Move object up and down while moving forward

Questions & Answers
1

I have a bird model with an animation of its wings flapping. It’s an “in place” animation. I’m trying to make the bird fly forward while moving up and down a little bit. I can get it to move forward and up, but it won’t go down. It seems to get stuck in between the rise and fall functions and just flies straight. Here’s my code:

using UnityEngine;
using System.Collections;

public class bird_fly : MonoBehaviour {
	void Update () {
		Go();
	}
	void Go(){
		Vector3 newPosition = transform.position;
		newPosition.z += 1 * Time.deltaTime;
		transform.position = newPosition;
			Rise();
	}
	void Rise(){
		Vector3 newPosition = transform.position;
		newPosition.y += 1 * Time.deltaTime;
		transform.position = newPosition;
		if (newPosition.y > 3) {
			Fall();
		}
	}
	void Fall(){
		Vector3 newPosition = transform.position;
		newPosition.y -= 1 * Time.deltaTime;
		transform.position = newPosition;
		if (newPosition.y < 1) {
			Rise ();
			}
		}
}
2 
    Transform myTrans ;

	//how long to keep moving up or down until switching direction
	public float verticalTime = 1f ;

	//how fast to move vertically
	public float verticalSpeed = 5f ;

	//how fast to move forward
	public float moveSpeed = 10f ;

	void Start()
	{
		myTrans = this.transform ;
		StartCoroutine(Rise()) ;
	}

	void Update()
	{
		myTrans.Translate(myTrans.forward * moveSpeed * Time.deltaTime) ;
	}

	IEnumerator Rise()
	{
		float t = verticalTime ;
		while(t > 0f)
		{
			myTrans.Translate(myTrans.up * verticalSpeed * Time.deltaTime) ;
			t -= Time.deltaTime ;
			yield return new WaitForEndOfFrame() ;
		}
		StartCoroutine(Fall()) ;
	}

	IEnumerator Fall()
	{
		float t = verticalTime ;
		while(t > 0f)
		{
			myTrans.Translate(-myTrans.up * verticalSpeed * Time.deltaTime) ;
			t -= Time.deltaTime ;
			yield return new WaitForEndOfFrame() ;
		}
		StartCoroutine(Rise()) ;
	}