Two weeks back brought the Fall Equinox, a surprising germinating rain, and the return of golden crowned sparrows. In such a short time, the season has shifted between summer and fall and all around us nature is transforming accordingly.
In case you don’t follow such things…a little about the significance of Fall Equinox. The first day of Fall was September 22, 2022. The very moment that the sun was shining directly above the Earth’s equator was at 6:04 pm that day. After that, the sun has moved south of the equator, and the days have become shorter than the nights. This week, daylight is shortening 2 minutes and 23 seconds each day. Here are sunrise and sunset times for Monday October 3rd through Wednesday October 6th, so you can see what’s going on:
|Monday 3rd||7:07 am||6:52 pm|
|Tuesday 4th||7:08 am||6:47 pm|
|Wednesday 5th||7:08 am||6:46 pm|
|Thursday 6th||7:09 am||6:44 pm|
That equinox week, an unusual storm brought much of our area enough rain to germinate annual grassland plants. Three-quarters to an inch of rain is all it takes to green up the grasslands. In the forest, redwood sorrel perked up, a newly lush green carpet under the towering redwoods. Curiously, I didn’t catch the ‘petrichor’ smell this round.
First Rains – What Next?
The shift to the rainy season demands attention. Our rainy season coincides with shorter days and a decline in average daily temperature. Cool, wet winters and hot, dry summers are what typify the rare Mediterranean climate regions like where we live. The wisdom of this area suggests that we must be prepared for the onset of stronger rains by October 15th, the average date of the first rainy storms.
Slow it Sink it Spread it
We prepare by making sure that things don’t runoff. “Slow it, sink it, spread it” is the rainfall mantra for our dry climate. Our job is to slow down rainfall so that it has time to infiltrate into the soil. We build raingardens to help sink the rain into the soil. Where we can’t sink it in small areas, we spread the flow out onto larger areas to give it more chance to slow and sink…and less chance to erode the precious soil which is impossible to replace, and which can pollute streams.
Rain isn’t the only thing that runs off with the advent of the rainy season: the first flush of rain carries with it a whole summer’s worth of accumulated pollution. The first flush, as the runoff from the first rainfall is called, is the most polluting runoff event of the year.
A Legacy of Runoff Monitoring, Disappearing
There used to be a program led by the Coastal Watershed Council that organized volunteers to sample the first flush runoff from municipal drainages from many cities around the Central Coast, including Santa Cruz. That ‘First Flush’ program gradually degraded and then apparently disappeared – one wonders if the very concerning data were the reason.
In the early years, the program actually sampled the first flush, but it later curiously shifted to sampling in summer months. What continued was something the group calls ‘Snapshot Day’ in early summer, after one would expect that rains had cleansed drainages and runoff declined; curiously, even that program found many areas of polluted runoff concern.
The First Flush monitoring program highlighted high concentrations of pollutants, especially phosphorous but also zinc and copper, which are toxic at the concentrations they documented. In 2003, the First Flush monitoring report suggested that all the sites had runoff that was toxic to mussels, the indicator species used to assess water quality. In subsequent years, that measure was excluded, and the reports became more and more difficult to interpret. Then, the program gradually declined in scope, and reports after 2016 are not in evidence on the Coastal Watershed Council’s website.
The Return of the Golden Crowned Sparrow
I have written another essay about golden crowned sparrows, but want to give you a synopsis and a few more interesting facts. I also hope that you will welcome the return of this species to your neighborhood. This species has a very distinct call that will help you to recognize them. I woke last Wednesday morning to the smell of fresh rain and to that distinct song. Flocks of golden crowned sparrows had returned to my yard! They had flown all the way from Alaska. Bruce Lyon at UCSC has shown that the birds have a good survival rate to return to the same shrub patches that they occupied the prior winter. I keep hoping that I can find the time to get to know the behavior and color patterns of enough of the 40 or so birds that flock around my house to recognize them when they return.
These sparrows are grazers, though when they arrive from their journey south they mainly eat seeds for a bit. Their grazing helps to create big barren areas at the edges of shrubs adjoining grasslands; the taller the adjoining bush, the farther out the bare patch extends. Golden crowned sparrows also graze my vegetable garden: soon, I will have to cover up anything they like, a drastic switch from the summer. I will guard my winter greens crop – kale, collards, chard, arugula, and lettuce – until early April when they depart.
For a while, I thought the golden crowned sparrows would leave at Spring Equinox just to keep things simple. After all, if they always arrive at Fall Equinox, why wouldn’t they leave at a similar time? I haven’t kept a good logbook of their departures, but I’ve been tricked several times when they stopped calling right around my house. It turned out that the flocks move out to graze the deep lush cover crops in the farm fields nearby before taking off for Alaska and British Columbia where they spend their summers.
Although we’ve had a germinating rain, we don’t know what the future holds…the past 2 years have had curious weather phenomena: rain followed by hot drought, grasslands drying out and then regreening. This year, there is a strong La Niña in effect – in recent years, this meant drought. The last two years had heavy duty heat waves right up to Thanksgiving when the first big rain occurred.
So, we may get some more time to prepare for the First Flush and the onset of the rains. Do what you can…create or maintain your raingardens – water them if you can to prepare them to filter runoff.
While the golden crowned sparrow friends are around, I hope you will say hi to them and appreciate their rainy season song.
Welcome the Fall!
-this post originally published by Bruce Bratton in his infomative BrattonOnline.com weekly blog: check it out!