River Cam: A Note on Moorhen Feeding Habits

 

With the initial first few days being quiet, apart from Rodents, one diurnal observation involved a Moorhen, with a bonus Kingfisher sat in the background (can you spot it). The Moorhen makes its way up the bank and plucks a snail from the wall of the bridge which it then eats and swallows whole, shell included. I cant say I have observed this before with Moorhen, other birds like Song Thrush break the snail out of the shell before swallowing. I wonder if this is perhaps linked to the size of the bird, a whole snail, shell and all is less of an issue for a Moorhen than a smaller thrush.  

Moorhens are omnivorous and feed on a wide variety of plant material, invertebrates and occasionally even fish, amphibians and carrion. There are even several documentations of Moorhen predating bird nests in which they feed on both the egg shell and egg contents, they additionally feed these to their own young these nest contents on occasion too. Various studies show that molluscs make up between 10-20% of the diet on average, which varies between studies, habitats and sites.  

The fact Moorhens will feed on bird eggshells and routinely feed on molluscs perhaps suggests this is fairly normal behaviour, and a behaviour which probably isn't always so clearly observed given most snails will be plucked from aquatic vegetation or basal habitats in and around ponds making it not too clear. Perhaps this individual has learned that the damp, shaded underside of the bridge provides excellent opportunities for feeding on molluscs, which foolishly sit exposed on its walls.