There will be a hiatus tomorrow as the photo tanks is dangerously low. But today we have photos from central California by UC Davis ecologist Susan Harrison. Her narrative and IDs are indented, and you can enlarge the photos by clicking on them.
Lake Berryessa and its Ospreys
The easternmost valley of Napa County is covered by Lake Berryessa, a reservoir that sends water to the burgeoning ‘burbs and Budweiser brewery of Solano County. The dam was built by the Army Corps in 1957 over bitter protests by the valley’s farmers, ranchers, and other residents who called their then-home an agrarian paradise. The valley’s demise was hauntingly chronicled by famous midcentury photographer Dorothea Lange.
(Oh well – giant vineyards would probably have been the valley’s modern fate, elsewise.)
Lake Berryessa:
The dam lies at a narrow gorge called Devils Gate, formed by – guess what – an earthquake fault. “If you want to find a fault, look for a dam,” once quipped late UC Davis geologist Eldridge Moores. If the Monticello Fault ever lets rip, the towns of Winters, Dixon and Davis would be inundated as shown in this simulation.
Devils Gate and Monticello Dam:
Because the canyon was too narrow for a conventional spillway, the dam has a huge vertical drain known to all as the Glory Hole, which is quite a dramatic sight when water spills into it. A Double-Crested Cormorant (Nannopterum auritum) was once filmed swimming into the Glory Hole; it emerged unscathed at the dam’s base 200 feet below!
The Glory Hole:
Lake Berryessa made national news in 1969 as the scene of a Zodiac killing, and in 2020 when California’s wildfire “Year from Hell” was epitomized by incinerating homes and habitats around the lake (no-one was hurt, thankfully).
Fire devouring Berryessa Senior Center, courtesy New York Times:
But let us speak of happier things: Osprey nesting season! The lake has at least eight Osprey (Pandion haliaetus) nests ranged along its western shore. Some nests, but not all, are on the nesting platforms meant to keep birds away from power lines.
Ospreys incubate their eggs for 36-42 days and feed their 1-4 nestlings for another 50-55 days, per AllAboutBirds. That’s parental dedication!
Nesting Osprey:
Calling to their mates who are hunting nearby:
Giving a photographer the stink-eye:
Taking a wing stretch:
Beneath at least two Osprey nests, House Finches (Haemorhous mexicanus) were nesting. Are finches doing this only because big nests are a nice shelter, or also because Ospreys scare away medium-sized predators like Cooper’s Hawks (Accipiter cooperii)? Hummingbirds and other songbirds are known to nest in the comparatively safe neighborhood of large hawks’ nests.
House Finch at Osprey nest:
Besides year-round Ospreys, Lake Berryessa supports wintering Bald Eagles (Haliaeetus leucocephalus), American White Pelicans (Pelecanus erythrorhynchos), Western Grebes (Aechmophorus occidentalis) and Clark’s Grebes (Aechmophorus clarkii). Perhaps this abundance of large fish-eating birds is some compensation for Paradise Lost?