The night dive of the emperor penguins

“Take it all in all, I do not believe anybody on Earth has it worse than an

Emperor penguin.”

- Apsley Cherry-Garrard, The Worst Journey in the World

The first description of an emperor penguin breeding behaviour was reported by Wilson in 1907. In 1961, Prévost showed that the male begins to fast upon arrival at the colony, where it remains through the egg-laying period as well as his incubation duties until the egg hatches. This amounts to a total of 115 days of fasting. All through the bird literature and feature films, there is much ado about dedicated emperor penguin males fasting for 115 days while they do all the incubation of the single egg.

Summary of an Emperor Penguin's yearly lifecycle - Crédit: Zina Deretsky, National Science Foundation

Sometimes, they may not fast for so long. During a winter visit to Cape Washington, we captured, weighed and attached Argos satellite tags with salt-water switches to four birds. By this means we could tell when the birds entered the water, and how far they traveled from the colony.

Movement of the four tagged birds | Each bird is represented by a different panel, A–D; bird identifier number is in the upper left-hand corner in each case. All birds were tagged at Cape Washington as labelled in A. Date labels in A–D are similar: the date of departure is the earliest date label; the last date label is the date of the last transmission.

If the birds can successfully hunt in the dark, it makes sense that they would feed during the prenuptial and pre-laying period. A shortened fast, from 120 to ∼70 days, provides greater assurance that males could successfully endure the entire incubation period without abandoning the egg.

The number and concentration of emperor penguin colonies in the high latitudes of the Ross Sea are some of the greatest in the Antarctic. The possibility of birds feeding in the winter may help to explain the robustness of some of these colonies compared with those found at lower latitudes along Antarctica’s continental shores. In the face of continued warming in the Antarctic, the success of these higher latitude colonies may be vital.

Source:

---------

Kooyman GL, van Dam RP, Hückstädt LA (2018) Night diving by some emperor penguins during the winter breeding period at Cape Washington. Journal of Experimental Biology 2018 221: jeb170795.

doi: 10.1242/jeb.170795.

Author: Mafalda Baptista