Some longtime residents of California’s San Bernardino County are up in arms. Well, they would be, if they had any arms. As suburban sprawl spreads farther into desert country, rattlesnakes confront their new human neighbors, often with calamitous results. This is one of the anecdotal tidbits found on “Venom ER” (7 p.m., Animal Planet), a new series set in the Loma Linda University Medical Center specializing in treating people bitten by venomous animals such as snakes, scorpions and spiders. Each episode’s drama features venom expert Dr. Sean Bush, who leads a team of medical pros and who is also “on-call” with the White House’s Medical Unit for any snake emergency the president may have while in Crawford, Texas. Meetings with House Majority Leader Tom DeLay don’t count.

• Some researchers don’t have the sense to come out of the rain — or out of the hail, thunder, lightning and 300-mile-per hour winds. These are the storm-trackers, celebrated in the 1996 drama “Twister” and documented tonight on “The Hunt for the Supertwister” on “Nova” (7 p.m., PBS). Fans of The Weather Channel should not miss this episode.
• Keith Carradine (“Deadwood”) narrates the new weekly series “Wild West Tech” (9 p.m., History), examining the inventions and technical developments behind the history and legends of the cowboy past. Tonight’s debut episode concentrates on the gadgets and devices central to cowboy culture, most notably the widespread use of barbed wire and, later, electrified fencing, two developments that changed the open range forever.

Tonight’s other highlights

• Ten remain on “American Idol” (7 p.m., Fox).
• Dr. Crane hires a matchmaker on “Frasier” (8 p.m., NBC).
• An implanted chip that saves a man’s sanity may cost him his life on “Century City” (8 p.m., CBS).
• Jack cuts Amador some slack on “24” (8 p.m., Fox). As if anybody remembers what’s going on here after Fox interrupted this series for more than a month.
• Ambitious parents enter the therapy fray on “Significant Others” (8:30 p.m., Bravo).
• An attorney’s misconduct halts a murder trial on “Judging Amy” (9 p.m., CBS).
• Cindy Williams guest stars on “Law & Order: Special Victims Unit” (9 p.m., NBC).
• Andy suspects that a shooting victim may have been a crooked cop on “NYPD Blue” (9 p.m., ABC).

Late night

Matthew Perry and Lou Reed appear on “Late Show with David Letterman” (10:35 p.m., CBS) … Jay Leno welcomes Amanda Peet, Adam Mesh and Kenny Chesney on “The Tonight Show” (10:35 p.m., NBC).

Bob Costas, Brian Posehn and Toby Lightman are booked on “Late Night with Conan O’Brien” (11:35 p.m., NBC).