"The elephants are big."

Translation: हाथी बड़े हैं ।

[This_is_Roshan]

Why isn't the plural form हाथीयाँ? And why isn't हाथी treated as a feminine noun, despite ending with "ी"?

[vinay92]

हाथी is a masculine noun. Whatever rules you might have read to predict noun-genders based on word endings are only rough guidelines and all of them have many exceptions. My suggestion is that any time you come across a new noun, learn it along with an adjective (like बड़ा कुत्ता, बड़ी बिल्ली). This helped me a lot while learning French.

The plural form '-iyan' is only for feminine nouns ending with -ī. Since हाथी is masculine, its plural form remains हाथी

[SanKahmei]

Can't we used 'bari here as well instead of 'bare'?

[vinay92]

No, because हाथी is a masculine noun.