From Joyce’s Ulysses to the Beatles’ “A Day in the Life,” Jeanne Dielman, 23 quai du Commerce, 1080 Bruxelles to Boyhood, the past century has brought us great art and greater attention to the potential of our everyday routines, and bats are no different. They too are locked into a life of routine, and while they may not be able to create Modernist, musical, or movie masterpieces about it, their day-to-day life is still worth considering.
What’s more, bats are highly seasonal animals. At the same times each year, they awaken from their yearly hibernation or return from their migration, take up residence in the same roost or cave they call home, go about their daily routine for several months, and then hibernate or migrate once more.
Still, while that routine may seem highly regimented, there is plenty of variation in bats’ lives as external factors and personal choice shape their lives. Maybe you’re someone who’s had to deal with bats roosting near your attic and you’re wondering how much time you have until they come back (and how you should prepare) or maybe you’re just batty about bats.
Whatever your own daily routine may be, learning more about bats’ daily and yearly routines can thus be beneficial.
A Day in the Life of Bats
First and foremost, we need to take a look at bats’ regular routines. At first blush, it may seem pretty simple – “Here Comes the Sun,” there go the bats until daytime ends and “A Hard Day’s Night” of hunting and eating begins for them.
Still, there’s a lot of nuance to that otherwise simple-seeming routine that complicates the question of “when do bats come out?” beyond a simple singular answer.
For starters, the end of the day and the start of night will vary according to the season, with dusk falling sooner in winter while the days are longer in summer. Bats don’t follow the time on the clock but the time set by the sun and moon. As dusk approaches, bats start to feed more voraciously, and they keep this upfor about two hours, though again, it should be stressed that they do not follow a rigid clock. In some conditions, the bats may feed for longer periods of time, especially when insects or the other animals and fruit on which they feed are in abundance. In fact, bat feeding times are so nicethey do it twice per night. In between, they need to rest and digest this food, especially given the fact that bats can eat so much that they can potentially be too heavy to fly immediately afterward.
Whenever it comes, you can typically find them feeding awaytwo to three hours after dusk. Because the days can get so short in summer, you might wonder “do bats fly during the day?” and the answer is no – but that doesn’t mean you might not be able to sneak a peek at them.Bats sometimes roost outside during the day, especially during the summer months when that transitional period between day to dust to full nighttime is longer.
For those familiar with bats hibernation and migration cycles (as discussed below) that may beg another question, “what time do bats return to roost?” First, it should be noted thatbats typically have three types of roosts – one for warmer weather, one for cooler weather and hibernating, and one for mating, with bats cycling through these as the seasons change and if they migrate.
Bats’ Yearly Cycles
Those daily routines form the building blocks of bats’ yearly activities.The Bat Conservation Trust in the UK breaks down bats’ yearly routines, which include the following:
- January and February: Bats in the UK are hibernating, with their metabolism drastically lowered, which in turn lowers their body temperature. Their heart rate and breathing are also slowed. By February, much of the fat they will have put on to live off of during their hibernation cycle will be gone.
- March: Bats are starting to emerge from their multi-month slumber. They start to feed as the weather gets warmer. If the weather is still cold and foul, they may be a bit slower and lethargic.
- April: By now bats have fully gotten back into the swing of things, flying and feeding most nights. They may choose to move their roosts. If the weather is still cold, they may be slower.
- May, June, July, August: Now that it’s summertime, bats are at their most active. Females will start forming special colonies with one another to take care of their young, while males build their own groups. June is the most common month for mothers giving birth. Mothers take care of their babies (which are less than an inch big at birth) with some species growing faster than others. Around the three-week mark after birth, bats learn to fly, and soon after learn to catch insects for themselves. This is also the time when insects are most plentiful and bats are feasting. In the right conditions, they can eat hundreds or even thousands of insects per night. By the end of August, the colonies disperse, and mating begins again. If you are looking to see bats fly around, this is by far the best time to do so (while taking proper precautions, of course.)
- September and October: Mating season is in full swing by September, andcan last through October. Male bats use special mating calls to attract females. In addition to mating, this is also the part of the year where bats are concerned with building up fat reserves in preparation for hibernation. By the end of October, the bats should start to be slowing down.
- November and December: Throughout November, the torpor the bats experience grows greater. The insects on which bats feast should likewise be receding, and by the end of November, the bats are hibernating, and should remain in a deep sleep through December and January, typically waking up late in February at the earliest before really emerging in March.
Other bats migrate rather than hibernate, withlittle brown bats in the United States and Canada flying south to California and Mexico for the winter.
How Humans Affect Bats’ Routines
With bats’ daily and yearly routine established, let’s take a step back and take a look at why bats function that way. We all know that bats are nocturnal, and that they follow the patterns prescribed above, but things are rarely as clear cut as those timetables make their lives out to be. External factors impact our own daily routines, and the same is true of bats. In fact, in recent decades, humans have become one of the biggest elements impacting bats’ daily routines – and not for the better.
For one thing, while bats may favor nighttime, that’s become more complicated given humans’ increased nocturnal activities. After all, bats favor nighttime in large part because of the darkness, but light pollution from cities and even lights in small towns have the potential to throw bats off their routine. For example,churches in Sweden have driven bats from their belfries in recent years since the little creatures don’t care for the newly-installed lights.
However, lighting up belfries and attics may be one way to drive bats out and keep them from roosting on your property, it does leave our furry flying friends vulnerable. Without these roosts to depend on, bats will have to find new, potentially less secure ones, which could make them easy prey for hawks and other potential predators. It isn’t just the disorienting power of lights that causes problems for these nocturnal creatures, either. Bats that have camouflage that adequately disguises them at nightmay be far more exposed at night, making it harder for them to surprise prey while leaving them still more exposed to predators. This is bad news for humans as well – if bats don’t eat those hundreds or thousands of insects during the night, there’ll be more to bother us during the day, including mosquitos.
That’s why bat conservation groups such asEurobats are devising guidelines for helping to manage a balance between lighting public spaces and keeping them bat-friendly so bats can maintain their nocturnal habits and not be driven from their habitats.
If you don’t want to risk throwing daily routine out of whack with too much light, you can instead prevent them from roosting in your attic or elsewhere on your property by making sure that you close off any open spaces on your property. Caulk up any holes in your walls, even if they are “only” a couple of centimeters. Pay special attention to bat-friendly parts, such as your attic and chimney.
Bats, like humans, have daily and yearly routines that can be part of a healthy lifestyle. When our routines come into conflict, it can be bad for both parties. That said, bats and humans don’t have to exist at cross purposes – “We Can Work It Out” and coexist, and understanding bats’ routines is a great start to that.