Penguin Parents' Labor Division May Hurt Chicks During Lean Seasons
Penguin chicks may be vulnerable due to their parents' division of labor. Scientists have found that the labor division between crested penguin parents increases their chicks' vulnerability to food shortages.
The main duties of all penguin parents are to provide food and to defend their offspring against predatory seabirds and other intruding penguins. While on guard duty, the penguins fast and do not go off to sea to feed. Most penguins avoid long fasting periods by alternating brooding and chick provisioning duties between the sexes. However, the seven species of crested penguins are an exception.
Male crested penguins guard and fast for the first three to four weeks after eggs have hatched. During this time, the females are the sole providers. During the next six weeks, chicks gather together in creches and can be fed by both parents.
In this latest study, the researchers examined Eastern Rockhopper Penguins on New Zealand's sub-Antarctic Campbell Island over two breeding seasons in 2011 and 2012. While 2011 was an abundant year, 2012 was a lean year. The researchers noted how often chicks were fed, their subsequent size at one month old and the colony's overall success in raising chicks.
The researchers found that chicks were hatched and reared more successfully during the 2011 season than the 2012 one. During the 2012 creche phase, males in particular spent more time at sea in search of food to regain the mass they lost during their chick-guarding fast. This made males less likely to regularly bring food to their offspring. Chicks that were fed less also grew more slowly.
The findings reveal that this rigid division in parental roles can hurt chicks when food is scarce. This is particularly important to note with climate change affecting food supplies.
The findings are published in the journal Behavioral Ecology and Sociobiology.
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