Mysterious Death on the Greenway

Transcription

1 Mysterious Death on the Greenway Introduction During the spring seasons of , biologists studied the behavior of a pair of Barred owls. The biologists collected a tremendous amount of data as this male and female have raised chicks and hunted for their offspring each year. On 23 February 2012, the researchers were searching for the owls near the nest when they came across an area of Barred owl feathers with two wings that looked like they had been pulled from the bird s body. The wings were surrounded by feathers concentrated into a small circular area. The feathers looked like they had not been disturbed since the kill had taken place, which led the researchers to assume the kill had happened earlier that morning. They were not scattered around as if a terrestrial animal had been through the area. It appeared as if whatever had taken the body had simply flown away with it. Feathers and part of a wing A few feet from the feathers, the body of a smaller bird was lying with its head completely detached. About 30 feet away and underneath a tree, whitewash was found. This was evidence that an owl had been in the area. It was originally guessed that the wings and feathers belonged to a female Barred owl. All these findings pose many questions. What was able to so violently pull the wings off a Barred owl? 1

2 Where did the rest of it go? Did the large pile of whitewash belong to the Barred owl that died or another owl? And what was the smaller bird s role in this mid-air drama, if that s what it was? Headless smaller bird Unknown whitewash Possible culprits Great-horned owl There is a Great-horned owl nest in the area that has been active for the past three years. During this three year span, the Great-horned pair has raised a pair of chicks each year. The chicks typically hatch around 20 January and fledge around 10 April of each year. This specific type of owl feeds on all types of animals including insects, fish, other birds, skunks, rabbits, and woodchucks. Red-tailed hawk There is also a known Red-tailed hawk nest in the area. The hawk pair usually has 3 chicks per nesting season to feed. The chicks hatch around 01 March and fledge around 20 April. These hawks feed on mice, birds, snakes, and insects. Another Barred owl Even though there are no other known Barred owl nests in the area, it is possible that a rival Barred owl killed this female in a territorial dispute. This would be the first documented case of a Barred owl killing and feeding on its own kind. 2

3 Problem set #1 The Google map image shows the locations of the three birds of prey. The following questions show you the distance from each nest to the others in feet. Please make the appropriate conversions and show all work. 1. From Great-horned nest to Barred nest = ft a. m b. yards 2. From Great-horned nest to Hawk nest = ft a. m b. yards 3. From Barred nest to Hawk nest = ft a. m b. yards 4. Great-horned owls need a circumference of approximately 500 yards of home range to hunt so that they can sustain a family. Judging by the distances, would this put them in direct conflict or competition with the other two birds? Also, think about what types of prey species these birds would be eating. Please explain. 3

4 Problem set #2- Please show work 1. Avg. weight of male Barred = 617g and avg. weight of female Barred = 779g a. Avg. male = oz b. Avg. female = oz 2. Avg. weight of male Great horned = 1287g and avg. weight of female Great horned = 1726g a. Avg. male = oz b. Avg. female = oz 3. Avg. weight of male hawk = 1028g and avg. weight of female hawk = 1225g a. Avg. male = oz b. Avg. female = oz 4. What are your thoughts as to which bird may have killed the Barred owl after looking at these measurements? Why? 4

5 Problem set #3- Show all work 1. An active great-horned owl can produce 1.15 L of whitewash per day. Please convert this to ml, gallons, and fluid ounces. a. ml b. gallon c. fluid ounce 2. One way to tell if birds of prey have spent a lot of time hunting and eating fish is to look for and count paramecium in a sample of whitewash. The Great-horned owls in this area do rely on a heavy diet of fish. You should look at each sample that was collected the morning of the kill for each bird under the 10x objective. Over 15 paramecia in a sample would indicate that the bird has spent the majority of its feeding time eating fish. a. Barred owl = # of paramecia b. Great horned owl = # of paramecia c. Hawk = # of paramecia 3. Does question 2 tell you anything about the possible culprit? Explain. 5

6 Problem set #4 You will be testing whitewash samples from the three birds for simple sugars, starch, lipids, and proteins. Use the grease spot test for lipids. These tests may help you discover more specifically what the birds have been eating. The presence or absence of lipids may confirm a finding from problem set #3. Please record your results. By putting + or and also recording color. Great-horned Compound Simple sugar Starch Lipid Protein Barred Compound Simple sugar Starch Lipid Protein Hawk Compound Simple sugar Starch Lipid Protein Result Result Result 6

7 Conclusion 1. Please write a recommendation to the NC Fish and Wildlife explaining what your group believes about the death of this Barred owl. In your recommendation, use the evidence you have collected from each problem set as well as other information in the introduction. Also provide any other ideas you might have to prove this. Please describe a possible controlled experiment you could set up to test your hypothesis. 7