Man's Impact on Ecosystems - The Channel Island Fox (Kathy Gumber)

Title: Man's Impact on Ecosystems - The Channel Islands Fox

Quickwrite: Island Fox Quickwrite

Principle(s) Investigated:

• Human Impact on Earth Systems
• Earth and Human Activity
• Evolution - Reproductive Isolation
• Selective Pressures
• Causes of Speciation - Geographic Isolation
• Ecosystem Carrying Capacity
• Population Limiting Factors

Key Terms: habitat, limiting factors, predator, prey, population , balance of nature, ecosystem

Standards :

Scientific and Engineering Practices:

• Asking questions
• Analyzing and interpreting data
• Constructing explanations
• Engaging in arguments from evidence

Crosscutting Concepts:

• Patterns
• Cause and effect: mechanism and explanation
• Systems and system models
• Stability and change

Core and Component Ideas in Earth and Space Sciences:

• MS-ESS3-3 Apply scientific principles to design a method of monitoring and minimizing human impact on the environment.
• LS2.C Ecosystem Dynamics, Functioning and Resilience
• LS3.A Inheritance of Traits
• LS4.A Evidence of Common Ancestry and Diversity
• LS4.C Adaptation

Common Core State Standard Connection:

• ELA/Literacy
  • RST.6 - 8.1 - cite specific textual evidence to support analysis of science and technical text
• Mathematics
  • MP.2 - Reason Abstractly and Quantitatively

Materials:

• Google spreadsheet for entering and plotting data or paper chart for the same purpose
• Google spreadsheet for answering questions (or Google survey)
• Channel Islands Map from Google Site or physical map of Channel Islands
• Instruction for Island Fox Game (Home Sweet Home / Oh Deer)
• Props (optional)
  • Mainland fox pelt
  • Island fox pelt
  • Golden Eagle cut out
  • Bald Eagle Transponder

Procedure:

1. Show students a map of the Channel Islands. Tell student that today the Channel Islands are a national park and have been visited by humans since before Europeans came to California.
2. Describe how the islands are separated from the mainland by water and the plants and animals living on the islands are in a unique situation in that they are an isolated ecosystem.
3. Have the students identify the two smallest islands. (Santa Barbara and Anacapa). Tell students that these two small islands lack something that is very important to sustaining life, things that all animals need as part of their habitat. Tell students that no mammals live on these two islands because of this. Ask students to list things all animals need (food, water, shelter). Ask students if they can guess what is missing from the two islands (neither has a natural source of water).
4. Tell students that the remaining islands are home to a number of animals, including the Island Fox. (show the island fox pelt)
5. Tell students that the island fox is the only carnivore species that occurs only in California and nowhere else. We know that the island fox evolved from the North American grey fox approximately 10,000 years ago. Show the grey fox pelt and ask if students notice any differences. (Smaller size, more gray / less red on sides, shorter tail)
6. Tell students that there is a tendency for larger mammals isolated on islands to become smaller, where small animals like rodents tend to become larger.
7. Tell students that the island fox almost became extinct in not long ago and is now making a good comeback. It took teamwork between the National Park service, scientists and others in the community to save the island fox. It also took some very interesting detective work. Today we will get to play detective and find a way to save the island fox.
8. Tell students that before we begin our investigation we will play a game to help us understand how the fox population naturally fluctuates. Take students outside and play Home Sweet Home / Oh Deer
9. Home Sweet Home / Oh Deer (see handouts for more details)
   1. Have students count off by four
   2. Have the ones form a line
   3. Have the twos, threes and fours form another line
   4. Tell the ones that they are now the island foxes
   5. Tell the two, threes and fours that they are the habitat
   6. Show students the signs for food (palms on stomach), water (palms on mouth) and shelter (forearms forming roof over head). Tell student to turn around so that the two lines are facing away from each other. Each student chooses one of the three habitat components. The foxes need the component, the habitat can give it.
   7. Tell students to turn around and foxes walk to the habitat component (student making the same sign) they need. The foxes bring the matching student back to the fox line and now there are double the foxes.
   8. Steps 6 and 7 above are repeated for each round. When there are more foxes than resources those foxes "die" and become part of the habitat again.
   9. At each round count the number of foxes and mark on the data collection sheet.
   10. At the end of 10 rounds bring the students together to discuss the activity
10. Post the data recorded during the game in the Google Spreadsheet or on the paper chart. If using a Google spreadsheet turn the table into a chart. Students will see a visual reminder of what they experienced during the game.
11. Ask students to post answers to the following questions in the quickwrite:
    1. What was realistic and unrealistic about this simulation?
    2. What do animals need to survive, and how do these impact carrying capacity?
    3. Are wildlife populations static or do they tend to fluctuate.
12. Tell students that although the island fox population historically fluctuated as in the fox game, it overall remained healthy enough that rangers did not even feel the need to count the number of foxes living on the Channel Islands. Then in the mid 1990's the island fox population started a sharp decline. Show students the chart showing the fox population from 1993 to 1997.
13. Tell students that national park rangers reached out to scientists for help in solving the mystery. Ask students to play the role of the scientists and speculate on what was happening to the island fox (something was killing the fox).
14. Ask students to list things that might be killing the fox (disease, lack of food or water, predators)
15. Tell students that on Catalina Island it was discovered that some island foxes had canine distemper and the park service captured and inoculated the island foxes on Catalina. But on the other islands there was no evidence of disease and the fox population continued to decline.
16. Tell students that around 1998 park personnel had placed tracking devices on the foxes so that they could tell when a fox died and hopefully determine how it died. (show picture of the tracking device)
17. Park personnel found a fox carcass that had been attacked by a large predator and nearby they found a feather (show the feather). Park personnel sent the feather to United States Fish and Wildlife Forensics Lab for analysis but then had to wait on a response. Ask students to play the role of the "detective" and propose some "suspects" in the fox murder. (sea gull, vulture, hawk, golden eagle, bald eagle). Have students review the list and see if they can eliminate any of the suspects: vultures are scavengers, bald eagle eats fish not mammals)
18. Tell students that when the results came back from the lab, it was determined that the golden eagle was responsible for the decline in the fox population. Ask students to propose ways to resolve this problem and save the island fox.

Student prior knowledge: Understanding of an animals basic needs for survival: food, shelter, water. Understanding that an ecosystem is a system of interdependent plants and animals.

Explanation:

Channel Islands National Park has a unique plant and animal population found no place else in the world. The Channel Islands fox is one of these unique species. The isolated nature of the islands has allowed the island fox to evolve from the North American gray fox into a unique subspecies on six of the eight Channel Islands.

The Channel Islands fox is the smallest fox species in North America, similar in size to most house cats.

Historically the fox population fluctuating normally but was so robust that park rangers did not keep a count of the number of foxes on the islands. Then in the mid 1990's the populations started a sharp decline. Park rangers enlisted the help of scientists to determine what was causing the sharp drop in the fox population. Tracking collars were place on the remaining foxes and rangers tracked the foxes in an attempt to locate a fresh carcass and hopefully determine what was killing the foxes.

Island fox with tracking collar

A carcass was found that had been partially eaten by a large predator. The feather found with the carcass was sent to the US Fish and Wildlife Forensics Lab.

The research team was able to determine that the island fox was being preyed upon by Golden Eagles. Historically golden eagles do not hunt on the Channel Islands because of the presence of bald eagles on the island. Bald eagles are protective of their hunting territory and drive other large predictor birds out. Because the bald eagle's diet consists primarily of fish, the birds presence on the island was beneficial to the island fox because it kept predictors that would feed on the fox out.

The bald eagle population suffered a steady decline across the United States including the Channel Islands from 1947 to mid 1970's. This decline was due to a number of factors including the use of the pesticide DDT. In 1978 the bird was listed for protection under the Endangered Species Act. Since 1980, gentler treatment by humans along with the banning of DDT (the bird's main pesticide threat) has led to a dramatic resurgence. By the late 1990s, breeding populations of bald eagles could be found throughout most of North America.

Bald Eagle with Fish

Although the bald eagle population was recovering throughout the rest of the United States by the late 1990's, it had yet to return to the Channel Islands. In its absence, golden eagles (who prey on mammals) had begun to use the islands as a hunting ground and were decimating the island fox population.

Golden Eagle

Bald Eagle and Golden Eagle Size Comparison

Bald Eagle and Golden Eagle Talon Comparison

Golden Eagle Hunting a Deer

Fox Population Restoration Actions:

The restoration of the island fox population required a multifaceted approach:

• The remaining 15 island foxes were captured and placed in a captive breeding program on the island(s)
• Golden eagles were trapped and relocated
• Bald eagles were reintroduced into the islands
  • Island foxes were reintroduced after their numbers had begun to recover through captive breeding

Questions & Answers:

1. What are the factors that keep populations of animals from becoming too large? (food, water, shelter and space)
2. What risks do you think the scientists and rangers might have considered when they began trapping the foxes for the captive breeding program? (the foxes might not breed well in captivity, they might not be successfully reintroduced into nature)
3. How do you think the disease canine distemper was introduced into Santa Catalina island? (originally thought to be brought by pet dogs, now we know it was most likely brought by raccoon(s) who came to the island on the ferry).

Applications to Everyday Life:

1. The plants and animals that exist within an ecosystem create a unique and complicated web of inter dependencies. This balance can be observed in a garden. Without insect to pollinate fruit and vegetables we would not be able to grow many of the foods we enjoy every day.
2. When populations of animals are intentionally or unintentionally isolated and prevented from breeding with others outside the population some traits in the population can become more evident. We see this in the many breeds of dogs that were selectively bread for certain traits.
3. When the necessary components of an ecosystem become scarce (limited food, water or shelter) animals seek these components elsewhere. A good example of this is the behavior of coyotes that come into populated areas looking for water.
4. Removing an entire plant or animal population from an ecosystem or introducing a foreign plan or animal can have profound effects on all parts of the ecosystem. The bamboo like plant Arundo Donax found growing along many rivers and streams is an example of non-native plant causing a profound change in the ecosystem

Useful Web Sites:

Channel Islands National Park

US Fish and Wildlife Forensic Lab

The Decline of the Island Fox

The Bald Eagle at Channel Islands

Channel Islands Live Distance Learning

Photographs: Include a photograph of you or students performing the experiment/demonstration, and a close-up, easy to interpret photograph of the activity --these can be included later.

Videos: