Spring is a fun time to migrate to the zoo

March 20 marks the first day of spring, and while the weather has been a bit back and forth with warm temperatures on some days and then snow the next, there are hints of spring if you know where to look. For instance, you might have noticed more birds singing on your morning commute, or maybe you were fortunate enough to spot some early flowers poking out of the ground. Either way, spring is in the air!

But how do animals know it is time to come back to their northern breeding grounds or wake up from hibernation? What is it that triggers the plants to start growing and the trees to sprout new leaves? It turns out that there are a variety of factors, often not fully understood, that work together to tell the world that it is time to start another green growing season.

Temperature is, of course, one of the biggest factors. As the weather warms up, it prevents frost from forming and damaging newly emerging plants. As the grasses, flowers and trees begin to grow, they form the basis of the food web and provide sustenance for all the hungry animals and insects that make up the next layer of the chain. Temperature changes are also a cue for animals to enter into hibernation in the fall and then wake up from their deep sleep in the spring.

Then there is the length of daylight, which is thought to be the most important factor to stimulate both hibernation and migration. Our recent change to Daylight Saving Time helps us notice what the animals have been observing for a while: that the days are gradually getting longer and the nights are getting shorter. In fall, the shorter daylight hours trigger a response in birds to migrate south. The longer daylight hours in spring trigger these same birds to start their long journey back north. Length of day also acts as a cue for hibernation in many animals, encouraging them to store up food and fat so they can snooze away the cold winter days.

Another influence that works very closely with the amount of daylight is hormone fluctuation. The reproductive cycle of many animals is often tied to the length of each day. The shorter days in winter affect the hormone levels in migrators and hibernators signaling them that it is time to either head south or head to bed. And spring is the ideal time to reproduce. Food and water are more readily available, temperatures are acceptable for baby-rearing and there is enough time for the young to grow stronger before they have to face the challenges of winter.

However, realizing it is time to migrate is only half of the battle. How do the animals know where to go? Birds are especially good migrators and use a combination of signals to help them navigate each year. From the position of the sun and stars, to landscape features such as rivers, coastlines and mountains, to the subtle pull of the earth's magnetic fields, these amazing travelers somehow know which way to go year after year.

So as spring approaches and we break out of our own winter dens and begin to enjoy the longer, warmer days that are ahead, don't forget to pause and appreciate all the animals that have survived yet another winter in their own unique ways. Also, be sure to migrate to the zoo where you can enjoy our animals year-round. Keep an eye out for possible spring babies, our extended summer hours (beginning April 1), the new Safari Shoppe Dippin' Dots and other fun, warm-weather activities. We hope to see you soon!