An online resource based on the award-winning nature guide

Archive for July, 2020

Mystery Photo

If you think you recognize the subject of this Mystery Photo, please go to the Naturally Curious blog, scroll down to “Comments” and enter your thoughts.  Size:  3” x 1 ½”.  Hint:  found near a large body of water. (Discovered and submitted by Jody Crosby)

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Marsh Wrens Nesting

More often heard than seen, the Marsh Wren has a distinctive song that quickly alerts you to the fact that they are nesting in the area. Sung by the male at dawn, dusk and sometimes throughout the night, the song is a rapid series of gurgling and buzzy trills. Though each note may only last for 1–2 seconds, they can sing continuously for up to 20 minutes, rarely repeating the same note. To hear their song go to https://www.allaboutbirds.org/guide/Marsh_Wren/sounds .

Even though their nests are plentiful (males build multiple nests) they are well hidden and difficult to detect in amongst the cattails and bulrushes where they are built.  About 50% of males mate with two or more females and most males build at least six dummy nests for every female they mate with.  (In some parts of their range males build an average of 22 nests.) Scientists aren’t sure why the males build so many dummy nests – perhaps as decoys for predators.  They are built two to five feet above the ground and are about 7” tall and dome-shaped with an entrance hole in the upper half. Once the female has chosen one of the male’s nests or built her own, she lines it with strips of grass, sedge, cattail down, feathers, and rootlets.

Possibly as a result of intense competition for resources in the marsh environments in which they nest and raise young, Marsh Wrens routinely destroy the eggs of other birds, including other Marsh Wrens.  (Note:  Pictured active Marsh Wren nest was built in rushes, which are preferred over cattails later in the nesting season, when cattails have dried out.)

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Scorpionflies Feeding On Carcasses

You can recognize a Scorpionfly (Order Mecoptera) by its long head which bears mouthparts at the end of a long beak. Its common name comes from the tail of one family of scorpionflies in which the male scorpionfly has prominent genitalia that are curled back up over the insect’s body (much like a scorpion).  They are, however, harmless.   Scorpionflies feed only on dead insects and have been known to raid spider webs for their meal.

Males with insect carcasses are said to acquire receptive females with relative ease.  Lacking a carcass, males have been known to throw up and use the spittle as a lure for females who feed on it while copulating with the male. (Photo:  Scorpionfly drinking innards of dead caterpillar)

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Juvenile Ospreys Fledging

Their red eyes tell you that both of these Ospreys are this year’s young (adults have yellow eyes).  During the last week they are in the nest, the young often exercise their wings by hovering over the nest.  After their first flight, fledglings generally remain at the nest or nearby.  Eventually they begin hunting for themselves, but the parents continue to bring fish back to their young for ten to twenty days, supplementing the food that the young start to catch on their own.  Within a month or so of fledging the juvenile birds begin their migration south. (In the accompanying photograph, one fledgling is returning to the nest after quickly circling a nearby field while its parents were off fishing.  Dinner was delivered shortly thereafter.)

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Sibling Rivalry

The male Osprey typically provides fish for the chicks, often feeding first and then presenting the remainder to the female who tears the fish apart into small pieces and feeds it to the chicks.  When food is delivered, there can be significant aggression on the part of the older Osprey nestlings if the parent hasn’t fed them in a while.

Incubation begins with the first egg, so they hatch sequentially, producing a brood of chicks that are not  the same exact age.  Once dominance is established, the older chicks feed until satiated and then allow the younger ones to eat.  If food is scarce, it’s not unusual for the younger chicks to starve to death, but if food is plentiful, a peaceable kingdom reigns.

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Osprey Nesting Behavior

Naturally Curious is back!  Different ecosystem (western vs. eastern Vermont) but same curiosity!  This week’s posts are going to be devoted to the nesting behavior of the Osprey — the only raptor that plunge-dives feet first to catch live fish as its main prey source.

Ospreys nest within six to twelve miles of water (usually much closer).  The male collects most of the nesting material and brings it to the nest site where the female arranges it. Sticks as large as an inch-and-a-half in diameter and three feet long are collected from the ground, or (less commonly) snapped off a tree while the Osprey is in flight.  Nest-building continues throughout the incubation of the eggs as well as the brooding period — even if a nest fails, Ospreys will continue to add material to it.

Although nests built on platforms are relatively small, those built in trees or on the ground can be 10 -13 feet deep and 3 – 6 feet in diameter (the largest nests are most likely the result of several generations of nesting Ospreys).  The shape of an Osprey nest changes during the breeding cycle.  When the eggs are being incubated, the nest is bowl-shaped.  After hatching the nest flattens out, but a rim of sticks is maintained. By the time the nestlings fledge (around 50-55 days) the nest is often completely flat.

Ospreys will reuse their nest year after year, saving themselves time and energy which allows earlier laying and more surviving young. Birds whose nests fail are likely to build alternate nests and use them in subsequent years. (Birds of the World Online).

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.