mjm@oliven.ATC.Olivetti.Com (Michael Mammoser) (04/27/91)
They travelled northward in the comforting cover of darkness. They wouldn't have it any other way. They differed in appearance and points of origin, with no seeming kinship, except the urge to travel. They may have been travelling alone or, meeting up with some of the others, formed into groups. They all had one thing in common, though. When the rains hit, they all took shelter in the same stretch of trees along the creek. The storm continued through the night, finally moving on before daybreak; too late for them to take up the journey again. They were stuck here for the day. When a couple of friends and I arrived at Coyote Creek, at the south end of San Francisco Bay, to do a bird census for the local biomonitoring research station, we knew that it had rained the previous night. However, this elicited no response other than a mild concern for how bad the mud would be on the drive in. A cloud of mosquitoes greeted us at the start and the census was underway, amid a frenzy of head shaking, blowing, and hand waving. Orange Crowned and Wilson's Warblers were singing, while Yellow Rumped Warblers foraged through the treetops. It was nice to see the bright breeding plumage of the male Yellow Rumpeds, both Audubon's and Myrtle. The thin, high "suwheet" calls coming from the thick foliage told us that Pacific Slope Flycatchers were around, though we wouldn't see one until a little later. Moving down the creek, we heard a Yellow Warbler singing but couldn't find it in the optics. Common Yellowthroats "chipped" and sang from the undergrowth. A few crowned sparrows and Fox Sparrows were still around, as well as a Lincoln's Sparrow. So far everything was pretty normal and expected, but things were destined to get more exciting. As we approached one of the mist net lanes where a hummingbird feeder was hanging, we were hoping to see one of the local Black Chinned Hummingbirds using it. Instead, a small bird up in the trees attracted our attention. It was a Nashville Warbler, a good bird for this location. Then a little later we found another, and another. We tracked down a buzzy song coming from the trees to its source; a Black Throated Gray Warbler. These warblers breed at the higher elevations in the hills, but are only migrants down here at bayside. While watching a Black Throated Gray, a female Hermit Warbler flew into the tree in front of us at eye level, foraging at close range for three or four minutes. No sooner had we finished watching this beautiful bird when a McGillivray's Warbler popped up out of the dense undergrowth, fluttering about low to the ground, plucking insects off of the leaves. Then a close up view of an empidonax flycaycher led me to believe that it was a Hammond's. Rounding out this list of migrants was a singing White Throated Sparrow. All of these birds were found in a stretch of riparian habitat along the creek that was a couple of hundred meters long. Although this day may not compare with a Texas coast "fallout" or the sheer numbers of warbler species in the east, we did see nine species of warbler out of the eleven that might normally be expected on the west coast. This was the first real "migrant wave" that I have observed out here and, keeping an eye on the weather reports, I hope to see many more. Mike