Filmed for the first time at the reserve, explore an interesting interaction between Grey Herons and Water Shrews in a new blog by local naturalist, Christopher Wren.
My trail cameras are usually set with a specific target in mind – those at the water’s edge are watching for Otters but they mostly record ducks, geese, Moorhens, Robins, Wood Mice and Brown Rats. Every now and then they show something very unusual.
There has been a lot of Water Shrew activity in the past few weeks – female Water Shrews have two or three litters a year with an average of six young in each so there are likely to be a lot of youngsters about at this time of year. Like other small mammals Water Shrews are vulnerable to predators such as foxes, Stoats, owls, Kestrels etc and perhaps because of this they are mainly active at night.
I have occasionally seen a Grey Heron on trail camera before but always too close for a good picture. This time the camera gave a clear view, not only of the heron but also of its prey – a Water Shrew. Notice on the video that a second shrew approached along the bank and then turned and ran when it saw the heron.
That was the second shrew caught by the heron on camera although the pictures weren’t as good the first time. A few days later the heron caught another one. This time it stalked it on the bank behind a tree but the outcome was the same.
There have been more Water Shrews on the cameras since then but always at night. Perhaps they are learning that it is safer to go out in the dark.
Grey Herons are deadly efficient predators. Although they mainly hunt for fish they will eat almost anything from insects and crustaceans to frogs, ducklings and small mammals. And although shrews are said to be distasteful to some predators, herons probably don’t taste their food because they swallow it whole. Perhaps dipping it in the water helps too. And a sip of water afterwards to take away the taste.