The lesser yellow-legs is more universally common than the greater and more apt to associate with other species of small waders, where it towers above them, as it stalks gracefully about on its long legs. It is more apt to be seen in large flocks, though the flocks are seldom compact and are usually much scattered, especially when feeding. And it is much less shy; although usually rather watchful and wary, not easily approached by a moving object, it is often surprisingly tame. If the observer is sitting down and motionless, even in plain sight, the birds will often fly back and forth over him or even alight on the ground near him.
I have often seen yellow-legs bathing, but Aretas A. Saunders (1926) describes it better than I can, as follows:
To do this a bird would go to the deeper, clearer water forming the mid-channel of the pond, the same spot where the black ducks bathed earlier in the morning. There it would sit down in the water, remaining still for a time. Then it would splash water over its back and wings, duck its head, and sit still again. When sitting thus in the water its tail was usually half spread, and resting on or just under the water surface. When the bath was over the bird would stand up, stretch its wings and then preen, taking care to go over carefully all the feathers of the back, wing, and breast and scratching with its toes those portions it could not reach with the bill.
He observed them fighting also and says:
Why they should fight at this season of the year, when the mating season was over and the food supply seemed abundant enough for all comers, is not easily explained. Yet it was a common thing to see two birds stand facing each other with heads and necks up, and bills tilted at an angle a little above the horizontal. After eyeing each other a short time, one would dart at the other, apparently trying to get its bill above its opponent's and strike at the latter's eyes. The second bird would dodge back and then return the attempted blow. They never actually struck each other, and after several such tiffs one bird would crouch down in front of the other, the yellow-legs' way of surrendering, and the other bird would stalk off and pick a fight with some other that had been peacefully feeding. Sometimes the fight varied from this form and the birds lowered their heads at the beginning like roosters and then fluttered up into the air as they went at each other.
The well-known bobbing habit is well described in some notes sent to me by Francis H. Allen, as follows:
Watched one on a slough for about an hour. Method of bobbing was to raise the head by stretching the neck and at the same time lower the tail, the whole body being held rigid, then lower the head with the bill pointing somewhat downward and raise the tail to normal. The body seems to turn on a pivot, but the lengthening of the neck is an independent movement.
Voice.—John T. Nichols has sent me some very elaborate notes on the varied calls of the yellow-legs, from which I quote as follows:
When on the ground in flocks the lesser yellow-legs is usually silent. The same is true frequently of single birds coming in. In the air it is more or less noisy and has two common, distinct notes—wheu and kip or keup, which seem to be used rather indiscriminately on various occasions and which vary into one another. Wandering singles and small companies seem to use the wheu more, often double. The combination wheu hip is frequent. From large companies, especially in uncertainty, one may hear a chorus of kips.