On a recent trip to Amrum, North Frisia, I observed an example of parental defensive behaviour that was as impressive as it seemed overacted..
A pair of Pied Avocets (Recurvirostra avosetta) was feeding in a larger puddle with its two chicks. When a pair of Common Shelducks (Tadorna tadorna) walked over from the adjacent pasture, the male Avocet flew into a fury. It started to attack (only) the female Shelduck, pecking and biting her, jumping on her and, above all, hitting her with its wings. Although it never approached the Avocet’s chicks and only tried to feed in the muddy water, the wader didn’t stop until the Shelducks were fed up and left – walking back to the pasture.
Few minutes later, they tried it again and the spectacle repeated itself. Surprisingly, the female Shelduck was again the lone target of the outraged Avocet, while the male was watching. This time, the victim persisted for maybe a quarter of an hour, trying to get some nibbles, while the Avocet was battering her constantly – only to cease when the ducks walked away.
I did a quick websearch and found that this behaviour, notably between these two species, is a common thing. The fact that only the female Shelduck is attacked in most cases is described here.
