Sunday, Sigrid outdid herself.
Then, in the afternoon, I walk into the kitchen and there is a medium-sized frog, maybe 3" long, in the dog's water bowl.
As there is no way for a frog to enter the house unless brought in, and Sigrid has been carrying in small frogs (but not eating them), for some time, I think she caught this large frog and carried it in, where it promptly hopped into water.
The alternative, suggested by MrsC, is that Sigrid put the frog in the waterbowl deliberately, as a way of stashing some food for later.