A cruise on the Delta

Five rivers feed into the 200,000+ acres of wetlands that make up the second largest river delta system in the U.S. just north of Mobile Bay in southern Alabama. The Mobile-Tensaw delta’s expanse of swamp, bog, natural rice paddies, canals, and rivers makes this area of Alabama a real biodiversity hotspot where you can find more species of fish, turtles, snails, crayfish, and oak trees than anywhere else in North America. Harvard ecologist E.O. Wilson has called it North America’s Amazon, and so it was a real treat to venture out on a small boat to explore some of the smaller waterways of the delta for ourselves.

Wild rice and Phragmites reeds grow along the edges of the river, almost closing off the small waterways in the labyrinth of corridors throughout the delta.
A variety of snails colonize the floating vegetation in the swampy bogs.
Clumps of rice seed fell into the bottom of the boat as we passed through narrow canals. A Yellow Warbler might not be interested in the seed, but there are plenty of insects in this vegetation.
We must look carefully on the river banks before stepping out of the boat — there are plenty of alligators in the delta waters.
Cruising up the Tensaw river we entered a cypress swamp where the trees grow right in the water, completely independent of any land surface.
Cypress forests are a haven for all kinds of birds — small migratory warblers as well as large waders like a Great Blue Heron.
In the Spring, these waterways are lined with brilliant flowers.
Spanish moss hangs from the Cypress’ lower branches, and odd vertical stumps arise from the tree’s roots. Their function is not certain, but they might assist in collecting more sediment to buttress the tree roots in the soft, muddy river bottom.
Honeybee nests can be found where large branches have broken away from the trunk. This is a “honey” tree.
Not only is there great diversity of vertebrate animals in the delta, but there are hundreds of species of insects as well. And some are really big — like the praying mantis..
and this 4-inch lubber grasshopper (which is not fully mature yet).

The southeastern U.S., and the Mobile delta in particular, was a refuge for species driven south during the ice ages of the Pleistocene glaciation. Warm temperatures year-round and plenty of rainfall (averaging 70 inches per year) ensure the most equitable conditions for life to survive, and so it has in this cradle of biodiversity.

Early bird catches “worm”

A little Spotted Sandpiper had the entire beach of Vadnais reservoir to itself and moved slowly along the shoreline probing now and then in the mud and under leaves as I stood quietly and watched.

It’s a rather plain looking, medium-sized, chunky-bodied shorebird, missing the spots for which it is named in its winter or juvenile plumage (can’t tell which). But the bird is instantly recognizable as it bobs its tail up and down as it walks, earning it the nickname of “teeter-bob” or “teeter-peep”.
Here and there, the bird probes its bill part way into the mud testing for the presence of buried larvae.
I’m not sure what this behavior is — did the bird hear something, or see something and tilted its head to localize the cue? Spotted Sandpipers hunt primarily by sight, looking for insects or crustaceans in the debris along muddy shores, but they also probe likely looking nooks and crannies where invertebrates may be hiding.
The bird has found something here — it takes a couple of minutes of probing up and down to extract it.
It pulls some yellow and black-striped “worm” from the muddy substrate. The prey might be the larva of a large stone fly or caddisfly.
It looks tantalizing (to a sandpiper) — why not gobble it up?
Nope, have to wash it off — thoroughly! Two or three dunks and swishes should do it.
Now, it’s edible.

Spotted Sandpipers are likely the most widespread breeding sandpiper in North America, nesting from northern most Alaska to the mid-continental U.S. along rivers, lakes, and streams.

And their breeding system is particularly interesting because they exhibit a sex role reversal compared to most other bird species. Instead of the typical female role of incubation and hatchling care, Spotted Sandpiper females “collect” multiple males, laying a clutch of eggs in each male’s nest, which he will then incubate. After they hatch, the male is in charge of protecting and providing food for the chicks, while the female goes off to find another male to mate with.

Female Spotted Sandpipers arrive first on the breeding ground, establish their territory, and then compete with each other for males to mate with. Since females can store sperm from multiple matings for up to a month, the male may be incubating and tending to chicks that are not his offspring! This breeding strategy, called polyandry, is rare among birds but is found in several shorebird species, in Northern Jacanas, occasionally in Acorn Woodpeckers, and in Harris Hawks.

Fields of gold

Prairie parkland landscapes are at their peak golden color now. The fall landscape is transforming daily, and with the nice fall weather lately, it’s a glorious time to be out walking around. I’ve given up trying to find the migrating birds at this points and am just enjoying the golden colors everywhere.

The prairie at Tamarack park in White Bear Lake looks golden with stems drying Big Blue Stem and Indian grass, as well as a healthy crop of Showy Goldenrod. Leaves of a few of the maples and ashes have begun to change color also.
There is a similar scene in the restored prairie at Reservoir Woods in St. Paul where the low vegetation is a solid mass of several species of Goldenrod, with a few purple and blue asters and the stems of Indian Grass mixed in.
Bright yellow plumes of Showy Goldenrod rise above the rest of the vegetation in this landscape. And the flowers are a major attraction for honeybees and bumblebees by the dozens.
I don’t think I’ve seen this many honeybees in a native landscape for quite some time. Goldenrod and Asters are the late blooming plants in the fall that bees depend on to stock their larders with pollen over the winter.
Stiff Goldenrod with its erect, rigid stems and fat, almost succulent looking leaves is also in full flower not, but is not nearly as attractive to the bees as the Showy Goldenrod.
Stiff Goldenrod flowers seem larger and more attractive to my eyes, but not to the bees.
Canada Goldenrod has already bloomed and is putting out seeds that the migrating sparrows and finches will appreciate.
Earlier in the fall the American Goldfinches began harvesting the seedheads of the Meadow Blazingstar and led their newly fledged offspring over to the seedheads of the Canada Goldenrod.
What new things will I see on tomorrow’s walk?

it’s feeling fallish

We spent a beautiful morning walking along the St. Croix river at Afton State Park recently, and I noticed that it seems more like fall weather now, and a lot less like summer. What a difference a couple of weeks makes in the climate here.

The beach along the Minnesota side of the St. Croix river is deserted…just the way I like it. There are a few warblers around, geese are flocking up in preparation for migration, and the last of the summer wildflowers are holding onto their blooms, just a little longer.
A somewhat bedraggled Great Spangled Fritillary was foraging on the Sneezeweed flowers — just about the only wildflowers left along this shoreline of the river. This is one of the largest, and longest lived butterflies here in MN. It mates in June but doesn’t lay eggs until August and September, somewhere near a patch of violets, on which its larvae will feed in the spring.
Cedar Waxwings were acting like flycatchers as they perched and then sallied out to catch whatever insects were flying by their perch.
And the ever-present and numerous Canada Geese are now gathering in large flocks to prepare for migration. Here they come downriver right at us…
They fly so closely together you would think their wings would get in the way of each other. In fact, so close that two birds on the right side of the photo look like one bird with four wings!
Nothing symbolizes fall in Minnesota like these flights of Canada Geese.
Fall may be my favorite season, even though it leads into my most dreaded season of bitter winter. But I love the fall weather and color as the landscape begins to glow.

Blooms in the backyard

In the Minnesota backyard, some of the summer blooms are in their full glory, particularly the purple coneflower. Butterflies and bees are drawn to these flowers…

A Great Spangled Fritillary stopped by…
And examined each of the disk flowers in the flower head intensively.
I caught the approach of one of the honeybees buzzing the coneflowers.
And was able to zero in on the bee when it landed.
Even the Goldfinches were checking on the flower heads, I suppose to see if they had made any seed yet. But these flowers have just opened up in the last few days.

A hike in a Sierra meadow

There are lots of trails to explore in the Lake Tahoe basin, and we took the grandkids on a “walk” from their cabin on Fallen Leaf lake all the way to a swimming beach on Lake Tahoe — an almost 7 mile hike. Naturally, there were a number of stops to rest and swim at places along the way, and there was a promise of ice cream at the end of the hike, and that’s all it took to get the kids there.

The water of Fallen Leaf lake is as clear as that of Lake Tahoe, but right now the water near shore is more of a greenish color due to all the pine pollen accumulating there. If the glaciers that created it had continued to carve their path from the Glen Alpine valley, this lake would simply be a bay of Lake Tahoe.
The trail along the east side of the lake wanders through countless meadows and stands of Jeffrey pine (the one that has a scent of vanilla wafting from the cracks in its bark). The tall meadow lupine was in full bloom.
Another blue-purple flower that I thought was forget-me-not turned out to be Pacific Hound’s Tongue, so named for the shape of its basal leaves that resemble a dog’s tongue. The flowers were loaded with small Two-banded Checkered Skipper butterflies feasting on nectar.
Juncos are already far along in their nesting cycle, feeding their rapidly growing chicks.
A Red-breasted Sapsucker checked us out as we walked under him on our trek by the salmon run on Taylor Creek. I wonder if this is the same bird we saw here in April at this spot?
White-headed Woodpeckers are somewhat common in the pine forest here in the Tahoe basin. This female was feeding chicks in the nest (on her left) and not at all shy about us walking near her.

Flowers of the desert

Although we have been a little early in some places and a little late in others, we still have seen some of the spring wildflower show as we travel.

One of the most exotic flowers we saw were on this claret cup cactus, actually an endangered species found only at the intersection of Arizona, New Mexico, and Mexico — which is exactly where we were when we saw it. The plant puts out brilliant scarlet flowers on cylindrical stems that mound together into a cactus clump.
The color of the flowers suggests it might be pollinated by hummingbirds, although the shape of the flower is wrong. However, the “flower” is actually the outer sepals and petals combined, and the nectar reward for the hummingbird pollinators is in the central chamber surrounded by hundreds of thready stamens.
Cylindrical flowers of the Ocotillo are the more typical hummingbird floral type, but a number of other birds enjoy these flowers for their nectar, as well as the insects they attract.
Why bother probing into the flower for nectar when you can just rip the flower off the stem and eat the whole thing, as this male Pyrrhuloxia is doing?
Looking for insects on unopened Ocotillo buds? A male Gila Woodpecker might enjoy both a nectar and an insect reward from these flowers.
A female Rufous Hummingbird foraged on a bunch of Penstemon flowers in the early morning at Cave Creek ranch in Portal Arizona.
A Clear-wing Moth and Pygmy Blue butterfly foraged on the bush lupine right outside our room at Cave Creek ranch in Portal Arizona. This plant had so many flowers and apparently so much nectar, it was constantly moving with the all the butterflies and bees swarming on it.
The Southern California deserts didn’t receive enough rain this year to produce much of a wildflower show, but the Desert Agave still bloomed here, along with many Ocotillo plants, giving this desert in Anza Borrego State Park some color. The Agave plants only send up one flower spike in their lifetime, as tall as the plant’s energy resources will allow, to attract bats to pollinate them.

the termite feast

The winged phase of termites were swarming last week in several places we hiked. And the local insectivorous birds were cashing in on some easy meals. One particular termite feast featured more than a dozen Little Bushtits, Chestnut-backed Chickadees, a Hermit Thrush, California Towhees, and a rare Townsend’s Warbler, all flitting about catching termites in the air or just emerging from a ground nest.

Winged phase termites emerging for their mating flight might get gobbled up by insectivores perched nearby. They emerge in swarms, but are rather clumsy, slow fliers, so they are easy to pick up.
A Chestnut-backed Chickadee was watching from a tree while Bushtits darted out from the bushes below it.
One of many Common Bushtits foraging on the termites. They flew right up to us, close enough to touch as they grabbed termites flying around us. The white iris means this is a female.
Adult male (or juvenile) on the left and female bushtit posed together briefly before darting out to catch termites flying by. Bushtits are highly gregarious even when foraging, and will line up on a branch sitting right next to each other when they are roosting. They only weigh about 5 grams, less than half of a chickadee’s weight, so their little bodies cool off quickly. Even on a warm day, they puff up their feathers so they look like little puff-balls.
A Hermit Thrush peeked out from the underbrush but wasn’t brave enough to approach the source of the termite emergence near where we were standing.

But another bird was completely unperturbed by our presence, and amazingly, hopped right in front of us to grab termites off the ground.

If it had not been for the termite explosion in the Bay Area the past couple of weeks, I’m not sure we would ever have seen this handsome Townsend’s Warbler, which normally hangs out in the tops of coniferous trees in coastal forests. I don’t think ground feeding is something it does often.
But when you’re hungry and on migration from the northwestern U.S. and western Canada to southern coastal and central Mexico montane forests, you capitalize on easy prey when it is available. This little male moved around on the ground right in front of us, grabbing bites of termites as they emerged from a hole in the ground.
Completely out of its usual habitat of cool coniferous forests, Townsend’s Warbler brief appearance in the scrub vegetation in an urban creek area was a real treat for us.

Fall reminiscence

After four days of the white stuff raining down on us, I need a shot of color from the brilliant hues of this past Fall season.  

Late in the summer and early fall, the dominant color in the prairie garden changes to yellow as several species of Goldenrod bloom. The yellow blooms and rust-brown grasses of this prairie are accented by the flowers of several aster species in shades of blue to purple.
Here is a feast of nectar and pollen for bees, and the flowers blooming this late in the summer and fall have their undivided attention.
Five-foot tall Maximillion sunflowers are just one of many sunflower species that bloom in the fall.
A New England Aster blooming along the sidewalk to my front door was a magnet for bumblebees, honeybees, and at least two species of syrphid (hover) flies.

One way to ensure seed set in a plant is to capture as many pollinators as possible, and this seems to be the strategy influencing the flowering times of Goldenrod and Aster species. By blooming so late in the summer and early fall, they are pretty much the only pollen and nectar sources around.

And to ensure that bees do visit their copious numbers of flowers, the plants need to advertise themselves with the colors that are most attractive to bee eyes — yellow-green and blue-purple. Bees also key in on light that is a combination of yellow and ultra-violet, something humans can’t detect, but probably marks landing platforms or serves as nectar guides on flowers.

Summer’s brilliant colors fade in the fall as the landscape transforms. It will be another 8-10 months before I can enjoy scenes like this again.

Hovering specialists in the backyard

A wide variety of animals can fly (more than just birds, butterflies, bees, or bats), and among those flyers, a select few can perform aerial acrobatics, like hovering — suspended in space, defying gravity in the process.

A few of those hovering specialists passed through the backyard this summer, and I attempted to capture their effort one wingbeat at a time.  And this is by no means easy when the subject a) darts from one hovering location to another in a millisecond (the hummingbird and the dragonfly) and b) is so small it’s difficult to focus on it (the dragonfly and the hoverfly).  The video clips below illustrate the difficulty.

A Ruby-throated Hummingbird in a sea of red Cardinal flower, delicately moving from blossom to blossom while beating its wings 80 times a sec.  I could stop the wing motion of this bird with the camera shutter speed at 1/2000 of a second.

Hummers move their wings in a figure-eight pattern, rather like the sculling motion of the hands of water ballet performers make to keep them static in a column of water. Forward and backward movement of the wings cancel horizontal movement, and the lift provided by the figure-eight motion keeps them suspended vertically.

A stocky bee mimic, the drone fly (Eristalis tenax) took up territorial residence outside my backdoor, hovering near the peonies in May.  One of the most widely distributed species in the world, drone flies maintain small territories near flower beds to attract females, occasionally darting out to chase off intruders.

Freezing the drone fly wing beat in time required the fastest shutter speed on my camera dial (1/8000 of a sec).  Two tiny wings propel the fly forward, backward, or keep it motionless in space, moving faster than the eye can see them — sort of like a helicopter rotor.

Dragonflies hover with two sets of wings, i.e., four moving blades swooping independently through the air.  Normally, dragonflies dart along the shores of ponds and streams, moving quickly from spot to spot, but occasionally they pause in their patrol efforts to hover over particular spots they are defending or to advertise their presence to females.

The 4-spotted Skimmer hovered almost motionless in space in front of me as I tried to focus on its abdomen.  Although the wings look synchronized in this view, front and back pairs move independently, as illustrated in the video below.  The wingbeats flutter in a blur to the human eye, but they beat at a much slower rate than those of hummingbirds or drone flies, and I was able to capture static shots at 1/1000 of a second.

It’s a most impressive feat of flying that is demonstrated by these animals, and one that has been copied by human engineers seeking to copy vertical take-offs and hovering efficiency in aircraft.