By Kevin Hong, Wild Oakland Intern
Kevin the intern here!
At 2 PM on Saturday, December 8th, we met at the Rotary Nature Center for a bird identification walk led by Ron Felzer, an instructor at Merritt College. He started off by talking briefly about the lake, which has been a wildlife refuge for over a hundred years (being the first wildlife refuge in the US) and so cherished by the people of Oakland that they voted to raise taxes – during the Great Depression – for its maintenance. By 2:10 there was a pretty large turnout, so we went straight to the birds!
We saw mostly the same birds as in the last identification walk: mallards and gulls, cormorants, night herons, cormorants, coots, scaups, many kinds of grebes, canvasbacks, goldeneyes, buffleheads, and ruddy ducks. We also caught glimpses of a great egret and a pair of white pelicans. Ron said that a tufted duck (rare ‘round these parts) has been visiting Lake Merritt every year for winter for a while (though it hasn’t been banded so we can’t actually tell if it’s the same duck); but we didn’t see it this time.
Ron, who has birded on every continent except Antarctica, had a lot of knowledge to share about practically all of these birds! He classified them into two kinds: diving birds and dabbling birds. Diving birds (like scaups, cormorants, coots, goldeneyes, buffleheads, and grebes) dive for food, while dabbling birds (like mallards) sort of just dip headfirst into the water to feed near the surface. Diving birds typically have legs located closer to the posterior than do dabbling birds, whose legs are closer to the centers of their bodies. This makes it harder for diving birds to walk on land, so they spend more time away from it.
Ron also explained sexual dimorphism in birds to us. Sexual dimorphism is the name for males and females taking different appearances in the same species. Mallards are a common species that exhibit this. Males attract the more drab females with their colorful plumage. The adaptive value of this can be found in the roles the different genders play in reproduction. Females must be more selective of the males they mate with, as they invest more energy and time into the matter of bearing and raising young. As a result, the males must compete for females’ attention. In addition, the females’ colors make her less conspicuous to predators as she gathers material for her nest.
Some bird profiles Ron shared with us:
Coots! They look pretty different from other waterfowl. They’re part of the rail family so they don’t have webbed feet, and they’re good at walking on land AND diving! Consequentially, they can be called wetland birds, and we see them more than other birds occupying the mudflats exposed by the leaving tide. They’re vegetarians.
Scaups! There’s barely a difference between the greater and lesser scaup. The head of the greater is slightly rounded, and has a green tint; whereas the head of the lesser is higher and has a purple tint. They’re pretty recognizable by their gray-white bodies tipped with a black tail and black anterior (and their mohawks). They go closer inland to rest, and they feed on mussels and other mollusks.
Cormorants! You’ll see mostly the Double-crested species around the Lake. Because they lack preen oil, they dive faster and swim better than other birds; however, this means they lack waterproof coating. They can be seen on the booms around the lake, sunning and drying out their wings. Fun fact: cormorants live in colonies, usually all confined to one or two trees. The host trees eventually die of nitrogen excess poisoning because all the cormorants poop on the trees.
We finished off near the pergola on the northeast side of the lake, looking out on bunches of floating grebes. Ron recommended we join him for his field class he’ll be teaching about the natural history and ecology of Owyhee River- check out our blog post from Dec 16, 2012 for more information.
Thanks for coming, and we’ll see you soon!