A Northwoods Almanac for 8/3 – 16, 2018 by John Bates
Spotted Coralroot (Corallorhiza maculate)
I led numerous trips in July into old-growth stands and two plants received the most oohs and aahs – spotted coralroot and Indian pipe. Spotted coralroot is an orchid, which is remarkable enough, but it’s also a “myco-heterotroph,” which means it lacks chlorophyll and gets its food by parasitizing the mycelium of fungi in the Russula family. The mycelium are the white thread-like perennial part of mushrooms that grow into a tree or into the ground – the mushrooms that we see above ground or on the bark of a tree are the fruits of the mycelium.
These fungi are mycorrhizal with trees, meaning their energy comes from photosynthesis of the tree passing through their mycelium. They in turn provide increased water uptake and soil nutrients to the tree. Then the coralroot latches on to the mycelium to get a free lunch.
All orchids are myco-heterotrophic at some point in their life cycle, so all orchid mycorrhizaehave a symbiotic relationship between their roots and various fungi. Orchid mycorrhizae are critically important during orchid germination, as an orchid seed has virtually no energy reserve and obtains its sugars and carbon from the fungus.
The rhizome and lower stem of coralroot are often knotted into branched coral-likeshapes, hence the name. Identifying a spotted coralroot is easy because the stem is usually red or brown in color and bears no leaves, while the intricate orchid flowers are white and spotted with purple dots.
Indian Pipe
I had thought for many years that Indian pipe lived on decaying leaves, and thus I called it a saprophyte. But this flowering plants turns out to be a myco-heterotroph as well, deriving its energy from the photosynthesis of a tree that passes through a mycorrhizal fungus on the way to the Indian pipe. Thus, like the spotted coralroot, this is a three-way relationship between a photosynthetic tree, a mycorrhizal fungus, and a parasitic plant!Indian pipe(Monotropa uniflora) forms its parasitic relationship with Russula and Lactarius (milky) mushroomspecies.
Indian pipes produce seeds like all flowering plants. As they age, the plants turn black and the “pipes” turn upwards.
Bird Migration Already in Motion
Mary and I usually wake up around dawn, and what a pleasure that is in late May and June when the air is filled with bird song. But by the end of July, it’s another story altogether as the birds’ quests for a mate and the defense of a territory no longer require full-throttled singing. In early August, some songbirds are still feeding young, but most have accomplished their mission of fledging their chicks and now have good reason to leave before the first frosts occur.
For nearly a month already, numerous shorebird species far north of us have been migrating through our area on their journey to Central and South America from their nesting grounds in northern Canada and the Arctic. It’s hard to call this “fall” migration when it’s only July or early August, but to these species of shorebirds, an Arctic autumn represents great hardship, so they need to stay ahead of the cold.
These shorebirds also migrate early because the far North offers only a brief window to successfully nest. If their first nest attempt fails, there likely isn’t time for a second attempt, so they give up and head south.
And then we can’t forget their lack of family values. One member of the pair, usually the male, leaves before the young are full-grown, or sometimes even before the chicks hatch. The other adult, usually the female, stays as long as necessary to successfully fledge the chick, then it, too, will head south, often a full month before the peak passage of the juveniles.
Some warblers, like yellow warblers, were also moving south as of the last week of July. And soon nearly all insect-eating songbirds will be leaving, all again needing to stay ahead of the first killing frosts.
Fledglings
Sarah Krembs sent me a photo of a male redstart feeding insects to two of its chicks. In redstarts, both sexes feed the chicks while they’re on the nest, evenly dividing up the task and making around six feeding trips per hour. After the chicks have left the nest, they usually divide their brood in half with each parent feeding only particular fledglings. Each adult then continues to feed his/her chicks for up to 3 weeks. If a chick continues begging, apparently refusing to become independent, one observer watched an older male attack a begging fledgling in order to force it to go out on its own.
From hatching to fledging only takes an average of nine days, which is amazing to consider given that a chick is born blind and helpless, opens its eyes to narrow slits at 3 days, has its first flight feathers begin to come in at 6 days, and is in full juvenile plumage by 8 days. Redstarts leave their breeding areas beginning in July and arrive on the northern coast of the Gulf of Mexico as early as late July, so these chicks are under the clock to get going. Most individuals, however, move south later than this. Peak movements occur from late August to mid-September in the upper Midwest, so perhaps these youngsters have a little time to learn to be adults.
Redstarts overwinter from the western coast of northern Baja in Mexico, to Bermuda and the Bahama Islands, and throughout the Caribbean to northern South America, including Venezuela, Colombia, eastern Ecuador, and northwestern Brazil.
They’ll be back again in mid-May, and be on a nest usually by late May or early June. They are known to frequently re-nest if their earlier nesting attempt was unsuccessful, and females have been observed to build up to 6 different nests in a season in effort to fledge a brood. That’s perseverance!
Kingbirds
Sarah Krembs also sent me a photo of an adult kingbird feeding two chicks. The Latin name for eastern kingbirds, Tyrannus tyrannus, means “tyrant or despot,” amply describing their aggressive defense of their nests and mates, and their domination of other birds.
Unusually for songbirds, if a pair survives to the following breeding season, they’ll very often reform their pair bonds and reuse their former territories. Having said that, the males are known to roam a little – a majority of nests contain young from multiple males.
The eastern kingbird migrates to western South America, returning to North America to begin laying eggs between late May and mid-June. Females raise only a single brood per season, so the fact that Sarah photographed a pair still feeding young could indicate poor initial nest success. The female may lay up to 4 clutches in a single season if successive replacement nests fail.
However, once the chicks fledge, the parents continue feeding the chicks for 3 to 5 weeks, an unusually long time for a songbird.
Don’t try getting too close to the nest or you’ll get attacked. The male in one study spent 50% of each hour perched either in the nest tree or a neighboring tree watching the nest during the nestling period. Apparently nest depredation is a major cause of nest failure, so vigilance is the name of the game. The parents will defend their young against predators for up to 7 to 8 weeks of age.
Their southward migration generally begins in mid to late August.
And Then There’s The American Goldfinch
While most songbirds are migrating or preparing to leave, goldfinches may yet be incubating eggs. They’re one of the latest breeders of all our songbirds, normally waiting to nest until late June or early July, and sometimes into mid-August. As a result, most pairs have time to produce only one brood in a season. However, some experienced adults produce two broods. Here the female abandons the first brood to her mate, and then leaves to find another mate.
The American goldfinch eats seeds almost exclusively, consuming very few insects, even when feeding nestlings. Thus, they can stay later into the autumn without the worry of the first insect-killing frost.
Celestial Events
In August, four planets are visible after dusk: Venus is brilliant (-4.5 magnitude) and low in the west, Mars is bright (-2.6) in the southeast, Jupiter is bright (-2.0) and low in the southwest, and Saturn is the dimmest (0.3) of the four, but still relatively bright in the south.
August 6thmarks the average midway point between ice-out and ice-up on Foster Lake in Hazelhurst (thanks as always to Woody Hagge for this data). A day later, August 7thmarks the midway between summer solstice and autumn equinox.
The Perseid meteor shower occurs between 8/8 and 8/13, but the peak occurs on the night of the 12ththrough the early morning of the 13th. The Perseids average one meteor per minute, but can number 3 to 4 per minute in an “outburst” year. This year the moon will be in its crescent phase and will set before the show gets underway after midnight, which will make for ideal meteor viewing.
The Earth passes through the dust and debris of Comet Swift-Tuttle every year, creating the annual Perseid meteor shower. The comet last passed near Earth in 1992, and the next time will be in 2126. Most of the meteors we see are about the size of a grain of sand, which seems impossibly small to flare with that much light, but so it is.
Thought for the Week
August brings into sharp focus and a furious boil everything I've been listening to in the late spring and summer – Henry Rollins
No comments:
Post a Comment