Bright side of the night – 2.1.2

Activity patterns

Nocturnal wildlife

About two-thirds of the world’s animal species are nocturnal, including about half of all insects. This means that they are active during the night. Nocturnal animals depend on darkness and natural light from the moon and stars for orientation, movement, breeding, hunting or foraging, and avoiding predators and food competitors. What they all have in common are special gifts of sensory perception and adaptation strategies to life at night.

High life in dark hours

When night falls, life awakens. Under the cover of darkness, animals like hedgehogs feel safe from predators. Others such as eagles or owls follow their prey. In summer nights, bats find sufficient food — available in the form of nocturnal insects. Moths pollinate evening primroses, which open their flowers only at dusk. Amphibians are active at night to protect themselves from dehydration, as they do not tolerate solar radiation and high temperatures well. Roe deer and red deer are generalists: they are often seen around dusk. Trout, for example, are also particularly active during twilight — they are sight hunters that can still profit from nocturnal insects at dusk. Small mammals such as field mice are often not clearly classifiable as day or night animals, as they have to eat in both halves of the day due to their high energy consumption. Other animals again have become nocturnal to avoid the human buzz, such as the European brown bear, wild boars, and foxes.

A specialised field of research for biologists

A special strand emerged in the natural science to focus specifically on darkness. This field of research is called scotobiology. The study of biology as directly and specifically affected by darkness. Some of this work has been going on for over a century, and lays the foundation for understanding the importance of dark night skies, not only for humans but for all biological species. A key observation is that most life has evolved to accommodate starlight and, plus, bright moonlight for about a week every month. Living species need the remaining three weeks of only starlight to recover from the bright moon. Any additional light is seen as a stressor that interferes with the rhythms and behaviors of humans and animals. This means that the lit environment is not one for which species have evolved. While behavior can change within some decades, biochemistry cannot. Rather, it evolves over ten thousands of years.[1]

Light and noise-multisensory pollution researchers at the University of Groningen found that “multisensory pollution” — the combination of light and noise at night — has special effects on species across the board and may therefore pose a considerable threat to wildlife. While reactions vary widely, they are significant.[2]

[1] CSbG Inc 2022

[2] Dominoni et al. 2019

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Eurasian pygmy owl – Image by Erik_Karits ̶ Pixabay

Bird in the moonlight – Image by Ruwadium ̶ Pixabay

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Images

There is a selection of photos of nocturnal animals available at pixabay.