Oecologia (2002) 130:485–495 DOI 10.1007/s00442-001-0836-x REVIEW Gerald L. Kooyman Evolutionary and ecological aspects of some Antarctic and sub-Antarctic penguin distributions Received: 24 May 2001 / Accepted: 27 September 2001 / Published online: 13 November 2001 © Springer-Verlag 2001 Abstract Penguins probably originated in the core of edge. Less is known about penguins during the pelagic Gondwanaland when South America, Africa, and Ant- phase between breeding cycles. What we do know is sur- arctica were just beginning to separate. As the continents prising in regard to their dispersal, which ranges from drifted apart, the division filled with what became the hundreds to thousands of kilometers from the breeding southern ocean. One of the remaining land masses colonies. moved south and was caught at the pole by the Earth’s rotation. It became incrusted with ice and is now known Keywords Aptenodytes · Eudyptes · Platform transmitter as East Antarctica. Linking it to South America was a terminal · Pygoscelis · Time-depth recorder series of submerged mountain ranges that formed a neck- lace of islands. The northern portion of the necklace, called the Scotia Arc, is now the “fertile crescent” of the Introduction Southern Ocean. The greatest numbers and biomass of penguins are found here as well as that of krill, the pri- Penguins are one of the oldest, most aquatic, and argu- mary prey species of most penguins, and many other ably most mystifying groups of birds. Their adaptation to marine predators. Today penguins are found throughout the sea was most likely a conversion from a procellariid the sub-Antarctic islands and around the entire Antarctic type of flying bird, such as a diving petrel (Simpson continent. Using satellite transmitters and time-depth re- 1976), to flying underwater, as modern penguins do. corders, while taking advantage of the parental dedica- There is no cladogram for penguins at the present time tion of breeding birds, numerous investigators have de- (Fordyce and Jones 1990). Most classification schemes scribed foraging habits of several species of penguins. are based on morphological characters. The exception is The information obtained is labor intensive and costly so the DNA-hybridization study used for the biochemical that studies are restricted to certain species, areas and classification of birds by Sibley and Ahlquist (1990). seasons. Here I review the patterns evident among six of Biochemical evidence indicates a much more detailed the most abundant and completely studied of the pen- classification with the addition of infraclasses, parvclass- guins. The variation in behavior is considerable from es and so on. The major difference from the classifica- those species that seldom dive deeper than 20 m in tion of other authors (Mayr and Amadon 1951; Cracraft search of prey to those that will dive to depths >500 m to 1981) is the placement of penguins in the order Ciconii- catch mesopelagic fish and squid. Foraging trips from formes rather than Sphenisciformes (Sibley and Ahlquist breeding colonies vary among species and with the sea- 1990). In the Sibley/Ahlquist classification, the order son. Often the birds travel no more than 30 km and at Ciconiiformes includes 1,027 species of birds. other times the trips may exceed 600 km. Sub-Antarctic Fossil evidence places the origin of penguins at least species often reach more productive waters near or with- in the Eocene (Fordyce and Jones 1990), and Simpson in the Antarctic Polar Front zone, where the mixing of suggests the origin was likely as early as the Cretaceous Antarctic and sub-Antarctic waters provide rich resourc- (Simpson 1976). The hybridization evidence agrees with es for their prey. Antarctic species usually remain close a divergence from procellarids about 47 million years to shore, along the continental slope, or near the sea ice ago (mya) (Sibley and Ahlquist 1990). All fossil locali- ties are in the present range of penguins, but conditions G.L. Kooyman (✉) have changed considerably. Over the past 50 million Scholander Hall, 0204, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA years the continental land masses have shifted and frag- e-mail: [email protected] mented (Fig. 1). Presumably the birds evolved on the Fax: +1-858-5641305 edge of the continental land mass of Gondwanaland, but 486 tinent and adjacent waters became colder. The ultimate conclusion of this drift occurred when Antarctica reached its present position, South America and Austra- lia assumed their separation from Antarctica and the cir- cumpolar Southern Ocean formed and cooled (Eastman 1993; Knox 1994). Penguin diving ability enables some of them to forage at depths unavailable to other sea birds, but it is with some sacrifice. Their flightlessness has placed important restrictions on their distribution. Awkward on land, and relatively defenseless against even moderately sized terrestrial predators, their breeding habitat is restricted, with few exceptions, to cold temperate islands or isolated shorelines of the island continents of Australia and Ant- arctica. Only the Emperor Penguin, by breeding on sea ice, has separated itself completely from the terrestrial habitat. As the southern seas cooled, only two species evolved in ways to cope with high latitude conditions: the Emperor Penguin and Adélie Penguin. In large part, the other 15 species of penguins are associated with New Zealand, South Africa, Australia, southern South America, and islands of the sub-Antarctic region. This review will address penguin foraging behavior during the critical time when constrained by the need to provide food to rapidly growing chicks. During incuba- tion of the egg and nurturing of the chick, penguins share duties, which change from long periods at sea during in- cubation to shorter periods as the chick matures and its Fig. 1 Distribution of the continents about 100 million years ago food requirements increase. If the foraging trip of the (mya) when Gondwanaland was separating (top), and at about 60 mya (bottom), shortly before the earliest known fossil penguin partner is too long, the mate will abandon the egg or of 50 mya. The hatched area represents the central region where brooded chick. Even when the chick no longer needs its penguins probably evolved parent’s physical protection, an exceptionally long fast because of a delayed return by the adults will result in the weakening of the chick. If it does not starve, it may there is no evidence of the location of their origin be killed by nearby colony predators such as skuas (Fordyce and Jones 1990). Most likely penguins fre- (Catharacta spp.) or giant petrels (Macronectes spp.). To quented near-shore islands which gave them protection maintain the chick’s condition it is vital that the parents’ from any continental predators that may have existed. foraging trips to sea become increasingly successful as With few exceptions they continue to enjoy (and require) the chick matures. High food intake is necessary to this isolation. Over the course of tens of millions of maintain body condition adequate to discourage preda- years penguins differentiated into many more species tors, to enhance overall growth and feather development, than exist today. There are 17 extant species, and 32 and therefore encourage the molt of the down and ulti- known extinct species (Simpson 1976). Incidentally, this mately the chick’s independent departure to sea. ratio is similar to that of the great avian diversity loss apparent in the Pleistocene. Over the course of 2 million years of great climatic changes, the number of species Tracking penguin foraging patterns declined by half to the present-day number of more than 9,600 species (Brodkorb 1971, as cited in Proctor and Perhaps the most significant technical advance in the Lynch 1993). Some of the earlier penguin species study of the behavior of marine birds and mammals at were probably substantially larger than the present-day sea has been the ability to track their movements with giant, the Emperor Penguin (Aptenodytes forsteri), which platform transmitting terminals (PTT). These transmit- is twice the mass of its congener the King Penguin ters are tuned to a nominal frequency of 401.650 MHz. (A. patagonicus) and 30 times the mass of the smallest They range in mass from about 150 to 400 g. Much of present-day penguin, the Little Penguin (Eudyptula this mass results from the thick casting necessary to minor). withstand pressures that occur when aquatic animals Penguins spread to many islands of the southern seas, dive to depth. The linear dimensions also vary with the as well as the southern continental coastlines of South size and number of batteries needed. A typical size is America, Africa and Australia. During this time the con- about 5 cm wide by 4 cm thick and 15 cm long. These 487 Table 1 Summary of the annual cycle and foraging range during conservative. Phase durations are the underlined values that are each phase of the cycle. Body mass is the average for the male and first in columns 3–7. Distances in kilometers are the bold last val- female parent during the crèche stage if reported. Unknown dis- ues of columns 3–8. References are cited by number in column 9, tances are indicated with a question mark. Dispersal patterns are and defined in the note below the table. The time and duration of just being determined by various means and the data presented are the cycles are from Williams (1995) Species; Breeding Incubation Guard Creche Fledging Molt Winter Referencesa mass (kg) dispersal Macaroni, Oct/Nov 35/Nov– 25/Dec– 35/Jan/ 60/Feb/? 25/Mar/ Apr–Sep/? (1) Eudyptes Dec/400 Jan/30 50 Colony chrysolophus; 4.6, 3.9 Royal, Sep/Oct 35/Oct– 21/Dec/ 43/Jan– 65/Feb/? 26/Feb–Mar/ Apr–Sep/? (2) E.