A walk round the two-mile square.

April 7.

Round the two-mile square. I see where the common great tufted sedge (Carex stricta) has started under the water on the meadows, now fast falling.

The white maple at the bridge not quite out.

See a water-bug and a frog. Hylas are heard to-day.

I see where the meadow flood has gone down in a bay on the southeast side of the meadow, whither the foam had been driven. A delicate scum now left an inch high on the grass  It is a dirty white, yet silvery, and as thin as the thinnest foil, often unbroken and apparently air-tight for two or three inches across and al most as light as gossamer. What is the material? It is a kind of paper, but far more delicate than man makes. 

Saw in a roadside gutter at Simon Brown's barn a bird like the solitary tattler, with a long bill, which at length flew off to the river. But it may have been a small species of snipe.

H. D. Thoreau, Journal, April 7, 1861

Hylas are heard to-day. See March 23, 1859 ("We hear the peep of one hylodes somewhere in this sheltered recess in the woods."); April 1, 1860 (" I hear the first hylodes by chance, but no doubt they have been heard some time."); April 5, 1854 ("Hark! while I write down this field note, the shrill peep of the hylodes is borne to me from afar through the woods."); April 6, 1858 (" I hear hylas in full blast 2.30 P. M."); April 8, 1852 ("To-day I hear the croak of frogs in small pond-holes in the woods, "); April 8, 1853 ("The hylas have fairly begun now.") See also A Book of the Seasons, by Henry Thoreau, The first frogs to begin calling

The white maple at the bridge not quite out.  See April 7, 1853 ("he staminiferous flowers look light yellowish, the female dark crimson. These white maples flower branches droop quite low, striking the head of the rower, and curve gracefully upward at the ends. ") See also April 9, 1852 ("The maple by the bridge in bloom”) and note to April 6, 1855 ("White maple stamens stand out already loosely enough to blow in the wind.")  and A Book of the Seasons,  by Henry Thoreau, White Maple Buds and Flowers

A bird like the solitary tattler, with a long bill, but it may have been a small species of snipe. [Probably Solitary Sandpiper (Tringa solitaria)] See September 23, 1858 (''In this marsh, saw what I thought the solitary tattler, quite tame. . . Met a gunner from Lynn on the beach, who had . . . what he called a sandpiper, very white with a long bill. Was this Tringa arenaria? [and] what I took to be a solitary tattler, but possibly it was the pectoral sandpiper, which I have seen since."); September 29, 1858 ("See what must be a solitary tattler feeding by the water’s edge, and it has tracked the mud all about. It cannot be the Tringa pectoralis, for it has no conspicuous white chin, nor black dashes on the throat, nor brown on the back and wings, and I think I see the round white spots on its wings. It has not the white on wing of the peetweet, yet utters the peetweet note!— short and faint, not protracted, and not the “sharp whistle” that Wilson speaks of. ") See also September 24, 1855 (" suppose it was the solitary sandpiper (Totanus solitarius) which I saw feeding at the water’s edge on Cardinal Shore, like a snipe. It was very tame; we did not scare it even by shouting. . . . It was about as large as a snipe; had a bluish dusky bill about an inch and a quarter long, apparently straight, which it kept thrusting into the shallow water with a nibbling motion, a perfectly white belly, dusky-green legs; bright brown and black above, with duskier wings. When it flew, its wings, which were uniformly dark, hung down much, and I noticed no white above, and heard no note."); September 25, 1858 ("In the evening Mr. Warren brings me a snipe and a pectoral sandpiper. This last, which is a little less than the snipe but with a longer wing, must be much like T. solitarius, and I may have confounded them. The shaft of the first primary is conspicuously white above.")

*****

Note per All About Birds: The the pectoral sandpiper (Calidris melanotos) has  distinctively stippled breast that ends neatly at a white belly. the solitary sandpiper (Tringa solitaria) has a black-and-white tail, bold eyering, a back marked with small white spots and blackish underwings in flight. 

The genus Tringa was introduced in 1758 by Carl Linnaeus iThe genus  nowcontains 13 species.^[7]

• Green sandpiper, Tringa ochropus
• Solitary sandpiper, Tringa solitaria
• Grey-tailed tattler, Tringa brevipes – formerly Heteroscelus brevipes
• Wandering tattler, Tringa incana – formerly Heteroscelus incanus
• Spotted redshank, Tringa erythropus
• Greater yellowlegs, Tringa melanoleuca
• Common greenshank, Tringa nebularia
• Willet, Tringa semipalmata – formerly Catoptrophorus semipalmatus
• Lesser yellowlegs, Tringa flavipes
• Nordmann's greenshank, Tringa guttifer
• Marsh sandpiper, Tringa stagnatilis
• Common redshank, Tringa totanus
• Wood sandpiper, Tringa glareola

The genus Calidris was introduced in 1804 by  Blasius Merrem with the red knot as the type species.  The genus contain 24 species: including Pectoral sandpiper, Calidris melanotos

Thoreau's Peetweet  is the Spotted Sandpiper  (Actitis macularia). His Upland Plover is the Upland Sandpiper (Bartramia longicauda).  He also obserfve the Lesser Golden-Plover (Pluvialis dominica ) and Piping Plover (Charadrius melodus) See Thoreau's Birds