我有一个列表变量，我想循环，我可以做到这一点，但我似乎不能调用它在我的 bat 语句，你知道如何？

def birds = ["Parrot", "Cockatiel", "Pigeon"]

pipeline 
{

    agent any
    stages 
    {

        stage('Build Job1') 
        {
            steps 
            {
                script 
                {
                    for (int i = 0; i < birds.size(); ++i) 
                    {
                        echo "Testing the ${birds[i]} browse"
                        bat 'echo ${birds[i]}'

                    }
                }
                
            }
        }
        stage ('Hello')
        {
            steps
            {
                script
                {
                    for (int i = 0; i < birds.size(); ++i) 
                    {
                        echo "Testing the ${birds[i]} browser"
                    }
                }
            }
        }
    }   

}