“Why are there so many rabbits in my neighborhood?” It’s a question that’s been showing up with increasing frequency over the last couple years, much like the rabbits themselves.
There are two native rabbits in Southwest Florida: The eastern cottontail (Sylvilagus floridanus) and the marsh rabbit (S. palustris). They’re pretty easy to tell apart. Marsh bunnies are smaller, darker and have much shorter ears. Also, marsh rabbits are more likely to walk than hop (though they will jump if they’re in a hurry, and cottontails sometimes walk also).
A woman emailed me a couple years back asking if we had wild guinea pigs here. I thought maybe she meant muskrats, but it turned out she had a couple marsh rabbits in the backyard. Of the two, the cottontail is much more common, and that’s the one we’re focusing on.
Cottontails truly do breed like rabbits, and it’s good thing they do. Nature’s main purpose for cottontails appears to be the feeding of various predators. They are staple menu items for bobcats, coyotes, foxes, great horned owls, red-tailed and red-shouldered hawks, and eastern diamondback rattlesnakes. Many smaller meat-eaters will dine opportunistically on the young.
A cottontail doe can produce her first litter as young as three months, with an average of three to six (but up to a dozen) kits born. Here in the land of no winter, she can continue to raise young year-round and may have a litter every two months.
You like math, right? Let’s do some real quick. In the absence of predators or disease, a single doe could realistically produce 36 kits a year (six per litter, six litters in 12 months). We’ll start her off in January. By April Fools Day, her female babies are having babies (three more does, times six babies each — another 18 rabbits every two months). Come June 1, half of those are having babies too.
It’s a tricky calculation, but assuming she and her female offspring each begin reproducing at three months, have litters every two months and average six kits per litter, that one mama bunny could multiply to 1,105 rabbits in a year. But she won’t. Only one in four kits survives long enough to reproduce, and the mortality rate for cottontail rabbits — the percentage that die annually — is about 85%.
So now we know why we’re not up to our ears in bunnies. But why are there so many lately?
Every species has its good years and its bad years. Sometimes we understand why. If the rains come late in summer, the amount of fresh green vegetation will be lower, so there will be fewer caterpillars, so birds that rely on those caterpillars to feed their babies will raise fewer nestlings. It’s direct cause and effect.
Cottontails don’t work that way. Instead, they boom and bust in cycles that are poorly understood.
Think back to about six or seven years ago. How many wild rabbits were you seeing? I’ll bet you can’t tell me, because you have no notes. But I can tell you this: You were almost certainly seeing fewer than you are now.
The bunny cycle lasts somewhere between six and 10 years. At the low point, you might think cottontails had gone extinct. They’ll be rare as proverbial hen’s teeth. You’ll have to look hard to spot just one or two, and when you see them, you’ll be surprised because it’s been so long since you saw a rabbit (and then you’ll be surprised to realize that, since they were so common not too long ago).
Slowly, over the next few years, you might notice bunnies becoming more abundant. Even in areas with great rabbit habitat (which I think we should call rabbitat), this is a gradual rise. Where there are predators, the population can’t explode. There are too many hungry mouths ready to eat them. But being such great multipliers, the rabbits generally win the race through sheer numbers.
That’s how we got to the point where we are today. Bunnies everywhere! Here a bun, there a bun, everywhere a bun-bun! These are good times for nature lovers and rabbit predators alike. More hippity-hops means more food to raise litters of bobkittens and fox kits. Let the good times roll. (Unless they’re in your vegetable garden, in which case a short 12-volt electric fence does an OK job of keeping them out.)
But on the horizon, disaster lurks. Just like the stock market in 1929, the crash is coming. We’re not really clear on what exactly happens at this tipping point. Denser populations may lead to higher disease rates. Perhaps too many rabbits leads to a shortage of greens with critical nutrients. The idea has even been floated that pheromones from other cottontails might lead to decreased fertility.
Whatever causes it, it happens fast. In the course of just a few months, rabbit numbers free-fall. Where does the decline stop? It’s different every time, but it’s believed that the population usually stabilizes at 15 to 30% of its peak. That’s a huge dip, and it comes with consequences for the whole food chain.
Predators that depend heavily on cottontails take a major hit. A much smaller rabbit population can’t support the number of bobcats and foxes and hawks it did before. Sure, they can switch to other prey — but not all of them will be successful in finding enough calories that way. In such lean times, survival of the fittest comes into its own.
While this may seem a heartlessly cruel trick for Nature to play, at least it’s a temporary one. As the rabbit population starts to build again, so too will their predators. This boom-and-bust cycle has been going on for thousands of generations. It’s the way the world works.
Capt. Josh Olive is a fifth-generation native Florida Cracker and a Florida Master Naturalist, and has been fascinated by all sorts of wild things and places since he was able to walk. If you have questions about living with wildlife, contact him at Publisher@WaterLineWeekly.com or 941-276-9657. You can also follow him on Instagram @florida_is_wild.