Squirrels Observed Hunting Mice: A Surprising Behavioral Discovery

Researchers have observed California ground squirrels, commonly known for their herbivorous diet of nuts and seeds, hunting and eating mice. This surprising behavior, indicating an aggressive side to these seemingly docile animals, was recently documented in a study published in the Journal of Animal Behavior.

Main Text

For 12 years, Professors Sonja Wild from the University of California, Davis, and Jennifer Smith from the University of Wisconsin, Eau Claire, have been conducting a long-term behavioral study of California ground squirrels. The research included tagging individual squirrels in the Briones Regional Park in Contra Costa County, California, to record data such as gender, weight, and reproductive status.

During observations in June and July, researchers documented 74 interactions between ground squirrels and mice, 42% of which showed active hunting behavior by the squirrels. While their typical diet consists of plants and seeds, this marks the first evidence of the squirrels hunting live vertebrates. However, no evidence of them preying on mammals other than mice was found.

The research team noted that squirrel hunting behavior peaked during the first two weeks of July, coinciding with a surge in the local mouse population. This suggests that the behavior may be opportunistic, driven by the abundance of prey. According to the scientists, this indicates the squirrels’ adaptability to changes in their ecosystem.

Squirrels, traditionally considered herbivores, may be better classified as opportunistic omnivores, hunting when live prey is plentiful. The mice provide significantly more nutrients than the squirrels’ usual diet of nuts and seeds.

Implications of the Study

The findings open new questions about the extent and genetic basis of hunting behavior among squirrels, as well as its impact on ecosystems. The researchers aim to return to the field next year to investigate the effect of mouse hunting on reproduction and other ecological factors.

Professor Smith emphasized that the study contributes to understanding how squirrels and other mammals adapt to their environments, highlighting the complexity and diversity of animal behavior.

Questions and Exercises

A. Vocabulary Practice

Choose the correct word from the list: herbivorous, vertebrates, adaptability, opportunistic, abundance.

1. Animals with backbones, like mice and squirrels, are called __________.
2. A diet consisting only of plants is referred to as __________.
3. The behavior of taking advantage of situations, such as hunting during a mouse population surge, is called __________.
4. The ability to adjust to changes in the environment is known as __________.
5. When there is a large number of something, such as mice in the park, it is described as an __________.

B. Comprehension Questions

1. What surprising behavior did researchers observe in California ground squirrels?
2. How did researchers gather data on the squirrels?
3. When did the squirrels’ hunting behavior peak, and why?
4. Why do researchers believe the squirrels’ hunting behavior is opportunistic?
5. What questions do scientists plan to explore in future studies?

C. Discussion

1. How does this discovery change your perception of squirrels?
2. What might this behavior suggest about the flexibility of animal diets?
3. Do you think this hunting behavior is beneficial or harmful to the ecosystem? Why?
4. Have you observed animals behaving in unexpected ways? Share your experience.
5. Why is it important to study animal behavior in the wild?

D. Research Project

Compare two types of squirrels based on their diet and behavior:

• Squirrel Type 1: California Ground Squirrels
• Squirrel Type 2: (Research another species, e.g., Eastern Gray Squirrels)

1. Primary food sources:
2. Notable behaviors:
3. Adaptations to their environment:
4. Interaction with humans:
5. How these factors influence their role in the ecosystem:

Answer Key

A. Vocabulary Practice

1. vertebrates
2. herbivorous
3. opportunistic
4. adaptability
5. abundance

B. Comprehension Questions

1. Researchers observed California ground squirrels hunting and eating mice.
2. They tagged squirrels and recorded data such as gender, weight, and reproductive status.
3. Hunting behavior peaked in early July, aligning with a population boom of mice.
4. The behavior appears driven by the sudden abundance of prey.
5. Scientists want to study how common hunting is, whether it is inherited, and its ecological impact.