September 8, 2011
Black-legged Kittiwake at nest
Black-legged Kittiwake at nest
I’m thinking that here in the September of our discontent with Arizona’s unrelenting monsoon heat, you could use a little relief from the gloom and doom of global warming. Wait, what? You don’t believe in global warming? Okay, stop reading this column and google global warming. Read everything you can about it (it’ll take you at least a week), then check back. This column will still be up on our website, and you’ll still need a little relief.

Back in July NPR ran a fascinating piece about the work of Scott Hatch, a researcher on Middleton Island in the Gulf of Alaska. Several years ago Hatch discovered a nesting colony of Black-legged Kittiwakes, a species of small gull, had taken over an abandoned radar tower on the island, and he set up an observation and banding station on the tower which allowed close, eye level observation of the kittiwakes’ home life. His goal was to find out why Middleton’s kittiwakes were such notoriously poor breeders, sometimes producing zero young for an entire nesting season.

Hatch’s interest was piqued by a decades old study of the same species in England where the birds are prolific breeders with ten year lifespans. He speculated his kittiwakes had much longer lifespans or their population would have long since died out. His initial research did indeed show that Middleton’s kittiwakes had a twenty year lifespan. Hatch figured that diet was playing some part in the mystery, so he then began offering some of the nesting gulls all the fish they could eat, considerably more than they were catching by themselves. The better fed gulls immediately began producing many more chicks, but preliminary figures show their adult survival rate has begun to drop.

These are two well documented phenomena in nature: if food supplies decrease, populations drop; and long-lived species have fewer offspring. Think about elephants and rabbits. The former live forever but produce few young. The latter are prolific but have short lives. The punchline in Hatch’s study, though, is that the Black-legged Kittiwakes are the first species documented showing flexibility in survival strategy. Atlantic and Pacific populations had evolved very different strategies, but both were thriving. The Middleton Island research implies that species can and do adapt to environmental change.

Here’s how Hatch sums up his study project--"Many wildlife populations may operate like this. And so, let's factor that into our thinking, rather than throwing up our hands and assuming all is lost. It could be that populations will adapt in ways they've already demonstrated they're capable of doing, in ways that are a little more palatable than going through the floor when we bugger their food supply."

Feel better? October is right around the corner and global warming issues, not to be dismissed, may not be as dire as the doomsayers predict.