The first two nights of Animal Planet’s Monster Week scared up plenty of viewers, particularly men.

Buoyed by new installments of its top series, River Monsters, Animal Planet slithered its way to the top of ad-supported cable's male demo charts on Sunday night and into the medium's top 10 among two adult groups on Monday.

The River Monsters' episode entitled "Bone Crusher" averaged 1.7 million viewers in the 9 p.m. hour on Sunday, May 18, according to Nielsen data. That total included 599,000 males 18 to 49 and 621,000 guys 25 to 54. The latter performance was the series' second-best ever with that demo.

Those deliveries vaulted Animal Planet to the top of ad-supported cable's primetime rankings for the night among males 25 to 54 (483,000) and 18 to 49 (450,000), and fourth- and fifth-best Sunday-night performances ever.

The Discovery Communications service finished third and fourth, respectively, among ad-supported cable networks in primetime among persons 25 to 543 (736,000) and total viewers (1.4 million), excluding sports.

Momentum continued on May 19, the second night of the nine-day Monster Week stunt. Led by the "Amazon Apocalypse" installment of River Monsters, Animal Planet garnered its best Monday night performance among persons 18 to 49 (444,000) and 25 to 54 (421,000) since last year's marathon. Those tallies ranked Animal Planet ninth and 10th in primetime with those respective demos.

Monday's River Monsters' episode averaged 792,000 viewers overall.