I have this code for a flock of birds and it won't work. Is something typed in wrong?
Here's the code:

class Bird extends Particle {
 float birdSize = 5.0;
 int currentFrame = int(random(0, birdImg.length));

 int frameCounter = currentFrame;
 float headAngle, colorR, colorG, colorB, tcR, tcG, tcB, curR, curG, curB;
 int birdNum, shapeNum;
 color birdColor;
 float colorSpd = 0.01;

 Bird(float ix, float iy, float spd, int n) {
   super(ix, iy, spd);
   birdNum = n;
   shapeNum = birdNum%numBirdShapes;
   colorR = min(random(144, birdNum%255), 255);  // Create random colors
   colorG = min(random(birdNum%144, 255), 255);
   colorB = min(random(144, 255), 255);
   tcR = colorR;
   tcG = colorG;
   tcB = colorB;
   curR = colorR;
   curG = colorG;
   curB = colorB;
   birdColor = color(colorR, colorG, colorB);
 }

 void update() {
   super.update();
   headAngle = atan2(dy, dx);        // Make 'heads' follow the cursor
 }

 void display() {
   currentFrame = (frameCounter/4)%numBirdImages;  // Create looping animation
   frameCounter++;
   pushMatrix();
   translate(x, y);
   rotate(headAngle);
   if (showSkin==1) {                  // Skin 1: PImage
     if (xDir > 0) {
       image(birdImg[currentFrame], 0, 0);  // Draw images
     }
     else {
       pushMatrix();
       scale(1.0, -1.0);
       image(birdImg[currentFrame], 0, -birdImg[currentFrame].height); // Draw reflected images
       popMatrix();
     }
   }
   else if (showSkin==2) {            // Skin 2: PShape
     pushMatrix();
     scale(birdSize/min(dist(x, y, mouseX, mouseY)+1, 10));
     rotate(-HALF_PI);
     shape(birdShape[shapeNum], 0, 0);// Draw shapes
     popMatrix();
   }
   else {                             // Skin 3: drawing
     scale(birdSize);
     rotate(HALF_PI);
     if (mousePressed) {
       tcR = 255 - min(dist(x, y, mouseX, mouseY), 255);   // Make birds red
       tcG = 0;
       tcB = 0;
     }
     else {
       tcR = colorR;     // Reset to previous color
       tcG = colorG;
       tcB = colorB;
     }
     curR += (tcR - curR)*colorSpd;
     curG += (tcG - curG)*colorSpd;
     curB += (tcB - curB)*colorSpd;
     birdColor = color(curR, curG, curB);
     fill(birdColor, 204);
     rect(0, 0, 5, 5);                // Draw birds
   }
   popMatrix();
 }
}

It says it "cannot find a type or class labeled as 'Particle'"

no,
could you perhaps tell me how to do that?
Thanks

is from here

http://www.openprocessing.org/visuals/?visualID=5245

you need the code from the other two tabs as well.

you also need to credit casper schipper as it's his code.