Squirrel Lab
Problem: How does competition between native and invasive squirrels affect population size?
Research:
http://en.wikipedia.org/wiki/Red_squirrel
http://en.wikipedia.org/wiki/Eastern_gray_squirrel
Red Squirrel
- Not sexually dimorphic, which means that males and females are the same size.
- Its long tail helps it to balance as it jumps and scurries up trees. Its tail also keeps it warm during its sleep.
- The coat of the red squirrel varies from red to black depending on region where they live.
- They are about 7.5 to 9 in long and weigh 8.8 to 12 oz.
- Sheds coat twice a year, switching to a thinner coat for summer, and then thicker for the winter and also has eat tufts during fall and winter.
- They have sharp, curved claws and also strong hind legs and they can also swim.
Eastern Gray Squirrel
- Fur color varies from gray to brown and a large bushy tail.
- Its length is 12 in long and weighs about 21 oz.
- Its tracks are difficult to tell apart from the fox squirrel and the Abert's squirrel.
- It can be found in Eastern US and Canada.
- Their bounding stride can be 2 to 3 feet long.
Hypothesis: The population of red squirrels will decrease when the invasive more fit grey squirrels are
introduced into the ecosystem over time.
Experiment: Squirrel Ecosystem (outside activity)
Data Table:
Research:
http://en.wikipedia.org/wiki/Red_squirrel
http://en.wikipedia.org/wiki/Eastern_gray_squirrel
Red Squirrel
- Not sexually dimorphic, which means that males and females are the same size.
- Its long tail helps it to balance as it jumps and scurries up trees. Its tail also keeps it warm during its sleep.
- The coat of the red squirrel varies from red to black depending on region where they live.
- They are about 7.5 to 9 in long and weigh 8.8 to 12 oz.
- Sheds coat twice a year, switching to a thinner coat for summer, and then thicker for the winter and also has eat tufts during fall and winter.
- They have sharp, curved claws and also strong hind legs and they can also swim.
Eastern Gray Squirrel
- Fur color varies from gray to brown and a large bushy tail.
- Its length is 12 in long and weighs about 21 oz.
- Its tracks are difficult to tell apart from the fox squirrel and the Abert's squirrel.
- It can be found in Eastern US and Canada.
- Their bounding stride can be 2 to 3 feet long.
Hypothesis: The population of red squirrels will decrease when the invasive more fit grey squirrels are
introduced into the ecosystem over time.
Experiment: Squirrel Ecosystem (outside activity)
Data Table:
Graph:
Questions:
It was easiest for the red squirrels to find resources during years 1 - 7 and it was hard for them to find resources during years 8 - 19, and then in year 20, the whole red squirrel population died. So during the first few years they had plenty of food, and then the gray squirrels came in with the same niche and then resources are limited so strongest gets the food.
Organisms in the same population compete for resources when they have the same niche and then natural selection will happen and the strongest of the organisms will survive and reproduce. So in this case, the gray squirrel is much stronger than the red squirrel so it survived and reproduced.
Resources are affected by competition when 2 different species need the same resources to survive. If two organisms are competing, then the resource supply would run low, from both species eating, and then the strongest of the 2 species would get the resources, the gray squirrels, and the other species would die out, the red squirrels.
To avoid extinction from competition, the red squirrels would have to eat something else than nuts and berries and would have to adapt to live somewhere else than the trees and migrate because gray squirrels already dominate that area.
Conclusion:
Claim: The population of the red squirrels did decrease when the invasive gray squirrels were introduced into the ecosystem.
Evidence: The red squirrels were doing fine from year 1 to 7 and in year 8 the red squirrels started to decrease. The red squirrels were at 150 squirrels at the highest without the gray squirrels and at 98 at the highest with gray squirrels in the area. The gray squirrels were at their highest in year 17 with 186 squirrels. In the beginning there were 87 red squirrels and 0 gray squirrels, and in the end there were 0 red squirrels and 178 gray squirrels.
Reasoning: In the beginning, the red squirrels had plenty of resources because the gray squirrels were not introduced to the ecosystem yet. Then gray squirrels were introduced into the ecosystem in year 8 and the red squirrels started to decrease because they were competing for resources with the stronger gray squirrels, who also had the same niche as them. The gray squirrels, the strongest of the 2 organisms got to the resources first, which left the red squirrels to starve and die out slowly. So in the end, the gray squirrels survived and reproduced and became the only species with that niche in the ecosystem in year 20 at a number of 186. But even when the red squirrels were thriving they only had 150 squirrels at the highest while on the other hand with the gray squirrels they had 186 squirrels when they were thriving so it clearly shows that the gray squirrels are the stronger species.