Nouns with same singular and plural forms and also takes a plural ending (-s).

Singular  Plural  Singular  Plural 
boar boar / boars reindeer reindeer/ reindeers
buck (animal) buck / bucks roe roe/roes
Eskimo Eskimo / Eskimos Sherpa Sherpa / Sherpas
Karen Karen / Karens shrimp shrimp / shrimps
mackerel mackerel / mackerels  trout trout / trouts
quail quail / quails whale whale / whales