When he discovers that Charisse would rather spend her sixteen birthday with her boyfriend Eric (LIL' ZANE) than them, Dolittle decides it's time for a family vacation. That plan is derailed, however, when the doc receives several visits from Joey the Raccoon (voice of MICHAEL RAPAPORT) and the Possum (voice of ISAAC HAYES) who want him to meet the God Beaver (voice of RICHARD C. SARAFIAN), the head of the local animal union.

The Beaver is concerned because lumber tycoon Joseph Potter (JEFFREY JONES) and his ruthless lawyer Jack Riley (KEVIN POLLAK) have taken steps to level their forest and the animals believe that Dolittle is the only human who can save their homes. Realizing the only way to stop the developers is to find an endangered species in the path of the deforestation, Dolittle discovers that a lone Pacific Western bear, Ava (voice of LISA KUDROW), lives in the forest.

Yet, she needs a mate and offspring for his plan to work, so Dolittle enlists the aid of Archie (voice of STEVE ZAHN), a circus performer bear to become Ava's suitor. The only problem is, she already has a bear boyfriend, Sonny (voice of MIKE EPPS), and Archie doesn't exactly know his way around the forest.

Thus, with just 30 days and counting on a court ordered suspension of leveling the woods, Dolittle takes his family out into the forest where he hopes to train the reluctant and skeptical Archie about how to be a real bear, all while Potter and Riley do what they can to stop that from happening.

That's pretty much my feeling about any screenwriter who's assigned or volunteered to draft a follow-up sequel to any popular film. While their job is a tad easier than creating something new - since the characters and basic storyline are already in place - not only must they meet or exceed studio, critical and viewer expectations, but they must also figure out some way to expand upon or play off the original film's plot. To no one's surprise, that usually turns out to be more difficult than one would initially imagine, resulting in sequels that are usually disappointing and/or inferior to the original.

All of which leads us to this week's inevitable sequel, "Dr. Dolittle 2," the follow-up to the 1998 box office hit that itself was a remake of the Oscar nominated 1967 film that starred Rex Harrison as the doctor who could talk to the animals. Certainly no great piece of filmmaking from an artistic level, the 1998 film played off the visual techniques used to make animals talk in the "Babe" films and offered some amusing moments and fun vocal performances from those voicing the various animals.

Thus, if you're screenwriter Larry Levin - who made his feature film debut co-scripting the first film (the remake) with Nat Mauldin - how do you proceed? Well, since the main draw of the earlier film obviously was in seeing star Eddie Murphy interacting with the animals, you simply set up as many similar moments here with an environmentally friendly plot as the skeleton upon which all of those scenes and jokes will hang.

The result is a mildly amusing film that gets a B for effort and a C- for execution, though it will probably play rather well to its intended audience of young kids. Although the plot may be a bit much for those who'd never be caught dead carrying the moniker of "tree hugger," Levin and director Steve Carr ("Next Friday") earn some points for never giving up in their quest to elicit laughs.

Despite those intentions and their efforts in setting up various gags, however, most of the intended humor falls short of the mark and comes off as slightly amusing rather than bust-a-gut hilarious. Case in point is the entire subplot about the "animal mafia" that alerts Dr. Dolittle about their deforestation dilemma and later takes matters into their own hands (or paws and feet, if you will).

While such a set-up has potential, is moderately clever and generates a few laughs - mainly through individual lines of dialogue as delivered by Michael Rapaport ("Bamboozled," "Men of Honor") who voices a mob lieutenant raccoon - little if any of it's as hilarious as one might expect or hope. The same holds true for other such efforts where one can see the joke coming - Murphy's character talking about the alpha male only then to be belittled by his wife - but the payoff isn't as strong as it should have been.

Perhaps sensing that or simply kowtowing to the stereotypical expectations of what children want from their comedies, the filmmakers then resort to the old standby of using scatological humor for the laughs. Accordingly, we're treated to the sights and sounds of a bear having some gastrointestinal distress while seated on a toilet (with Murphy reacting to the smell) and various scenes involving animal urine. The kids, of course, will laugh at such material as they're either pre-wired or now conditioned to do so. Yet, is this - the latest such film to use such material - what Hollywood has stooped down to in terms of children's live action entertainment?

That aside, and as was the case with the first film, the best moments and performances come from the animals themselves, obviously assisted by the vocal talent that gives them their human characteristics and the visual effects supplied by supervisor Douglas Hans Smith ("Independence Day," "The Flintstones in Viva Rock Vegas") and his team.

Norm Macdonald ("Screwed," TV's "Saturday Night Live") returns as the voice of Lucky the dog (and occasional story narrator), while Isaac Hayes ("Shaft," "Reindeer Games") provides the voice for a possum, Lisa Kudrow ("Lucky Numbers," TV's "Friends") does the same for a female bear and Jacob Vargas has some fun with a chameleon who can't change colors.

The best vocal performance, however, comes from Steve Zahn ("Saving Silverman," "That Thing You Do!") as the lazy and self-centered circus bear who'd rather not be sent out into the wild. While bears aren't the most emotive of all creatures, Zahn delivers a terrific take on the character and the filmmakers get a decent physical performance out of Tank the bear.

As far as the human performances are concerned, Eddie Murphy ("Nutty Professor II: The Klumps," "Bowfinger") is pretty much relegated to playing the exasperated straight man to the many animals and their antics. While generally amusing, his performance is a far cry from the hilarity of his vocal work in "Shrek." Kristen Wilson ("Dungeons & Dragons," "Get on the Bus"), Kyla Pratt ("Love and Basketball," "Barney's Great Adventure") and Raven-Symoné ("The Little Rascals," TV's "The Cosby Show") return as the rest of Dolittle's family, but aren't much more than filler this time around and their non-animal scenes completely halt the film's comedy.

A subplot featuring Lil' Zane (making his debut) as the oldest daughter's boyfriend goes nowhere and is then suddenly abandoned, while Jeffrey Jones ("Heartbreakers," "Sleepy Hollow") and Kevin Pollak ("3000 Miles to Graceland," "The Whole Nine Yards") embody the standard, one-dimensional cartoon villains that do little for the film beyond providing some conflict for the protagonists (if only Jones's character had been Mr. Rooney from "Ferris Bueller's Day Off," that might have been another matter).

Certain to entertain kids -- who will automatically root for the animals to defeat those villains - and not terribly boring or torturous for adults who will see it with them, the film has some amusing moments and lines of dialogue, but - like many sequels - isn't as good as it might have been had other talent been beyond the keyboard and camera. "Dr. Dolittle 2" rates as a 4 out of 10.