An online resource based on the award-winning nature guide

Archive for July, 2014

Black-throated Blue Warblers Incubating Second Brood

8-1-14 -female black-throated blue warbler on nest 054Male and female Black-throated Blue Warblers differ strikingly in appearance, so much so that the two sexes were considered separate species by early naturalists, including John J. Audubon. While the male is a brilliant blue, the female is dull gray which makes her practically invisible when she’s on a nest.

Black-throated Blue Warblers have anywhere from one to three broods in a summer, the first usually in June, a second, if there is one, in July and rarely a third in late July or early August. The nest is usually within three feet of the ground, and is built out of thin strips of birch bark and bits of rotten wood bound together by cobwebs and saliva. Fibers, rootlets, needles and mammalian hair line the nest. Female Black-throated Blue Warblers are known for sitting tightly on a nest until a potential threat is very close, at which point they drop to the ground, and, similar to Killdeer, engage in a distraction display, feigning injury to their wing.

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Carrion Beetles Feeding

7-30-14 carrion beetle feeding 129When an organism dies, such as the pictured American Toad, a series of decomposers appear and break it down. Some of the first insects to arrive at the scene are blowflies, and they lose no time in laying eggs which rapidly hatch into larvae, or maggots. A bit later, carrion beetles move in. Both of these insects live in dead carcasses, where they eat raw flesh and fungi. There is great competition, believe it or not, for rotting bodies, and carrion beetles such as the pictured American Carrion Beetle (Necrophila americana) have managed to find a way to eliminate some of it. They carry tiny mites on their backs which travel from carcass to carcass with the beetles, devouring the eggs of maggots as well as the smallest maggots themselves. In addition, carrion beetles secrete a strong offensive odor that irritates other insects and predators, a second effective way to reduce the number of insects competing for a corpse.

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Blue Vervain Flowering

7-29-14  blue vervain IMG_5431Blue Vervain (Verbena hastata) is a fairly tall (2 – 5 feet) flowering plant found in wet meadows. Its flower spikes branch upwards like the arms of a candelabra, and each has a ring of blue-purple flowers. The flowers at the bottom of the spike bloom first, and the ring of flowers advances upwards to the tips of the spike. Although Blue Vervain flowers have no scent, both long- and short-tongued bees are attracted to it primarily for its nectar, but also for its pollen. While Verbena Moth caterpillars feed on the foliage, most mammalian herbivores avoid eating this plant because of the bitter leaves. Various songbirds occasionally eat the seeds, including Cardinals, Swamp Sparrows, Field Sparrows, Song Sparrows, and Dark-eyed Juncos.

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Common Wood Nymphs Mating

7-28-14 mating common wood nymphs 066If you’ve walked in a shrubby meadow lately, you are probably well aware that Common Wood Nymphs (Cercyonis pegala) are everywhere. Each step seems to flush one, which, after some erratic flying, settles back down beneath the grasses, hidden from view. These butterflies are in a group called “satyrs” which consists of mainly medium-sized, brown butterflies. They belong to the Nymphalidae family, also known as brush-footed butterflies, or four-footed butterflies. The reason for these common family names is immediately apparent when examining a Common Wood Nymph (or Monarch, Painted Lady, fritillaries or checkerspots). Butterflies in this family look as though they only have four feet. Being insects, however, they have six. The front two legs are folded up in front of its head, and are extremely small and bristly. These reduced legs are present in all brush-footed butterflies, and are not used for walking or clinging. Rather, the bristles on these legs are sensory organs, used for detecting smells and for tasting. The butterfly’s proboscis is coiled up between this front pair of legs.

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Bunchberry Fruiting

7-24-14 bunchberry fruit IMG_8240Bunchberry, Cornus canadensis, is among the smallest of a genus of mostly shrubs and trees, and the only dogwood species that is herbaceous. The white flowers (resembling one flower, but actually consisting of many flowers , each 2 mm in diameter, surrounded by four modified leaves, called bracts) develop into red fruits which some people and a few birds, including ruffed grouse, veeries and vireos, find tasty. Bunchberry prefers cool, acidic soil — look for it where you find partridgeberry, goldthread and twinflower. If you find it, look closely, as Nashville warblers sometimes nest beneath it.

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Twelve-spotted Tiger Beetle Larva at Work

7-24-14 tiger beetle adult and larva 040Without doubt, I have one of the most erudite readerships in the land of blogs. Several people recognized this uncommon phenomenon. To clear up a few misconceptions, however, being a male, this dragonfly was not laying eggs. Neither was it fertilizing them – male dragonflies perform this act when coupled with a female. This Chalk-fronted Corporal had the misfortune to sun itself on a tiger beetle-inhabited patch of sand. One of the most aggressive groups of insect predators is the tiger beetle family. They are especially known for their speed – up to 5.6 mph, which is comparable to a human running 480 mph. If you watch an adult tiger beetle hunting, you’ll notice that it stops and starts frequently. This is because it runs so fast it goes blind — its brain has trouble processing the information it sees, and the beetle must stop to regain its sight.

The larvae of the Twelve-spotted Tiger Beetle live in tunnels that they dig in the sand (some of you noticed tiny holes near the dragonfly) that can be up to a foot deep. The larvae have hooks located on the back of their abdomen to anchor them to the side of the burrow. Tiger beetle larvae are also predators, and after digging a tunnel the Twelve-spotted Tiger Beetle will crawl up it until just the top of its head is visible. From this position the larva watches for prey wandering by. When it sees a potential meal, such as yesterday’s dragonfly, it flips backwards faster than you can blink an eye and grabs its prey, pulling it down as far as it can into its tunnel, where it safely feasts on its catch. The portion of the Chalk-fronted Corporal’s abdomen that was inside the tiger beetle tunnel was completely consumed except for the outer skeleton.

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Dragonfly Mystery Photo

7-23-14  dragonfly mystery photo 020Do you know what is happening in this photograph? All guesses welcome. The answer will be revealed tomorrow!. (Photo: male Chalk-fronted Corporal dragonfly, Libellula julia)

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