I should have known, when Kassie disappeared from the immediate vicinity of the stable area, that she was up to no good.
Kassie is a confirmed "guts". Give her the slightest opportunity, and she'll find something she shouldn't eat, and eat it. For instance: A while ago a friend gave me a sack of "off" chaff to use as bedding in my aviaries. I decided to put some in the chicken yard, which happens to be a converted stable between Haji and Kassie. I dragged the sack of chaff over there, opened it, and discovered that it wasn't off at all. It smelt nice and sweet. Too good for chickens. It was nearly dark, so I left it up against the fence for the night. In the morning I would pour it carefully into a drum, checking that the whole bag was good, and not just the top. WRONG! I had forgotten Kassie's cunning. She managed to reach the sack (must have got down on her knees and stretched her neck like a piece of elastic), drag it into her yard and have a jolly old time pigging out on chaff. It must have been ok: she didn't get colic. But then, she's the sort of horse who wouldn't (not from over-eating anyway). And I am still raking chaff out of her stable! (and have you ever tried separating chaff from sand??!! It's not easy!)
Back to tonight: I was "doing" the horses, and had let Kassie out, because I'm such a nice kind person. Kassie is usually very good: Beaver is so madly in love with her that he won't let her out of his sight. She usually respects his wishes, and stays nearby.
Letting Beaver and Kassie out together is a different story. After Beaver has raced around like an idiot for a while, encouraging Kassie to do the same (not much encouragement needed), they usually go straight down the to gate to see if it's open. If it is, they go straight through and start exploring the neighbouring properties. If not, they settle down to nibbling grass (I wouldn't quite call it grazing, they "play" with the grass - after all, they're not really hungry).
On Sunday I figured they should spend the day "out". I put up with the silly running around, and was relieved when they settled down to nibble grass (having, of course, checked the gate first). I forgot all about them until I heard a thudding noise on the verandah (I was trying to have a nice peaceful afternoon watching a video). Kassie, greedy witch that she is, had discovered my bird seed! She had, of course, managed to open one of the bins, and was enjoying a nice feed of large parrot mix. She'd also spread copious quantities of it on the cement. Grrrrrr....
Tonight I had absolutely no doubt she'd stay around the stables. After all, she always does when Beaver's not out with her. But, I'd forgotten the lure of the birdseed. The horses were almost all done: rugged, fed and yards cleaned. I was putting the last rug on Haji when I realised that I hadn't seen or heard Kassie for a while, and Beaver was not eating. Instead he was standing in the outside part of his yard, looking wildly into the darkness and singing out occasionally. I still didn't think anything of it, she'll be behind the shed or beside the round yard, I figured. I finished rugging Haji and set off to collect the wanderer. And as I approached the house it dawned on me: BIRDSEED!
Kassie had a lovely feed of large parrot mix - once again. Of course. How could I possibly be so stupid: she knows where it is now (the birdseed needs to "move house"). Just think of all those "heating" ingredients - I think I'll stay off her back for a couple of days!