Angela's Tools · Chapter 27 · Biodiversity Worksheet 8 of 10

The Island Fox Jigsaw: Twelve Cards, Five Solutions, One Recovery

Learning target: I can work with a team to trace how an invasive species and a pesticide led to the near loss of the island fox, evaluate five real solutions against shared criteria, and explain why a combination of solutions worked.

Collaborative investigationAbout 55 minJigsaw MS-LS2-5 · assessesMS-LS2-4 · practiceMS-ETS1-3 · supports collaborationreadingdiscussion
NameDatePeriod

Directions

Work in home groups of four. Step 1, expert round (10 minutes): each member takes one expert set of three cards (Set A: cards 1-3; Set B: cards 4-6; Set C: cards 7-9; Set D: cards 10-12), reads them, and meets with students from other groups who hold the same set to agree on the two most important facts and complete Part A. Step 2, home round (25 minutes): return to your home group, teach your cards in order from Set A to Set D, and complete Part B together. Step 3, individual (15 minutes): answer Part C alone, without your group.

You will need: Twelve cards per group, cut from the card sheet, Scrap paper or a large sheet for the cause-and-effect chain, Pencils, Calculator

Twelve evidence cards: the Channel Islands fox
1 Card 1 (Set A): The island foxA small fox, about the size of a house cat, that lives on six of California's eight Channel Islands and nowhere else. The foxes on each island are a separate subspecies with their own genetic differences. Island foxes eat insects, deer mice, birds, fruits and seeds, and they are active in daylight as well as at night. For thousands of years they had few predators.
2 Card 2 (Set A): The crashIn the 1990s, fox numbers collapsed on the three northern islands. San Miguel Island fell from about 450 foxes to 15. Santa Rosa Island fell from about 1,780 to 15. Santa Cruz Island fell from more than 1,400 to about 55. In 2004, four island fox subspecies were listed as endangered under the U.S. Endangered Species Act.
3 Card 3 (Set A): Evidence about the killerBiologists fitted foxes with radio collars and found the bodies of the ones that died. Most had been killed by golden eagles. Golden eagles live on the mainland and were not known to nest on the islands until the 1990s. Biologists found no sign that disease, a food shortage or habitat change caused the crash on the northern islands.
4 Card 4 (Set B): Why the golden eagles stayedRanchers brought pigs to Santa Cruz Island in the 1800s, and some went wild. Thousands of feral pigs rooted up native plants and loosened soil on hillsides, and their piglets gave golden eagles a plentiful meal all year. Non-native deer and elk on Santa Rosa Island added more food. Eagles that stayed to eat piglets also hunted foxes, which are about the size of a piglet and active in daylight.
5 Card 5 (Set B): The missing guardsBald eagles once nested on the Channel Islands. They eat mostly fish and seabirds, and they drive other eagles out of their nesting areas. The pesticide DDT, released into the ocean near Los Angeles in the mid-1900s, built up in fish and made bald eagle eggshells so thin that they broke. By the early 1960s bald eagles had disappeared from the islands, leaving an empty niche that golden eagles moved into.
6 Card 6 (Set B): Catalina's different problemFoxes on Santa Catalina Island also crashed in the late 1990s, but golden eagles were not the cause there. Canine distemper, a virus that infects dogs, foxes and their relatives, probably arrived with an animal from the mainland and killed most of the foxes on much of the island.
7 Card 7 (Set C): Solution 1, captive breedingStarting in 1999, biologists caught surviving foxes and bred them in pens on the islands. Over the program, 226 foxes raised this way were released into the wild. Strengths: stopped the slide toward extinction quickly, and pens kept foxes safe from eagles. Weaknesses: foxes released while golden eagles remained could be killed; a few captive foxes hold only part of their subspecies' genetic diversity; pens need staff and money every day.
8 Card 8 (Set C): Solution 2, moving golden eaglesFrom 1999 to 2006, biologists captured 44 golden eagles on the islands and released them on the mainland. Strengths: removes the main cause of fox deaths directly, without killing the eagles, which are a protected native species. Weaknesses: the eagles were hard to trap, so it took years; as long as piglets remained, new golden eagles could arrive to replace the ones removed.
9 Card 9 (Set C): Solution 5, vaccinating foxesOn Catalina, biologists vaccinated captive and wild foxes against canine distemper and also bred foxes in pens. Strengths: targets the real cause on that island. Weaknesses: new pups are born every year and need vaccinating too, and the virus could still arrive with pets or stowaway animals from the mainland.
10 Card 10 (Set D): Solution 3, removing feral pigsIn 2005 and 2006, professional hunters removed 5,036 feral pigs from Santa Cruz Island. Strengths: takes away the food that drew golden eagles, and native plants recover once pigs stop rooting up hillsides, which also reduces soil erosion. Weaknesses: costly and slow to plan; some people objected to killing so many animals; it does nothing for foxes that have already died.
11 Card 11 (Set D): Solution 4, bringing back bald eaglesBeginning in the early 2000s, young bald eagles were released on the Channel Islands. In 2006, the first bald eagle chick in more than 50 years hatched there without human help. Strengths: restores a native species that keeps golden eagles out of its nesting area, and once established it needs little help. Weaknesses: slow; DDT still buried in ocean mud near Los Angeles can harm eggs.
12 Card 12 (Set D): The resultsAs of 2015 there were about 700 foxes on San Miguel, 1,200 on Santa Rosa, 2,100 on Santa Cruz and 1,800 on Catalina. In August 2016, the San Miguel, Santa Rosa and Santa Cruz foxes were removed from the endangered species list, the fastest recovery of any U.S. mammal listed under the Endangered Species Act. The Catalina fox was moved from endangered to threatened because disease is still a risk.
Criteria and constraints for judging a solution — Criteria (what a good solution does): A. acts fast enough to prevent extinction; B. removes a root cause rather than only a symptom; C. keeps working without constant human help; D. restores native species and the ecosystem services the islands provide, such as soil held in place by native plants. Constraints (limits every solution must respect): scientific (it must be possible with the tools and knowledge available), economic (money and staff are limited), and social (the public and the agencies involved must accept it). Your group may add one criterion if everyone agrees.

Part A: Expert round (one set per person)

1.Your expert set: ______. Write the two most important facts from your three cards, including at least one number, and one question your cards raise that another set might answer.

Part B: Home group task

  1. Teach your cards in order, Set A first. Listeners write one fact from each set.
  2. Build a cause-and-effect chain on scrap paper from DDT and the feral pigs to the fox crash, using arrows. Every arrow must be supported by a card number.
  3. Score each of the five solutions against criteria A to D in the decision table.
  4. Decide as a group which combination of solutions explains the recovery on the northern islands, and why Catalina needed something different.
  5. Every member must be able to explain one arrow in the chain and one score in the table.
2.Group answer: Write your cause-and-effect chain from DDT and feral pigs to the fox crash on the northern islands. Put the card number that supports each link in brackets, for example [Card 5].
3.Group answer: Score each solution 2 (meets the criterion well), 1 (partly) or 0 (not at all). In the last column, name the constraint (scientific, economic or social) that makes the solution hardest to carry out.
A. FastB. Removes a root causeC. Lasts without constant helpD. Restores natives and servicesTotalHardest constraint
1. Captive breeding
2. Moving golden eagles
3. Removing feral pigs
4. Bringing back bald eagles
5. Vaccinating foxes (Catalina)
4.Group answer: No single solution scored 2 on every criterion. Explain why the northern islands needed a combination, and say which solutions handled the emergency and which handled the root causes.
5.Group answer: Why would moving golden eagles and removing pigs have done little to save Catalina's foxes? Which solutions fit Catalina's problem?

Part C: Individual accountability (complete alone)

6.Feral pigs never ate a fox. Explain how pigs, an introduced species, still caused fox deaths. Is this a direct or an indirect effect?
7.Santa Rosa Island's foxes went from about 15 to about 1,200 by 2015. How many times larger was the 2015 population? Then explain why the recovered foxes may still carry less genetic diversity than the foxes before the crash.
8.Predict what would most likely have happened if managers had removed the pigs but had not started captive breeding or moved any golden eagles. Use card evidence about timing.
9.A classmate says, 'Captive breeding saved the island fox, so it was the best solution.' Evaluate this claim using at least two criteria and evidence from at least three different cards.

Root cause or symptom?

A symptom is what you see going wrong: foxes dying. A root cause is what keeps making it happen: golden eagles that stay because piglets feed them, and an empty bald eagle niche. A solution that treats a symptom works quickly but must keep going. A solution that removes a root cause may be slow but can stop the problem for good. For each solution card, ask: 'If we stopped doing this tomorrow, would the problem come back?'

Write card 13

Today, island fox managers worry most about disease, ticks and other threats arriving from the mainland. Write a thirteenth card in the same style as the others that proposes a new solution for keeping a disease such as canine distemper off the islands. Include its strengths and weaknesses and the constraint (scientific, economic or social) that would make it hardest to carry out. Then score it against criteria A to D and explain whether it should be combined with vaccination.

Angela's Tools · Chapter 27 · BiodiversityWorksheet 8 of 10