What do you call a person who reconnoitres?

If a saboteur is one who sabotages, and a spy is one who does espionage, what do you call one who reconnoiters or performs reconnaissance?

Here is some research on the topic. Etymononline produces the following pairs, but not one for reconnaissance:

sabotage (v.) 1912, from sabotage (n). Related: Sabotaged; sabotaging.

saboteur (n.) 1912 (from 1909 as a French word in English), a borrowing of the French agent noun from sabotage (see sabotage (n.)).

espionage (n.) 1793, from French espionnage "spying," from Middle French espionner "to spy," from espion "a spy" (16c.), probably via Old Italian spione from a Germanic source akin to Old High German spehon "spy" (see spy (v.)). For initial e- see e-. Middle English had espiouress "female spy" (early 15c.).

spy (n.) mid-13c., "one who spies on another," from Old French espie "spy, look-out, scout" (Modern French épie), probably from a Germanic source related to spy (v.).

reconnaissance (n.) 1810, from French reconnaissance "act of surveying," literally "recognition," from Old French reconoissance "recognition, acknowledgement" (see recognizance).

A scout.

Scout noun 1 A soldier or other person sent out ahead of a main force so as to gather information about the enemy’s position, strength, or movements: forward scouts reported that the enemy were massing at two points ahead - ODO

Scout is the common word for that. — M-W

1.a. one sent to obtain information; especially : a soldier, ship, or plane sent out in war to reconnoiter

But the exact answer is the obsolete word reconnoiterer (noun) — TFD, Dictionary.com

_{Usage examples provided by @deadrat:}

From Vienna in 1848 by H J Coke (1849)

Now and then the sentry fires at the incautious reconnoiterer, till all is hushed!

From Stasi: The Untold Story of the East German Secret Police by J O Koehler (1999)

The film extolled the virtues of Horst Hesse as a "heroic comrade," a "reconnoiterer for peace" who had insinuated himself into a U.S. intelligence service.

_{Related words: lookout, lookout man/woman, outrider, advance guard, vanguard, spy; avant-courier}

If you wanted to be fancy, you could use reconnaisseur, which would be the correct French. (Wiktionary also shows "reconnoisseur" in a sixteenth-century source.)