Cut out the shapes of the animals you want on your board from construction paper. If free-hand sketching is not your strongest forte, use stencils or trace over printouts of the animals in illustrated books. The size of your cutouts will depend upon the size of the bulletin board and how strong of a presence you want the animals to have on it. Consider just doing half-body cutouts of some animals and positioning them with their bodies running right into the sides of the bulletin board.
Arrange the animal cutouts on your board before you decorate them, but do not secure any of the animals yet. Make sure you have enough animals for a fun, dynamic layout.
Use poster paints to give base colors to all of your jungle critters. Don't worry too much about detail for this step of the process; work mainly to give basic features to all of your animals so that they are now shaded in whatever natural hues they are in their wild habitats. This is primarily to give all of the animals a base color, to which fun details can be added later in the crafting process.
Make all of your animals a bit more exciting by adding texture to them. Use felt to form the patterns on giraffes or stripes on zebras, or use yarn for a cheap texture option. You can add short sections of pond flex piping/tubing to your elephants to make three-dimensional trunks. If you've made any jungle birds, be sure to give them a full body of colorful craft feathers and possibly construction paper beaks. Use "googly eyes" on all of your jungle animals to ensure that they give off a friendly, non-threatening feeling.
Secure the animals to your board. Use a staple gun for best results, being careful to provide extra enforcement in any areas where the animals have heavier parts than others.