"Merry it is while summer lasts,
With birds in song;
But now the wind's blast draws near,
And the weather grows harsh."
So goes one modern translation of one of the oldest surviving secular songs, written nearly 800 years ago.
It captures something people have always known: summer is fleeting and winter is hard. For wildlife, that reality is measured not in comfort, but survival.
As the days begin to shorten, changing day length triggers hormonal changes that tell animals winter is on its way, long before the first snowfall. For the wildlife of the Great Lakes region, the coming season brings relentless pressures.
The long nights leave less time to forage, while food becomes increasingly scarce. At the same time, bitter cold forces animals to burn precious calories every hour simply to maintain their core body temperature.
Water, too, can become surprisingly difficult to find.
Ice seals ponds and streams, and while animals can eat snow, melting it inside the body costs valuable metabolic energy. Whenever possible, they seek flowing water or moisture from the foods they eat instead.
Deep snow creates another obstacle. Every single step requires more physical energy, making it harder to reach what little food remains hidden beneath the drifts.
By late winter, many animals have exhausted much of the fat they accumulated during autumn. Females of some species enter spring in poorer condition, leaving less energy for pregnancy, nursing and raising healthy young.
So when the days grow short and the birds stop singing, some creatures hibernate. Others migrate.
But for many of our resident mammals, winter is coming.
"The weather grows harsh," and they are preparing now — not to thrive, but simply to endure until spring.
