Thirty-thousand Dunlins are reported to overwinter in the Fraser River Delta! These medium-sized sandpipers are attracted to the wetlands located near agricultural fields, which provide them with a rich source of food.
Dunlins use their long, dark droopy bill to probe the ground for invertebrates. Some of their favourite snacks also happen to be agricultural pests: wireworms and leatherjackets. Agricultural fields have been known to account for almost half of a juvenile Dunlin’s diet, and over a quarter of an adult’s.
Photo by Changhua Coast Conservation Action
They tend to feed on fields at night and have a preference for fields recently fertilized or laser-levelled. Winter Cover Crops with short cover, or bare fields are where the majority of Dunlin frequent to forage. Here, you may hear them delivering their buzzy, rising and falling shrill, or a raspy “kree”.
Up to 11, 600 have been spotted on farmland in only one day. A unique behaviour found amongst Dunlins that overwinter in the Fraser River delta is called ‘over-ocean flocking.’ When waiting for the tide to go down, they fly over the ocean for hours at a time, a behaviour that we have only noticed since the mid 1990’s. Perhaps it is a safer way of spending time since they are less vulnerable to birds of prey than if they roost on the beaches.
In their winter plumage, Dunlins are dull brown all over with black legs. See them in their breeding plumage and you have a different story; they are distinct by their rusty-coloured back and their dark belly. However, you won’t find Dunlin here when breeding season occurs, for they flock up north to find a mate and will not return south until winter beckons them home.