Erect-Crested Penguin

Distribution / General:

The Erect-Crested Penguin belongs to the Eudyptid (Crested) penguins, together with the closely related Snares and Fiordland Penguins which also breed only on New Zealand territory, and the Rockhopper, Macaroni and Royal Penguins. It can be most easily distinguished from the other species of crested penguins, as its name suggests, by the upwardly angled superciliary stripe which runs into an erect brush-like yellowish crest.

Breeding populations of Erect-Crested Penguins are largely found on the Antipodes and Bounty Islands. Small numbers of breeding birds have also been reported on Campbell and Auckland islands in the past. In part due to the remote locations of the colonies, the Erect-Crested Penguin is the least-studied of all penguin species. Hence, for a better understanding of its behaviour, the reader may wish to also view the sections on the related species. Most of the general information in this section is based on studies by John Warham in the 1970s and the chapter on the Erect-Crested Penguin in "Bird Families of the World - The Penguins" (T.D.Williams 1995). Populations on the Antipodes appeared to have declined significantly when partial census figures for 1998 were compared with counts from 3 years earlier (Spencer-Davis 2001. Natural History Magazine). No complete data is available. It is possible that only 100000 or less breeding pairs remain.

Feeding:

Diet

The diet of the Erect-Crested Penguin is thought to largely consist of crustaceans and cephalopods. No detailed studies are available.

Foraging Behaviour

No detailed studies available. Absent from breeding grounds from May to September.

Reproduction:

Nest & Partner Selection

Erect-Crested Penguins tend to nest on sloping rocky terrain with little vegetation up to about 70m above sea level. Small nest bowls may be constructed in relatively flat areas. Small stones may be used to form the nest, and a small lining of grass is sometimes added if available. However, in some cases, these penguins do not bother to make nests at all and simply lay their eggs on the bare ground.

Colonies usually contain more than 1000 breeding pairs with average distances between nests of 66 cm. On the Bounty Islands, colonies are found wherein nesting sites are interspersed with nests of Rockhopper Penguins and Shy Albatrosses.

Little is known about pair and site fidelity, although based on other crested penguins, long-lasting pair bonds are probably established and nest sites frequently reused.

Male birds tend to arrive at nest sites at least a week before the females. Little fighting is observed after the females return, and the Erect-Crested Penguin appears more docile than the other eudyptid penguins, also in terms of sexual activity. Even in established pairs, copulations were observed only once every 30 hours (Spencer-Davis 2001. Natural History Magazine). Females often rejected initial attempts shortly after arrival and males also seemed hardly interested. The relatively low testosterone levels found in blood samples may account for this, yet the reason for these is not known.

Sexual displays include "vertical head swinging" which can evolve into "mutual displays" when both partners join in. This is accompanied by repeated throbbing calls composed of series of 60 msec pulses, increasing in length from 0.15 to 0.5 sec as the call progresses. Each throb is separated by a 0.1-0.2 sec interval. Frequencies cover a wide range from 0-3.5 kHz, mainly 0.1-0.25, and the duration of the entire call is usually from 3-6 secs. The "trumpet call" is performed by lone birds (forward trumpeting) and by pairs ((mutual) vertical trumpeting). This can last from 4-14 secs with repeated throbs comprising 6-12 from 50-60 msec long pulses with progressively declining pitch. Throb lengths increase from approx. 0.5 to 0.9-1.7 sec as the call progresses, whilst intervals increase gradually from 0.2 to 0.4 secs. The main frequency range is from 1.5-2.0 kHz. Bowing and quivering is also observed as part of partnership rituals especially around the nest, yet is not accompanied by calling.

Timing of Breeding

First eggs are laid at the beginning of October on the Antipodes, with peak laying just over a week later. Breeding is thought to commence 2-3 weeks later at the slightly more northerly Bounty Islands. This seems questionable, given that in Rockhopper Penguins more northerly populations tend to breed earlier.

Laying / Brood Reduction Mechanism

First eggs are usually laid about 2 weeks after the arrival of female birds at the colony. Two eggs are laid over a period of about 4 days, a smaller greenish (A) egg, followed by the larger whitish (B) egg.

All crested penguin species display egg dimorphism and associated brood reduction mechanisms, favouring the second and larger (B) egg. There are however significant differences in the extent of dimorphism and the kind of brood reduction behaviour displayed. The first (A) and second (B) eggs of the Erect-Crested Penguin averaged 83.7 and 150.7 g (80% mean difference), making them the most dimorphic of any penguin species (Miskelly and Carey 1990. Univ. Canterbury Antipod. Isl. Exped. Rep. p.2-11). Macaroni Penguins eggs are also highly dimorphic with the egg having respective mean masses of 94 and 145 g, and a mean difference of about 55% (Barlow 2001. Antarctic Sci. 13(3), p.286-287).

Macaroni, Royal and Erect-Crested Penguins show the most extreme form of brood reduction and appear to actively remove the first laid (A) egg from the nest, whilst the Rockhopper, Fiordland Crested and Snares Penguins do not actively remove the (A) egg and may in rare cases even raise 2 chicks. To what extent eggs are intentionally ejected from the nest is a matter of debate. In one study, about half of all egg losses were considered deliberate whilst the rest occurred as an accidental result of egg rearrangements in the nest (Miskelly and Carey 1990). 97% of pairs lost one egg in the four days following clutch completion, and in 98% of cases this was the (A) egg. However, studies on Antipodes in 1998 reached the conclusion that egg loss was accidental (Spencer-Davis 2001. Natural History Magazine). This was based on the observation that it was mechanically difficult to incubate both eggs and that the birds frequently moved around trying to accommodate both, in the process often dislodging the smaller (A) egg. Further, displaced eggs were recovered if placed near the incubating adult, which was interpreted as meaning that they had not intended to lose the egg (although this may be a simple reflex-like behaviour).

The reader is referred to the detailed section on brood reduction mechanisms on the Macaroni Penguin page, since this species has been subjected to much more study and has the apparently most similar mechanism.

Incubation Duties / Nest Relief

The incubation period of the Erect-Crested Penguin is thought to last for about 35 days. The distribution of incubation duties is not known in detail. It has however been noted that males often remain at the nest for days after completion of the clutch. This seems wasteful since only the female parent is initially needed for incubation and the other could theoretically forage. It is possible that this serves to protect the female from aggression by unmated birds or neighbouring males, which has been observed to result in egg loss (Spencer-Davis 2001. Natural History Magazine).

Brood / Guard Phase

Only a single chick is generally raised. Chicks hatch with a thin coat of down (protoptile plumage) which allows efficient heat transfer from the brooding parent. A thicker down (mesoptyl plumage) is developed within 2-3 weeks. Young chicks are brooded under the parent, but rapidly become too large to fit entirely under it. Large chicks lie partially covered with their heads under the parent or lean closely against it. The mesoptyl down is crucial for thermoemancipation of the chicks, and is a prerequisite for the transition from the guard to the creche phase which usually occurs after about 3 weeks. The male parent is responsible for the chick for the first 2-3 weeks of the brood / guard phase, whilst the female forages and returns regularly to provision the chick.

Creche Phase

Once the parents stop guarding them and are absent foraging at the same time, Erect-Crested Penguin chicks tend to congregate in groups known as creches. Chicks generally join creches located within a few meters of their nests. Upon return to the nest, parental birds may call their chicks (see below) in response to which the chicks approach the parent in order to be fed. Food chases have been observed in Erect-Crested Penguins. The exact function of these chases, where the adult runs away from the chick causing the latter to chase it, are not known.

Acoustic Parent-Chick Recognition

Detailed studies have not been performed on acoustic parent-chick recognition in Erect-Crested Penguins. It is however likely that it bears resemblance to that observed between parents and chicks in other crested penguin species. Contact calls are considered most similar to those of the Fiordland Penguin. Chicks call by way of short "cheeps" lasting about 0.1-0.3 sec which are usually repeated several times with about 0.5-0.7 sec intervals. The "cheeps" are characterized by a rapid rise in pitch followed by a fall from 5 to 3 kHz (Warham, 1975. "The Biology of Penguins" (ed. Stonehouse), p.189-269).

Fledging

Erect-Crested Penguin chicks must develop their water-proof juvenile down so that they can depart to sea to forage. Before fledging, males may reach masses of over 3.5 kg with females about 500 g less. Fledging generally occurs after about 70 days. Fledglings and yearlings are both distinguishable from adult birds by having paler chins and short, paler, and non-erect crests. Breeding age is generally reached after about 5 years.

Post-Breeding Moult

On the Antipodes Islands, once their chicks have fledged, adult birds spend about 1 month at sea foraging in order to gain weight in preparation for the annual moult. The moult occurs at the colony starting near the end of February and lasts 26-30 days. Non-breeding birds tend to moult about 2 weeks earlier.

General Behaviour:

Antagonistic behaviour similar to other penguins. Birds lower heads and "growl" or "bark" at each other with beak open and head often tilted to side. If a fight ensues, bills may become interlocked and birds twist and bite at each other. Birds try and also bite each other on the neck and may hold on there whilst beating the adversary with the flippers. When fights do occur, the may be extremely savage and result in loss of blood.

Appeasement may be achieved by posturing, e.g. when birds lower their necks and walk with their flippers facing forwards. This is often used as birds approach their nests, passing in close proximity to other breeding pairs.

Threats:

Skuas steal many eggs and small chicks according to observations on Antipodes Isl. (Moors 1980. Notornis 27, p.133-146). However, this does not present a major threat to the population as a whole. The same applies to sporadic killing of penguins by fur seals as observed at the Antipodes (Spencer-Davis 2001. Natural History Magazine).

Where To See:

Due to the location of their breeding colonies on remote Antipodes and Bounty Islands, Erect-Crested Penguins are difficult to observe in the wild. Access to these Islands is prohibited, although it is possible to cruise off the coast in zodiacs. New Zealand based Heritage Expeditions runs expedition cruises, some of which include driving zodiacs along the coast of these islands.

No Erect-Crested Penguins are kept in captivity.