Undated (AP) _ Abducted children suffer even when Daddy or Mommy is the kidnapper - a notion which experts on missing children say the public has been slow to accept.

''We find that about 95 percent of the children who are recovered do require psychiatric care,'' says Georgia Hilgeman, director of the Vanished Children's Alliance in Los Gatos, Calif.

Parental kidnapping, she said Tuesday, is ''really a devastating form of child abuse.''

''First of all, the type of person who kidnaps a child is not the stable sort,'' says Katheryn Rosenthal, director of Children's Rights of Florida, Inc.

''Kids are being taken from their beds, their pets, their schools. No one would do that to a child that they love.''

Parental kidnapping - often a desperate last act in a failed marriage or love affair - is far more common than kidnappings by strangers, and is estimated to occur anywhere from 25,000 to 500,000 times a year in this country, according to the National Center for Missing and Exploited Children in Washington.

The last case to draw national attention involves a five-year-old boy, Benjamin Lee Studer, who recognized himself last week on an NBC-TV program on missing children.

A court hearing was scheduled today in Birmingham, Ala., where Benjamin Lestser Studer was arrested on charges of kidnapping and unlawful flight.

The father had brought the boy from Covington, Ky., to Alabama a year ago. Studer's former wife, Jennifer, claims she had been awarded legal custody by a Kentucky court. Studer, who was arrested on charges of kidnapping and unlawful flight, claims he had not been served with a divorce decree and had no knowledge of the custody award.

Benji appeared to have been well-treated by his father. Sadly, that is not always the case.

''The basic reason for abduction, we have found over the years, is revenge,'' Mrs. Rosenthal said. ''Anytime you have a situation like that, you end up with children who very quickly become excess baggage.''

A parent on the lam, for instance, can't use his or her Social Security number for fear of being traced, and thus can't work. Inevitably, the child is blamed for the hardship, Mrs. Rosenthal said.

In some cases, children are kidnapped and then abandoned or put up for adoption by a parent who only wants revenge against a former spouse.

Mrs. Rosenthal recalled one case in which a father kidnapped his children, then would telephone his former wife to make her listen while he beat the children.

In another case, children were found near starvation living with their mother in an abandoned school bus in a Texas junkyard. ''If we hadn't found them, they would have been dead in a couple of weeks,'' Mrs. Rosenthal said.

''We have had so much of this, we know it's not a case of Mom or Dad loves the kids.''

Her organization, based in Pinellas Park, has located 175 children in the past three years, she said.

When her own stepson was the victim of a parental kidnapping in 1981, Mrs. Rosenthal said, police dismissed it as a civil matter. She looked up the law and explained to police that it was a felony.

Ms. Hilgeman, whose agency works on missing children's cases in the San Francisco area, said she has not encountered one case in 10 years in which the kidnapper-parent appeared to be genuinely motivated by love.

The children may suffer a variety of traumas - a change of name, being held out of school, or being told that the other parent no longer loves them.

Yet, she says, law enforcement agencies and the public often do not believe a child will be harmed by a parent.

''I think things are starting to change,'' she said, ''but we have a long way to go. I think a lot of law enforcement officers around the country do not regard it as a serious crime.''

The Studer case illustrates changes in public attitudes in Kentucky, where the boy allegedly was kidnapped. Until 1984, the case would only have been a misdemeanor, said Ron Pregliasco, the director of safety in Jefferson County, which includes Louisville.

Now, it is a class D felony, with a maximum prison term of five years. Because it's a felony, Mrs. Studer was able to obtain a warrant charging her ex-husband with unlawful flight to avoid prosecution, which brings the FBI into the case.

According to the National Legal Resource Center for Child Advocacy and Protection, 46 states classify parental kidnapping as a felony.

While there are no definitive statistics on parental kidnapping, it clearly is more of a problem than kidnappings by strangers.

The Center for Missing and Exploited Children has received 2,306 reports of parental kidnapping in the last 15 months, compared to 295 cases in which the suspect was a stranger. In the parental cases, 582 children were recovered, while 73 of the children taken by unknown kidnappers were recovered and 31 others were found dead.