“Then the very dark Gulls I have seen off our beach in winter are the young ones?” said Rap; “I never knew that before.  I don’t believe many people remember how birds change their colors, and a great many never heard about it at all, I guess.”

“Gulls walk very nicely,” said Nat.  “Much better than Ducks; and how they bob up and down like little boats when they float!”

“Wake! wake! wake! wake!” screamed half a dozen, flying up as if to tell the Brotherhood of the coming of strangers.

“What can be the matter with all those Sea Swallows on the other side of the island?” asked Nat as they walked across, and a flock of a hundred or more Terns angled by, crying mournfully.  “What a very sad noise they are making—­do you think they are afraid of us?”

“They have reason enough to cry and be sad,” answered Olaf, who was walking on, a little way ahead.  “They have been driven from almost all these islands—­shot for their pretty feathers, and had their nests robbed.  There wouldn’t be any here now, only that some people pay the light-keeper at the little island yonder to see that the law is kept and that no one hunts them here.  See!  He is coming over now to find out what we are doing here!”

“Who are the people that pay him, Uncle Roy?"’ asked Dodo; “the Wise Men?”

[Illustration:  Common Tern.]

“Yes, the Wise Men, and some Wise Women too.  You can give a part of the money in your tin bank to help the poor birds if you wish.”

“Oh yes—­that is—­I forgot,” and Dodo whispered in her uncle’s ear that she, as well as Nat, was saving money to buy Rap a whole bird book for Christmas.

“It seems to be a very open place for nests, out here on the sand,” said Rap.  “I suppose the little Gulls and Terns must be hatched with down-feathers on.”  “Yes—­though they are not able to take care of themselves as quickly as young Ducks.  But as soon as they can leave the nest, they walk down to the water’s edge and eat a sort of gluey stuff that floats in on the water.  So you see that unless the law protected them they might be very easily stolen or destroyed before their wings were strong enough to fly.”

“It must be very cold for them here in the winter.”

“It would be if they were obliged to stay; but both Gulls and Terns scatter all over the country to winter, though the Terns travel much further south.”

By this time the lighthouse keeper had made his way over to them.  Finding who they were, he invited them to bring their luncheon and row over to Little Gull Island with him, to see the lighthouse.

There was a dancing breeze when they turned homeward that afternoon; the boat canted saucily, and little feathers of spray kept tickling Dodo’s nose.

“Are there any more water birds that we are likely to see this fall?” asked Nat, as the Gull Islands disappeared behind them.

“There will be great flocks of Wild Geese coming down from the North, and they often rest on the mill pond; or a Loon may chance down the river, and a Grebe or two.”