SPNAugust, 1991 Spheniscus Penguin Newsletter

In this Issue

vol. 4, number 1

The British and Irish Humboldt Studbook, 1990

Planning for the Future of North American Humboldts

Hand-rearing Humboldts at Sea World, San Diego

Building Better Nesting Sites for Spheniscus Penguins

A Survey of Spheniscus Field Studies

A Selected Bibliography of Spheniscus Penguins

11

2

8

10

16

This issue of SPN :

The major articles in this issue, with the exception of 'Nesting Sites for Spheniscus Penguins/"are from papers presented at the SpheniscusWorkshop held at the AAZPA Regional Conference inSacramento, California, in March 1990. Other papers presented at that workshop were included inthe November, 1990 SPN, and it was intended to include all remaining papers in this issue.Unforhmate realities of printing costs/ however, forced a change in plan (see below for informationon contributing toward production costs of this publication). Papers remaining, for our next issue,are: "Avian Malaria/" "Incubation Behavior Patterns in Adelies/" "Molt Patterns of Black-footedPenguins," and "Diet, Feeding Regimen, and Growth Rates in Hand-reared Magellanic Chicks."Thanks to the authors and to the American Association of Zoological Parks and Aquariums, forpermission to reprint these papers.

Publication information:

SPN Spheniscus Penguin NewsletterISSN # 1045-0076Indexed in Wildlife Review

SPN is published twice aIUlUally, with financial support from the Portland Chapter of theAmerican Association ofZoo Keepers, and the Metro Washington Park Zoo. Subscription is free, tothose with a serious interest in Spheniscus penguins. Contributions toward printing and postagecosts arewelcome (and tax-deductible in the US) ; please make checks payable to "Portland Chapter,AAZK," and send to the Editor at the address below.

Articles submitted for publication should be tYPed. For articles which include graphs (such asline or bar graphs) please include a separate sheet giving the data used to generate the graph.Authors who work on a Macintosh computer can help our layout process by sending their work ondisk (accompanied by a paper copy just in case).

Thedrawingwhich servesas our cover logo is reproduced bykind permission of the artist, AnnMunson.

Thanks to Kathy Ivanov for help with word processing for this issue.

Please address all correspondence to: Cynthia Cheney, EditorSpheniscus Penguin NewsletterWashington Park Zoo4001 SW Canyon Rd.Portland, Oregon 97221 USA

Telephone: (503) 226-1561FAX: (503) 226-6836

Field Studies of Spheniscus PenguinsDAVID CAMERON DuFFY

THE POPULAR IMAGE OF PENGUINS IS ONEOF ICE. HOWEVER, PENGUINS OF THE GENUSSPHENISCUS RARELY IF EVER SEE ICE ANDinstead inhabit areas more tropicalthan polar. This has been both boonand bane. The Spheniscus penguinshave taken the brunt of human ex-ploitation, while until recently beingmore or less ignored as research sub-jects compared to polar penguins.Human exploitation and research ne-glect have now diminished, althoughmuch remains to be done concerningboth conservation and research.What follows is a selective over-

view, but the papers ci ted will provideaccess to the rest of the literature oneach species. I would like to note thatmost of what we know is mostly theresult of work by a very few people:Boersma on Galapagos Penguins;Scolaro on Magellanic Penguins;Araya and Hays on Humboldt Pen-guins; and Cooper, Rand, Randall, andWilson on African Penguins, presentlythe best known of the species.

Taxonomy

There are currently believed to befour species of Spheniscus penguin: theHumboldt Spheniscus humboldti,Galapagos Spheniscus mendiculus,Magellanic Spheniscus magellanicus,and the African, Black-footed, or Jack-ass Spheniscus demersus, all with a verysimilar morphology (Livezey, 1989).I prefer African as the common namefor the last species, as Jackass is alsoused for Magellanics and Humboldts,and Black-footed is singularlyuninformative. The other three have

David Cameron Duffy,Executive Director

The Seatuck FoundationP.O. Box 31Islip, Long Island, NY 11751

SPlV August1991 page 10

Long Island, New York

geographic names, so why not theAfrican Penguin? George GaylordSimpson (976), the godfather of fossilpenguinology, made the same plea.Given the propensity of the vari-

ous species to interbreed in captivity,a few words on their evolutionary re-lationships are in order. Genetically,there is at present only one study, byGrant et a1. (in press), on theHumboldt, Magellanic and Africantaxa, using electrophoretic analysis ofgene frequencies. The three species arevery closely related, suggesting that ifthey are species, rather than subspe-cies, they are very recent ones. TheGalapagos Penguin probably evolvedfrom a stray colonization of the is-lands by Humboldt Penguins,although its double-breast pattern ismore similar to that of the double-banded Magellanic than of thesingle-banded Humboldt. Similarly,the single-banded African Penguinmay have evolved from the Magel-lanic or vice-versa.Occasional individuals of the Afri-

can and, less frequently, the Humbold t,have double stripes, suggesting eitheroccasional immigration and past in-terbreeding with Magellanics, or thata recessive gene for double-bandednesslurks in the best of birds.

Distribution

The Spheniscus penguins range tothe Equator in the Pacific and strayalmost to the Equator in the Atlantic(Gabon: Shelton et. a1.1984), but theyare cool-water specialists, associating

with upwelling marine ecosystems(Murphy, 1936).The Galapagos Penguin has an ex-

tremely restricted range, nesting onlyon the west side of Isla Isabela and onIsla Fernandina in the westernGalapagos Islands (Harris, 1974). TheHumboldt Penguin is confined to theupwelling of the Humboldt Currentof the west coast of South America,nesting from northern Peru to ChiloeIsland,Chile (Araya, 1983; Hays, 1983).The Magellanic Penguin nests on thePacific coast, from central Chile, southaround Cape Horn, and north on theAtlantic, to central Argentina, as wellas on the Falklands and on several ofChile's offshore islands (Murphy, 1936;Araya and Millie, 1986). The AfricanPenguin nests from central Namibiasouth around the Cape of Good Hopeand along the south coast of SouthAfrica (Rand, 1960; Shelton et a1. 1984).Only the Magellanic and Hum-

boldt overlap in breeding range, overapproximately 1750km of Chileancoast (Duffy, 1987a; Duffy et aI., inprep. a). Mixed pairs have been ob-served but not studied. We haven't aclue as to how the species differ intheir courtship and mating behaviorto prevent interbreeding in the wild.

Colony Size And Distribution

The Spheniscus penguins don't nestin colonies so much as they nest wheresuitable access to the sea and suitablenesting sites occur, with nestingranging from solitary Galapagos Pen-guins to immense colonies ofMagellanic and African penguins. Thereasons for these differences need fur-ther study. The Galapagos Penguinnests in small, scattered groups(Boersma, 1977; Harcourt, 1980; Valle,1986). Much of its range appears toocliff-bound for birds to get ashore

Field Studies of Spheniscus Penguins

(Boersma, 1977), a problem faced bythe other species. The Humboldt Pen-guin in Peru nests mostly in smallcolonies in sea-caves on islands andthe coast or in burrows on islandswhere it is slightly safer from intensepoaching pressure (Hays, 1983, Duffyet aI., 1984a), whereas in Chile, wherehuman disturbance is much reduced,it nests in much larger colonies on is-lands (Araya, 1983). The Magellanicand African Penguins nest or nestedin colonies of 10,000 to 100,000+(Scolaro and Arias de Reyna, 1984;Scolaro et aI., 1980a, 1984; Shelton etaI., 1984; Capurro et aI., 1988). Exceptfor several small colonies which maysuffer periodic bouts of catastrophicdisturbance from humans and at leastonce from a leopard (Panthera pardus)(pers. observ.), African Penguins neston islands (Shelton et aI., 1984).Magellanics nest on both islands andthe mainland, and it remains a mys-tery to me why terrestrial predatorshave not exterrninated whole colonies.Scolaro (1985) suggests that humanshave reduced local populations of ter-restrial predators.

Numbers

Counting Penguins

Not the least of problems involvedin studying penguins is counting them.The Galapagos and Humboldt arefrequently counted from boats, pitch-ing just beyond the surf, as observerstry to see birds in caves or under rocks,(Boersma, 1977; Hays, 1984). As bothspecies are partially nocturnal on landor feed at sea during the day (Boersma,1977; Duffy et aI, in prep a), day countsare underestimates. Counts at coloniesalso have problems, as many nest sitesare unoccupied, depending on time ofday (Frost et aI., 1976a; Hays, 1984;Capurro et aI., 1988) and one par mayvisit several sites (Capurro et aI., 1988).Even worse, with the exception of the

Magellanic Penguin, the Spheniscusspecies can be found breedingthroughout the year (Koepcke, 1970;Boersma, 1978; Cooper, 1980) so thatsingle counts, even at peak breeding,miss many pairs that breed at othertimes of year Randall et a1. (1986a)developed a method of countingmoulting birds throughout the year ata frequency similar to the duration ofmoult, so that each moulting bird wascounted only once. Assuming thatbirds do not move to other islands tomoult (Randall et aI., 1987), this wouldgive a 'true' count of the population.

Population Fluctuations and Trends

With the possible exception of theMagellanic Penguin, the Spheniscuspenguins have suffered either short-term or historical populationdecreases. The Galapagos Penguin,apparently otherwise stable at between3,000 and 15,000 birds (Brasset, 1963;Harris, 1977; Boersma, 1977), lost 77%of its counted population during thestrong El Nino oceanographic eventin 1982-1983 and subsequently expe-rienced poor reproduction through1984 (Valle and Coulter, 1987). Morerecent data have not been published.Humboldt Penguins in Peru have

been in decline since the 19th century,perhaps in part because of the removalof the guano substrate they used fortheir burrow nests (Murphy, 1936). Isuspect, however, that human exploi-tation for food has been and continuesto be a serious, if not the principalproblem (Duffy et aI., 1984a). The Pe-ruvian and Chilean combinedpopulation was estimated to be ap-proximately 20,000 (Hays, 1983,1984)before the 1982-1983 El Nino whichreduced numbers by 65% in Peru to2,000-3,000 (Hays, 1986). Similar re-ductions occurred in Chile (Araya,1984 ms; Araya and Todd, 1988). Morerecent data are not available.

The Magellanic Penguin, with apopulation on the order of a millionbirds or more, is increasing in Argen-tina, perhaps because of changes infood availability or reduction ofpredators (Scolaro, 1985; Boersma etaI., 1990). The status of its populationin Chile is unknown, although thespecies is common (Schlatter, 1984).The African Penguin has suffered apopulation crash since the tum of thecentury (Burger and Cooper, 1984;Shelton, et aI., 1984) Between 1956and1978, the population decreased from230,000 to 100,000 (Burger and Coo-per, 1984), but its recent dynamics havebeen complex, decreasing in the cen-ter of its range and increasing orremaining stable to the north and east(Frost et aI., 1976a; Siegfried andCrawford, 1978; Shelton et al., 1984).These changes have been linked tochanges in fish stock (Crawford andShelton, 1978, 1981; Burger and Coo-per, 1984; Crawford et aI., 1985) andoverfishing (Crawford and Shelton,1978, 1981), but the mechanisms foroverfishing are unclear, as penguinsand fishermen don't fish in the sameareas (Broni, 1986; Wilson et aI., 1988)and fishery landings bear no relationto penguin diet or growth (Duffy etaI., 1987a). Breeding success for pen-guins at one island studied near.fishing grounds was the same as thaton a control island in an unfished area(La Cock et aI., 1987). At present, webelieve that penguins and fishermencompete during the pelagic first-yearof life of the African penguin, whenjuveniles from decreasing coloniesdisperse to areas of intense fishing andhave low survival rates, whereas thosefram stable or increasing colonies dis-perse to unfished areas and survivebetter (La Cock et aI., 1987; Duffy andCooper, 1990).

please turn to page 12

SPN August 1991 page 11

Field Studies of Spheniscus Penguinscontinued from page 11

Natural and Unnatural Mortality

Accounts of the natural predatorsof Spheniscus penguins are numerous(e.g. Galapagos Penguin: Boersma,1977; Humboldt Penguin: Hays, 1984,1986; Araya and Duffy, 1987; Magel-lanie Penguin: Boswall, 1972;Rodriguez, 1983; Scolaro, 1985, Afri-can Penguin: Cooper, 1974; Brooke andWallett, 1976; Frost et aI., 1976a;I.Randall et aI., 1988). Parasites mayalso be important (e.g. Boersma, 1977;Randall and Bray, 1983; Duffy andDaturi, 1987), but we have almost noidea of the impact of either parasitesor predators on penguins at the popu-lation level. Such studies are urgentlyneeded.Human exploitation ranges from

poaching (Duffy et aI., 1984a; Hays,1984; Schlatter 1984) to indigenousclothing (Avery, 1985) and industrialglove production (Scolaro, 1986) to zooexports (Hays, 1984). Exploitation ofeggs (up to 500, OOO/year and 13 mil-lion in 30 years: Siegfried andCrawford, 1978) in South Africacaused population decreases on at leastsome of the islands (Frost et aI., 1976a).Oiling has been especially noticeableoff South Africa, on the route of muchof the world's tanker traffic (Westphaland Rowan, 1971; Morant et aI., 1981),but there is some disagreement overits impact. Frost et aI. (1976a) estimatedthe oiling rate to be only 0.7-0.9%/year, but Randall et aI. (1980) workingfarther to the east considered oilingthe main cause of adult mortality. Amajor public effort, the South AfricanNational Foundation for the Conser-vation of Coastal Birds, operates apermanent rescue and cleaning opera-tion that has been highly effective inreturning birds to the wild and in edu-cating the public about oilcontamination (Randall et aI., 1980;Morant et aI., 1981). Oiling rates inGalapagos and Peru are apparentlylow, but there is considerable concernabout oiling rates and resulting mor-

SPN August 1991 page 12

tality of Magellanic Penguins in Ar-gentina (Jehl, 1975; Perkins, 1983;Boersma et aI., 1990).NaturaI disasters, ranging from 10-

caI heavy rains (Crawford et aI., 1986;Randall et aI., 1986b; Duffy et aI., 1988)and anomalous cold-water events(Schumann et aI., 1989) to species-wideEl Nino-caused mortali ty (Vogt, 1942;Boersma, 1978; Boersma, 1987; Duffyet aI., 1984a,b, 1988; Hays, 1986; LaCock, 1986; Valle and Coulter, 1987;Araya and Todd, 1988; Duffy, 1990),have been well documented, but againthe population effects have been diffi-cult to document because, with theexception of the Galapagos (Valle andCoulter, 1987) and locally with the Af-rican (La Cock et aI., 1987; La Cockand Hanel, 1987) and Magellanic(Boersma et aI., 1990) penguins, long-term population or breeding data arenot available. Computer models ofpenguin populations (e.g. Jackson etaI., 1976; Scolaro, 1987b; Scolaro et aI.,1981) may help assess the possible im-pact of natural, and unnatural,disasters, long before we have directdata (Duffy, 1990).

Nesting Biology

Breeding Seasons

Humboldt (Koepcke 1970; Castroand Ishiyama, 1985-1986) and Afri-can Penguins nest throughout most ofthe year, (Cooper, 1980; Randall andRandall, 1981, La Cock et aI., 1987) butshow strong seasonal which have beenlinked to differences in food availabil-ity (Wilson, 1985c) and nesting success(Wilson, 1985c; La Cock et aI., 1987).Boersma (1977, 1978) showed that nest-ing by Galapagos Penguins can occurthroughout the year, in response toappropriate oceanographic and foodconditions. In contrast, MagellanicPenguin nesting is strongly seasonal(Scolaro, 1984a; Scolaro et al. 1980a;Boersma et aI., 1990), perhaps because

the southern distribution leaves toofew daylight hours for foraging dur-ing the winter (Duffy et aI., in prep a).

Nest site

The biggest problem for nestingSpheniscus penguins is the sun (Drentand Stonehouse, 1971; Frost et aI.,1976b). They avoid it by nesting inburrows and sea caves or under veg-etation (Murphy, 1936; Scolaro andArias de Reyna, 1984b), or, if surface-nesting, doing so during the winter(La Cock, 1988) or when there is astrong windchill. When penguins neston the surface, they tend to nestdensely, to protect their eggs andyoung against aerial predators(Siegfried, 1977). Burrow nests appearmore successful than surface nests(Frost et aI., 1976a) which may be usedwhen covered sites are occupied orsubstrates are unsuitable for burrow-ing because of texture or susceptibilityto flooding (Scolaro, 1984; La Cock,1988). Nest sites must also be acces-sible to the sea and, for surface nesters,essentially level, as penguins buildonly rudimentary nests (Duffy and LaCock, 1985). These habitat require-ments combine to produce complexmosaics of nesting colony distributionsand nest densities (e.g. Bodano et aI.,1982; Scolaro and Arias de Reyna,1984a,b; Scolaro, 1984; Scolaro et aI.,1979, 1984, 1985; Duffy and La Cock,1985; Capurro et aI., 1988). These inturn complicate estimates of colonysize (discussed above).

Breeding Behavior and Ecology

Breeding of the Spheniscus pen-guins appears relatively similar acrossspecies, although we lack details forthe Humboldt Penguin in the wild.Boersma (1977); Scolaro (1978, 1980,1983,1984a,b,d), Scolaro et al. (1980a);Cooper (1980), Hockey and Hallinan(1981), Randall (1983), Williams and

Cooper (1984), and Wilson (1985c) pro-vide details of various aspects of thebreeding of Galapagos, Magellanicand African penguins, respectively.For the African Penguin, the normalclutch is two eggs, laid about threedays apart, with an incubation periodof 38 days, and both young are usu-ally raised in about 80 days, exceptduring poor food conditions, when theyounger of the pair dies (Cooper, 1980;Williams and Cooper, 1984). For theMagellanic Penguin, the incubationperiod for the two-egg clutch is 38-42days, with a two to four day periodbetween eggs and an extremely vari-able growth of young to fledging(Boersma et al., 1990). The GalapagosPenguin also lays two eggs, three orfour days apart, has an incubation pe-riod of approximately 38 days andyoung reach adult size at thirty days,"although some chicks remained inthe nest until after 50 days of age"(Boersma, 1977), which is a very shortfledging period compared to the othertwo species.

Growth

Growth of young in the field hasbeen extensively studied in AfricanPenguins (Cooper, 1977; Williams andCooper, 1984; Duffy et aI., 1987a).Heath and Randall (1985) examinedgrowth of African penguins fed dif-ferent diets. Boersma (1977) providedthe only growth data for theGalapagosPenguin, and Scolaro (1984d) andBoersma et a1. (1990) for Magellanics.No published data exist for HumboldtPenguins.

Moult

Moult takes approximately 20 daysin Humboldt Penguins, 10-15 days inGalapagos Penguins, and 18 days inAfrican Penguins, during which timethe birds fast and usually do not enter

the water (Boersma, 1977; Cooper,1978). For Magellanic Penguins, moultoccurs during a relatively short, fixedtime of year, after breeding and priorto dispersal from the colony (Scolaro,1984d). This fixed pattern appears tobe a response to the strongly seasonaland consistent pattern of climate andfood availability, not found in the en-vironments of the other species.African and Galapagos Penguins canbe found moulting throughout theyear, but African Penguins exhibit astrong seasonal peak in October-November (Randall and Randall,1981). Moulting is a pre-breeding ac-tivity in Galapagos Penguins(Boersma, 1977). lt occurs, althoughnot in the same birds, both immedi-ately before and after breeding inAfrican Penguins (Cooper, 1978), butappears to be predominantly post-breeding (Randall and Randall, 1981).Galapagos Penguins moult twice ayear (Boersma, 1977), perhaps as a re-sponse to damage to plumage by theequatorial sun. If this is the case, asimilar frequency of moult should oc-cur in Humboldt Penguins. Moult inAfrican Penguins and Magellanics ap-pears to be annual (Randall andRandall, 1981; Scolaro, 1984).

Moult appears to be extremelystressful, and birds may be forced toreturn to the water to forage beforecompletion (Boersma, 1977), eventhough they lack thermal protectionagainst the cold (Erasmus et aI., 1981)and may be too slow to catch theirnormal prey (Wilson, 1985b).

Foraging Biology

Diet

Early diet work involved killingbirds. The development of an effec-tive stomach pump (Wilson, 1984)removed all necessity to slaughter pen-guins for diet studies. Problemsremain, however, as diet analyses can

be biased by a variety of factors, in-cluding methods of analysis, andcomparisons of data can be hinderedby differing methods of presentation(Duffy and Jackson, 1986). Anothercomplication is differential digestionof prey species, which has led to stud-ies of penguin digestive ra tes (Furnessand Laugksch, 1983; Duffy et aI., 1985a;Wilson et aI., 1985; Laugksch andDuffy, 1986; Wilson et aI., 1989b).Diet reviews which summarize

previous work include: African Pen-guin: Rand (1960); Randall and Randall(1986); Duffy et a1. (1985a, 1987a,b);Humboldt: Wilson et a1. (1989a); Duffyet a1. (in prep. a); Galapagos: Boersma(1977) and Magellanic: Gosztonyi(1984); Scolaro and Bodano (1985). Ba-sically, Spheniscus penguins eat a widevariety of species and sizes of prey,from 10 to 310 mm (Wilson and Wil-son, 1990> bu t specialize on small,schooling fish, such as anchovyEngraulis spp. and sardines Sardinops.

Distribution at Sea

Measurement of distribution at seais extremely difficult, as penguins ridelow in the water and travel underwa-ter, reducing the chance of seeingthem. The two traditional ways ofstudying them have been to measurethe duration of foraging trips and torun transects at sea. In the first case,the departure and return times of pen-guins, especially those with smallyoung, are measured (Boersma, 1977;Wilson, 1985a). By assuming a certaintraveling speed and time spent actu-ally foraging, a maximum range canbe calculated (Wilson, 1985a,b; Duffyet aI., 1987a;Wilson et aI., 1988). Thesemeasurements are necessarily rathercrude.In the second case, direct observa-

tion, penguins are counted on transectsfrom moving vessels. Observations

please turn to page 14

SPN August 1991 page 13

Field Studies of Spheniscus Penguinscontinued from page 13

include distance from shore, groupsize, social behavior, and attendancein foraging groups (e.g. Rand, 1960;Siegfriedeta1., 1975; Duffy, 1983, 1989;Broni, 1986;Wilson et aI., 1986b, 1988).Unfortunately, transects require strongstomachs, are extremely expensive torun, and are frequently interrupted bybad weather.The presence of a vesselmay also influence penguin behavior.

More recently, methods havebeen developed to measure Spheniscuspenguin foraging at sea, through re-mote sensing. Small measurementpackages are placed on the bird (e.g.Heath, 1987; Wilson and Wilson,1989a) and either store data until re-covered or transmit them by radio.Speed, depth and distance meters storedata on x-ray film, using smallamounts of radioactivity to mark thefilm (Wilson and Bain, 1984a,b) or usea counter to store counts of propellerturns (Wilson and Achleiter, 1985).When combined with diet data frombirds returning colonies, the devicesallow estimates of foraging effortversus food ingested (e.g. Nagy et aI.,1984).Radio-transmitters provide con-

tinuous signals while birds are on thesurface (Heath and Randall, 1989). In-terruption of the signal is caused bysubmergence, so the device can beused to measure dive frequency andduration. Range of signal can be aproblem, as penguins ride so low inthe water that waves intercept signals.Also, triangulation of radio-signalsand pursuit of animals with airplanesor boats is necessary for locating thebirds at sea. Nevertheless, radio-trans-mitters can provide an abundance ofdetailed data which can be combinedwith direct, simultaneous observationsof foraging situations and prey. Wheretelemetry is not possible, a new dead-reckoning device may provide similardata, although it requires recovery ofthe bird with the device (Wilson andWilson, 1988).

SPN August 1991 page 14

A potentially serious problem withdevices and methods of attaching themis the increased drag or water-resis-tance they can create when thepenguins are diving. Drag may ham-per foraging or cause birds to deserttheir nests (Wilson et aI., 1986a), sorecent devices have tended to be assmall as possible. In addition, eitherthe devices or their attachments mayannoy the birds sufficiently to gener-ate aberrant behavior. Wilson andWilson (1989b) developed a device tocount the number of pecks directed atdevices, as a measure of disturbance.Finally, the disturbance caused by cap-turing the bird to install and removedevices may be a serious problem, es-pecially perhaps for birds such asHumboldt Penguins in Peru, that ap-pear much more shy than otherSpheniscus populations (pers. observ.).Automatic injection of sedatives byremote control may reduce trauma(e.g. Wilson and Wilson, 1989c).During the breeding season, pen-

guins return to shore. Frequently,especially when feeding young, sothey tend to be distributed at sea neartheir colonies. During their first yearof life and, while non-breeding, pen-guins may be pelagic for extendedperiods of time (Wilson et aI., 1988;Duffy and Cooper, 1990).

Foraging Behavior

Wilson and Wilson (1990) have re-cently reviewed Spheniscus foraging.They report that Spheniscus penguinstravel at 6.8 -7.4 kph underwater andat 12.3 kph while porpoising. Divescan last as long as 146 sec and reachmean maximum depths of 60+ m, al-though most dives are shallower.Theymay travel as much as 72 km per daywhile providing food for young.Unfortunately, we know relatively

little about actual foraging behavior,as events take place tens of metersbelow the sea-surface, at high speeds

in murky waters. Most of our infer-ences come from indirect observationsor devices measuring depth, speed,and duration of dive, size of foraginggroup, stomach samples, and fish be-haviorBeing flightless, Spheniscus pen-

guins must encounter frequent,inshore food sources, as the birds mustswim, not fly, to their foraginggrounds and underwater searchingvisibilities are short (Frost et aI.,1986a). Penguins seem to travel di-rectly, often in groups (e.g. Siegfriedeta1., 1975; Boersma, 1977; Broni, 1986)to a certain area, then begin searching(e.g. Wilson and Wilson, 1988; Heathand Randall, 1989). We do not knowwhether physical (e.g. depth, bottomtopography, currents, wave height,temperature) or biological (turbidity.,presence of fish schools) clues leadthe birds to stop traveling and startsearching, by diving. Locating theschool at a fishing area may be doneby an individual bird, or it may beattracted to calls by other penguins(Broni, 1986) or by foraging by otherspecies (Duffy, 1983, 1989).Most dives are relatively shallow

(Wilson, 1985b), suggesting feeding onfish schools near the surface. Most pen-guin prey form schools and, while thismay facilitate locating fish, penguinsmay find it difficult to target a singlefish, amongst tens or hundreds ofthousands of similarly-sized, similarlybehaving fish. Based on bite marks onfish, penguins attack from below, per-haps silhouetting the fish against thesurface (Wilson and Duffy, 1986; Wil-son et aI., 1989a) and using their darkdorsal plumage as camouflage (Cairns,1986). They may also use the alternat-ing black and white of the breast bandas an aggressive display, herding thefish in a school closer and closer, untilthe minimum distance between fishbreaks down and the school structurecollapses (Wilson et aI., 1987). Pen-guins may also use group fishing tobreak up school structure (Sumner,

1934; Boersma, 1977; Boswall andMaclvor, 1975; Wilson et al., 1987) ormay join with other predators that ef-fectively serve the same role (Boersma,1977; Broni, 1986), although Wilson(l985b) suggests that African Penguinsforage on smaller schools of fish thando other birds. Finally, penguins maydrive fish to the surface for other, moreshallowly-diving birds (Broni, 1986).

Contributions From Captive Studies

Those who have an opportunity tostudy the Spheniscus Penguins in cap-tivity have much to contribute to ourbasic knowledge and research that willaid in penguin conservation. Such re-search can range from the intensive,such as behavioral studies, to low-key,such as consistent measurements ofmass and body measurement of indi-vidual penguins over time.Careful measurements of several

generations of penguins, raised underconstant conditions, will give us amuch-needed idea of heritability ofbody size. If we can measure the rela-tive contributions of envirornnentaland genetic factors, we can perhapsuse changes in body size to monitorpopulation dynamics of Spheniscuspenguins (Duffy, 1987b). This will beinvaluable in examining the possibleeffects of competition with corrnner-cial fisheries and of climate change.Measurement of known genetic lin-eages can also give us some idea ofthe genetic basis for partial and com-plete double breast banding in Africanand Humboldt penguins and can becompared with molecular geneticstudies.We know something about the

courtship and mating behavior of twoof the species (e.g. Boersma, 1977;Eggleton and Siegfried, 1979), but wehave little information aboutHumboldts or Magellanics (Jouventin,1982). lt would be extremely useful to

have basic ethograms of the four spe-cies, to allow comparison of theirspecies-specific and sex-specific behav-iors in captivity (e.g. Merritt and King,1987; Scholten, 1989). Adding or re-moving breast bands would be aninteresting experiment to test the im-portance of such coloration betweenspecies (d. Ryan et al., 1987).lt wouldalso be interesting, without allowingactual reproduction, to study the be-havior of mixed-species pairs incaptivity.

Work on aging and sexing pen-guins is extremely important anduseful (e.g. Cooper, 1972; Bulfon et al.,1986; Boersma and Davies, 1987;Scolaro, 1987a; Scolaro et al., 1983).Measurements of captive birds, underconstant conditions, over time willgreatly aid field studies (e.g.Edgington, 1989). Determination of thegrowth of young (Cooper, 1977), en-ergetics (Erasmus and Smith, 1974),and of age of first-breeding under con-trolled, captive conditions would alsobe very useful for comparison withsimilar measurements made in themuch more variable natural condi-tions.

Birds, such as those kept at SeaWorld, Inc. in Mission Bay, San Di-ego, may potentially play an importantrole in our understanding of howpenguins detect El Nino. Linda Henryand I have been examining data thatseem to show that the HumboldtPenguins at Sea World stoppedbreeding during the severe 1983 ElNino.These birds were fed ad libitum,sofood shortage was not responsible.What clues caused them to stop (d.Merritt and King, 1987)?

Finally, the development of inex-pensive, safe artificial burrows andtheir testing in captivity would pro-vide a useful management tool forpenguin managers in the field. For ex-ample,lack of sites on small islets mayforce penguins in Africa andGalapagos to nest on the mainland oron larger islands where they are vul-

nerable to terrestrial predators. Arti-ficial burrows could raise the'carrying capacity' of such sites.

Conclusion

This is a highly condensed reviewof the literature on field studies ofSpheniscus penguins. It does not, forlack of space, do justice to many finestudies and to the physical environ-ments in which the birds nest andforage or to the ecology of prey spe-cies. We know a great deal aboutSpheniscus penguins, especially theirnesting ecologies and diets, but, evenwith the development of increasinglysophisticated means of studying pen-guins at sea, we are really onlybeginning to understand the marinepart of their existence. Unfortunately,field researchers can be criticized, witha few bright exceptions, for not apply-ing our knowledge to the managementand conservation of Spheniscus pen-guins. The managers of captivepenguins with their direct manage-ment experience, albeit at a very smallscale, can play an important role inapplying the insights of field work tothe management of wild, as well ascaptive populations. n

Referencesare included in the bibliographywhich follows.

SPN August 1991 page 15

David Cameron Duffy,Executive Director

The Seatuck Foundationp.o. Box 31Islip, Long Island, NY 11751

A Selected Bibliography of the Spheniscus PenguinsDAVID CAMERON DuFFY

I have attempted to make this bibliography as complete as possible and it probably contains most of the moreimportant Sphenisclls ecology papers published before 1987. Historical, local colony counts and more recent papers,especially those in regional journals, may have been omitted. I would appreciate references or reprints ofmissing recentpapers.

Araya. 1983. A preliminary report on the status and distribution of the Humboldt Penguin in Chile. In J. Delacour (ed.).Proceedings of the International Foundation for the Conservation of Birds Symposium on Breeding Birds in Captivity,Los Angeles. pp. 125-135.

Araya and Millie. 1986. Guia de Campo de las Aves de Chile. Editorial Universitaria, Santiago.Araya and Duffy. 1987. Animal introductions to Isla Chanaral, Chile: their history and effect on seabirds. Cormorant

15:3-6.Araya and Todd. 1988. Status of the Humboldt Penguin in Chile following the 1982-83 El Nino. Spheniscid Penguin

Newsletter 1:8-10.Avery. 1985. Late Holocene use of penguin skins: evidence from a coastal shell midden at Steenbras Bay, Luderitz

Peninsula, South West Africa-Namibia. Annals of the South African Museum 96;55-65.Berry, Seely and Fryer. 1974. The status of the Jackass Penguin Spheniscus demersus on Halifax Island off South West

Africa. Madoqua Ser. II 3:27-29.Bodano, Scolaro and Upton. 1982. Distribucion espacial de la nidificacion de Spheniscus magellanicus en Cabo Dos

Bahias, Chubut, Argentina (Aves: Spheniscidae). Historia Natural 2 (27):241-251.Boersma. 1977. An ecological and behavioral study of the Galapagos penguin. Living Bird 15:43-93.Boersma. 1978. Breeding patterns of Galapagos Penguins as an indicator of oceanographic conditions. Science

200: 141-148.Boersma. 1987. El Nino behind penguin deaths? Nature 327:96.Boersma. 1988. Magellanic Penguins of Patagonia. Spheniscid Penguin Newsletter 1:2-3.Boersma and Davies. 1987. Sexing monomorphic birds by vent measurements. Auk 104: 779-783.Boersma, Stokes and Yorio. 1990. Reproductive variability and historical change of Magellanic Penguins (Spheniscus

magellanicus) at Punta Tombo, Argentina. In J. Darby and L. Davies (eds.), Penguins, Academic Press, Orlando,Florida

Boswall. 1972. The South African Sea Lion Otana byronia as a predator on penguins. British Ornithologists Club Bulletin 92:129-132.

Boswall and Maciver. 1974. The Magellanic Penguin. In. B. Stonehouse (ed.). The Biology of Penguins. University ParkPress, London, pp. 271-305

Bowmaker and Martin. 1985. Visual pigments and oil droplets in the penguin, Spheniscus humbold ti. Journal ofCompara-tive Physiology A 156:71-77.

Broni. 1982. First recorded mainland breeding by the Jackass Penguin Spheniscus demersus. Cormorant 10: 120.Broni. 1983. An apparent instance of courtship feeding in the Jackass Penguin Spheniscus demersus. Cormorant 11:63-64.Broni. 1986. Social and spatial foraging patterns of the Jackass Penguin Spheniscus demersus. South African Journal of

Zoology 20: 241-245.Brooke and Wallett. 1976. Shark predation on seabirds in Natal waters. Ostrich 47;126.Brosset. 1963. La reproduction desoiseaux de mer des iles Galapagos en 1962. Alauda 31 :81-109.Bulfon, Bee de Speroni and Scolaro. 1986. An attempt at aging Magellanic Penguins Spheniscus magellanicus by

histological analysis of feather follicles. Cormorant 13: 168-171.Burger and Cooper. 1984. The effects of fisheries on seabirds in South Africa

and Namibia. In D.N. Nettleship, CA. Sanger and P. F. Springer(eds.) Marine birds: their feeding ecology and commercial fisheries rela-tionships. Canadian Wildlife Service Special Publication, Ottawa, pp.150-160.

SPN August 1991 page 16

A Selected Bibliography of the Spheniscus Penguins

Cairns. 1986. Plumage colour in pursuit-diving seabirds: why do penguins wear tuxedos? Bird Behaviour 6:58-65.Capurro, Frere, Gandini, Gandini, Holik, Lichtschein and Boersma. 1988. Nest density and population size of Magel-

lanic Penguins (Spheniscus magellanicus) at Cabo Dos Bahias, Argentina. Auk 105:585-588.Castro and Ishiyama. 1985-1986. Algunas consideraciones acerca del Pinguino de Humboldt. Reuista de la Associaci6n

Nacional de Biologos del Peru. 3:37-41.Cooper. 1972. Sexing the Jackass Penguin. SAFRING News 1:23-25.Cooper. 1974. The predators of the Jackass Penguin Spheniscus demersus. Bulletin of the British Ornithological Club 94:21-24.Cooper. 1977. Energetic requirements for growth of the Jackass penguin. Zoologica Africana 12:201-213.Cooper. 1978. Moult of the Black-footed penguin. International Zoo Yearbook 18:21-27.Cooper. 1980. Breeding biology of the jackass penguin with special reference to its conservation. Proceedings of the Fourth

Pan-African Ornithological Congress, pp. 227-231.Cooper. 1982. Methods of reducing mortality of seabirds caused by underwater blasting. Cormorant 10:109-113.Cooper, 1984. Changes in resource division among four breeding seabirds in the Benguela up-welling system. Proceed-

ings of the Pan-African Ornithological Congress, pp. 217-230.Cooper. 1986. Runt eggs of the Jackass Penguin Spheniscus demersus .. Cormorant 13:1 12-117.Cooper and Morant. 1981. The design of stainless flipper bands for penguins. Ostrich 52: 119-123.Crawford and Shelton. 1978. Pelagic fish and seabird interrelationships off the coast of South West and South Africa.

Biological Conservation 14: 85-109.Crawford and Shelton. 1981. Population trends for some southern African seabirds related to fish availability. In I.

Cooper (ed.) Proceedings of the Symposium on the Birds of the Sea and Shore, 1979. African Seabird Group, CapeTown, pp. 15-41.

Crawford, Cruikshank, Shelton and Kruger. 1985. Partitioning of a goby resource amongst four avian predators andevidence for altered trophic flow in the pelagic community of an intense, perennial upwelling system. SouthAfrican Journal ofMarine Science 3:215-228.

Crawford, Williams and Crawford. 1986. A note on mortality of seabirds off western southern Africa, October 1985-February 1986. South African Journal ofMarine Science 4:119-123.

Drent and Stonehouse. 1971. Thermoregulatory responses of the Peruvian penguin, Spheniscus humboldti. ComparativeBiochemistry and Physiology 40A:689-71O.

Duffy. 1983. The foraging ecology of Peruvian seabirds. Auk 100:800-810.Duffy. 1987a. Three thousand kilometers of Chilean penguins. Explorers Journal 65: 106-109.Duffy. 1987b. Ecological implications of intercolony size-variation in jack-ass penguins. Ostrich 58;54-57.Duffy. 1989. Seabird foraging aggregations: a comparison of two southern upwellings. Colonial Waterbirds 12: 164-175.Duffy. 1990. Seabirds and the 1982-1984 EI Nino/Southern Oscillation. In P. W. Glynn (ed.) Global Ecological Conse-

quences of the 1982/83 El Nino Southern Oscillation. Elsevier, in press.Duffy and La Cock. 1985. Partitioning of nesting space among seabirds of the Benguela upwelling region.

Ostrich 56:156-201.Duffy and Jackson. 1986. Diet studies of seabirds: a review of methods. Colonial Waterbirds 9:1-17.Duffy and Daturi. 1987. Diel rhythms of tick parasitism on incubating African penguins Medical and Veterinary

Entomology 1:103-106.Duffy and Siegfried. 1987. Temporal variations in food consumption by seabirds of two upwellings. In J. P. Croxall (ed.).

Seabird .Feeding Ecology. Cambridge University Press, pp. 327-346.Duffy and Cooper. 1990. Distribution and survival of juvenile jackass penguins at sea: an explanation of population

trends. South African Journal of Science, in press.Duffy, Hays and Plenge. 1984a. The conservation status of Peruvian seabirds. In J. P. Croxall, P. G. H.

Evans and R. W. Schreiber (eds.). Status and Conservation of the World'sSeabirds. ICBP Teclmical Publication 2, pp. 245-259.

Duffy, Berruti, Randall, and Cooper. 1984b. The effects of the 1982-1983warm-water event on breeding South African seabirds. SouthAfrican Journal of Science 10:65-69.

Duffy, Furness, Laugksch and Smith. 1985a. Two methods of measuringfood transit rates of seabirds. Comparative Biochemistry and Physiology82a:781-785. please turn to pagel8

SPN August 1991 page 17

A Selected Bibliography of the Spheniscus Penguinscontinued from page 17

Duffy, Wilson, and Berruti. 1985b. Anchovy in the diets of Dyer Island penguins: a test of two models of anchovydistribution. South African Journal of Science 81:552-554.

Duffy, Wilson, Ricklefs, Broni and Veldhuis. 1987a. Penguins and purse-seiners: competition or coexistence? NationalGeographic Research 3:480-.188.

Duffy, Siegfried and Jackson. 1987b. The Benguela ecosystem: seabirds as consumers: a review. South African Journal ofMarine Science 5:771-790.

Duffy, Arntz, Tovar, Boersma and Norton. 1988. The effects of El Nino and the Southern Oscillation on seabirds in theAtlantic Ocean compared to events in Peru. Acta XIX Congresus lnternationalis Ornithogici 1740-1746.

Duffy, Wilson, Wilson, Araya and Klages. (in prep. a). The ecology of Humboldt and Magellanic penguins in Chile ms.Duffy, Wilson and Wilson. (in prep. b). The use of seabirds to monitor the recruitment of anchovy.Edgington. 1989. Behavioural and morphological sexing of the Humboldt Penguin (Spheniscus humboldti). Spheniscid

Penguin Newsletter 2: 1.1-20.Eggleton and Siegfried. 1979. Displays of the Jackass Penguin. Ostrich 50:139-167.Erasmus and Smith. 1974. Temperature regulation of young Jackass Penguins Spheniscus demersus. Zoologica Africana

9:195-203.Erasmus, Randall and Randall. 1981. Oil pOllution, insulation and body temperatures in the Jackass Penguin Spheniscus

demersus. Comparative Biochemistry and Physiology 69A:169-171.Frost, Siegfried and Cooper. 1976a. The conservation of the Jackass Penguin (Spheniscus demersus). Biological Conservation

9: 79-99. "JFrost. Siegfried and Burger. 1976b. Behavioural adaptations of the Jackass Penguin, Spheniscus demersus to a hot, arid

environment.Journal of Zoology 179:165-187.Furness and Laugksch. 1983. An attempt to use barium meals and X-ray photography to determine gastric evacuation

rate and gut retention time in Jackass Penguins Spheniscus demersus. Cormorant 11:3-6.Gosztonyi. 1984. La alimentacion del pingiiino magellanico (Spheniscus magellanicus) en las adyacencias de Punta

Tombo, Chubut, Argentina. Centro Nacional Patag6nico Contribuci6n 95:1-9.Grant, Leslie, and Duffy. 1990. Molecular evolution of Spheniscus penguins. Proceedings of the Pan African Ornithological

Congress. in press.Harcourt. 1980. Report on a census of the Hightless Cormorant and Galapagos Penguin. Noticias de Galapagos 32:7-11.Harris. 1974. A Field Guide to the Birds of Galapagos. Collins, London.Harris. 11977. Comparative ecology of seabirds in the Galapagos Archipelago. In B. Stonehouse and C. M. Perrins (eds

).Evolutionary Ecology. MacMillan, London, pp. 65-76.Hays. 1983. Informe preliminar sobre la situacion del Pingiiino de Humboldt en el Peru. Primer Symposio de Ornitologia

Neotropical, pp. 61-68.Hays. 1984. The Humboldt Penguin in Peru. Oryx 18: 92-95.Hays. 1986. Effects of the 1982-83 EI Nino on Humboldt Penguin colonies in Peru. Biological Conservation 36: 169-179.Heath. 1987. A method for attaching transmitters to penguins. Journal of Wildlife Management 51:399-400.Heath and Randall. 1985. Growth of Jackass penguin chicks (Spheniscus demersus) hand reared on different diets.Journal

of Zoology 205:91-105.Heath and Randall. 1989. Foraging ranges and movements of jackass penguins (Spheniscus demersus) established

through radio telemetry. Journal of Zoology 217:367-379.Hockey and Hallinan. 1981. Effect of human disturbance on the breeding behaviour of jackass penguins Spheniscus

demersus. South African Journal of Wildlife Research 11 :59-62.Hui. 1985. Maneuverability of the Humboldt penguin (Spheniscus humboldti) during swimming. Canadian Journal of

Zoology 63: 2165-2167.Jackson, Siegfried and Cooper. 1976. A simulation model for the population dynamics of the jackass penguin, Transac-

tions of the Royal Society of South Africa 42:11-21.Jehl. 1975. Mortality of Magellanic Penguins in Argentina. Auk 92:596-598Jouventin. 1982. Visual and Vocal Signals in Penguins: their Evolution and Adaptive Character. Paul Prey, Berlin.Kerley and Erasmus. 1986. A note on transporting oiled penguins. South African Journal of Wildlife Research 16:109-111.Kerley, Bowen and Erasmus. 1987. Fish behaviour-a possible role in the oiling of seabirds. South African Journal of

Wildlife Research 17: 128-130.

SPN August 1991 page 18

Koepcke. 1970. The Birds of the Department of Lima. Livingston, Wynnewood.La Cock. 1986. The Southern Oscillation, environmental anomalies, and mortality of two southern African seabirds.

Climatic Change 8:173-184.La Cock. 1988. Effect of substrate and ambient temperature on burrowing African Penguins. Wilson Bulletin 100:131-1132.La Cock and Hanel. 1987. Survival of African Penguins Spheniscus demersus at Dyer Island, Southern Cape, South Africa.

Journal of Field Ornithology 58:284-287.La Cock and Cooper. 1988. The breeding frequency of Jackass Penguins on the west coast of South Africa. Journal ofField

Ornithology 59:155-156.La Cock, Duffy and Cooper. 1987. Population dynamics of the African penguin Spheniscus demersus at Marcus Island in

the Benguela upwelling ecosystem: 1979-1985. Biological Conservation 40:117-126.Laugksch and Duffy. 1986. Food transit rates in cape gannets and jackass penguins. Condor 88:117-119.Livezey. 1989. Morphometric patterns in Recent and fossil penguins (Aves: Sphenisciformes). Journal of Zoology

219:269-307.Martin. 1985. Through a penguin's eye. New Scientist 14 March 1985: 29-31.Merritt and King. 1987. Behavioral sex differences and activity patterns of captive Humboldt Penguins (Spheniscus

humboldti). Zoo Biology 6: 129-138.Morant, Cooper and Randall. 1981. The rehabilitation of oiled jackass penguins Spheniscus demersus, 1970-1980. In J.

Cooper (ed.). Proceedings of the Symposium on the Birds of the Sea and Shore, 1979. African Seabird Group, CapeTown, pp. 267-301.

Murphy. 1936. Oceanic Birds of South Africa. American Museum of Natural History, New York.Nagy, Siegfried and Wilson. 1984. Energy utilization by free-ranging Jackass Penguins Spheniscus demersus. Ecology

65:1648-1655.Perkins, 1983. Oiled Magellanic Penguins in Golfo San Jose, Argentina. Marine Pollution Bulletin 14:383-387,Perkins. 1984. Breeding ecology of Magellanic Penguins Spheniscus magellanicus at Caleta Valdes, Argentina. Cormorant

12:3-13.Rand. 1949. Some early references to the Cape Penguin. Ostrich 20:2-5.Rand. 1960. The distribution, abundance and feeding habits of the Cape Penguin (Spheniscus demersus) off the south-

western coast of the Cape Province. Investigational Report of the Division of Fisheries of the Union of SouthAfrica 41.

Randall, 1983. Biology of the Jackass Penguin Spheniscus demersus (L.) at St Croix Island, South Africa. Ph.D. thesis.University of Port Elizabeth, South Africa.

Randall and Randall, 1981. The annual cycle of the Jackass Penguin Spheniscus demersus at St Croix Island, South Africa,In J. Cooper (ed.). Proceedings of the Symposium on the Birds of the Sea and Shore, 1979. African Seabird Group,Cape Town, pp. 427-450.

Randall and Bray. 1983. Mortalities of jackass penguin Spheniscus demersus chicks caused by trematode wormsCardiocephaloides physalis. South African Journal of Zoology 18:45-46.

Randall and Randall. 1986. The diet of jackass penguins Spheniscus demersus in Algoa Bay, South Africa, and its bearingon population declines elsewhere. Biological Conservation 37:119-134.

Randall, Randall and Bevan. 1980. Oil pollution and penguins-is cleaning justified?Marine Pollution Bulletin 1: 234-237.Randall, Randall and Baird. 1981. Speed of movement of jackass penguins over long distances and their possible use of

ocean currents. South African Journal of Science 77:420-421.Randall, Randall, Cooper and Frost. 1986a. A new census method for penguins tested on Jackass Penguins Spheniscus

demersus. Ostrich 57:211-215.Randall, Randall and Erasmus. 1986b. Rain-related breeding failures in Jackass Penguins. Le Gerfaut 76:281-288.Randall, Randall, Cooper, La Cock and Ros. 1987. Jackass Penguin Spheniscus demersus movements, interisland visits

and settlement. Journal ofField Ornithology 58:445-455.Randall, Randall and Compagno. 1988. Injuries to Jackass Penguins (Spheniscus demersus): evidence for shark involve-

ment. Journal of Zoology 214:589-599.Rodriguez. 1983. Estructura de la jerarquizaci6n de la predaci6n de huevos y pichones de Spheniscus magellanicus

Doiiana, Acta Vertebrata 10:210-212.Rosenberg and Harcourt. 1987. Galapagos Penguin and Flightless Cormorant. Noticias de Galapagos 45:24-25.

please turn to page 20

SPN August 1991 page 19

A Selected Bibliography of the Spheniscus Penguinscontinued from page 19

Ryan, Wilson and Cooper. 1987. Intra-specific mimicry and status signals in juvenile African Penguins Spheniscusdemersus. Behavioural Ecology and Sociobiology 20: 69-76.

Saburo and Scolaro. The eye of penguins, is it an adaptation for deep diving? Comunicadones biologicas 6:225-232.Schlatter. 1984. The status and conservation of seabirds in Chile. In J. P. Croxall, P G, H, Evans and R. W.Schreiber (eds),

Status and Conservation of the World's Seabirds ICBP Technical Publication 2, pp, 261-269.Schmidt-Nielsen and Sladen. 1957. Nasal salt secretion in the Humboldt Penguin, Nature 181:1217-1218.Scholten. 1989. Individual recognition of Humboldt Penguins. Spheniscid Penguin Newsletter 2: 4-8.Schumann, Ross and Goschen. 1989. Old water events in Algoa Bay and along the Cape South Coast, South Africa, South

African Journal of Science 84:579-584.Scolaro. 1978. El pingilino de Magellanes (Spheniscus magellanicus) IV. Notas biologicas y de comportamiento. Publicaciones

Ocasionales dellnstituto de Biologia Animal, Series Cientifica 10: 1-6.Scolaro. 1980. El pingiiino de Magellanes Spheniscus magellanicus, VI. Dinamica de la poblacion de juveniles, His toria

Natural (25): 173-178.Scolaro. 1983. The ecology of the Magellanic Penguin Spheniscus magellanicus: a long-term breeding study of a temperate-

latitude penguin in southern Argentina. M. Phil. thesis, University of Bradford, U.K.Scolaro. 1984a. Biologia y selecci6n de habitat de reproducci6n de Spheniscus magellanicus en Patagonia, Argentina, Facultad

de Ciencias, Universidad de Cordoba, Spain.Scolaro. 1984b. Timing of nest relief during incubation and guard stage period of chicks in Magellanic Penguin

(Spheniscus magellanicus) (Aves: Spheniscidae), His toria Natural 4 (29):281-284.Scolaro. 1984c. Madurez sexual del pingiiino de Magellanes (Spheniscus magellanicus) (Aves: Spheniscidae). Historia

Natural 4(31):289-292.Scolaro. 1984d. Revision sobre biologia de la reproduccion del pingiiino de Magellanes (Spheniscus magellanicus). El cicio

biologico anual. Centro Nacional Patagonico Contribucion 91:1-26.Scolaro. 1985. Vertebrate species associated to breeding sites in a colony of Magellanic Penguins (Spheniscus magellanicus)

(Aves: Spheniscidae). Historia Natural 5:23-24.Scolaro. 1986. La conservacion del pingiiino de Magellanes: un problema de conflicto e intereses que requiere de

argumentos cientificos. Anales del Museo Historia. Natural de Valparaiso 17:113-119.Scolaro. 1987a. Sexing fledglings and yearlings of Magellanic Penguins by discriminant analysis of morphometric

measurements. Colonial Waterbirds 10:50-54.Scolaro. 1987b. A model life table for Magellanic Penguins (Spheniscus magellanicus) at Punta Tombo, Argentina. Journal

ofField Ornithology 58:432-441.Scolaro and Arias de Reyna. 1984a. Distribudon espadal achJalizada de la nidificadon y tamailo de la pobladon de Spheniscus

mageIlanicus en Punta TomOO, Chubut, Argentina. (Aves: Spheniscidae).Historia Natural 4 (27:249-256.Scolaro and Arias de Reyna. 1984b. Principales factores ecologicos que afectan la nidificacion del pingiiino de Magellanes

(Spheniscus magellanicus) en la colonia de Punta Tombo. Centro Nacional Patagonico Contribucion 97:1-14.Scolaro and Bodano. 1986. Diet of the Magellanic Penguin Spheniscus magellanicus during the chick-rearing period at

Punta Clara, Argentina. Cormorant 13: 91-97.Scolaro, Hall, Ximenez and Kovacs. 1979. El pingiiino de Magellanes (Spheniscus magellanicus) 1. Evaluacion y estratificacion

de densidades de su poblacion en Punta Tombo, Chubut, Argentina. Revista del Museo Argentino de CienciasNaturales Bernardino Rivadavia, Ecologia 2(4):87- 102.

Scolaro, Hall, Ximenez and Kovacs. 1980a. EI pingiiino de Magellanes (Spheniscus magellanicus) II. Biologia y desarrollode la incubacion en la colonia de Punta Tombo, Chubut, Argentina. Revista del Museo Argentino de CienciasNaturales Bernardino Rivadavia, f.cologia 2(5):104-110.

Scolaro, Rodriquez and Monachio. 1980. El pingiiino de Magellanes (Spheniscus magelianicus) V. Distribucion de las coloniasde reproducdon en el territorio continental argentino. Centro Nacional Patagonico Contribucion 33:1-18.

Scolaro, Ares, Alessandria, Estecondo, Ghersa, Gomez, Hoffmeyer, Prozco Storni, Perez and Zavatti. 1981. EI pingiiinode Magellanes (Spheniscus magellanicus) VIII. Aspectos de la dinamica de su poblacion en Punta Tombo(Chubut). His toria Natural 2 (5):5-20.

Scolaro, Hall and Ximenez. 1983. The Magellanic Penguin (Spheniscus magellanicus): sexing adults by discriminantanalysis of morphometric characters. Auk 100:221-224.

Scolaro, Bodano and Upton. 1984. Estimacion de la poblacion y estructura de la nidificacion de Spheniscus magellanicusen Punta Loberia, Chubut. Argentina (Aves: Spheniscidae). Historia Natural 4 229-238.

SPN August 1991 page 20

Scolaro, Bodano, Upton and Beloso. 1985. Ecologia de la nidificacion del pingiiino de Magellanes (Spheniscus magellanicus)en la colonia de Punta Loberia, Chubut, Argentina. Centro Nacional Patagonico ContribuciOn 103:1-17.

Shelton, Crawford, Cooper and Brooke. 1984. Distribution, population size and conservation of the Jackass PenguinSpheniscus demersus. South African Journal ofMarine Science 2: 217-257.

Siegfried. 1977. Packing of Jackass Penguin nests. South African Journal of Science 73:186.Siegfried and Crawford. 1978. Jackass Penguins, eggs and guano: diminishing resources at Dassen Island. South African

Journal of Science 74:389-390.Siegfried, Frost, Kinahan and Cooper. 1975. Social behaviour of Jackass Penguins at sea. Zoologica Africana 10:87-100.Simpson. 1976. Penguins: past and present, here there. Yale, New Haven.Sivak, Howland and McGill-Harelstad. 1987. Vision of the Humboldt penguin (Spheniscus humboldti) in air and water.

Proceedings of the Royal Society B 229:467-472.Sumner. 1934. Does /protective coloration' protect? Results of some experiments with fishes and birds. Proceedings ofThe

National Academy of Science 20:559-564.Valle. 1986. Status of the Galapagos Penguin and Flightless Cormorant populations in 1985. Noticas de Galapagos

43:16-17.Valle and Coulter. 1987. Present status of Flightless Cormorant, Galapagos Penguin and Greater Flamingo populations

in the Galapagos Islands, Ecuador, after the 1982-83 EI Nino. Condor 89:276-281.Vogt. 1942. A report on the guano-producing birds of Peru. 132 pp./ translation and notes by D. Duffy. (subm. to Colonial

Waterbirds).Westphal and Rowan. 1971. Some observations on the effects of oil pollution on the jackass penguin. Ostrich (Suppl.)

8:521-526.Williams and Cooper. 1984. Aspects of the breeding biology of the Jackass Penguin Spheniscus demersus. Proceedings of the

Fifth Pan African Ornithological Congress, pp. 841-853.Wilson. 1984. An improved stomach pump for penguins and other seabirds. Journal of Field Ornithology 55:109-112.Wilson. 1985a. Diurnal foraging patterns of the Jackass Penguin Spheniscus demersus. Ostrich 56:212-214.Wilson. 1985b. The Jackass Penguin (Spheniscus demersus) as a pelagic predator.Marine Ecology Progress Series 25:219-227.Wilson, R. P. 1985c. Seasonality in diet and breeding success of the Jackass Penguin Spheniscus demersus. Journal fur

Ornithologie 126: 53-62.Wilson and Bain. 1984a. An inexpensive speed meter for penguins at sea. Journal of Wildlife Management 48:1360-1364.Wilson and Bain. 1984b. An inexpensive depth gauge for penguins. Journal of Wildlife Management 48:1077-1084.Wilson and Achleiter. 1985. A distance meter for large swimming marine animals. South African Journal of Marine

Sciences 3:191-195.Wilson and Duffy. 1986. Prey seizing in African penguins Spheniscus demersus. Ardea 74:21 1-214.Wilson and Wilson. 1988. Dead reckoning: a new technique for determining penguin movements at sea. Meeresforschung

32:155-158.Wilson and Wilson. 1989a. Tape: a package attachment technique for waterbirds, Wildlife Society Bulletin 17.Wilson and Wilson. 1989b. A peck activity record for birds fitted with devices. Journal ofField Ornithology 60:104-108.Wilson and Wilson. 1989c. A minimal-stress bird-capture technique. Journal of Wildlife Management 53:77-80.Wilson and Wilson. 1990. The foraging ecology of breeding Spheniscus penguins. In. J. Darby and L. Davies (eds.).

Penguins. Academic Press, Orlando, Florida.Wilson, La Cock, Wilson and Mollagee. 1985. Differential digestion of fish and squid in Jackass Penguins Spheniscus

demersus. Ornis Scandinavica 16:77-79.Wilson, Grant and Duffy. 1986a. Recording devices on free-ranging marine animals: does measurement affect foraging

performance? Ecology 67:1091-1093.Wilson, Wilson and McQuaid. 1986b. Group size in foraging African Penguins Spheniscus demersus. Ethology 72:338-341.Wilson, Ryan; James and Wilson. 1987. Conspicuous coloration may enhance prey capture in some piscivores. Animal

Behaviour 35:1558-1560.Wilson, Wilson and Duffy. 1988. Contemporary and historical patterns of African Penguin Spheniscus demersus distribu-

tion at sea. Estuarine, Coastal and Shelf Science 26:447-458.Wilson, Wilson, Duffy, Araya and Klages. 1989a. Diving behaviour and prey of the Humboldt Penguin (Spheniscus

humboldti). Journal fur Ornithologie 130:75-79.Wilson, Ryan and Wilson. 1989b. Sharing food in the stomachs of seabirds between adults and chicks--a case for

delayed gastric emptying. Comparative Biochemistry and Physiology 94A: 461-466. Q

SPN August 1991 page 21