#REHAB ACORN WOODPECKER DRIVER#

Although multiple paternity and maternity are common within groups containing multiple cobreeders, no extra-group paternity has been detected. Once all the females start to lay, they stop removing eggs. A female usually destroys any eggs in the nest before she starts to lay. In groups with more than one breeding female, the females put their eggs into a single nest cavity. However, reproductive vacancies-formed when all the breeders of one sex die-are filled by unrelated birds from elsewhere, so Inbreeding is rare, despite the high degree of relatedness among most group members. As mentioned above, the breeder males are often brothers, and the females are usually sisters. Nesting groups can also contain up to ten offspring helpers. However, most nests consist of only a single breeder female and 1 to 3 cobreeder males.

īreeding coalitions consist of up to eight cobreeding males and up to four joint-nesting females.

#REHAB ACORN WOODPECKER DRIVER#

It is generally believed that limited territories are a key driver of cooperative breeding behavior in birds, and in the case of the acorn woodpecker, the availability of acorn storage granaries (see Food and feeding) is a key limited resource. Most cooperative breeding species have helpers at the nest, but acorn woodpeckers are unusual in exhibiting both helping at the nest and cooperative polygamy (polygynandry). Cooperative breeding, defined as more than two birds taking care of nestlings in the nest, is a relatively rare evolutionary trait that is thought to occur in only nine percent of bird species. There is considerable variability within and among populations, suggesting extraordinary social plasticity. Regardless of composition, all breeder males (who are usually brothers or fathers and their sons) compete for matings with all breeder females (who are sisters or a mother and her daughter), the latter of which lay their eggs communally in the same nest cavity.

Field studies have shown that within the same population, groups range from monogamous pairs to polygynandrous breeding collectives consisting of coalitions of up to 8 males and 4 females, along with nonbreeding ' helpers at the nest' that are offspring from prior breeding events. Nests are excavated in a cavity in a dead tree or a dead part of a tree.īehaviour and ecology Breeding Īcorn woodpeckers are cooperative breeders, living and breeding in family groups of up to 15 individuals. This species may occur at low elevations in the north of its range, but rarely below 1,000 m (3,300 ft) in Central America, and it breeds up to the timberline. The acorn woodpecker's habitat is forested areas with oaks in the coastal areas and foothills of Oregon, California, and the southwestern United States, south through Central America to Colombia. Acorn woodpeckers have a call that sounds almost like they are laughing. White circles on their wings are visible when in flight. When flying, they take a few flaps of their wings and drop a foot or so. The white neck, throat, and forehead patches are distinctive identifiers. In most subspecies, adult males have a red cap starting at the forehead, whereas females have a black area between the forehead and the cap.

There is a small part on the small of their backs where there are some greenish feathers. The eyes are initially dark in fledglings, turning to white within a few months. The adult acorn woodpecker has a brownish-black head, back, wings and tail, white forehead, throat, belly and rump. striatipectus Ridgway, 1874 – Nicaragua to west Panama lineatus ( Dickey & Van Rossem, 1927) – Chiapas (south Mexico) to north Nicaragua albeolus Todd, 1910 – east Chiapas (southeast Mexico) to Belize and northeast Guatemala formicivorus ( Swainson, 1827) – southwest USA to southeast Mexico angustifrons Baird, SF, 1870 – south Baja California (Mexico) bairdi Ridgway, 1881 – Oregon (USA) to north Baja California (Mexico) Within Melanerpes the acorn woodpecker is sister to a clade containing two South American species: the white woodpecker ( Melanerpes candidus) and the white-fronted woodpecker ( Melanerpes cactorum). The acorn woodpecker is one of 24 species now placed in the genus Melanerpes that was introduced by Swainson in 1832. The type locality is Temascaltepec in Mexico. The specific epithet combines the Latin formica meaning 'ant' with -vorus meaning 'eating'.

The acorn woodpecker was formally described in 1827 by the English naturalist William John Swainson under the binomial name Picus formicivorus from a specimen collected in Mexico. The acorn woodpecker ( Melanerpes formicivorus) is a medium-sized woodpecker, 21 cm (8.3 in) long, with an average weight of 85 g (3.0 oz).

Rehab acorn woodpecker