Sounds like one of those elk had an infection, possibly a cow with a yeast infection?

It's common to hear bulls bugle year around, every month of the year they're vocal. During the rut it happens to get hot and heavy. Of course cows are the same way, they communicate year around.

It's very possible there's a cow in heat there, one or more of his cows may not have been covered effectively, cows can come into estrus up to 4 times a year, this being the latest that happens. If you can't find the elk next time, try a cow in heat call for location, be very aggressive with it, you never know? elknut1