"These are three pigeons."

Translation: ये तीन कबूतर हैं।

[justusbalentine]

कबूतरें isn't plural pigeon?

[Zesul]

Nope. Masculine nouns that end in a consonant do not change on pluralization (so long as they are in direct case). कबूतरें would have been correct had कबूतर been feminine.

[clintack]

Huh. Someone ought to tell the dropdown hints that.

[ElaBader]

कबूतरों is the plural version in the oblique case only. The plural form when acting as a subject remains the same as its singular form; कबूतर.

You'll notice that even in your original question, you wrote the feminine plural ending (for words ending in a consonant), not any masculine plural ending.

औरतें, for instance.

The masculine ending, as far as i know, really only changes when the subject ends with आ, and it'll change to ए.

लड़के, for instance.