I know I'm late to the party here.
When it comes to Big Mama, she had breasts. The trick behind that is you never saw them because they were strategically placed behind a console. She was lying on a table, nothing on top and there was a console in the foreground covering her chest. Then throughout the comics, her chest piece covers just a wee bit lower and on both sides.
This isn't to say they have prominent breasts like humans do with a thin waist BUT females do honestly change shape when they come in season. Don't think of that dreaded Forever Midnight book either. Not like that. The changes are subtle. Heat is also viewed on the tendrils and females in season are hotter than usual, so those tendrils will show their body temperature is higher due to the body change.
Then you have a breeding season. Think like hunting seasons. You can hunt all year long, but hunting out of season doesn't give the prey a chance to reproduce properly to raise their young. So for one reason or another, they have breeding seasons and you now have a bunch of horny gals who are in pain due to their body changing and just all around not happy because they had to wait and are not feeling themselves.
Now, not done yet. There are also sub-species of Yautja. Meaning females of different sub-species can look different. Our poor young Yautja from Prey was a sub-species.
Add all of that together and you have males who are praying before they step into the ring.
