Wednesday, June 16, 2010
Nesting season update on Alcatraz's newest western gulls!
Let's start with some cuteness as this baby western gull falls over, then dances and twirls around like a tiny ballerina, enthusiastic for days but lacking of any physical coordination. Please don't write us to tell us you aren't touched. We can't take that very seriously:
At any rate, here's what we're up to in the coming week: a set of posts, one each on the island's larger breeding birds. Today, it's the avian face of the island, the western gull.
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Ahhh, nesting season... that lovely time of year when each utterance I hear of the word "baby" is less likely to conclude a mysoginistic quip than it is to refer to a fuzzy ball of serious cuteness... Oh, the novelty.
Our baby gulls have hatched en masse.
And some of them are very, very sleepy.
Their salt-and-peppery down, however, doesn't protect them from the predatory animals that see ample opportunity in their helplessness. Often, the worst enemy of a western gull chick is an adult gull that is not their parent. These birds kill and eat the young of their own species, usually whole and head first, and they often vomit up a pellet of bones and the remains of downy fibers. Fun.
The raven pair and its current brood will also predate gull chicks and eggs. Recently, Maganrord took a video of our juvenile raven consuming a WEGU chick (the video is available two posts prior).
Yesterday, we observed a dangerous game of cat and mouse between two large gulls, their young and two large ravens. More on that in an upcoming post.
Today, I found what is very likely the dried, regurgitated head of an unfortunate western gull chick. We'll post pictures of that soon. Today's post is about the appreciation of live baby gulls, available for viewing now but for a very limited time:
They just get uglier from here. Stay tuned to Maganrord for full coverage of that process, including a special post on a baby western gull from last summer, affectionately referred to as "runty", for whom BourbonHawk has uncharacteristically expressed an undying love.
Focusing back upon cuteness, here's one little fluffball stretching its little wings and then running too fast and falling over...:
The feeding process: western gull beaks have what nerds call a "red subterminal dot". It's a bit of red pigment near the end of a gull's beak. The chicks instinctively poke at it and somehow, the adult gull regurgitates the contents of its stomach, providing food for its young:
Studies have found that large gull chicks will instinctively peck at any red dot, no matter what bears it.
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Although we find gull parenting absolutely abhorrent, due to rampant cannibalism and infanticide, there is one aspect of good parenting at which humans largely fail but at which gulls positively excel: providing nutrition to their young:
One study, performed locally on Alcatraz western gulls, found that the diet of our local WEGUs consists almost entirely of salvaged garbage (surprise!), more than 90% of which is some form of discarded chicken.
But when their eggs hatch, the diet changes. The junk food is absolutely forbidden and fresh fish from the bay is the only acceptable food item. Here is Maganrord's tiny contribution to the body of evidence:
Why don't human beings take the birth of their children as a cue to embrace what is healthy and sustainable? McDonald's advertising may have us all figured out, but you'll never convince a WEGU to feed its baby a French fry, let alone a double cheeseburger or a sausage breakfast burrito from the dollar menu:
Sorry, human parents: In one important way, infanticidal, trash eating gulls are better parents than you are.
To close, here's a video of a baby WEGU that surprised me on the west side of the island:
It hung out, peeped, scratched its face and wandered into the bush. What more do I want from a baby WEGU around hatching time?
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As a postscript, I would only add that the anecdotal evidence from employees working on Alcatraz for both the National Park Service and the Golden Gate National Parks Conservancy has been that there are fewer WEGU nests in view and fewer large broods than in years past. Instead of three and four chicks per nest, we've been seeing one, two and only sometimes three.
This year, we've had massive construction projects as well as aggressive management of gulls in areas accessible to island visitors, which may be contributing to these observations.
At the end of the summer, we'll ask our professional biologists what happened this year, and how normal 2010 was for WEGU breeding on Alcatraz.
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