Appendix (for reading content...etc)
Read the passage 'Emperor Penguins'. On a piece of paper, take notes on the main points of the reading passage.
Reading time: 3 minutes
Emperor Penguins
Emperor penguins are not only the largest species of penguin in the world but also one of the most unique. They are very social, living in colonies that can include hundreds of thousands of individuals. Nevertheless, emperor penguins are monogamous. Having selected a mate, emperor penguins remain faithful to each other for life, using vocal calls to find one another when they return to their breeding site on the compacted ice of the Antarctic continent. It is believed that different frequencies alert mates to the sound of their partner's call.
Another interesting aspect of emperor penguins is that they return to the same site, called a rookery, to nest each year. Although their path to the rookery is different every year due to the shifting sea ice, in general, the penguins continue to use the rookery where they were hatched. Their loyalty to a particular breeding ground results in increasingly larger penguin colonies, some with more than a million birds. Males tend to arrive first to reestablish and defend their preferred nesting sites and females return a day or so later.
Emperor penguins are not considered endangered and are not currently protected under international law. In fact, in areas where reliable population counts have been conducted, the evidence suggests that populations are stable. However, due to harsh environmental conditions, some colonies have not been monitored on a consistent basis. Estimates of population sizes are at about 240,000 breeding pairs. Taking into consideration the non-breeding birds as well, the total translates into about 600,000 adult birds. Emperor chicks that reach adulthood can survive for 20 years.
Now listen to the passage. On a piece of paper, take notes on the main points of the listening passage.
[audio|src:'\listening\toefl_advanced\EmperorPenguins.mp3']
Although the reading passage about emperor penguins in your textbook was correct for the time that it was written, new data have come to light since the book was printed. In fact, we now know that all three assumptions in the passage about this interesting species are probably not true.
First, let's consider whether emperor penguins are monogamous. That is, do they mate for life? With greater observation, we find that the answer is yes and no. Yes, they're monogamous for the mating season and the pair is committed and diligent in caring for their chick, but we also now know that if they don't locate their previous mate the following year in a timely way, they'll mate with another penguin. So this means that it would be more correct to consider them serially monogamous, mating with one partner per season. When the pair can find each other within a tight time frame, then, yes, they'll continue to mate with the same partner, but it looks like that happens about only 15 percent of the time.
Now let's look at nest loyalty. A new study by the University of Minnesota used satellite images to verify that emperor penguins were returning to the same location to nest every year. Researchers found six instances in which the penguins didn't return to the same rookery and, in addition, found a new rookery that appears to confirm the relocation of an entire colony. This could also account for the disappearance of banded birds from previous studies. And, of course, this disproves the previous assumption about penguins returning to the same rookery every year.
Last, let's revisit the issue of whether emperor penguins are endangered. Just a few years ago, they were given endangered status under the Endangered Species Act because models of declining numbers estimated that their population could decline by as much as one-third by the end of the century. Disappearing sea ice and radical changes in the marine life in current feeding habitats have convinced the scientific community that emperor penguins must be protected if they're to survive.
Summarize the main points in the lecture, and then explain how they cast doubt on the ideas in the reading passage.
|
emperor penguins new data
|
|
mate for life
|
|
faithful, monogamous
vocal calls, frequencies to locate
|
for mating season only
15% find same mate next yr
|
|
return to rookery
|
|
next yrly
diff path
males 1st – females day + later
|
U minn satellite
6 diff rook
new rook
|
|
not endangered
|
|
not protected
stable pop
240,000 breeding prs = 600,000
|
now endangered status
model 1/3 decline end century
ß disapp sea ice + changes in f habits
|
|