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Sitta pygmaeapygmy nuthatch

By Jordan Kieliszewski

Geographic Range

Pygmy Nuthatches are found along the Pacific coast from Baja up into southern British Columbia, and range as far south as central Mexico. Pygmy Nuthatches can be found as far east as central Montana and Colorado. They also live in patches throughout the mountainous regions of Mexico (Bent, 1948).

Habitat

Pygmy Nuthatches prefer to make their homes in long-needle pine forests, especially in Ponderosa, Monterey, and Jeffrey pines. They are found in their highest density in old-growth forests that are undisturbed and contain numerous dead pines. Pygmy Nuthatches live in valleys, and they are also found in mountainous areas all the way up to the tree line, as long as there is an abundance of old-growth pine trees (Kingery and Ghalambor, 2001).

  • Range elevation
    4250 (high) m
    13943.57 (high) ft

Physical Description

Male Pygmy Nuthatches have a grayish-brown crown on their heads; they also have a black stripe through their eyes, and a white line over their eyes. Their back and central tail feathers are bluish gray, and they have reddish brown underbellies. Pygmy Nuthatches have white spots on their outer tail feathers and have dark brown bills and feet. Female Pygmy Nuthatches are very similar to the males, differing in that the females have a bluish gray crown along with underbodies that are usually paler then the underbodies of males (Hoffman, 1927).

  • Range mass
    9.3 to 11 g
    0.33 to 0.39 oz
  • Range length
    9 to 11 cm
    3.54 to 4.33 in

Development

ThPygmy Nuthatches' eggs are 15.76 mm in length and 12.21 mm in breadth. Young Pygmy Nuthatches are capable of reproduction at 1 year of age, though some males may become helpers and not reproduce for another year (Kingery and Ghalambor, 2001).

Reproduction

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).

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
  • Average eggs per season
    7
    AnAge
  • Range time to hatching
    12 to 17 days
  • Range fledging age
    19 to 21 days

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).

Lifespan/Longevity

The lifespan of Pygmy Nuthatches was determined by recapturing birds that were banded. The maximum recorded lifespan was 8 years 2 months (Kingery and Ghalambor, 2001).

  • Typical lifespan
    Status: wild
    1 to 6 years

Behavior

Pygmy Nuthatches move quickly when they walk, hop, or climb. When they climb on a tree they always move head first going up or down the tree. Pygmy Nuthatches do not fly for extended periods; most of the time they fly only for quick, short trips between trees to look for food. A breeding pair of Pygmy Nuthatches occupies a territory year round but usually only defends it during the breeding season. Pygmy Nuthatches commonly bath in pools of rain water and melted snow, they also engage in preening and allopreening while in flocks. This species of nuthatch does not migrate so it must find a place to roost for the winter. Pygmy Nuthatches usually choose an old-growth pine for their winter roost and they have been known to roost in groups of 170 individuals. Pygmy Nuthatches roost together in large groups to reduce their loss of thermal energy. They can also engage in controlled hypothermia while roosting to conserve energy, this allows them to lower their body temperature and reduce their metabolic rate while they are sleeping. Pygmy Nuthatches become very aggressive towards other Pygmy Nuthatches and other organisms in their territory during breeding season. They actively guard against other Nuthatches that are feeding in their area, and they chase off larger predators that venture too close to their nest (Kingery and Ghalambor, 2001).

Communication and Perception

Food Habits

During the breeding season Pygmy Nuthatches have a diet which consists of 60-85% insects, such as beetles, wasps, ants, and caterpillars. The other portion of their diet includes seeds from pine trees and other plant materials. Pygmy Nuthatches use their bills to probe the cracks of trees and peel off bark to expose the insects that are inside the tree. They also search inside the crevices of pine cones on trees and on the ground for insects. Pygmy Nuthatches feed in flocks, especially during the non-breeding season. This appears to increase the ability of the flock members to find a food source. The winter diet of this bird comprises of seeds or insects, depending on the birds location and the food available (Kingery and Ghalambor, 2001).

  • Animal Foods
  • insects
  • Plant Foods
  • seeds, grains, and nuts

Predation

Pygmy Nuthatches have many adaptations to help them avoid predators. This species of nuthatch sometimes feeds in flocks, which helps it to look for predators and confuse them if they attack. If a predator attacks a flock of Pygmy Nuthatches all the birds in the flock scatter at the same time, and this sometimes confuses the predator long enough for all or most of the Pygmy Nuthatches to fly to a safe location.

When solitary Pygmy Nuthatches spot a predator they position themselves on the opposite side of a tree or branch from the predator to block the advance of the predator.

When squirrels try to invade nests that contain eggs or juveniles, female Pygmy Nuthatches perch at the entrance of their nest, spread their wings, and sway back and forth slowly in a rhythmic movement. Pygmy Nuthatches have also been seen mobbing hawks or other larger birds that may invade their area (Kingery and Ghalambor, 2001).

Ecosystem Roles

Pygmy Nuthatches prefer to nest in old-growth pine forests and they eat pine tree seeds and insects. So, they are responsible for some seed dispersal. Since the majority of Pygmy Nuthatches' diet is insects, they are also responsible for influencing the population of insects in their territory (Kingery and Ghalambor, 2001).

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

No significant economic contributions were attributed to Pygmy Nuthatches, though this species of nuthatch could be a source of insect control.

Economic Importance for Humans: Negative

No significant negative economic aspects were attributed to Pygmy Nuthatches.

Conservation Status

Pygmy Nuthatches need old-growth pines for nesting and collection of food, so they are excellent indicators of the health and age of the pine forests where they are found. Since Pygmy Nuthatches need a specific type of environment to live in they are especially vulnerable to deforestation, by humans and natural causes, which results in significant depletion of old-growth pine trees. Pine forests that have been logged or destroyed because of other reasons have resulted in significant drops in populations of Pygmy Nuthatches (Kingery and Ghalambor, 2001).

Contributors

Jordan Kieliszewski (author), University of Michigan-Ann Arbor, Kerry Yurewicz (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cooperative breeder

helpers provide assistance in raising young that are not their own

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

References

Bent, A. 1948. Life Histories of North American Nuthatches, Wrens, Thrashers and their Allies. Washington D.C.: United States Government Printing Office.

Hoffmann, R. 1927. Birds of the Pacific States. Cambirde Massachusetts: The Riverside Press.

Kingery, H., C. Ghalambor. 2001. Pygmy Nuthatch. The Birds of North America, 567: 1-32.

Sydeman, W. 1989. Effects of Helpers on Nestling Care and Breeder Survival in Pygmy Nuthatches. The Condor, 91: 147-155.

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