Time Warner (NYSE: TWX) CFO John Martin offered some more details on AOL’s 23 percent revenue decline in Q1, which he attributed generally to the recession. Ad revenue was down 20 percent to $443 million. Looking at the current quarter, Martin said that ad revenue trends are similar to Q1.

—Display was down 17 percent to $158 million. Martin: “As has been the case in recent quarters, yield declined as more inventory was monetized through lower-priced ad channels, which pay lower CPMs,” meaning that the remnant business is pulling display down. AOL has also been starting to see more pricing pressure on its reserve inventory and the main categories: finance, autos and telecom are pulling back.

More analysis, after the jump.

—Paid Search revenues declined 12 percent to $152 million, due to lower query volume, Martin said. Unspecified AOL properties also produced lower revenues per search query, and lower click-through rates were also offset by increases in cost-per-click. Martin: “We do expect search revenues to remain pressured due to the continued migration of domestic users to AOL.com and away from the client, and changes put into place by Google (NSDQ: GOOG) that reduce our effective cost-per-click.”

—Third party revenues dropped 29 percent to $133 million. This segment was hurt by the absence of education provider Apollo Group, which contributed $16 million to the year-over-year decline—that’s about one-third of those revenues, Martin noted. In August 2007, Apollo, which had an exclusive ad management deal with AOL, acquired online advertising network Aptimus. That led to the ending of its agreement with AOL in Q108, which means that third party revenues will no longer have that comparison factored in. But that doesn’t mean the segment will have more positive numbers: excluding Apollo, third party revs were still down 23 percent. That separate decline reflected softness in retail and autos, and lower demand in general for both performance and branded advertising on AOL’s network.

• Earnings: Time Warner Meets Expectations, Including AOL’s 23 Percent Rev Decline