Ronald J. Jakubowski
A certain amount of pertinent information is necessary in teaching any Science unit. In this next section I will impart some of this vital information while also citing some resources for those who would like to delve deeper into the subjects discussed.
1.
The gray squirrel
Gray squirrels are common to cities and forests all across America. They live in the cavities of trees; often times enlarging a natural cavity and waterproofing it with leaves. Gray squirrels are naturally more abundant near a major food source. Therefore it is no wonder that oak, chestnut and hickory forests are teaming with squirrels. Squirrels feed on nuts, buds, fruits and berries in the main. They will eat an occasional insect and sometimes invade a birds nest devouring either the young bird or the eggs.
Gray squirrels are mostly observable when foraging for food. They can be seen most often in the early morning hours or in the late afternoon because that is when they eat. In the fall squirrels bury acorns and other nuts as well as mushrooms in anticipation of winter. The gray squirrel does not usually venture out of its nest in inclement weather. However it is possible for a squirrel to find nuts buried under several inches of snow. This amazing feat is attributed to the marvelous sense of smell squirrels possess.
Squirrels have two litters a year. They mate in mid-winter and produce two or three babies in about forty-four days. They mate again in early summer and have another litter by the end of summer. Young squirrels begin to move about on their own after about five weeks in the nest. Adult squirrels play a mating game that involves chasing and running around before settling down.
Gray squirrels have slightly different coloration in the summer and winter. While underparts remain white all year round, the coat changes from a silvery color in the winter to a yellowish brown in the summer. The long bushy tail stays gray all year long. Sharp claws for grasping bark and powerful hind legs make the squirrel a swift mover in trees and on the ground. In the city, man is the main threat to gray squirrels. They are sometimes used for target practice. During the Revolutionary War, marksmen gained skill at shooting by using gray squirrels as targets.
Gray squirrels seem to regulate their own population. An area can only support so many squirrels. Others move to an area where food is abundant for survival. An interesting phenomenon did occur in the 1930’s dealing with the overpopulation of squirrels. Thousands of gray squirrels left Connecticut and emigrated to New York by way of the Hudson River. Most died trying to cross the river to get to New York. Scientists concluded overpopulation was the reason for this mass emigration. A very good account of this phenomenon can be found in Monica Shortens’ book,
Squirrels
.
2.
House Sparrows
(English Sparrows)
In Brooklyn, New York back in 1850, eight pairs of English sparrows were introduced by an Englishman who felt there were not enough birds in New York City. Today the population of these sparrows has multiplied to such enormous proportions that it is considered a pest. House sparrows will nest most anywhere: in gutters, eaves of buildings and mailboxes. Because of their boisterous habits and defacement incurred on buildings, they have been described by some as “vermin of the air.”
House sparrows eat grain, berries, fruits and garden vegetables. They also eat a small amount of insects-especially caterpillars. Their water is supplied from dewdrops that form on the grass. At times house sparrows will infest premises associated with food such as bags of grain or flour. This causes real problems for the proprietor.
House sparrows, as was previously mentioned, will nest most anywhere and in a haphazard fashion. The nests are ragged and loosely put together. Grass, straw and even string are used in nest construction. Sparrows are very proficient reproducers. The male is an ardent wooer. He does a hopping dance with trailing wings to a seemingly indifferent mate. They have from four to eight eggs at a time from four to eight times a year. The eggs are whitish, spotted and blotched with shades of gray and black. The mother sits with them until hatched. When they do hatch they are fed insects by their parents. This high protein diet accelerates growth and strength in the young birds. The insect portion of their diet becomes less important as the bird grows older.
The average house sparrow has around 3,000 feathers. They are used naturally in flight but also to hold in body heat. The feather amount increases to around 3,500 in the winter which provides additional body heat during cold temperatures. The body temperature has been measured at 106.7 degrees even in the severest of weather.
House sparrows have been classified by many as pests. They roost on buildings in great numbers and deface property with their droppings. Many naturalists dislike them because they drive other birds more beautiful and rare away. They are fierce competitors for food. Ornithologist Elliot Coues said of the sparrows temper in 1873: “they attack, harass, fight against, dispossess, drive away and sometimes actually kill various of our native birds which are much more insectivorous by nature than themselves.” Dealing with their overpopulation is a problem since they have too few natural enemies to even make a dent in their numbers. Shooting and trapping are not effective in urban areas for obvious reasons. Recently scientists have been experimenting with a chemical called x-chloralose to reduce the sparrow population. This chemical, when ingested, has an adverse effect on ability to produce fertile eggs. People can discourage sparrows from roosting in undesirable places by shooting a stream of water into particular sites while the sparrows are sleeping. More often than not, though, they just pick another undesirable spot to roost and the problem lingers.
3.
Starlings
Starlings are often confused with blackbirds. They are distinguishable from blackbirds by their yellow beaks. In the spring, starlings have a purplish green tint to their feathers while in the winter their feathers become speckled with light dots.
Starlings have a background similar to house sparrows. They were introduced, one hundred strong, in Central Park New York City by an Englishman who wanted to have British birds in the United States in the late 19th century. Today they number in the millions and Roger Tory Peterson has declared that they are the number one bird in America. They roost in trees and on buildings in the city. They have taken over territory once held by native birds in the United States. Starlings eat grains and berries and sometimes the eggs of other birds. They feed their young insects, just as house sparrows do. They are effective destroyers of insect pests such as cutworms, grasshoppers and weevils. This makes them less hated than the otherwise useless sparrow. Starlings raise two broods a year with four to six eggs in a brood. The eggs are a pale bluish green in color.
Starlings are often observed roosting together in flocks of great numbers. They stay together for many reasons one being protection from predators. This flocking together causes many problems, the least being the noise a group of starlings can make. (ln fact starlings are great imitators of sounds. Some have been heard in forests imitating the sounds of chain saws.) More serious problems are those associated with human diseases and interference with airplanes. Starling droppings, when dried, form a powdery dust that can infect humans with a tuberculosis type disease called histoplasmosis. Although very rare, it is a serious illness. Cities have had to develop ways of dispersing this undesirable guano with chemicals not harmful to humans. Interference with aircraft is a more common problem. An airplane in Boston crashed at takeoff in 1960 killing 62 people. The reason for the crash was engine malfunction due to starlings being sucked into the engines at takeoff. This problem has become more prevalent recently as the starling population has been soaring.
Urban dwellers have little recourse in dealing with these noisy birds. One suggestion is to play a tape recording of the starling distress call over a loudspeaker. This disperses flocks. Another is to water the birds down while they are sleeping. Scientists have sprayed flocks with a detergent called Tergitol. Tergitol dissolves the oils on the feathers causing death due to exposure. This must be done when temperatures are below 45 degrees F and in the rain.
4.
Pigeons
The former cliff dwellers of hundreds of years ago now inhabit “man-made cliffs” in the form of nooks and crannies of buildings. Pigeons are probably the most recognizable bird on earth. Roger Tory Peterson in
The Birds
says that pigeons need no description everyone knows them. Pigeons live in shabbily built nests located in gutters, corners of buildings and rooftops. In fact the nests are so flimsy they must be sat in to protect them from the blowing wind.
While some people classify the pigeon as a pest, many people have developed an affinity for the bird. People go to parks to feed them. Because of this relationship, pigeons are less afraid of humans than the birds previously discussed. People have been known to have a special favorite pigeon in a particular park that they feed often. It comes as no surprise then to find that the main foods of pigeons is people food garbage, crumbs, scraps and the like. An interesting diversion does take place in the feeding of their young. I have mentioned that the starling and sparrow (and most other birds) feed their young insects for protein.
The pigeon does not need to do this. Instead pigeons feed their young a protein-filled, cheesy secretion called “pigeon milk”. The mother builds this secretion up naturally and regurgitates it into the mouths of her young ones. This satisfies the nutritional requirements of young pigeons.
The mating habits of pigeons are also very interesting. They consist of four stages: 1. head bobbing, 2. preening of partners, 3. the “bow-coo” session and 4. male regurgitation of food into the females mouth. Once these four stages have taken place the mates begin their lives together. They stay together for life. When the eggs are laid each partner takes a turn sitting on the brood. Usually two eggs are laid at a time. Pigeons are capable of nesting seven times a year.
Pigeons are considered pests by some for similar reasons as the starling and sparrow. They have overpopulated many of the large cities of the world causing considerable defacement of buildings and property. They also are responsible for a rare disease called ornithosis. It is a pneumonia-like disease that takes quite a while to recover from. It is contracted from the dust of dried pigeon droppings. Reports of such cases are rare but do cause a stir among populated regions. For this reason controls have been instituted on the pigeon population. Screens are placed over gutters to discourage nesting. Pigeons have been poisoned, shot, had their eggs taken all to no avail. Recently a method of chemosterilization has been started to reduce the pigeon population. Putting mestranol in food produces infertile eggs. The level of success, however, has been minimal.
Earlier in this century in New York City pigeons had a natural predator peregrines. Peregrines were falcon-like birds whose only food source was pigeons. But the peregrines died off eventually becoming extinct. The reason DDT poisoning. So pigeons are left to thrive bringing solace to some and rage to others.
5.
Other Birds
There are many other species of birds that occur in New Haven far too many to name here. A trip to the Peabody Museum to see the stuffed bird collection can be an asset in identifying birds observed on field trips or at feeding stations. Also several books described in the Student and Teacher reading lists can help in this most interesting activity.
