exam 3 Flashcards
why are weddell seals easy to study/how do we study them
They like to be on the fast ice/beaches close to land so they are easily observable. They are curious so they are easily approachable. They make open holes in the ice that they use for breathing/entryway to the sea to get prey. They keep the holes open with their procumbent incisors. We can send instruments down the holes.
weddell seals appearance and life history
They have a muddled appearance (dark grey top, lighter bottom), and are about 2.5 m long. The females are longer than the males. They give birth in early summer (October) and nurse their pups for 6-7 weeks. They’re more spread out than elephant seals. Enemies include leopard seals and orcas.
history of exploitation, fur seals, elephants seals, and whales
Fur seals were first exploited for their pelts. Next, elephant seals were exploited for their blubber (specifically the oil in it). Whales were then targeted after the other populations were depleted, for their blubber.
how was sealing started and spread
Sealing began on the Falkland Islands in 1765 and spread to South Georgia in 1786. In 1775, 13,000 fur seal skins were taken from Falkland by one ship.
how many seal skins were taken between 1793 and 1807?
3.2 million
what happened when sealing spread to the south shetland islands and antarctic peninsula
operations moved here in 1819 and 300,000 fur seal skins were taken from the AP in 4 years
when and why did sealing end
in 1822 sources were depleted and they moved on to elephant seal blubber
when did whaling began
in the mid 1800’s when other populations were depleated
methods and history of whaling
- people would row out and hunt the whales with hand spear one by one.
- whaling stations were developed and allowed them to hunt right around the station/process them on land.
- The swivel canon was invented and allowed whalers to kill more whales faster, but they still needed to be processed on land.
- factory ships allowed for whales to be killed and processed at sea.
fencing platforms
platforms on the whaling stations where the whales were processed. Long knives were used to cut out chunks of blubber. The blubber was then boiled to extract the oil.
how was the blubber though to be exposed of after extracting the oil
A slope in the back of Grytviken was thought to be used to drop blubbler sections off.
swivel harpoon canons
This took whaling from being done with hand spears to being able to kill the whales from the ships. It was invented in 1865 by Svend Foyn. The guns not only contained gun powder on the ships, but also in the gun head which exploded in the whale instantly killing it.
Svend Foyn
Invented the swivel gun in 1865 which increased exploitation of the whales.
Grytiviken
Established on South Georgia, it was the first whaling station (1904). It increased the rate of exploitation.
how many humpbacks were taken from right around Grytiviken station in the first few years
6,000
In the first decade how many whales were taken
1700 blue whales, 4800 finback, and 22000 humpbacks were taken
What was baleen from the whales used in
corsets
when was the station Grytiviken abandoned
when factory ships were invented (ghost towns today)
deception island and whalers bay
Norweigen whaling station from 1906-1931 in whalers bay on deception island. It got affected by volcanic eruption that caused people to leave. Prime location because of the inlet/protection it provided. There’s also warmer water due to the volcanic vents.
factory ships
Allowed whales to be killed and processed at sea, which increased exploitation.
when were factory ships first invented
in 1925, by 1930 there were 41
how much did whale intake increase
from 14000 to 40000
what happened after ww2
whaling continued. blue whales, then fin, sei, and minke were depleted (largest–>smallest)
when did whaling end
most ended in 1960 as stocks depleted, but illegal whaling still takes place
Convention for the Regulation of Whaling 1935
A convention for the regulation of whaling was established in 1935, but Japan and Germany refused to join
whale sanctuary
A whale sanctuary was established in 1938 south of 40º latitude, that included complete protection of humpback whales.
krill surplus hypothesis
First proposed by Sloden (1964) to account for increasing penguin/fur seal populations on the AP from 1940s-1970s. Whales and seals that eat krill died off, so krill numbers increased (150 million tons of excess). Extensive slaughter of whales/seals in the 18th/19th/20th century suggest that penguins switched their diet more to krill since early 1800s.
stable isotopes in determineing diet of Adelie penguins
Heavier nitrogen isotopes indicate a diet shift up the food chain. Can compare tissues pre/during/post whaling to see diet change. Carbonate in eggshells reflects isotopes during egg formation in late spring/early summer.
dietary shifts during whaling
Within 200-300 years diet had shifted down the food chain. Eggshells from RFS cabin 1911-1917 indicated diet had already shifted during the most intense whaling period. Ancient penguin isotope ratios show litle variation 9000-200 ya. Rapid loss in heavy nitrogen/carbon isotopes thereafter.
current status of krill hypotehsis
Evidence now indicates the KSH is ending due to climate change (less sea ice and marine mammal recovery). There may not be food source for penguins to revert back to other than krill, so we may see future declines of Adelie and Chinstrap penguins in the AP.
5 species of penguin in antarctica
- emperor (endemic)
- Adelie (endemic)
- gentoo
- chinstrap
- macaroni (only in the northern ap)
how many penguin species in the Southern Hemisphere
17 off the coasts of Africa, New Zealand, Subantarctic islands, etc.
Distribution (seabirds), subantarctic species
Diversity decreases from subantarctic to the continent. Some species include petrels, gulls, terns, skuas, some penguin species (gentoo, rockhopper, chinstrap etc.)
ecology of Adelie penguins
They live 15-20 years, and their diet is fish, squid, and some crustaceans. They stand at 3 feet tall, can dive more than 500 m (though they usually dive no more than 150 m for 18 minutes), and are active mainly in the winter. They have a circumpolar-antarctic distribution.
breeding cycle of emperor penguins
They nest on the sea ice or ice shelves. They may walk hundreds of kilometers across ice to nesting location, but ice breakup in summer may put them closer to shore. They pair bond for life. Females produce one large egg (lot of cost so they leave to feed after laying the egg). The male incubates the egg on his feet to prevent the egg from freezing. It takes 5-6 months to incubate/hatch/raise the chick/egg so by the time the chick fledges it’s summer. The male fasts for 180 days and feeds the chicks mucus until the female returns with food (after two months of feeding). They switch off keeping the egg warm on their feet/feeding until it can survive on the ice shelf/sea ice on its own. The more experience the parents have, the higher reproductive success they’ll have.
Adelie penguins mating & nests
mate for life, come back to the same nest site, dig out, and rebuild with pebbles. The male comes first and waits for the female (finds a new one if she doesn’t show).
Adelie egg cycle
Female produces 2 eggs and goes back to sea to feed. the male takes over the incubation/fasts for two weeks until female comes back with food (find each other b call). Female then takes over for a week until the male finishes feeding. Switches on an dog over 35 days.
When do both parents leave and how do feed chick Adelie penguin
as chicks become more independent both parents leave to feed. they feed the chicks by direct regulation of freshly eaten whole krill.
when does the chick leave the colony with Adelie penguins
must weigh enough (over 3000, 3300 better) to survive the winter and reproduce the next year
parental experience effect on reproductive success Adelie penguins
positive
if a chicks down gets wet what happens Adelie penguin
chick can die from hypothermia
what happens when the parents leave Adelie penguin
chicks form a creche to protect themselves from predators. parents coming in and out of rechecked are harassed for food.
when do Adelie penguin chicks start flapping their wings
around 6-8 weeks to build muscle to use as a defense/for swimming
creche disbanding in Adelie penguins
one leaves the creche first and the rest follow. struggle cos Wim at the surface before realizing swimming below is easier. Mortality can be up to 75% in low ice years.
pygoscelid penguins
brush tailed penguins (feathers act as rudder) usually occur in one large colony near a polynya with smaller ones surrounding
two types of psygoscelid penguins
1) Adelie - endemic, circumpolar-subantarctic distribution, ice-free areas in AP & continent (gap from AP to Ross Sea)
2) Gentoo/Chinstrap - more subantarctic, found N & S of convergence
pygoscelid penguins population changes in AP since 1970’s
The 3 species occur on the peninsula. Adelies are declining (climate change losers) with warming (need open water, but also sea ice for food). Gentoos and Chinstraps like open water and extend south with warming (winner). Chinstraps have seen a slight decline.
researchers on penguins using flipper bands
Most seabirds are banded on their lower leg, but penguins are banded on their flipper (can restrict hunting). Provides info on population changes, diet, breeding success.
research on penguins using fweigh bridges
Another study method is sectioning part of a colony off with only one door out. There’s a weigh bridge/bar scanner at the door to provide info on diet quantity (no diet specifics though - no stomach pumping).
three endemic species of seabird sin Antarctica
1) Adelie Penguin
2) Emperor Penguin
3) Snow Petrel (mainly around sea ice, most southerly in the world)
giant petrel ecology and predation on penguins
Nest on islands in the subantarctic/peninsula. They produce one large egg - long incubation period (1st half of the summer). They produce an oil in their stomachs that they feed chicks when they first hatch (mate out getting food). Also use the oil as a defense (STINKS). Go after larger chicks (in creche)/adults (sometimes).
tubenoses and salt glands
Petrels (giant, snow, storm) are the tubenoses. They have salt glands that act as a second kidney, extracting salt from seawater to flush out of their body via the tubenose. There’s a depression in their bone for the gland.
Skua ecology
They can regonize your face/extremely smart/brave. They live 25-30 years, mate for life, dive bomb you unless you stare them in the eyes. They project a long-call to alert an area is their territory. South Polar skuas (EA/AP) and Brown skuas overlap in the AP. Skuas have been seen up to NA (migrate out of Antarctica in the winter). They practice siblicide (1st chick eats 2nd) stimulated by hunger (parents don’t interfere).
obligate sublicide vs facultative siblicide
happens no matter what (south polar)
Facultative siblicide
skua predation
Some nest around penguin colonies and eat the eggs/young chicks (most eat krill/silverfish). They’ll dive into the middle of an Adelie colony and take an egg/chick (or patrol the edge), bringing it back to their nest to feed. Gentoo/Rockhoppers are less aggressive than Adelies, and smaller so they do ground attacks in these colonies. A specific behavior includes a pair harassing a penguin/distracting it until one can steal the egg (uncommon).
american sheathbill ecology, unique niche
Occupy a niche around penguin colonies on the subantarctic islands, antarctic peninsula and east antarcitca. There are only two families (greater and lesser). Have excess sheath/warts on their bill. They eat copepods, undigested krill in fresh guano, and peck at eggs to get yolk. Scavenge carcasses.
