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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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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Raccoons Seeking Dens
Pregnant female Raccoons have recently been exploring potential natal dens where they will soon give birth to four or five young. This year’s litters will be well hidden from potential predators deep inside the tree cavities, caves and rock crevices their mothers have chosen. We won’t see the offspring for another month or two, after they have developed enough motor skills to be able to walk. Sometime in June or July their mother will venture out of the den at night with her offspring and introduce them to solid food and the great outdoors.
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Spotted Sandpipers Returning To Breeding Grounds
Northern New England is starting to see the return of Spotted Sandpipers, small shorebirds easily identifiable during the breeding season by their spotted chest and belly, teetering movement and stiff wingbeats while flying low over the water.
Spotted Sandpipers distinguish themselves in a number of ways, most notably when it comes to their reversed sex roles. Females arrive first on breeding grounds, stake out territories and attempt to attract males (this is the opposite of the standard avian breeding procedure). Females are more aggressive and active in courtship than males, and males are the primary parent. While some pairs are monogamous, females may mate with up to 4 males, each of which cares for a clutch and a brood.
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