Monday, February 22, 2010
10:08 PM | Posted by Sweep Commander | Edit Post
'WEGU' is bird nerd speak for western gull.
Here's your Alactraz birding update:
- For a number of weeks now, an injured juvenile western gull has been living on the west side of the island, hobbling about near the old prison incinerator. When I first observed the individual, I thought he or she would surely starve or be killed by an angry adult, tired of the endless begging for food. Somehow the bird has endured and because of this very good fortune displayed the enfeebled gull, I've decided to name it 'Lucky'.
- Fellow western gulls respond to Lucky in the same way that the typical city dweller responds to a homeless person aggressively trying to hock copies of The Street Spirit. As he/she whines hoarsely and desperately pecks at their lower mandibles in an attempt to force them to regurgitate food, the mature birds shift their gaze, looking to the side or at the soil as they go about their business or walk fleetly away. They avoid looking Lucky in the eye as they evade or ignore.
- Curiously, the other western gulls almost never show an interest in harming Lucky. Once, I did see a gull try to deter Lucky's begging with violence, but another adult gull intervened, apparently to help the poor WEGU. I don't know whether the gull who intervened to aid Lucky was of any relation to him or her, but on the whole it struck me as a strange behavior for any western gull to display. These are not compassionate creatures.
- Several pairs of mallards have arrived on the island and from our observations over the last several days, these are some very sleepy ducks.
- The male falcon could be seen darting, diving and weaving inside a hostile mob of western gulls at around 4:30 this afternoon. Eventually it squirmed away and perched on the lighthouse.
- The female falcon has adopted a fairly predictable daily routine. More mornings than not, she perches on the water tower's railings facing west. When afternoon comes around, she moves to the other side and faces east. This may indicate a preference to face away from the sun, perhaps because direct sunlight interferes with her ability to perceive her surroundings or assess her prey.
Click on the image for a larger size
- After speaking with a number of former Alcatraz bird biologists, I've learned that falcons have been spotted on the island with regularity going back to the early 2000s, and perhaps earlier. As far as I can tell, however, it was assumed that any sighting was of an individual belonging to a known and established local pair, such as the pair that nest on the bay bridge. This year is unique because we've observed that we do indeed have a pair and we've seen them with enough brute regularity to surmise that they spend the vast majority of their time on Alcatraz.
Click on the image for a larger size
- I saw the pair flying together recently in high wind, performing yet more joint aerial acrobatics, spinning circles around each other, dive bombing one another and just doing a whole lot of what I'm assuming was falcon flirting. When one falcon disappeared, the other soared over a pair of gulls and aggressively fell towards one with talons extended. Gulls are not the fools of the sky, however, and this one simply executed an evasive falling maneuver of its own. The falcon then proceeded to approach the other gull in the same way with the same result.
- An adult western gull is probably a bit big for a peregrine to make a serious attempt to predate it. Rather, the falcon was probably feeling a bit feisty from all the courtship and hey, you've gotta direct that energy somewhere.
- Two western gulls aggressively chased a brown pelican over Alcatraz today, perhaps in an attempt to force it to give up its catch of fish. This behavior is called kleptoparasitism.
- Mourning doves and American crows have been spotted on the island in the last week.
That's it for today.
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- ▼ February (12)