Every PenguinTracker dispatch tagged penguins. 7 posts.
At one emperor penguin colony in Marie Byrd Land the sea ice season has gone from 322 days a year to 207, and it has shortened at both ends at once.
You do not count penguins from orbit, you count their guano. Here is how the method works, and the measurements that show our own version of it failing.
An iceberg knocked the Mertz Glacier Tongue off in 2010 and grounded nearby. Summer sea ice at Cape Denison went from 4 percent to 54 percent.
Antarctica has 729 known penguin breeding sites. Measured against sea ice they are 56 independent places, and the species with the most sites have fewest.
Our sea ice metric reproduced five published emperor penguin breeding failures and completely missed a sixth. The miss is the more useful result.
Emperor Island in Marguerite Bay held emperor penguins from 1948 to about 2009. Its sea ice season is 75 days shorter, and it is shorter at one end.
Antarctica has 729 known penguin breeding sites. Three adjacent slices of longitude hold 510 of them, and the reason is a species list, not a survey bias.