Leaves now flutter and rustle in the breeze.

June 1.

It was so cold last night and still that I surely expected a frost and covered all our melons. But either the wind changed or clouds came over in the night, and there was no frost here. Here is another cool day. I sit with window shut and walk with a thick coat, as yesterday. Do we not always have these changes about the first of June?

Black-throated green warbler
Setophaga virens

Hear my evergreen-forest note, sounding rather raspingly as usual, where there are large oaks and pines mingled. It is very difficult to discover now that the leaves are grown, as it frequents the tops of the trees. But I get a glimpse of its black throat and, I think, yellow head. 

This and the red-eye and wood pewee are singing now at mid day.

Within little more than a fortnight the woods, from bare twigs, have become a sea of verdure, and young shoots have contended with one another in the race. The leaves have unfurled all over the country like a parasol. Shade is produced, and the birds are concealed and their economies go forward uninterruptedly, and a covert is afforded to the animals generally. But thousands of worms and insects are preying on the leaves while they are young and tender. Myriads of little parasols are suddenly spread all the country over, to shield the earth and the roots of the trees from parching heat, and they begin to flutter and rustle in the breeze.

H. D. Thoreau, Journal, June 1, 1854