Penguins, more and less

Let's talk penguins.
Even among our flightless, tuxedoed adorables, the Antarctic breeds are a rarity. The world knows 17 varieties wandering the Southern Hemisphere.
But in Antarctica we have, principally, three kinds.
You can spot the gentoo by its orange beak and the white stripe atop its head.

Then there's the chinstrap, so named because, well, it has a chinstrap.

And finally the dominant species of the Antarctica peninsula, the Adelie, sports classically black feathers on its head. The Adelies, named for the wife of French explorer Dumon d'Durville, tend to waddle around in massive colonies like so many Whos down in Whoville.
In recent years, the number of gentoos and chinstraps that are more native to warmer climes in the north has skyrocketed. In 1975, there might have been fewer than 100 nesting pairs of chinstrap penguins around the western Antarctic peninsula. Today, there may be 300. Gentoos were practically nonexistent here as recently as 1990. Today estimates put the number of nesting pairs above 1,000 and climbing.
Adelies, meanwhile, are in steep decline. There may have been more than 15,000 nesting pairs along the peninsula and its scores of small islands in 1975. Now there may be fewer than 4,000 pairs.
The Adelies feed in spots where the churning of warmer and cooler water stirs up nutrients and promotes the growth of fish and shrimp-like krill. But to get to those feeding grounds, the Adelies need winter sea ice to launch their hunts.
As that ice has receded, so have the penguin numbers.

So how do we know how many penguins there are here? In part because very tough people like Jennifer Blum, left, and Kristen Gorman coat themselves in Gore-Tex, fleece and sunblock on a daily basis, hop in a tiny rubber boat and scoot from one island to to the next. They count birds. They monitor the number of eggs laid, how many of those eggs end up in the bellies of predators, how many chicks hatch. And so on. For month after Antarctic month.