Remarks on the terminology used to describe developmental behaviour among the auks (Alcidae), with particular reference to that of the Great AukPinguinus impennis

Abstract

Much of the historical record relating to the breeding biology of the Great Auk Pinguinus impennis consists of statements on which it is not safe to rely without corroboration. There is, nevertheless, sufficient evidence for a strong case to be argued for the species having evolved a precocial chick‐rearing strategy, together with an incubation period that is remarkably brief for a bird of its size. In this way, the species would have minimized the time for which it had to remain ashore to raise its young. Before the evidence for this proposition is evaluated, a review is undertaken of the history and usage of the terminology most frequently used to describe the developmental condition of young birds on hatching. Modifications to the terminology have been suggested where there is a potential for confusion, and an entirely new term, ‘hypoprecocial’, introduced for downy young that require an appreciable period of brooding before quitting the breeding site. Regarding the species itself, it is suggested that the Great Auk had evolved a strategy that was more fully precocial than that of any seabird whose breeding biology is known to science.

Osteological Histology of the Pan‐Alcidae (Aves, Charadriiformes): Correlates of Wing‐Propelled Diving and Flightlessness

“…Albeit somewhat speculative, some evidence suggests that the chicks of † P. impennis were among the most precocial of pan‐alcid species; however, little consensus exists on this issue (Bengston, ; Gaskell, ; Houston et al, ). The fibrolamellar texture of the FBL in all sampled pan‐alcid species is indicative of the fast growth rates that are common to Aves, and there is little data to suggest that large flightless pan‐alcids grew in different ways or at different rates than their volant counterparts.…”

A middle Pleistocene bird community from Saint Lucie County, Florida

“…The presence of both adult and juvenile Great Auk fossils at DCP may indicate the presence of more southerly breeding colonies in the middle Pleistocene, although young individuals of P. impennis were at least moderately precocial and may have left their nesting areas shortly after hatching to join their parents at sea (Gaskell, 2004;Houston et al, 2010). Juvenile birds may have needed a number of months to complete skeletal development (Meldgaard, 1988).…”

How did the Great Auk raise its young?

“…After around 20 days at the colony, the chicks, often weighing less than 25% of the full adult mass, go to sea with the male parent who feeds them for several weeks (Sealy, 1973; Gaston, 1985a; Gaston & Jones, 1998). (We follow the terminology used by Gaston & Jones (1998); for a detailed review of terminology, see Gaskell (2004). )…”

“…In their chapter on development of the auks, Gaston & Jones (1998) suggest that the Great Auk could not have adopted the semi‐precocial strategy unless it fed its chick by regurgitation. They conclude (p 100) that ‘We cannot rule out the possibility that the young of the Great Auk were completely precocial and were never fed on land.’Gaskell (2004) reviews the data and argues that the Great Auk followed a precocial strategy. We now provide the first formal evaluation of how the Great Auk raised its young.…”