Calculating r From A Published Data Set 4A

First of all if you have never seen an Egyptian Goose here is what they look like:

Photo Courtesy of: Sonja Vinck

Below you will find the table of my data and graph representative of that data. Krystaal helped me out with the graph since I do not have graph paper nor do I have the ToolPak for Excel (though Excel really should come with all the necessary tools, but I digress).

1. The exponential growth equation is Nt =N0(e^rt) (I can't get the formatting right). Nt is the population at the time of observation (variable). N0 is the initial population (constant). e is a mathematical constant (2.718). r is the rate of growth of a population (constant). t is time (variable).

2. In 1994 the population estimate for the Egyptian goose was 7,666 (which is higher than the number of geese actually observed). I believe that this may be due to predation (an increase in prey = an increase in opportunity for predation) or it may just be human error.

3. The method we used for calculating "r" is more reliable because points on the graph may not fall on the line of best fit. Choosing only two points on the data table would mean holes in your analysis.

4. A brief word on Egyptian Geese. Originally from Africa, there are many feral populations in Europe in places like the Netherlands. Their increase in population in Europe may be because it is up to meso-predators (raccoons, foxes, possums, etc) to limit the population. It is likely that there are fewer predators in Netherlands that prey upon the Egyptian Goose. To equate the feral Egyptian Goose to a similar invasive waterfowl, imagine the population of Muscovy Ducks in Florida.

5. Another famous exotic invasive bird species is the European Starling (Sturnus vulgaris). In 1890 a man by the name of Eugene Schieffelin (president of the American Acclimatization Society at the time) decided to release every bird species named in all of Shakespeare's works into Central Park, New York. There are roughly 200 million European Starlings in America all descended from the 60-100 birds that Eugene let loose in New York. This event is considered an environmental disaster (because "STARLING-OCALYPSE" is too hard to say). This highly invasive bird edges out native species and destroys crops. They also travel in huge flocks which pose a threat to air travel. Their droppings are highly corrosive and cause millions of dollars worth of damage to buildings every year. Irony of ironies, the European Starling is now considered rare, vulnerable, with populations declining in it's native European habitat (including England). Below is a picture of an adult European Starling.