May 2003 PRBO Riparian Songbird Study Post-fire Observations Along Wilson Creek

May 2, 2003
Sacha Heath
PRBO Conservation Science

PRBO’s field season began today in the Mono Basin. We have been conducting nest searches at Wilson Creek since 2000 and point counts since 1998, covering from the Power Station downstream to about 1 km below Cemetery Road. Several of our upstream point counts and one section of our nest plot were thoroughly burned in the fire of April 24, 2003. The nest plot section that was burned is near the fish hatchery and rearing area. Willows and grasses are burned (or cut during fire response) to the ground in about a 250m by 150m patch adjacent to the hatchery.

I found 5 active American Magpie nests on Wilson Creek this morning: 2 with eggs, 1 with 2 day young and 1 that just hatched today. 3 of these nests were in unburned willows within 50 – 200m of the northwestern edge of the burn. In the past 3 years, there has been a Magpie colony of about 9 nests in the area of the burn. I found 3 of them, so it is likely that at least 1 and possibly up to 6 active American Magpie nests were destroyed in the fire. Nests that now have young were first initiated around April 12 of this year. Our earliest first egg dates for American Magpies in 2002 was April 10.

Several other bird species were foraging in and around the burn area including American Robins, Song Sparrows, American Kestrels, Western Meadowlarks and Savannah Sparrows. A flock of about 30 American Pipits were foraging in the burned and blackened meadow. Flocks of Turkey Vultures, California Gulls, Snowy and Great Egrets were perched on Tufa and Willow around the fish hatchery. Presumably, these carrion eaters and opportunistic foragers were enjoying the benefits of the fish kill, although I did not observe any birds foraging on the dead fish. In past years, the burn area has supported nesting Song Sparrows, Red-shafted Flickers, Western Meadowlarks, Red-winged Blackbirds, Savannah Sparrows, Mourning Doves, a Long-eared Owl and a Common Yellowthroat – all which initiated their nests in mid May in past years, so it is unlikely that they had active nests at the time of the burn. The exception would be Red-shafted Flickers, which began nests as early as May 3rd last year, and could potentially have started earlier this year. Mallards also started nests as early as mid April in past years, but we have never found Mallard nests in the immediate area of the burn.