Presentiment is that long Shadow on the Lawn — Sun-Bird

The plural form of "Suns go down" is a hint to extend the word sun. Sun-birds are coming with long shadow for the startled grasshopper.

Presentiment－is that long Shadow－on the Lawn－
Indicatives that Suns go down－

The Notice to the startled Grass
That Darkness－is about to pass－

(F.487/J.764)

[1] Presentiment:: foreboding, a notice of something bad to happen. long shadow:: shadow of the sun-bird.
[2] Suns:: sun-birds; the plural form is a hint.
[3] Grass:: grasshopper.
[4] Darkness:: misfortune.

On the banks of the Guiana rivers there is a bird named by the English Sun-bird, . . . Its food consists of flies and other insects, which it seizes just as the heron does a fish or frog, by approaching close to them and then darting its beak at them so quickly that the prey has no time to escape. . . . Its generic name is derived from the great size of the tail, a character not very common among the birds to which it is allied. ─ A Popular History of Birds (1855)