Pygmy Nuthatches appear to be monogamous and form pair bonds that last through the entire year. Male Pygmy Nuthatches court females by bringing them food before mating has taken place. The males also continue to feed the females after mating, during nest building, egg-laying, and through the incubation process. During the nest building period of the courtship, which takes 3-6 weeks, males and females work together to build the nest. Pygmy Nuthatches can build their own nests but prefer to use nests and other holes that have been made previously by other organisms (Kingery and Ghalambor, 2001).
Mating System: monogamous ; cooperative breeder
Female Pygmy Nuthatches initiates copulation; females perch next to the males on a horizontal branch and face the males with their bills open. Then the females make high pitched calls and hold their tails stiffly away from their bodies to signal to the males that they are ready to mate. Female Pygmy Nuthatches then shake their wings and begin a swinging motion that is common to many nuthatch species. This swing motion is similar to trembling and prompts male Pygmy Nuthatches to sit behind the females and begin the same trembling-swinging motion. The males then mount the females and sometimes peck at the back of the female's head. Copulation lasts less than 5 seconds, then both will fly away (Kingery and Ghalambor, 2001).
Breeding season: April to August
Range eggs per season: 5 to 9.
Range time to hatching: 12 to 17 days.
Range fledging age: 19 to 21 days.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Average eggs per season: 7.
Female Pygmy Nuthatches start laying their eggs in the early morning and continue throughout the day. The eggs of Pygmy Nuthatches are white and speckled with chestnut-red or purplish brown spots. The females do not begin incubating the eggs until all of the eggs have been laid, but the females do cover the eggs with nesting materials until the entire clutch is laid. Male Pygmy Nuthatches bring the females food and nesting material during the incubation process. Pygmy Nuthatches also engage in cooperative breeding, with 1 to several brood helpers (Sydeman, 1989). The helpers are usually male yearlings from the previous year and will help for about 1 year. The helpers feed the females and the young Pygmy Nuthatches when they hatch. Once the young hatch the parents take the egg shells and fly them away from the nest (Kingery and Ghalambor, 2001).
Parental Investment: altricial ; male parental care ; female parental care