Research conducted over the span of 20 years at Tall Timbers Research Station by biologist Jim Cox revealed that male brown-headed nuthatches outnumber females by a ratio of 5:4.

       The reason for this may be the fact that the female nuthatch incubates the eggs. The male, however, will bring food to a nesting female.  Snakes, predominately red and gray rat snakes, are the number one nest predator on brown-headed nuthatches. Therefore, since females spend far more time in nesting cavities, they are far more likely to become a meal for snakes seeking food located in a tree cavity.