Breaching is one of the most spectacular things you can see while on a whale watch. Whale watchers and scientists alike have often wondered why whales sometimes engage in this most impressive and acrobatic of all whale behaviors. Thus I figured I’d write a page dedicated to discussing the various theories which have been prosed to explain breaching behavior in whales… Humpback Whales in particular.
In this spectacular display of athletic prowess, the whale will dive beneath the surface for a few seconds or minutes only to surface vertically with great speed. Often the animal will twist while in mid-air and then come crashing down with thunderous splash.
While all whales have the ability to breach, none do it as often as the Humpback Whale. But while breaching is quite common amongst Humpback Whales it is certainly not something that we see on every whale watching trip.
Trying to predict the odds of seeing a whale breach when you go whale watching is difficult. In essence, your chances of seeing a Humpback whale breach is quite good– maybe 50%– when there are a lot of whales in the area. When there are fewer whales in the area the chances that one of them will become active is, of course, less (maybe less than 10%). So, to some extent at least, the chances of seeing breaching on a given trip is dependent upon the overall abundance of whales.
Another reason that predicting when whales will become active is that there is no time of the year or day that whales are more likely to breach! You simply need to be in the right place at the right time to see it when it does. Obviously the more time you spend watching whales the better the chances you will see one breach. Ultimately that’s really how ALL of nature watching works: The more time you spend watching, the more you will see.
Sure there are those that go out on their first whale watch and see lots of breaching/active whales… but that’s really just luck. There are plenty of people who go whale watching many, many times before seeing a whale breach. So it all averages out. The one possible exception to this is that we it seems as if breaching may happen more in rough weather than in calm seas. So it can be a reward for people who venture out to sea on less-than-ideal days. I’ll explain the reason for this possible connection between rough weather and surface activity in a bit…
But WHY do they breach?
All this talk about what the Humpback Whales do when they breach and when they are likely to do it doesn’t tell us anything about why they are doing it. There are many different theories that have been put forth that attempt to explain breaching behavior, and, to be honest, I think they are all true at least some of the time.
Some of the main theories include:
1. REMOVAL OF PARASITES
Whales breach ( or flipper-slap/tail-breach/etc) to help rid themselves of parasites. Whales, Humpback Whales especially, sometimes carry a variety of external (as well as internal) parasites that may cause itching and irritation to their sensitive skin. These parasites include barnacles (Humpback can carry close to 1,000lbs of barnacles on their body which sounds like a lot of extra weight to lug around but relative the total mass of the whale it is only equivalent to us wearing shorts and a t-shirt!) as well as small crustaceans called “Cyamids” or “Whale Lice.”
Above: A close-up of three Cyamids. Below: A photo of a “spy-hopping” Humpback Whale where you can see a few Cyamids who are living on the whale’s chin! 
Barnacles tend to cluster on the whale’s chin, flippers, tails, and bellies. Cyamids tend to congregate on rough or folded regions of the whale’s skin and feed directly on the whale’s skin tissues.
Perhaps the tremendous forces associated with surface activity helps the whales rid themselves of these unwanted pests.
2. AID IN DIGESTION
Whales may breach to help move food along in their digestive tract. While visiting the coastal waters of Massachusetts a Humpback Whale might consume over 1 ton (2,000lbs) of fish every day! That’s equates to well over a million calories worth of food each day! Some people have theorized that increased activity may help move food along through the whales digestive system… a lot like if you were to go for a walk after eating a big meal.
A feeding Humpback Whale.
3. JUST FOR FUN!
Certainly in the case of young calves breaching could very often just be for fun! Young whales, just like the young of any mammal, do have a keen sense of play which is actually quite important for exercising growing bones and muscles, as well as building body awareness and coordination.
A breaching Humpback Whale calf.
So just like a puppy, kitten, or even a human toddler, whale calves can be very playful and active, especially when the adults are occupied with other things like feeding.
Imagine bringing a child to a restaurant where you are meeting a few friends who are also bringing their kids. When you and the other adults are gathered around the table talking about grown-up stuff the kids might get a little bored, restless and start running around and getting into mischief. This might be similar to when the adult whales are busy feeding on the massive schools of fish so commonly found in our area and the calves are left unattended.
4. COMMUNICATION
Perhaps the most widely accepted theory of whale surface activity, however, is that it is a non-vocal form of communication amongst whales.
If you are fortunate enough to take a whale watching trip to Stellwagen Bank or Jeffrey’s Ledge and witness surface active Humpback Whales yourself, you will no doubt be struck by the tremendous amount of sound created by the body of the animals pounding at the water’s surface. Now consider that sound travels about 4.5X faster through water than it does through air, and that water also conducts sound signals “better” than air in the sense that sound signals do not degrade as quickly in a liquid medium (such as seawater) as they do in a gaseous medium (such as air). So it is not unreasonable to think that when a whale is breaching that other whales, possibly tens-of-miles away, could be hearing the sounds produced by this activity.
There have been many times when we are watching a whale that suddenly becomes active and then we observe splashes in the distance a short time later from other whales that we didn’t even know where in the area! It seems as if these whales heard the activity of the whale that we were observing and then answered back by performing a similar activity. This would lend credence to the idea that the activity is a means of communicating with other whales. This is, perhaps, why we do tend to see breaching more regularly in rough weather. As the sound of wind and waves at the water’s surface get louder, breaching may be a way to overcome the noise and keep in contact with other whales in the area.
But what are they trying to say? Well, no one knows for sure. I like to make an analogy however and say that it is similar to shouting in humans. Imagine if aliens came down to Earth and asked you why people shout. You might have trouble answering that question decisively because people shout for all kinds of reasons. People shout when they are angry, or excited, or frightened, or when they are trying to get someone’s attention to warn then of some impending danger, or when they are trying to communicate with someone who is far away. In other words, people shout for lots of reasons and the reason someone is shouting depends on the context in which it is done. I think the same could be said for breaching in whales. Whales breach for lots of reasons and to “say” lots of different things. But if we could translate what a whale was saying with a breach it would be typed in all caps and have an exclamation point after it!
In conclusion: No one knows why whales exhibit this spectacular behavior. They probably become breach for all these reasons listed above at one time or another… and maybe for reasons that haven’t even occurred to us yet. All we as whale watchers can do is hope to be present when these behaviors occur… and hopefully we’ll have our cameras ready too!