Raising the Young of Others

Female goldeneye ducks regularly lay eggs in a woodpecker’s home and take their brood after hatching [2]. This unique behavior is described in Season 1, Episode 9 of The Life of Birds (The Problems of Parenthood). Goldeneye ducks belong to the family Anatidae, which comprises about 147 species in total [4]. They are the perfect example of sexual dimorphism, as the male has a glistening green-black head while the female has a chocolate brown head.

Since parenthood is such a demanding business, goldeneye ducks have evolved several mechanisms to increase the survival of their offspring [1]. Brood parasitism is one of them. It is a reproductive strategy in which individuals lay eggs in another’s nest.

After the ducklings break open the egg, the mother goldeneye takes her brood to a nearby lake where they can feed themselves. However, when a river is already claimed by another goldeneye and her brood, the mothers will fight for territory. David Attenborough records a fierce fight between the new comer and the old one. Interestingly, whoever loses flies away, leaving her brood to the other. Therefore, one female goldeneye can accumulate a flock of brood, sometimes up to twenty [2]. The remaining mother has no problem raising more children because they can feed themselves, and they reduce the chance of her own child being attacked by predators. This is another mechanism that helps the young goldeneye ducks survive.

Brood parasitism, defending territory, and leaving offspring to another are seen in other birds and are the result of natural selection [3]. However, evolution only states the facts of history – it doesn’t make the process the “right” decision. We as humans, need to decide what constitutes moral and ethical for us. Please, don’t leave your kids by the river.

by Laura Sun

The Life of Birds (1998), Season 1, Episode 9, The Problems of Parenthood, starting at approximately 16:50

 References

  1. Assia D, Nasser B, Farrah S, Ahmed A & Boudjéma S. 2018. Distribution and breeding ecology of the Ferruginous Duck Aythya nyroca in Algeria. Ostrich 89 (1): 5-12.
  2. Bruce L & John E. 2008. Conspecific Brood Parasitism in Birds: A Life-History Perspective. Annual Review of Ecology, Evolution, and Systematics 39: 343-363.
  3. David L. 1990. Frequency-Dependent Fitness Consequences of Intraspecific Nest Parasitism in Snow Geese. Evolution 44 (6): 1436–1453.
  4. Malte A & Mats E. 1982. Nest Parasitism in Goldeneyes Bucephala Clangula: Some Evolutionary Aspects. The American Naturalist 120 (1): 1–16.

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