Mystery Photo

Photo: a 15′ x 5′ puddle in a grassy field after many days without rain. Any guesses as to what the rough patch is? Please submit all interpretations under “Comments” on the Naturally Curious blog site. Answer will be revealed on June 18th.

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The Perils Of Being A Duckling

Recently I encountered a single Common Goldeneye duckling frantically peeping as it swam around and around a pond with no other ducks or ducklings in sight. The gray-brown color of its eyes and the remains of an egg tooth at the tip of its bill indicated that it had hatched very recently. Because it couldn’t fly (it takes 50-70 days for most ducklings to attain flight status) nor swim fast enough to escape predators (such as largemouth bass, northern pike and other big fish, bullfrogs, snakes, snapping turtles, foxes, mink, raccoons, hawks, owls, gulls, crows and herons), it was extremely vulnerable. 

In addition to predation, weather conditions threaten duckling survival.  While their fuzzy down feathers are an excellent source of natural insulation in dry weather, they are of little value when wet. In addition, ducklings also lack the thermal protection of adult contour feathers. Cold, rainy, and windy conditions can lead to death from exposure (hypothermia) and may reduce food availability.

There was no obvious explanation for why this duckling was not in the company of its mother and siblings.  One can only hope that they were reunited in short order, as there is a bit more safety in numbers. Hopefully the fortitude it took for this youngster to leap from its nest cavity to the water below will serve it well in the days to come.

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Painted Turtles Laying Eggs

The courtship of Painted Turtles begins shortly after they emerge from hibernation in April and May.  It is quite an elaborate process, with the male swimming in front of the female and rapidly vibrating his long toenails along her head.  Mating follows and a month or two later females look for terrestrial nesting sites, often late on a rainy afternoon. 

Frequently the female will dig several “false” nests before depositing her half a dozen or so eggs in a nest. After carefully covering her eggs with soil and leaving the ground looking relatively undisturbed, she returns to her pond, providing no care for her offspring. 

Painted Turtle eggs hatch in the fall.  In the Northeast some young Painted Turtles emerge above ground shortly after hatching, while others remain in the nest and don’t dig their way out until the following spring. (Turtles from the same nest can emerge at different times.) Those turtles emerging in the fall usually have an egg tooth and a fresh yolk sac scar; those that overwinter and emerge in the spring lack both of these. (Thanks to Jody Crosby for photo op.)

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Common Grackles Raising Young

Although female Common Grackles do all the incubating, both males and females provide food for their nestlings.  Males average almost two feedings an hour, females almost four. Judging from the size of the larvae the pictured Grackle has in its beak, its nestlings are midway to fledging, perhaps a week old. The older/larger the nestlings, the greater the size of the food they receive.  Male and female nestlings received items of equal quality and quantity.

During the breeding season, both nestlings and adults feed primarily on insects in addition to a small amount of grain (and an occasional fish, small rodent or leech).  During the winter, their diet consists mostly of agricultural grains and tree seeds such as acorns.

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Aquatic Turtles Shedding Scutes

The spine and expanded ribs of a turtle are fused through ossification to plates beneath the skin to form a bony shell. Both upper and lower sections of the shell have an outer layer of plates called “scutes” made primarily of keratin (as are hair, feathers, hooves, claws, horns and nails).  Scutes protect the shell from scrapes and bruises.

In most land turtles and tortoises, scutes remain on the shell for life, which causes the shell to thicken and protects it. Growth of the scutes occurs through the addition of keratin layers to the base of each scute.

For most water species, as the turtle grows, the epithelium, or thin layer of tissue between the scutes and the bony plates, produces a new scute beneath the old one that is a larger diameter than the one layered on top of it, allowing the shell to expand.as the turtle and its shell grow.  The old scutes shed or peel away to make way for the newer, larger scutes (see top of shell, or plastron, of Northern Map Turtle on right in photo). Basking in the sun helps turtles shed scutes by drying them and leaving them ready to fall off. Usually this happens without any assistance, though there are some species of turtles which do pull loose scutes off each other’s shells.

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Brown-headed Cowbird: Brood Parasite

One has to admire a creature who has managed to eliminate the laboriousness of raising its offspring.  Brown-headed Cowbirds, renowned brood parasites, have done just that.  These birds do not build nests; females lay up to 40 eggs a summer in the nests of more than 220 species of birds which raise their young for them.  Cowbird eggs are generally larger than the host bird’s and hatch in fewer days, thereby putting Cowbird chicks at a distinct advantage over the host’s chicks when it comes to parental attention.

In this photo a Brown-headed Cowbird has deposited three eggs in the nest of an Eastern Phoebe (which has constructed its nest inside an abandoned American Robin nest). Unlike some songbirds, Phoebes do not recognize and remove the Cowbird’s eggs. Neither do they build a new nest on top of the old one, as some smaller songbirds (i.e. Yellow Warblers) are known to do.

Cowbird chicks develop faster than the chicks of the host bird, thereby often getting the first crack at the food parents bring to the nestlings.  Not only are the host species’ chicks often at a disadvantage when it comes to parental care, but they are at the mercy of the Cowbird chicks which often remove both the eggs and chicks of the host. (Thanks to friends in Thetford, VT for the use of their photograph of this parasitized Eastern Phoebe nest. The three larger, speckled eggs are Brown-headed Cowbird eggs; the four smaller white eggs are Eastern Phoebe eggs.)

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Cecropia Moths Mating

Cecropia moths (Hyalophora cecropia) are the largest native North American moths. They are members of a group of moths known as giant silk moths (family Saturniidae), renowned for their large size and showy appearance.

Having overwintered as pupae inside silk cocoons they spun (as larvae) in the fall, the adults emerge at this time of year often during the first spell of hot, humid weather by dissolving one end of their cocoon with their saliva.  The female Cecropia emits pheromones at night that are so strong that males can detect them with their feathery antennae from as far as a mile away.  Once paired, Cecropia moths proceed to mate for a full day before parting company. 

Shortly thereafter the female moth lays up to 100 eggs, often on both sides of a leaf. Due to a lack of functional mouth parts and no digestive system, the adults seldom live more than two weeks after mating. (Photo: female Cecropia moth on left (larger abdomen filled with eggs; narrow antennae); male on right (smaller abdomen; broader, more feathery antennae). Many thanks to Lorraine Vorse for photo opportunity!

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Note that mating took place very near the (female’s) cocoon (lower right).

The Lure of Bird Lores

An avian field mark that warrants special attention this time of year is the color of a bird’s lores — the area between a bird’s eye and bill on both sides of its head.  In some birds, especially wading birds, lores change color quite dramatically during the breeding season. 

Because birds can see blue, green and red (like humans) as well as UV light, and because the change takes place just as the breeding season begins for birds, the change in lore color, often to a more vibrant hue, is thought to play a part in attracting a mate.  (The bills, legs and feet of some birds also change color at this time.)

At the height of the breeding season, Great Egret lores go from yellow to an emerald green.  Green Heron lores turn from a yellowish-green to a bluish-black.  Snowy Egrets (pictured) lores become bright pink.  This happens to both sexes ever year. 

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Conifer Cones Developing

There are two kinds of seed-producing plants, flowering and non-flowering. Flowering plants are called angiosperms; their seeds grow inside tissue that is part of the plants’ ovaries, more commonly called fruit. Non-flowering plants that produce seeds are called gymnosperms.  Conifers are gymnosperms; their seeds are “naked,” or unprotected by an ovary/fruit and are often located on the scales of a cone. 

Some cones are male and some are female. The male cones produce pollen and the female cones produce ovules which, if fertilized, develop into seeds.  The pictured tiny, magenta cones are this year’s seed (female) cones of White Spruce, (Picea glauca) which, when the time is right, open their scales to allow wind-blown pollen to reach and fertilize their ovules.  The scales then close and will not open again until the seeds are fully mature.  At this point the scales open a second time in order to release the fully developed seeds which are dispersed primarily by the wind.

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Purple Martins Face Challenges Upon Returning To Breeding Grounds

Many of the Purple Martins that return from South America to the Northeast to breed have flown across the Gulf of Mexico to get here.  Once they’ve made this impressive trip, their challenges are far from over.  The reproductive success of Purple Martins depends not only on their arriving on their breeding grounds, but on surviving once they have arrived. One of the largest challenges that faces them upon their return is related to their diet, which consists exclusively of flying insects.  Purple Martins are particularly susceptible to spells of cold and rainy weather during the spring and early summer which can drastically reduce their supply of food.

Even when the weather doesn’t present them with nutritional challenges, Purple Martins have to contend with European Starlings and House Sparrows, both of which aggressively compete with them for artificial/human-made nest sites. Human intervention and management is often needed in order to protect the martin population. (Photo: male Purple Martin)

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