What is the summer solstice?
The summer solstice — aka, June solstice — marks the beginning of the astronomical summer season. On this day, the sun’s path arcs higher, making its trip across the sky longer than usual. As a result, the day of the solstice is longer than any other day of the year.
It is also during this period that the Earth’s axis — which is what gives our planet its seasons — changes to about 23 degrees, causing the Northern Hemisphere to get a better view of the sun for the season.
While this slight tilt might seem like no big deal, it’s quite the opposite. 23.4 degrees is the most the Earth can tilt towards the sun, meaning that on the June solstice, the Earth’s axis is at its maximum.
What does all of this have to do with animals? Find out, ahead.
How the summer solstice affects animals
Humans are notoriously bad at telling time during mostly dark or light periods of time. In large part, that’s because sunlight has a major influence over our natural sleep-wake cycle. If you’ve ever fallen asleep with your curtains open and woken up with the sun beaming on your face, you know what we mean.
While dark and light help us decide when it’s time for bed or time to wake up, the same can’t be said for animals. In an interview with Live Science, biologist Cory Williams explained how many animals — especially those in the northern latitudes — can control their sleep-wake cycles naturally, even during the longest days of the year. “There are animals that stop having a prolonged period of sleep,” Williams told Live Science. Instead, these animals do away with their typical daily sleep routines and adapt to a new cycle for the season.
In addition to sleep, the summer solstice can also affect the way an animal eats. When foraging at night, species in the more northern latitudes can no longer guarantee protection from predators because it’s daylight at all hours of the day. Instead, many animals — such as reindeer — base their sleep schedules on their digestion (don’t we all). As soon as they feel they need to digest, they get some shut-eye, resulting in many naps throughout the day.
That said, not all polar animals experience such a drastic change to their hunting (and sleeping) schedules. Case in point: Long summer days don’t phase the arctic ground squirrel. It carries on with its usual sleep schedule and calls it a day when the sky is at its darkest (which isn’t even that dark).
Right now, scientists are studying the difference between the polar animals that stick to their respective schedules and those that don’t. As the Earth’s temperatures increase, many species are migrating north in search of cooler weather. Scientists like Williams are interested in how these species will respond to the extreme conditions in the North. This includes extended periods of daylight caused by the summer solstice.
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