possessive is stepsisters'.
The plural form is inches. The plural possessive is inches'.
The plural possessive of "Father" is, "Fathers"
Studies' is the plural possessive of study.
The plural possessive of bandit is bandits'.
The plural possessive is pals'.