What is "night warbler"

Sedge \Sedge\, n. [OE. segge, AS. secg; akin to LG. segge; -- probably named from its bladelike appearance, and akin to L. secare to cut, E. saw a cutting instrument; cf. Ir. seisg, W. hesg. Cf. Hassock, Saw the instrument.]

1. (Bot.) Any plant of the genus Carex, perennial, endogenous, innutritious herbs, often growing in dense tufts in marshy places. They have triangular jointless stems, a spiked inflorescence, and long grasslike leaves which are usually rough on the margins and midrib. There are several hundred species.

   Note: The name is sometimes given to any other plant of the order Cyperace[ae], which includes Carex, Cyperus, Scirpus, and many other genera of rushlike plants.

2. (Zo["o]l.) A flock of herons.

   Sedge hen (Zo["o]l.), the clapper rail. See under 5th Rail.

   Sedge warbler (Zo["o]l.), a small European singing bird ( Acrocephalus phragmitis). It often builds its nest among reeds; -- called also sedge bird, sedge wren, night warbler, and Scotch nightingale.