Reference no: EM133196353 , Length: Word count: 1 Page

Assignment Task: Answer each of the following questions to the best of your ability. If you type your answers on this sheet, please make sure your answers are in bold to distinguish them from my questions.

Question 1: You are interested in studying the density of red winged blackbirds (Agelaius phoeniceus) in marshes throughout northeastern PA. In advance of the field season you: identify 50 suitable marshes; hire 5 inexperienced undergraduate field assistants; and set aside a few days to train the students before they head off for the summer to each measure the density of blackbirds in 10 of the marshes. Considering the nature of your research question and inexperience of your researchers, what technique do you use to sample the bird populations in this study?

Question 2: You are interested in measuring the density of wood frog tadpoles (Lithobatessylvaticus) in 15 vernal pools within several tracts of the Pinchot State Forest. To estimate tadpole density, you visit each pool twice and expend a standardized effort to catch tadpoles using 20 "sweeps" with a dipnet. In the first pool on the first visit you collect, mark (with a Visible Implant Elastomer), and release 85tadpoles. You return to the same pool several days later, expend the same effort, and collect 95tadpoles, 25 of which were marked. What's your best estimate of the tadpole population size in the pool? Show your work or describe how you came to the answer.

Question 3: You're a scientist who studies the history of mammals in Europe. Your observational field data show a strong relationship between mammal species richness and human population density; local mammal species extinctions increased over the past 1000 years as human population density increased. Are these data strong evidence that human populations caused mammal extinctions? Why or why not?