Followup to my previous question re huge cloud-like bird --does anyone recall a cable tv episode -- details:?

I respect all of you that answered, relating there is nothing doented in history that even faintly resembles such a lifeform. So, the program I saw must have been fiction;. it was a cloud-like high flying lifeform, got its nutrition from the air, as I recall. It's wing-like appendages had a very slow rythmn; they soared in medium size family groups -- with their young. Mountainous land mes were far below. Their only enemies were fierce prehistoric type birds that lived in and around caves in the mountains below. They would patiently wait for stragglers or young that would drop to lower altitudes for feeding, at which time a group of the predators would attack, easily overcoming them. It seems this was possibly a production on a Nat. Geo type cable channel --long before there was today's Nat. Geo channel. I remember it being produced probably 10-15 years ago. Does anyone else remember such a program? I know I didn't dream this up!