How rats are trained for TV & Movies

• Rats can be trained to act in movies just like cats and dogs, but working with a pack of rodents on a film set requires someone with a lot of organizational skills and a close attention to detail.
• More specifically, a rat trainer needs to be able to identify a rat's personality, strengths, and weaknesses to be able to cast them in the best possible role.

• To find out exactly what it takes to train rats for movies, we spoke with Mark Harden, a senior trainer at Animals for Hollywood, who worked with 300 rats on "Bram Stoker's Dracula" and 600 on the 2003 horror film "Willard."

Following is a full transcript of the video.

[rats squeaking]

Narrator: Having a swarm of rats crawl up your legs may seem like your own personal nightmare. But for Hollywood animal trainer Mark Harden, it's just another day of work.

To teach them to climb up his pants for the 2003 movie "Willard," multiple rats had to repeat the task over and over again at different angles.

Mark Harden: At the beginning, we certainly want to make it as easy as possible, give them as much confidence as possible, and then we gradually make it more difficult.

Narrator: But being a rat trainer isn't just about getting a rat to run from point A to point B, although that is a big part of it. It's also about understanding the unique personality of every rat you cast.

Rats are social animals that can be trained just like a cat or a dog, and they have a similar genetic makeup to humans. And just like humans, they can have a variety of behaviors and personalities, which means rat trainers need to be able to sort through them and identify their strengths and weaknesses.

For each main rat character in a film, Mark actually needs to find multiple rat actors to play the part.

In "Willard," Mark used six different rats to play the main white rat, Socrates, who was on camera most of the film doing a variety of specialized tricks.

Mark: This guy's a really good runner. This guy seems pretty handleable and stable, so if the actors have to hold him, this will be my actor rat. So you sort of slot them into the arc of the character.

Narrator: A horde of rats is called a mischief. And once Mark has cast the mischief, the rats need to be sorted by what they can and will do.

Mark: Henry Ford would be very proud of how we train rats in the groups.

Narrator: And he has trained a lot of rats, even for a single project. 300 for "Bram Stoker's Dracula," and 600 for "Willard."

After casting, the first step is to split them up by gender, so they don't reproduce while filming. Then he splits them into smaller groups and puts them into boxes based on their assigned task, which is based on what they're good at, according to the trainer's observation.

Each box might have a different trainer or trainers in charge of it. They might start out with five rats in a box, and eventually they would work their way up to 20 at a time. To keep track of who is who, all rats are tagged on their tail with a different color marker.

Mark: It was a team effort. I didn't sit there and have, you know, 600 rats on a leash.

Narrator: One of the types of rats he wants to identify early on are the more aggressive rats, or biters, for safety reasons. Yes, rats do bite people, and Mark himself has been bitten. But in general, they won't go out of their way to attack someone.

Mark: So, we encourage biting certain things. But what you would hand to an actor would be one that you're 100% sure is not a biter.

Narrator: But let's say he does want the rat to bite something on camera. In this case, a rat that likes to chew is exactly what he'd want. The trick is putting food near the object, then eventually putting the food inside the object. A biter rat will chew its way through to get to it, just like they do in this scene from "Willard" with the newspaper and this scene with the tires.

Mark creates a special mixture of nut butter and food coloring, which he paints on a prop. For example, in this scene in "Willard," the rats were actually chewing fake balsa-wood legs covered in this edible paste.

Mark: If I want him to look like he's biting a finger, I'll just put some scent on the finger. Not enough to make him want to taste it, but enough to make him interested.

Narrator: If a real bite is required close up on camera, usually a prosthetic is used, with fake blood of course. No matter what the rat's personality or specialty is, they all have one trait in common.

Mark: The problem with rats is they're very sound sensitive and smell sensitive, and they're very tactile. So when you're training them, as soon as you move, it's all different, right? The first smell that wafts through that they don't recognize, they shut down.

Narrator: So the more details about a set he knows in advance, the better, so he can prepare them for anything.

Let's look at this scene in "True Blood" that Mark worked on as an example. A rat needed to run on dirt through a tunnel while a camera was pushing towards him. It then had to crawl through a grate and run to a mark, where it would then stand on its hind legs and transform into a human.

So Mark needed to first identify a good runner rat who could deal with these obstacles. He replicated what it would look like as much as possible in his training area, using a simple dog toy on a paint stick to mimic the camera.

And how did he get the rat to move in the first place? No matter the personality, he has to use several basic behavior-modification tools to get it to do what he wants on command. First is positive reinforcement, in which he rewards the rats with food after the trick is complete. Or he might reward them with safety by giving them what's called a sanctuary.

Mark: We have little plastic shoeboxes with a little mousehole cut in it. They're dark, they're black. They're very attractive to a rat. Their food's in there. So we start introducing them to the concept of food and sanctuary at the same time.

Narrator: But food alone isn't going to get a rat to run. Often, Mark also has to take advantage of its flight reaction by making a loud sound.

Mark: A rat is built to deal with stress. If you don't give them any stress, they tend to do self-destructive behaviors anyway. So, their whole psychology is built from scurrying from this thing to that thing.

Narrator: For the "True Blood" scene, Mark made a makeshift rattle with pebbles to get the rat to run and rewarded it with a sanctuary at the end where it would get food.

Mark: And then we start increasing the distance, but we add a buzzer to it.

[buzzer sounding]

So we're calling them and giving them some aversion to being here while we're calling them there. So by the time you get on set, you usually, just the buzzer is enough. But if he goes sideways or something, you might wanna shake your little stick.

Narrator: To get the rat to hit its final mark, he used an almond-oil scent so it knew where to stop. He uses this same basic method when he needs specialized tricks, like jumping or climbing.

Mark: They behave well on props. They can walk tightropes and go up ladders and do things like that.

Narrator: Let's say he wants a rat to jump in a scene, a more difficult trick for a rat. He puts the food behind him on a platform, so the rat has to use his shoulder as a bridge to get it. Then he gradually increases the distance, so it has to hop over.

Or if he wants it to climb his leg, as we mentioned earlier, he puts the food at waist level off camera, so it needs to go up his leg to get to it.

And sometimes he needs to adjust the props to give the rats a boost. For example, in "Willard," they created a set of prop steps that the rats could easily run down that were much shorter than the ones Crispin Glover would use.

Now, working with a single rat is one thing, but what happens when he needs a whole group to do something? How do their personalities change?

Mark: The groups become individuals. I mean, if you have a group of 300 rats, you break it down into manageable pieces, and those pieces each become an individual.

Narrator: And each rat needs to learn the trick. They won't follow the herd or follow a leader, like pigeons or other flock animals.

Mark: As groups, they're all stupid. One rat will never lead another group of rats through something difficult, but one rat will stop an entire army of rats.

Narrator: A common scene with rats in movies is swarms of them running together from one point to another.

Let's look at an example of how a group of some runners were trained for "Willard." Mark starts by putting each box one at a time on top of a table in the middle of a room. He opens it and has them run to a different sanctuary box at the other end. He does this on a table, both to get them out of their comfort zone and so they're easier to control.

Mark: They naturally want to hug a wall. So, I'm in the moviemaking business, so anything they wanna do naturally we train against, because chances are that's not what you want in the movie.

Narrator: He will gradually lower the table until the rats learn to run on the floor.

Mark: And then we start introducing them to multiple surfaces. They'll run over carpet, they'll run over wood, they'll run over tile. We'll put water, we'll put dirt, we'll put whatever they need.

Narrator: Lastly, he preps the groups together on the actual set. Usually, two rehearsals is enough.

In groups, rats all need to be weighed two to three times per day to make sure they are all eating and healthy. Faster, smarter rats in the group will get to the food first more often, so Mark occasionally needs to identify and remove them to let the other rats get the prize. So a lot of time on set is spent just making sure the animals are all safe and healthy.

And just how strong is their group identity?

Mark: We would prep the blue team, then we would prep the red team, and then we'd turn them all loose and see what they would do. And we kept track, and about 85% of the rats ended up in their own boxes.

Narrator: Many films these days use CGI to create realistic animals like rats. But with CGI, you're also losing the personality that comes with the real thing.

Mark: It's really less dynamic and less dramatic.

Narrator: And you just wouldn't get that same visceral reaction watching a bunch of CGI rats crawl up a human leg as you would with a real swarm.

Mark: On one time in the rehearsal, the rat, one rat got inside my pant leg. And that just freaked me out, because you got 100 rats on the outside and one on the inside. And it was the freakiest feeling.