Of course, they're available--they have to be. Hardly any employer will hire a job candidate with references. So instead of just stating your references' availability, ask your references to write a letter of recommendation and attach these letters to your resume after having them professionally reviewed by an HR professional. The employer will still call your references, as they should, but they will now have concrete information to discuss with each reference when they talk.
Make sure the references you list are previous coworkers or managers, not friends or family members. For this purpose, it isn't relevant what friends and family members think about you. They already know you are great. What your future employer needs to know what kind of employee employee you are you can offer their organization.
Tell your references that you've listed them on your resume and that they should expect phone calls regarding your previous work together. IF you dont alert them to this, a reference may not accept a a call from an unknown person or number. This could slow down or even derail the hiring process.