Towhee and Frazil

Cold and snow chill Yosemite. We had frazil ice in Yosemite, Sentinel and Ribbon Creeks yesterday morning; a bit late in the season, but not unheard of. The Merced River has dropped just below the average flow rate for mid-May; it has been running at above-average volume since the big storms got started in November. Though average, the falls are still big, but they'll get bigger, and they'll still look good in July. Fire season gets delayed, though the moisture likely means more growth of small fuels like grasses.
A highlight on yesteday's birdwalk was seeing Superintendent Don Neubacher dash out of his office with binoculars in hand to stalk a seldom-seen green-tailed towhee outside the Administration building. He was accompanied by ace ranger-naturalist Karen Amstutz who spotted the unusual bird out her window and had the inspiration to pull the park's boss (a dedicated birder) away from his desk to see the towhee. I'm glad to know that our park is being looked after by such people. My group was surprised to see a second green-tailed towhee a short time later near Yosemite Creek.
Ranger JT reports snowplant emerging near Sentinel Bridge. I've seen a couple in the west end of the Valley, too. Along with new birds and plants, it's exciting to see the seasonal increase in park staffing as more interpretive rangers return to duty or start their first summer as seasonal rangers. Park visitors are lucky to have all these people leading walks and campfire programs, answering questions in the visitor centers, conducting tram tours and cultivating another 24,000+ Junior Rangers.
There is still room in the Yosemite Conservancy's 3-day "White Wolf Botany" course in early July. This is going to be some terrific field time for casual botanists in a special part of the park. We also have space for people to join us for the two "Family Camping Jamborees" in late-July in Tuolumne Meadows.

Warm then Storm

Last weekend's overcast and rain caused the Merced volume (and the tributary waterfalls) to drop back down to near average flow. One might think that rain would raise the river level, but, in fact, the cloud cover and cooler temperatures reduce the snow melting rate much more than a bit of rain can increase the runoff. Warm sun brought the flows up again through the week. Again this weekend we expect a cool storm to bring a bit of rain (and snow -which, of course, reduces the near-term runoff much more than rain does), so the waterfalls will be smaller at the start of next week than they are now.
On most days, the river (and tributary) volume exhibits a nice 24-hour cycle of rise and fall. The hottest part of the day is when the most snow melts up at 7-13,000'; this surge of melt doesn't reach the two Yosemite Valley river gauges until many hours later. It's odd that our highest water flows in the Valley happen after midnight - about 12 hours after the hottest part of the day. That's the lag time for high country runoff to make it down to 4000'.
It was cold enough in the Valley this past Tuesday morning (9 May) for people to observe frazil ice in Yosemite Creek and in Ribbon Creek. A deposit outside the eastern channel at Ribbon Creek persisted into the next day, looking like an anomalous patch of snow.
NPS road crews have reached Glacier Point, and they've reached the White Wolf area on Tioga Road, through average snow depths of 8' and 10' respectively.
The bizarre red snowplant is emerging from the ground in Yosemite Valley. Bracken fern is tall and unfolding its fiddlehead fronds. Dogwoods are fully alight now. Western Wood Pewees arrived this week in the Valley. The concentrations of yellow-rumped warblers and some other birds have dispersed from the Valley to higher elevations a bit. I've been seeing 1-2 bears a week in the Valley, more than has been my usual experience.
If you're up early and have a good eastern view, check out the concentration of planets in the east before dawn.

The burst of spring

I encountered my first Western Tanager of the year on Monday's Conservancy bird walk - just moments after a participant asked about them. It was a stunning, bright male in the black oaks in front of the visitor center - lots of exclamations from all present. Since then, more males have arrived and are singing in Yosemite Valley. This morning we had the triple feature of the bright neo-tropicals when within a short time we also saw the male Black-headed Grosbeak and Bullock's Oriole. Surprises on Monday were the Lark Sparrow feeding on the gravel trail along Cook's Meadow and the Western Kingbird sallying out from the black oak canopy over the meadow. This morning we had a decent look at Vaux's Swifts.
Those black oaks are pale green with dangling flowers now and a few leaves are starting to emerge. The early dogwood below the former diversion dam site, along 140 has 'blooms' almost 3 inches across which are almost fully white. Most Valley dogwoods are still pale green - they're more than a week behind an average spring schedule.
The Merced River has leapt in volume with the warm weather this week; it's doubled in volume in the past five days. This morning it had already exceeded the average springtime peak - and there are still a few weeks of potential increase to the average high flow date. Low-lying Valley trails are starting to get wet, but there's no real flooding yet. (Last year peak flow reached 2.5 times what it is now!)

Wild, Wild Life

Black-headed grosbeaks are now singing in the Valley, there were more orioles on Thursday's birdwalk, and several dozen yellow-rumps encountered in 3 flocks -a tiny portion of them singing. Three Vaux's swifts patrolled over the Valley Visitor Center. Hummingbirds are doing display flights. About a month ago NPS volunteer interpreter Kirsten discovered a rare Virginia Rail near the boardwalk in Cook's Meadow.
On the mammal side, a dark brown bear has been grazing the Ahwahnee Meadow area lately. Two rescue helicopters there on Tuesday night didn't disturb its feeding. Biologists researching our fisher populations are delighted to have encountered a mother with young, moving them from place to place in the south area of the park. Good news for predators and general food web health; bad news for mice and squirrels.
Road crews are grinding away at the extra-deep snow on both Glacier Point and Tioga Roads, slowly making progress to open up the high country for our cars. Tomorrow morning might be cold enough for frazil production, but then it warms up for the early part of the week. There is still a chance for big frazil flows for another few weeks; just because April's over doesn't mean that we won't have some sub-freezing nights in Yosemite Valley.

Slow spring

Too warm for frazil ice, too cool for rapid snowmelt, our recent unsettled weather continues this week with a bit of cloudy damp. The weather forecast leads us to anticipate no frazil ice this week.
Black oak leaves are not quite starting to burst out of buds yet, though they have lower down. Cottonwood flowers are out along the river. Insectivorous orioles are in the Valley now, ahead of most insect food. Redwings are singing in Cook's Meadow, mallards swim in pairs, yellow-rumped warblers sing a bit on sunny days.
Former Yosemite employee Paul Keel, back for a visit, added a new species to the park's birdlist: our first ever white-faced ibis. Paul is a state park ranger now, down on the coast, and he got good photos of the ibis in El Capitan Meadow. You never know what you'll come across, if you're paying attention.
This morning we watched a male belted kingfisher working the oxbow lake in Cook's Meadow. Fun to see a fish predator well away from the river channel.
More predators will be on display in the Conservancy's "Hawks and Owls" field seminar the first weekend of June. Park ornithologist Sarah Stock and great grey owl specialist Joe Medley (yes, the son of Steve Medley) are the two instructors. We are delighted to have these two knowledgeable experts (and charming individuals) teaching this fun program. There's still space available; free camping and free park entry are part of the package. Raptors rule the skies...

National Parks Week

I am back in Yosemite after two weeks away, and what changes there are. The free entrance to Yosemite for National Parks Week, combined with some school spring breaks has meant a busy week in the park. The natural scene is busy, too.
Snow is gone from the Valley floor except in a few shady spots. Waterfalls are bigger than average, with the recent warmth getting a start on melting off our exceptional snowpack. Cooks, Leidig, El Capitan, Stoneman, Ahwahnee and Slaughterhouse (lovely, I know) Meadows all have standing and/or running water in them now; some paths are blocked, but none of the main ones yet. Table Rock, our local visual river gauge for Valley commuters, is underwater.
Frazil ice forecast for this weekend: POOR.
Yellow-rumped warblers are at their brightest in the black oak canopies, where tiny pink leaves are barely starting to emerge in the Valley. Black-throated gray warblers are doing their excited, buzzy call in the live oaks in the Valley now, too. A great gray owl was reported on its nest up near Crane Flat, though there's so much snow there still, their food is out of reach and it's hard to imagine successful breeding at this point.
Our "Moonbow Photography" Outdoor Adventures course was a success on Sunday night, with a bright bow visible for a couple hours in-between overcast periods. Next up is Ken Rockwell and Dave Wyman's "Spring Light Photography" course, and then an excellent "Hawks and Owls" program the first weekend of June.
Our regular public birdwalk will be seeking John Muir's favorite bird tomorrow, Cinclus mexicanus. Thursday is his 173rd birthday. Friday is Earth's birthday; stand up for what you stand on, as they say.

Yosemite Recovered

The storm of 20-21 March goes into the record books as one of the most significant in decades: over 12 feet of snow at the 7-8000' level, and 9 inches of heavy snow that broke down thousands of live oaks and other trees at the 2000' level. Electricity was restored after 6 days, and visitation has now picked up.
We've had very warm weather the past few days. Bird activity has increased, flowers are on the rebound, and the Merced River has doubled in volume and is really turbid. The river has gone over 1500 cfs at Pohono Bridge, more than twice the average flow for this date. Sierra-wide snow surveys show 165% of normal water content in the snowpack; our local results come out shortly and will surely be comparably abundant.
We all look ahead to the waterfall season of the next 3 months, hoping that all this snow runs off over a long span of summer, rather than all at once. Photographers Ken Rockwell and Dave Wyman have timed their "Spring Light Photography" course to coincide with predicted high volume, 19-22 May.
We're also coming into peak frazil season this month. The frazil ice forecast is poor for the next few days, as temperatures are mild. But the warmth makes more mist, which will produce more frazil particles when the temperature does drop again.
I'll be away from the park the next two weeks.