Is this surprising?

Gender Bias Uncovered in Children's Books With Male Characters, Including Male Animals, Leading the Fictional Pack

Among the study's findings:

• Males are central characters in 57 percent of children's books published per year, while only 31 percent have female central characters.
  
• No more than 33 percent of children's books published in any given year contain central characters that are adult women or female animals, but adult men and male animals appear in up to 100 percent of books.
  
• Male animals are central characters in more than 23 percent of books per year, while female animals are in only 7.5 percent.
  
• On average, 36.5 percent of books in each year studied include a male in the title, compared to 17.5 percent that include a female.
  
• Although books published in the 1990s came close to parity for human characters (with a ratio of 0.9:1 for child characters; 1.2:1 for adult characters), a significant disparity of nearly 2 to 1 remains for male animal characters versus female.
  

Here's the citation: J. McCabe, E. Fairchild, L. Grauerholz, B. A. Pescosolido, D. Tope. Gender in Twentieth-Century Children's Books: Patterns of Disparity in Titles and Central Characters. Gender & Society, 2011; 25 (2): 197 DOI: 10.1177/0891243211398358 [The PDF is available there for free!] Via LISNews.