adult Greater Yellowlegs in breeding plumage

It was a relief to find a Greater Yellowlegs at Montlake Fill today. June has been an agonisingly slow month with very little activity in the way of waders. However the arrival of this bird heralds the start of Autumn migration - a mere six weeks after the majority of birds had passed through Washington on their way north.

Breeding in the northern hemisphere is a race to get to the breeding grounds, find a mate, raise chicks and get out before the weather changes for the worse. Waders have relatively large eggs for their body size so a typical clutch of four eggs puts a lot of physiological stress on the female. In most species of waders that breed in the arctic and sub-arctic the females typically depart within a few days of the eggs hatching and so are the first birds to appear in the Autumn (a relative term since the official start of summer here in the USA was only 8 days ago).

Although wader chicks can feed themselves however they are not able to regulate their body temperature. With two parents, one bird can brood the chicks while the other keeps a look-out for potential predators such as arctic foxes and skuas. After three days or so, the chicks can keep themselves warm so the female leaves the male to look after the chicks. The males will stay for the next two weeks before leaving the chicks to fend for themselves for the last week until they can fly.

Autumn migration is more leisurely than in Spring with birds migrating in three broad waves. The females are the first to return, followed by the males and finally the chicks that survived to fledging. Here in Washington the first birds show up in the first week of July. By late July, when the first young birds appear, most of the adults have passed through on their way south though the exact timing depends on the species and the distance they have travelled.