Ice glistening in the sun.

March 29.

Coldest night. Pump freezes so as to require thawing. 

See two marsh hawks, white on rump. 

A gull of pure white, - a wave of foam in the air. How simple and wave-like its outline, two curves, - all wing - like a birch scale.

Fair Haven half open; channel wholly open. Thin cakes of ice at a distance now and then blown up on their edges glistening in the sun. 

A hen-hawk, - two - circling over Cliffs.

H. D. Thoreau, Journal, March 29, 1854

A gull of pure white. See March 22, 1858 ("We see many gulls on the very opposite side of the meadow, near the woods. They look bright-white, like snow on the dark-blue water. It is surprising how far they can be seen, how much light they reflect, and how conspicuous they are.")

Fair Haven half open; channel wholly open. See March 29, 1855 ("Fair Haven Pond only just open over the channel of the river"). See also March 28, 1855 ("The river has not yet quite worn its way through Fair Haven Pond, but probably will to-morrow."); March 28, 1858 ("Fair Haven Pond is open."); March 30, 1852 (" Fair Haven Pond is open over the channel of the river, . . .The slight current there has worn away the ice. I never knew before exactly where the channel was")

Thin cakes of ice at a distance now and then blown up on their edges glistening in the sun. See March 29, 1855 ("A field of ice nearly half as big as the pond has drifted against the eastern shore and crumbled up against it, forming a shining white wall of its fragments.”)

See two marsh hawks, white on rump. ... A hen-hawk, - two - circling over Cliffs. See March 29, 1858 ("Hearing a quivering note of alarm from some bird, I look up and see a male hen-harrier, the neatly built hawk, sweeping over the hill."); See also   March 15, 1860 ("These [hen]-hawks, as usual, began to be common about the first of March, showing that they were returning from their winter quarters. . . . An easily recognized figure anywhere.” ); March 27, 1855 (“See my frog hawk. . . .It is the hen-barrier, i.e. marsh hawk, male. Slate-colored; beating the bush; black tips to wings and white rump.");  March 30, 1856 ("See probably a hen hawk (?) ... may have been a marsh hawk or harrier.")

What HDT calls the "marsh hawk/hen harrier" is the northern harrier. The “hen-hawk” is the red-tailed hawk. ~ zphx  See A Book of the Seasons, by Henry Thoreau, the Marsh Hawk (Northern Harrier).; The hen-hawk