ed not to be jealous of my proximity, and soon returned
to his customary position; but when I came back to the apple-tree, after
a visit to a clump of oaks at the top of the hill, he again came over. I
could find no sign of a nest, however, nor did the female show herself,
as she pretty confidently might have been expected to do had her nest
been near by. After this I went to the edge of the wood, where I could
keep an eye upon both trees without being myself conspicuous. The
sentinel spent most of his time in the ash, visiting the apple-tree but
once, and then for a few minutes only. I stayed an hour and a half, and
came away no wiser than before. The nest, if nest there was, must be
elsewhere, I believed. But where? And what was the object of the male's
watch?

My curiosity was fully roused. I had never seen or heard of such conduct
on the part of any bird, and the next forenoon I spent another hour and
a half in the clearing. The hummer was at his post, as he always was. We
had never to wait for him. Soon after my arrival he flew to the
apple-tree, the action seeming to have no connection with my presence.
Presently he went back to the ash, and drove out of it two intruding
birds. A moment later two humming-birds were there, and in another
moment they flew away in a direction opposite to the apple-tree. Here,
then, was a real clue. The birds were probably our sentinel and his
mate. I made after them with all speed, pausing under such scattered
trees as had been left standing in that quarter. Nothing was to be
found, and on my return there sat the male, provokingly, at the top of
the apple-tree, whence he soon returned to the ash. A warbler entered
the tree, and after a while ventured upon the branch where the hummer
was sitting. Instead of driving her away he took wing himself, and paid
another visit to the apple-tree,--a visit of perhaps five minutes,--at
the end of which he went back to the ash. Then two kingbirds happened to
alight in the apple-tree. At once the hummer came dashing over and
ordered them off, and in his excitement dropped for a moment into the
leafy top of a birch sapling,--a most unnatural proceeding,--after which
he resumed his station in the ash. What could I make of all this?
Apparently he claimed the ownership of both trees, and yet his nest was
in neither! He sat motionless for five minutes at a time upon certain
dead twigs of the ash, precisely as our female was accustomed to sit in
her appl