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Illinois Summer Nights
Who’s awake and who’s asleep?
Many different animals have different times when they are active. Some animals in the same area may never see each other because of when they are awake or asleep. This is called temporal niche differentiation. Some animals shift between times when they are active based on the time of year or where they live.
It’s All in the Numbers
Mammals Across the World
- 70% of mammals are nocturnal
- 20% are diurnal
- 2.5% are crepuscular
- 8.5% are cathemeral (active at irregular intervals across both day and night instead of following a strict daytime or nighttime schedule)
Mammals in Illinois
- over 60% are nocturnal
- Mammals in urban areas are more nocturnal than in rural areas to avoid humans
