Field Notes Answers
Here are the explanations for the pictures in Field Notes.
When penguins search an area to make their own nest, they frequently squabble with other penguins nearby for the territory they want. It is safer to be in the center of the group (protection against skua attack), but those nest are usually taken by older birds, who arrive in spring early. If a site is vacant, a new bird may take it, but if the previous owner shows up, a fight likely will occur. Here is a picture of 2 penguins fighting over a nest territory.
|2. The white markings around the nest are "poop squirts." The adult on the nest does not want to poop on its egg or chick so it lifts its tail and squirts the poop in whatever direction it is sitting. Over time it makes a ring of white lines around the nest site. Any penguins within squirt distance will get a stripe on it. Here is a picture of a penguin that is too close to his neighbor.|
|3. The brood patch is not covered with feathers, so the egg and then the chick can nestle close to the parent's warm skin. It is not the feathers that are warm, but the penguin's skin. The feathers then wrap around the egg or chick to keep it from the wind, snow and cold.|
nests are about 1 meter apart center to center. If they were closer
together the penguins would be able to touch one another and would
fight. Here is a picture of a neighbor who is too close to the other
and is getting his tail bit. Also any closer and they would be covered
in poop (see #1 above). If the nests are further apart, neighbors
lack help with skua attacks. The birds will not leave their nests
to peck at an attacking skua. It will only do so if it can reach the
skua from its nest. Being close to a neighbor means if a skua comes
close to you, your neighbor will help fend it off.
|6. Eggs are laid 2-3 days apart; they may hatch on the same day or only 1-2 days apart. That’s because parents don’t incubate the egg closely until both are laid. If food is scarce, it is an advantage to being the first born chick as you will be the stronger one and able to be more aggressive in getting food from the parent. Sometimes it is better to be the second one born. When parents leave the nest to forage, the mate staying behind is fasting. It could be that when the first chick hatches the fasting parent does not have any food to feed it and it will die. The second born allows the foraging parent a few more days to return with a fresh supply of food. In this picture you see a first born that is clearly out-growing the second born. He is stronger and taller, and able to out-reach his sibling for food from the parent.|
|7. Nesting penguins will not leave their nest for any reason. The skua is sitting close but not close enough for the penguin to reach and bite him. The penguin is no doubt very aware of the skua's presence, but is not reacting now because the skua is not attacking. If the skua were to move closer or show interest in the nest, the penguin would become agitated and get ready for a fight. The picture at right shows a skua in flight. These are very strong birds; note the hooked beak which, like other predatory birds, help them grab their food.|
|8. The Antarctic breeding summer is very short. Adelie Penguin parents have only a few weeks to raise their chicks to a weight and age when they can fend for themselves. If the winter sea ice starts to form before the chicks have their adult feathers and are strong enough to swim, they will not have the strength to walk to the ocean. Chicks hatched from late-laid eggs will not be old enough by that time. Eggs laid too early risk the chance of a short food supply. The parents must walk many miles to get food, and in some years this can be a very long way. If a parent must make a long journey for food at the beginning of the season, they may not get back in time to feed the newly hatched chick. As the season progresses, the sea ice breaks up bringing the open ocean closer and trips for food shorter. This year the penguins have a short walk to the open ocean.|
|9. Sometimes mates do not return from a foraging trip to relieve the nesting adult. They may have been eaten by a seal, hurt or otherwise not able to make the trip back. The nesting parent has been fasting while sitting on the nest. The urge to stay on the nest and brood the eggs is strong, but the adult will not starve itself for the sake of the eggs or chick. At some point the need to replenish the body will become the larger urge and they will abandon the nest and the eggs to the skuas. The parent on this nest was here for many days, as the mate did not return. The chick hatched but died as there was no food to feed it, after which the adult left the nest to feed itself. In a couple of hours both this chick and the egg became food for skua families.|
10. Being in a group is a protective behavior. Skuas will attack the nests on the edge of a group but not the center. Close neighbors will attack any skua within reaching distance so it helps to be in the center. Being in the center also has some down sides. Returning adults must pass through all the nests on the outside to get to the center and they are subject to pecks from everyone they pass by. This picture shows a skua attacking an isolated nest. This penguin does not have help from its neigbors, and must fend off the skua alone.
|11. It is important for researchers to know what Adelie Penguins eat so they can understand their place in the food web of the Southern Ocean. Knowing about food chains and webs helps us understand how the flow of energy in the world works. If we know what kinds of fish penguins eat then we do not want to harvest those fish for our own food supply. That would interfere with the lives of these special birds. This picture is a very common food source for penguins, an Antarctic silverfish.|
|12. The more we know about Adelie Penguins helps us understand how these birds are coping with changes on the Earth. Climate change, which alters sea ice patterns, food sources and habitats means the penguins must adapt by moving their breeding areas, changing their food source or life patterns. Cape Royds (at right) is increasing in population size because more persistent wind, due to global warming, is dispersing the sea ice thus making it a better place for penguins to live. Other colonies way to the north are declining because the sea ice has totally disappeared. Penguins want some sea ice nearby, but not too much!|
|13. Changes occur in our world that we can not see. When we monitor Adelie Penguins over several years and notice changes in their population size or living patterns then it is a signal for us to explore what is happening. In the case of Adelie Penguins their population is shifting to more southern breeding areas. Colonies in the north are no longer there and colonies in the south are getting larger. After exploring several factors it was determined that changes in the amount of sea ice in the northern colonies was causing the penguins to abandon those breeding sites. Penguins require a certain amount of sea ice and with the warming climate the sea ice was disappearing. This map shows the relationship between sea ice and penguin colony population growth and decline. For more on this topic click here.|
|14. When we watch penguins swim it seems they are having fun. They swim easily and make large circles in groups. But that is looking at it from our eyes as humans. The name for that kind of thinking is anthropomorphizing. It means we give human thoughts to non human animals or objects. It is fun, but not scientific. We do not know if penguins swim for fun and pleasure. We know they must swim to gather their food, but the water is full of danger, so maybe they do not stay in any longer than they need to. This penguin has just entered the water and is swimming through the waves near the beach.|
|15. Penguins choose nest sites that are high on mounds, not in gullies where melt water and snow accumulate. Many will select sites near large rocks to help protect against Skua attack, and others will choose sites close to lots of other penguins for protection. Here is a picture of an Adelie Penguin colony showing the pattern of nests. These areas are raised and will protect the groups from melt water run off. In between these areas are low and will become muddy when the snow fields melt.|