Oksana Throws Daughter First Birthday Party - Without Mel Gibson

Credit: Lester Cohen/WireImage.com

On Saturday, Oksana Grigorieva threw a first birthday for daughter Lucia at their home in Sherman Oaks, Calif.

Naturally, the baby's father, Mel Gibson, wasn't there.

The 20 or so guests began arriving around noon for the bash, which featured several bouquets of white tulips and a birthday cake from Viktor Benes Bakery, a source tells UsMagazine.com.

Grigorieva's ex, Timothy Dalton -- with whom she has a son, Alexander, 13 -- was among the first to arrive.

"One guest brought a giant bouquet of pink balloons and signs that said '1st Birthday,'" the witness tells Us. "Several of the children wore their Halloween costumes for the party. Kids played in the yard while the parents chatted."

As her parents continue their ugly custody battle, Lucia lives with Grigorieva, 40, but sees Gibson, 54, nearly every other day, including overnight visits once a week.