Our association maintains an on-site security office. Calls to that office are automatically recorded. Do we need to disclose to the members that their calls to the security office are being recorded?

Yes. And this doesn't just apply to members. Anyone who might be recorded should be told beforehand. When it comes to recording phone calls, California is a "two-party consent" state. Any person (and that includes an HOA) who records a confidential communication without the consent of the other party violates Penal Code section 632. The punishment is a fine of up to $2,500 and/or imprisonment for up to one year. Worse, under Penal Code section 637.2., the person who is surreptitiously recorded may recover, as damages, either three times their actual damages or $5,000, whichever is greater. That's as much as $7,500 total and a year in prison for a single violation! If an HOA wants to record calls, it should provide notification at the beginning of the call that the call may be recorded. A taped message to that effect is fine. Then, the HOA won't run afoul of the Penal Code.  See Kearney v. Salomon Smith-Barney (2006) 39 Cal.4th 95, 100, 118.  You've probably noticed just such an announcement when you place a call to a bank or virtually any other customer service number. That's how those companies protect themselves from violating California's "two-party consent" rule, and how HOAs should do so, too.

Does the ADA apply to our homeowners association?

Sometimes it will but generally not. An association, however, cannot unreasonably deny a member or resident the full enjoyment of their property and/or the common area. Thus, the association must be willing to “accommodate” an owner by suspending provisions of the governing documents that would otherwise unreasonably deny the disabled person the full enjoyment of the premises; the association must also permit an owner, at his or her expense, to make “reasonable” modifications to their separate interests and the common area even though such modifications might otherwise be banned under the governing documents. The extent of the accommodations and modifications required will depend on the nature and extent of the disability and other factors including their impact on the association's “business operations”.