Civilization exists by geological consent, subject to change without notice. Will Durant

A week late and so it goes.

As autumn deepens, my walk home is coinciding with sunset.

I had a little post about gulls published on Jerry Coyne’s blog today: Reader’s Wildlife Photos

With fall migration underway, many species of birds are passing down the Pacific flyway to winter further south – some as far as Central or even South America.

It struck me earlier this week how poor my knowledge of both Central and South America is, so I spent a little time studying their geography. Political borders aside, what I really wanted to learn about were the ecoregions… the ecosystems that support these birds.

I also couldn’t help going back in time – deep time and evolutionary biology are two intertwined obsessions of mine – to learn more about the Great American Biotic Interchange.