PORTLAND – This spring, when Maine high schools release their lists of the 10 seniors with the highest academic rankings, girls are likely to outnumber boys by a ratio of nearly 2-to-1.

Boys score lower on standardized reading and writing tests, men earn only 38 percent of the bachelor’s degrees from Maine’s public universities and boys are twice as likely as girls to receive special education services.

Various measures of academic performance show that in Maine, as elsewhere in America, boys are trailing girls, and no one seems to know why.

“It’s absolutely a concern,” Jeanne Crocker, principal at South Portland High School, told the Maine Sunday Telegram. “It’s a tough problem, and I don’t think there are answers yet. Is it that school, as we know it, is not working as well for guys as it is for girls? If so, what are we going to do with it?”

The economic impact of the gender gap could be particularly severe in Maine because of its loss of high-paying manufacturing jobs that have long been a source of support for men who lack a college degree.

The trend knows no geographic or social boundaries. It is found in poorer northern Maine and the richer south, affecting educated families as well as those in which neither parent is college-educated.

The poor performance of male students is a turnabout from decades ago. In 1972, men made up 55 percent of the nearly 24,000 students enrolled in the University of Maine System. This fall, 38 percent of the more than 34,000 students were men.

Whereas girls used to lag in educational achievement, today the reverse is true.

“Everything has flip-flopped,” said Maryjane Stafford, a math teacher at Winslow Middle School. “Now these little boys are endangered.”

The problem appears to begin early on. A study of 52 state-funded pre-kindergarten systems in 40 states found that in Maine, boys are 41/2 times more likely to be expelled than girls.

“The gender gap starts very early,” said Professor Walter Gilliam of Yale University, who conducted the study.

A task force formed by Maine’s Department of Education to study boys’ poor academic performances is expected to issue a report in the coming weeks.

Students say the achievement gap is obvious. When asked why boys don’t measure up academically, boys themselves cite laziness, disinterest and the fear of being branded a nerd.

“I think girls work harder than boys. Maybe not doing your work is a sign of being cool,” said Jack Niveson, a 14-year-old student at Winslow Middle School.

At Bonny Eagle High School, Liz Waters said girls are more competitive within the class rank. “In English, it’s girls that dominate. I’m in (Advanced Placement) English and there’s only five boys in a class of 14.”

Various theories have been offered, ranging from differences in boys’ and girls’ brains to a failure of schools to address the needs of boys. Some point to gender stereotypes that depict tough guys as heroes and smart kids as wimps. Or to the preponderance of female teachers in elementary and middle schools that leaves boys with a lack of male role models.

There is also an economic theory offered by those who find a better job market for 18-year-old boys than girls, which encourages more girls to go to college. A strong construction industry enables many boys to earn decent money at age 18, which may explain why some boys see higher education as unnecessary.

But U.S. Census figures show that over the course of the average man’s working life, a bachelor’s degree is worth more than $1 million more than a high school diploma.

“Want that new car?” said Lynne Miller, an education professor at the University of Southern Maine, mimicking a concerned parent. “You’re not going to make it, you know, if you don’t go to college.”