I have read that in Italian, the words maschio and femmina can be used as adjectives after the names of animals to specify that an animal is male or female, and that these adjectives are invariable in this context, so a singular feminine noun still takes maschio (like la giraffa maschio) and a single masculine noun still takes femmina: Modern Italian Grammar: A Practical Guide,
But maschio and femmina don't seem to always be invariable between singular and plural when used as adjectives: for example, there is a phrase colleghi maschi which Reverso says means "male colleagues".
So I'm confused about what the plural forms are like with animals: should I say le giraffe maschio, le giraffe maschi, or are both used? One source I found gave examples of maschio and femmina with plural animals (Using Italian A Guide to Contemporary Usage, By J. J. Kinder, V. M. Savini, 2004, page 240). But also, when I searched online for "le giraffe maschi", I found many examples; e.g.
Quanto sono alte le giraffe?
Le giraffe maschi possono superare i 5,5 metri (18 piedi) di altezza e le giraffe femmine possono raggiungere circa 4,5 metri (circa 14 piedi).