Date: September 7, 2016
Source: Central Ornithology
Publication Office
"Survival of the
fittest" usually means that animals put their own needs first, but
occasionally it pays to work together. A new study in The Auk:
Ornithological Advances describes an unusual example of cooperative
breeding in an introduced pheasant population in Hawaii, where young males help
care for chicks and defend against intruders rather than striking out on their
own.
Cooperative breeding, where
members of a social group provide care to young that are not their own
offspring, is rare in "precocial" bird species like pheasants --
those where chicks are already well-developed when they hatch and don't require
intense parental effort. However, Lijin Zeng of the University of
California-Riverside and her colleagues have discovered that cooperative
breeding is the norm among Kalij Pheasants in Hawaii's Volcanoes National Park.
While females incubate their eggs alone, all group members, including up to six
males as well as the breeding female, feed the chicks after they hatch and
defend the group against intruders. Dominant males father the most chicks, but
almost a third are fathered by subordinate males within the same group or males
from other groups.
This is only the third time
cooperative breeding has been observed in the pheasant family, and Kalij
Pheasants, introduced in Hawaii in the 1960s, are not known to breed
cooperatively in their native range in Asia. Possibly due to a lack of
predation and disease, their population density in Volcanoes National Park has
grown very high, and overcrowding may prevent young males from being able to
establish their own territories. Instead, their best hope to pass on their
genes is to stay with the group and wait to move up in the dominance hierarchy,
fathering a few chicks in the meantime.
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