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Common Grackle

Mystery Photo I.D. – Leeches feeding on the blood of a Snapping Turtle

IMG_1812Leeches are segmented worms (annnelids) which feed predominantly on blood, although some species do eat insects. Of the 700 species of leeches, 500 inhabit fresh water, as opposed to salt water or land. Blood-sucking leeches are common parasites of many freshwater vertebrates including turtles, amphibians and fish.

Generally speaking, leeches of the genus Placobdella are commonly found on turtles. Bottom-dwelling species such as the Common Snapping Turtle, Mud Turtle and Musk Turtle usually have more leeches than other turtles, and they are often attached to the skin at the limb sockets. Aerially-basking species such as Painted Turtles often have fewer of these parasites, possibly because basking forces leeches to detach in order to avoid desiccation.

A leech can ingest several times its weight in blood from one host before dropping off and not feeding again for weeks, or even months. Leeches inject hirudin, an anesthetic, to keep the hosts from feeling them break the skin. They also inject an anticoagulant to keep the blood from clotting so that they can feed. Although leeches (especially large ones) can be a significant health detriment to smaller animals, they are not harmful to most large animals, such as Snapping Turtles.

Some of the most common predators of leeches include turtles, fish, ducks, and other birds. Map Turtles allow Common Grackles to land in basking areas and peck at leeches clinging to their skin, and minnows have been seen cleaning leeches from Wood Turtles in the water. At times turtles bury themselves in ant mounds to rid themselves of these pesky parasites.

For those readers who may hesitate before going into a leech-laden pond, it may be comforting to know that leeches are mainly nocturnal. (Photo by Jeannie Killam)

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Nestling or Fledgling?

6-7-16  grackle fledgling 057We are at the time of year where finding a young bird on the ground is not unusual, and many well-meaning people assume that if a bird can’t fly, it has been abandoned by its parents.  While some of these birds may be young that have fallen out of their nest, the fledglings of many species spend as many as two to five days on the ground before they can fly any distance.  While they are on the ground, the birds are cared for and protected by their parents and are taught vital life skills (finding food, identifying predators, flying).  To deprive such a fledgling of this developmental stage by removing it from its parents is to lessen its chances of survival, so it’s behooves us to be able to tell whether or not a young bird belongs out of the nest or not.

If the young bird is nearly naked or covered with down, not quill feathers, or its eyes haven’t opened, it is obviously a nestling.  If you can’t find its nest, a berry basket in the vicinity of where you found it, suspended from a branch, is a good facsimile.  Birds have a poor sense of smell and very strong parental instincts and more often than not continue to care for their young after a disturbance, although it may be a few hours before they do so.  If, after several hours, there is no sign of a parent, a local museum or nature center should be able to direct you to a nearby wildlife rehabilitator.

Fledgling birds, birds that have voluntarily left their nest, are usually fully feathered and have a very short (one inch or so) tail.  They are able to walk, hop and flap, and they may attempt short flights.  You may not see them, but a parent or two is nearby, keeping an eye on them, feeding them and teaching them how to survive on their own (see insert).   These are the birds that humans often mistakenly “rescue.”  If you find a fledgling, it should be left alone or, at the most, placed in a nearby shrub. If possible, keep people and pets away so the parents will continue to care for it until it can fly. (Photos:  fledgling and attending adult Common Grackle)

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Common Grackles Returning

3-30-15 common grackle 083Male Common Grackles have started to arrive on their northeastern breeding grounds (females will arrive in another week or so), having migrated from southern U.S. Common Grackles typically migrate in large flocks containing hundreds of birds, not all grackles. Red-winged Blackbirds, Brown-headed Cowbirds, European Starlings and occasionally American Robins can be found alongside Common Grackles in these migrating flocks. In the early 1990’s, magnetic material was found in the heads and necks of Common Grackles, indicating that the geomagnetic field may play a role in their migratory navigation.

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Common Grackle Threat Display

5-3-13 common grackle DA8A1629Although the common grackle, a member of the blackbird family, is the bane of many corn growers as well as a threat to songbirds trying to raise young (grackles eat other birds’ eggs and nestlings), it is quite a colorful bird, with its pale yellow eyes and iridescent purple plumage. Grackles have already begun nesting and defending their territory, as can be seen from the stance of the bird in this image. This “bill-up display” is a position assumed when a male is being approached on its territory by another male. It moves its head upwards so that its bill is almost vertical, signaling to the approaching grackle that it would be in its best interest to depart.