Question

a biologist is studying the population of song sparrows in a region. the graph shows the number of song sparrows in the region from 1975 to 2000.
the winters in 1980 and 1989 were particularly severe. which factor most likely explains the decline in the song sparrow population during these two years?
loss of habitat
less food availability
increased reproductive rate
increase in predator population

Explanation:

1. Analyze each option:

• Loss of habitat: Severe winters don't directly cause habitat loss (habitat loss is more about human activity, deforestation, etc.).
• Less food availability: Severe winters can make it hard for plants (food source for sparrows or their prey) to grow, reducing food. This is a direct result of harsh winter conditions.
• Increased reproductive rate: Would increase population, not decrease it.
• Increase in predator population: Severe winters would likely affect predators too, and there's no info suggesting predator increase.

1. The most logical factor tied to severe winters is less food availability.

Answer:

less food availability