Differences Between Male and Female Birds

Size

• In the avian world, males are almost always larger (in both height and weight) than females, although sexual size dimorphism will vary depending on the species. Sandhill cranes are just one of many species where sexual size dimorphism is obvious, with males weighing up to 12 lbs. and females weighing 9 1/2 lbs. Birds of prey and flightless birds are the exception to this rule: Female red-tailed hawks are larger than their male counterparts, for example, with males weighing between 2 and 3 lbs. and females weighing between 2 and 5 lbs.

Plumage

• Males are typically more brightly colored in the avian world; they are also likely to be ornamented with excessive plumage not found on females. A token case of plumage dimorphism is the peafowl: male peafowl (peacocks) don a large and eye-catching train of colorful feathers, while female peafowl (peahens) remain largely drab and brown.

Male and Female Behaviors

• A bird's behaviors can give clues that reveal its sex. Male birds are the more territorial of the two sexes, so typically become more agitated by intruders than their female counterparts. Males are more generous with sound alarm calls and are more willing to reveal themselves to chase away predators. It is almost exclusively male birds that sing songs -- at least in North America -- since they are more more involved in defending territories and attracting mates.

Parental Behaviors

• Watching birds tending a nest can be another way to determine a bird's sex. While both parents usually care for the young, it is usually the female that sits on the brood. Except for some species (like the red-eyed vireo), it is usually males that retrieve for food for the young.