Sphenisciformes [Compatibility Mode]

Sphenisciformes [Compatibility Mode] - 3/16/2010 Penguins,...

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Unformatted text preview: 3/16/2010 Penguins, Order Sphenisciformes, Family Spheniscidae Unique characters: Flightless bird with keeled sternum and no flight feathers Inflexible elbow No apteria Penguins Compact and distinctive avian order 1414-15 species, 6 genera Name of Welsh origin, means ‘white head’ – originally applied to Great Auk (not a penguin, family Alcidae) – Transferred to the southern birds by early seafarers Scientific name, Spheniskos, is Greek and Spheniskos means small wedge, refers to flipper-like wing flipper- About 14 - 18 species Features Only in Southern Hemisphere – Only two species confined to Antarctic, the Emperor and the Adelie Ancient and primitive – Presence a strong keel and brief appearance of wing quills in early embryonic life is evidence of flying ancestors – Flipper is stiff and moves only at shoulder – The beak, coalesced from several horny plates is also peculiar (resembles Procellariiformes) Penguin skeleton Features Most truly marine of all birds Many species adapted for pelagic life – Stiff, close packed feathers, with no apteria – Feathers impervious to water (hypothermia) – Legs set far back on body – Webbed feet, heavy, used as rudders – Necks short, but flexible 1 3/16/2010 Mobility Adelies 16 knots, others 25+ knots, jump 6 ft out of water, waddle on land, Crested penguins hop Only leave water to breed or molt, most species are able to fast for prolonged periods Swimming penguin Penguins porposing Predators No terrestrial carnivores Harassed by predatory birds that prey on eggs and chicks on eggs and chicks – Sheathbills – Giant petrels – Skuas At sea predators are killer whales and leopard seals Egg and chick predators Prey Fish, squid, and shrimp are their major foods Prey are caught under water are caught under water Must be trained to eat on land 2 3/16/2010 Migrations Emperor and Adelie penguins make long migrations over Antarctic ice to reach nesting grounds They can ‘snow toboggan’ (i.e., sled) using flippers and feet and move faster than a skier Sizes Emperor and King penguins are the largest, 3.5 and 3 feet tall Adelie is next, 2 ft Smallest in size is the Little Blue Penguin ~1 ft of New Zealand and Australia Breeding Some small species on NZ and Aust. nest in burrows Most species are highly gregarious and Most species are highly gregarious and breed breed in colonies Density is 500,000 nests/500 acres = 2,475 / hectare = 0.2 / m2 Site tenacity is high Breeding Site Tenacity – Sites are important niche dimensions (Hurlbert 1981. Evolutionary Theory 5: 177-184. ‘Niche’= 177set of resources used = energy (food), materials (f (rocks), and space (sites)). – Space is only considered a resource when defined as space occupied – Tagging studies show that individuals return to the same nest site year after year Breeding Emperor Penguin Probably the only bird on earth that almost never sets foot on land (i.e., ‘dirt’) Spends life off cold coast of Antarctica, Spends life off cold coast of Antarctica, living living much of year in the broken offshore ice pack and feeding in krill-rich waters krill Only bird to start its reproduction cycle in the fall instead of spring Old birds come ashore in late March--fall in March--fall S. H. Two largest, Emperors and Kings, don’t nest – They stand upright and hold single egg on top of their feet and huddled under a fold of belly skin All other species incubate their eggs (usually 2) 2) in in the more normal fashion – Some sort of nest is built – Yellow-eyed and most Spheniscus spp nest in YellowSpheniscus burrows – Practically all other species nest on surface using mud or pebbles to construct nest 3 3/16/2010 Emperor Penguins Emperor Penguin ... Move inland to a spot on shore where they bred in years past Courtship occurs in May just as sun sets for for the long Antarctic night – Females lay single egg – Male takes charge of egg Female returns to sea to break fast of 7-8 7weeks – Males form pods; mill in and out, carefully holding egg Emperor Penguin ... Temperature in June and July is -40 C and winds reach 100 mph A dropped egg is dead, egg mortality is high Incubation lasts 62-64 days 62 Male accomplishes entire stint without relief Male loses 1/3 weight, 75 down to 50 lbs Male feeds hatchling on a crop exudate for first day or two Emperor Penguin ... Female shows ups, sleek, glossy, fat and full of food – Male heads for open water – In a few weeks, by end of August, males return to feed chicks 2 months incubation plus 4 month growth period for chick places chick at a point where it is ready to fend for itself at most favorable time of year, early December, and the start of the Antarctic summer Emperor Penguin ... Adelie Creches A remarkable suite of features allow males to withstand 100 days of fasting in the depth of the Antarctic winter: – – – – – – – largest species (40 kg, 3x mass of King penguin) Body size and shape yields lowest s-v ratio sFlippers & bill proportionally 25% smaller than other species Circulatory heat-conservation sys 2x extensive as King heatHighly developed nasal heat-recovery sys heatlong, double-layered, dense feathers, even cover legs doublemilling behavior allows further 25% reduction of heat loss (5000 non-aggressive individuals) non- Adelies are surface nesters – Nest is 2-2.5 ft in diameter (60-80 cm) 2(60– Lots of quarrelling around the nest and an occasional battle Kindergarten (Creches) are aggregations of young that form when parents are away – Creches serve no nursery function, young are fed only by their own parents – Creches provide some protection from skuas and the young aggregate to keep warm – Parents and young are reunited after recognition by voice 4 3/16/2010 Adele nest spacing Adelie Penguins Adelies on ice Adelie Penguin on nest (left) David Lack Brood Reduction Hypothesis If food is scarce, smaller members of a brood cannot procure adequate resources and die, allowing only the larger, better nourished members to fledge nourished members to fledge An initial size gradient of hatched young with the brood is usually brought about by differences in egg size and by starting incubation before laying is complete 1954. The natural regulation of animal The numbers – pointed out that females of many bird species lay more eggs than can typically be reared to more eggs than can typically be reared to independence independence – In most non-passerine birds, the later eggs of a nonclutch are smaller and less likely to survive – A situation that is thought to facilitate brood reduction reduction, a strategy that enable birds to adjust the number of offspring they rear in response to prevailing environmental conditions Typical time sequence of egg size: 000000 5 3/16/2010 Six species of Crested penguins (Eudyptes spp.) Macaroni Penguins Crested penguins (Eudyptes spp.) Crested penguins (Eudyptes spp.) Display a striking exception to the usual egg size pattern, contradicting what would be predicted from brood reduction theory: 00 Never rear more than one chick – In contrast to all other penguins that lay two eggs All five species lay two eggs First is significantly smaller Only bird group that exhibits a reversal in the size of eggs laid Wh Why are two eggs laid if two chicks are never eggs laid if chicks ne reared? Why is the first egg smaller? Crested penguins (Eudyptes spp.) Extra egg may be insurance against egg loss Brood reduction is not a sufficient explanation -- in part because Crested penguins do not begin to incubate the th smaller egg until the larger is laid First egg is smaller because it is often lost during inter-male territorial fights during the interearly nesting stage, and it represents the minimum investment that could result in a viable offspring Crested penguins (Eudyptes spp.) The mechanism is inter-adult aggression interrather than intra-brood aggression, as intraoccurs in other avian species A smaller egg represents a smaller investment lost The greater probability of loss is a major selective factor favoring its small size Several predictions can be made 6 3/16/2010 Crested penguins (Eudyptes spp.) Predictions: Nest sites are closely spaced and limited in number (ex 1 sp) Males defending nest sites are larger than females (ratio 1:1.28-1.37) 1:1.28 Males arrive at nesting area earlier 1st and 2nd eggs should be equally viable (2nd egg may be absent or inviable) Crested penguins (Eudyptes spp.) Findings: Eudyptes spp. – 72% of all Macaronic eggs fail or lost – 60% of all Rockhopper eggs fail or lost NonNon-Eudyptes spp – 21% of all Magellanic eggs fail or lost – 24 - 41% of all Little eggs fail or lost – 10% of all Chinstrap eggs fail or lost Data support “Egg Insurance Hypothesis” Egg Insurance Hypothesis Nests are closely spaced Males engage in territorial fight early in season Fights result in egg loss and breakage When one egg is lost, it is nearly always the first for Macaroni and Rockhoppers For the genus, more small eggs are lost Males stand over first egg but do not incubate it ‘The Far Side’ Ecological segregation Ecological segregation ... Adelie and Chinstrap penguins are shallowshallowdiving, offshore foragers that avoid competition by differences in breeding chronology pre breeder behaviors and molting chronology, pre-breeder behaviors and molting strategies strategies Adelie chicks fledge as Chinstrap chicks reach Cre Creche age Different migration times and molting locations further reduce niche overlap of Adelie, Gentoo, and Chinstrap penguins nesting on King George Is. during summer results from: – Breeding chronology chronology – Foraging behaviors – Life history tactics Gentoos feed inshore and are deep divers – small populations size reflects the large amount of food needed to rear chicks and the small foraging range dictated by a short nest relief schedule and nonnon-fasting behavior 7 3/16/2010 Peruvians and Magellanics Gentoo Penguins Gentoo Penguins Macaroni and Chinstrap penguins Chinstrap and chick on nest References: Emlen, J. T. and R. L. Penney. 1966. The navigation of penguins. Sci. Amer. 215(4):105-113. Johnson, K. and J. C. Bednarz. 1987. Crested penguins: why are first eggs smaller? Oikos 49:347-357. Muller-Schwarze, D. and C. Muller-Schwarze. 1977. Interactions between south polar skuas and adelie penguins The proceedings of the Third SCAR symposium polar skuas and adelie penguins. The proceedings of the Third SCAR symposium on Antarctic biology: 619-646. Muller-Schwarze, D. and C. Muller-Schwarze. 1975. Relations between leopard seals and adelie penguins. Rapp. P.-v. Reun. Cons. int. Explor. Mer. 169:394404. Simpson, G. G. 1976. Penguins: Past and present, here and there. Yale University Press, New Haven. Stonehouse, B. (ed.). 1975. The biology of penguins. University Park Press, Baltimore. 555 p. Trivelpice et al. 1987. Ecological segregation of Adelie, gentoo and chinstrap penguins at King George Island Ecology 8 ...
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