NBC was the broadcast leader in key demos Monday thanks to a nice return for “American Ninja Warrior” and an OK start for another alternative series, “The Island.”

Early ratings weren’t available for History’s miniseries “Texas Rising,” which launched last night. Over at ESPN, Game 4 of the NBA Western Conference Finals between Houston and Golden State averaged a 6.0 overnight household rating, which should translate into more than 7 million viewers in the nationals.

According to preliminary national estimates from Nielsen, “American Ninja Warrior” averaged a 1.8 rating/6 share in adults 18-49 and 5.9 million viewers overall to stand as the night’s No. 1 series in both categories. It was up 12% (0.2) from the show’s year-ago premiere, which aired from 9 to 11, and matched the show’s season finale of last summer. “Ninja” was followed by the series premiere of Bear Grylls’ latest show for the network, “The Island” (1.2/4 in 18-49, 4.0 million viewers overall). The survival series came in right between NBC’s two unscripted series launches of last summer (a 1.0 for “Food Fighters” and a 1.4 for “Running Wild with Bear Grylls”).

At ABC, gameshow “500 Questions” (1.1/4 in 18-49, 5.2 million viewers overall) drew its second best demo score and its largest overall audience to date, placing second among the Big Four nets in the 8 o’clock hour. And from 9 to 11 p.m., “The Bachelorette” (1.6/5 in 18-49, 5.3 million viewers overall) was down 24% (0.5) from last week’s good premiere score but on par with its Memorial Day night rating of a year ago. The dating series was Monday’s No. 1 series in adults 18-34 (1.4/5)

CBS aired encores of its regular-season Monday regulars “2 Broke Girls” (1.0/4 in 18-49, 5.3 million viewers overall), “Mike & Molly” (1.0/3 in 18-49, 5.2 million viewers overall), “Scorpion” (0.8/2 in 18-49, 5.0 million viewers overall) and “NCIS: Los Angeles” (0.7/2 in 18-49, 5.1 million viewers overall).

Fox aired a two-hour encore of “MasterChef” (0.7/2 in 18-49, 2.3 million viewers overall), and CW went with a repeat of the theatrical “Memorial Day” (0.3/1 in 18-49, 1.1 million viewers overall).

Preliminary 18-49 averages for the night: NBC, 1.6/5; ABC, 1.4/5; CBS, 0.8/3; Fox and Univision, 0.7/2; Telemundo, 0.4/1; CW, 0.3/1.

In total viewers: ABC and NBC, 5.3 million; CBS, 5.1 million; Fox, 2.3 million; Univision, 2.0 million; CW and Telemundo, 1.1 million.