Upchuck or drop down?

Upchuck or drop down?

Observation - Upchuck or drop down? - Southern Africa. Description: Residue of mainly smashed crab-shells with some fish scales dotted about a grassy bank just off the Nkomba River mouth (estuary). No signs of Otter activity - no polished egress scrapes, no spoor and no dung. Cape Clawless Otters do apparently occur in th

Residue of mainly smashed crab-shells with some fish scales dotted about a grassy bank just off the Nkomba River mouth (estuary). No signs of Otter activity - no polished egress scrapes, no spoor and no dung. Cape Clawless Otters do apparently occur in the river, but the site is exposed and subject to quite heavy human traffic, not the ideal place for a latrine I would think. On the other hand, the area had had heavy rains (100 mm +) the previous 2 days so has been washed clean.

So, who dunnit? Not Marsh Mongoose (leave carapace largely intact). Possibly Cape Clawless Otters? Possibly large birds flushing crops? But what bird smashes crabs so finely?