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Archive for August, 2013

Waterfowl Vulnerable When Molting

8-23-13 canada goose remains 043All North American birds replace their old, worn plumage with new feathers at least once a year, a process known as molting. Most birds have what is called a “sequential molt,” in which their flight feathers are lost one at a time (from each wing). This allows many birds to continue flying while molting. However, during their annual molt, waterfowl undergo a “simultaneous wing molt,” losing all of their primary wing feathers at once, preventing them from being able to fly for a month or more while their new primaries are growing in. During this period, they are extremely vulnerable, as this photograph testifies to. If you look closely at the remains of the Canada Goose’s wing on the right in the photograph (dark feathers), you’ll see that the new primaries have almost, but not quite, grown out of their sheaths, making them not yet functional. It’s apparent that this bird was unable to take flight during its molt in order to escape its predator.

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Black Swallowtail Larvae Soon to Form Chrysalises

8-29-13 black swallowtail larva and QALace 028In its younger days, this Black Swallowtail larva resembled a bird dropping, but in successive molts a green (or white), yellow and black pattern develops. Often discovered in vegetable gardens on carrot, parsley and dill plants, it also feeds on wild members of the carrot/parsley family (Apiaceae), including its favorite, Queen Anne’s Lace (pictured). Seeds as well as leaves are rapidly consumed, as the time for one last molt and the development of a chrysalis in which to overwinter approaches.

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Young Spring Peepers Now The Size Of Your Baby Fingernail

8-28-13  spring peeper & Jap. beetle 066It takes roughly two months for Spring Peeper tadpoles to metamorphose into adults, and unlike other frogs, they don’t complete this process in the water. Young Spring Peepers leave their ponds at an earlier stage of development than most frogs – they have four legs and lungs when they come out of the water, but most of them also still have a tail which is absorbed shortly after they become land dwellers. Adult Spring Peepers measure roughly ¾” (males) to 1 ½” (females) in length. As you can see in this photograph, this fully metamorphosed young Spring Peeper is hardly bigger than a Japanese Beetle, and it has completely lost its tail, so it was even smaller when it hopped out of the water!

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Nursery Web Spiders Hatching

8-27-13 nursery web spider 169Nursery Web Spiders look a lot like Wolf Spiders, and the females of both families carry their respective egg sacs around with them until they hatch, but they do so in a different manner. Wolf Spiders grasp their egg sacs with the spinnerets (silk nozzles) located under their abdomen, whereas Nursery Web Spiders carry their egg sacs with their mouthparts. When hatching is imminent, the female Nursery Web Spider lashes leaves together with silk to form a protective shelter, or “nursery web,” for her egg sac and hatching offspring. The mother stands guard over her spiderlings, aggressively defending her young until they have had their first molt, after which both the spiderlings and the adult female disperse.

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Spiny Witch Hazel Galls

8-26-13  spiny witch hazel gall 045Aphids are responsible for the formation of two different galls (abnormal plant growths caused by insects, fungi, bacteria and viruses) on Witch Hazel (Hamamelis virginiana). A cone-shaped gall forms on leaves and a second type of gall covered with spiny points grows from branches. The latter gall, referred to as the Spiny Witch Hazel Gall, provides many aphids (Hamamelistes spinosus) with both food and shelter while they are developing inside the gall. (Their two-year life cycle involves birches as their next host.) The pictured Spiny Witch Hazel Gall has split open enough to allow ants to discover and have access to the aphids. Once the ants enter the gall, they stroke the resident aphids with their antennae, stimulating the aphids into producing droplets of tasty “honeydew” from the tips of their abdomens, which the ants find irresistible. In return, the ants protect the aphids from predators.

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What a Snake’s Eyes Can Tell You

8-5-13  snake eyesYou can tell a lot about a snake just by looking at its eyes. Snakes that burrow underground usually have relatively small eyes compared to those that live above ground. The size of the eye and the shape of the pupil can often tell you if the snake is diurnal or nocturnal – typically diurnal snakes have comparatively small eyes with round pupils and nocturnal snakes have larger eyes with elliptical pupils. Both of these characteristics have to do with maximizing or minimizing the amount of light that enters the eyes. The larger the eye, the more light it can gather. The reason for the difference in pupil shape is that round pupils can close very tightly, to a pinpoint opening, shutting out bright sunlight very effectively. Elliptical pupils can open wider than round pupils, and consequently collect more light. (Photo is of a Common Gartersnake.)

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Blue-headed Vireos Begin Migration

8-21-13 blue-headed vireo 094Blue-headed Vireos (formerly called Solitary Vireos) are fairly distinctive birds, given their white “spectacles” or eye-rings. (Trying to make their heads blue seems to be a bit of a stretch, however.) They are the latest species of vireo to migrate, beginning about now and peaking at the end of September/beginning of October. After spending the winter in southern U.S. or Central America, they will head north, one to two weeks earlier than any other species of vireo.

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