When I walked on the beach this morning, I hoped to see willets. And almost like a clockwork, they have returned to their breeding grounds in MA. By the end of April, willets return and start to stake out their territories. On May 1st, the beach was alive with the pill-will-willet and Kip-Kip-Kip calls of returning willets. I found at least five pairs vocalizing and announcing their arrival.

The eastern subspecies of Willets are primarily monogamous, bonding for life. Most willets arrive on the shores of Massachusetts as pairs, ready to set up their nesting territories. The male of the bonded pair engages with the unpaired male trying to attract his mate. When on the nesting territory, the bonded pair often gives out the loud pill-will-willet call announcing their arrival to the other birds. 

I have often noticed a wing-up display by the male willet when another willet comes near. 

The paired willets engage with the intruder if the bird lands nearby. I have seen this behavior for the first couple of weeks after their arrival to the breeding grounds in Massachusetts. It is always fun to watch and photograph these birds engaging in territorial displays and fights accompanied by their emphatic call.
In the photograph below, the intruder on the left was slowly backing away as the male in the middle successfully defended his territory and mate.

The male Willets often chase the intruders away.

Now that Willets have returned to our beaches, Least Terns are not that far behind. The beach will really come alive once Least Terns are back.