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Naturalist’s Notebook: May 17 to May 23

The continued references of feeding whales this week remind me that the area around Cape Cod and Stellwagen Bank are very much a huge restaurant for whales, as well as numerous other species.  Most of the whales that come to our waters in the springtime are returning here from warmer waters, further to the south, where they have spent the winter months giving birth to their calves and possibly mating.

Humpback whales are spending the winter months in the warmer waters of the Carribean, off the coast of the Dominican Republic and Puerto Rico.  In the waters of Samana Bay and Silver Bank, they are giving birth and mating.

Right whale females spend the early winter months off of the coasts of Florida and the Carolina’s, giving birth to their young.

Gathering together in large groups for the purposes of mating and birthing is a defensive strategy.  When a female is giving birth, she and the calf are vulnerable to predators.  Being in large groups helps to dissuade predators like large sharks and orcas from attacks.  It is like going to the mall with your frineds.  There is safety in numbers.  Also, and in a beautiful demonstration of how nature works, just like being in a school of fish, the closer other vulnerable whales are to you the better your chances of survival.

Minke whales and Finback whales appear to use a very different strategy when giving birth.  Rather than gather closer together, they spread themselves out over the open ocean.  This changes the chance of their survival to the chances of a large predator finding them in the huge amount of water that is the open Atlantic.  This is more like when you are playing paintball and you spread your team out so that you are harder to find in the field.  As a single operative, you are less likely to be located because all of you are spread out and there is no group to focus on.

Anyway, the point is that whether the whale is spending its winter months in the warmer waters or deep at sea, there is little food for it to feed upon.  In the subtropical and tropical waters, the nutrients are quickly absorbed by the coral reef and little is left to support free-floating phytoplankon.  There are huge numbers of different kinds of small fishes but very small numbers of any individual kinds.  Nothing exists there in suitable enough quantity to be a food source for a large whale.  And in the open sea, the surface waters are nearly a desert because there is no current bringing the nutrients from the deep to the surface where there is the benefit of sunlight.  Either way, for that part of the year, most of the whales are not eating anything because there is nothing for them to eat.

When they return here in the spring, they are coming to our area  for one reason and one reason only.  TO EAT.  They will spend the next six to eight months feeding on as much food as they can possible find, hoping to rebuild the blubber layer that has sustained them through their winter fast.

When we look in the mirror,  we may not think so, but blubber is an incredible invention of nature.  In addition to being a way to store nutrients for future use, it is also an effiecient way to store water (as in the fat in the hump of a camel), and a beautiful way to provide insulation for warm-blooded animals against not just the colder waters around them but also the warmer waters as well.

For our purposes, now, we will focus briefly on blubber’s use as a storage container.  In our bodies, our cells get the energy to work from the calories found in simple sugars and nutrients are generally used to build proteins.  When there is an overabundance of calories and nutrients, they are generally converted to fats for storage until they are needed.   If they are needed quickly, they are converted back into sugars and used.  If they are not, they are converted to fat (blubber) for long term storage.  That is when they start to effect our belt size.  Unlike with us, a whale wants to put on as much fat or blubber as it can during the feeding season so that it has a stockpile of nutrients and energy for the four or five months where it won’t be eating.  Since a pregnant female may loose as much as a third of her body weight over the period of 3 or 4 months when she gives birth to her calf and nurses her calf, she wants to be as big as she can when she goes to give birth and she needs to put that weight back on as quickly as she can once she has done so.

Ok, blubber is really cool for other reasons too.  And one is its ability to act as an insulating agent.  Most whalewatchers understand that when the warm-blooded whales are in colder waters, it is blubber that helps them maintain their internal body temperatures.  But blubber is like the pizza delivery bag.  Not only does it help to contain the internal body temperature (hot pizza temperature) in colder places, it also helps maintain that same temperature when the whales are in really warm waters.  Like the pizza bag.  If you take the hot pizza out and put a cold soda in it, the soda stays cold.

And, as I alluded to earlier, the blubber of a whale is like the fat in the hump of a camel.  Chemically, it is a storage place for water.  While the whales are feeding, they get their fresh water largely from the bodies of the fish that they are eating.  Just like our bodies, the bodies of schooling fish are roughly 70 percent fresh water with a handful of salt.  But in the months when the whales are living off of their fat stores, this is incredibly important.  It would be like a camel without the storage ability of its hump.  The whale would become dehydrated.  Just like our bodies, the bodies of whales are not designed to process large amounts of salt water.  It cannot just drink salt water, it needs to rely on the fresh water of its fat reserves.

So the waters around Cape Cod are a feeding ground, very much like a restaurant.  And with baleen whales, seeing them in a group here is very much like going to a restaurant with a couple of friends.  You might go in there with a friend or two, but there will be 50 or 60 or 70 other people there.  You didn’t all come in together.  You don’t all know each other.  But you all came there for the same reason.  Either that is where the food is the best or that is where it is the most affordable (plentiful).  And that is exactly what is seen here with whales.  And it is sometimes like a family-style restaurant where you go in and sit at a table with whoever is there and share a meal.  In the feeding grounds, feeding interactions are largely about who just happens to be there.  Sometimes, everyone does their part to guarantee a good meal, and sometimes there are those that just take advantage of others that are doing all the work.

Over the past several years, scientists from Woods Hole, in association with a variety of research and educational programs have been placing suction-cup tags on groups of feeding whales to kind of gauge just how cooperative some of the feeding groups really are.  So the tag is really cool.  In addition to having instruments that measure how deep the whale is and a hydrophone to record what sounds the whale is hearing and is making, there are instruments that measure the pitch of the whale from front to back and also from side to side.  And, of course, to measure its movements.  Essentially, once the information is fed into a computer, a likeness of the whale’s movements can be created that show its technique in bubble feeding.

A really cool sideline of this was what it had to say about how whales cooperate in feeding groups.  Sometimes, the whales all appear to do their part.  Sometimes, however, humpback whales appear to take advantage of the work of others.  A number of whales in a feeding group were working together and tags were placed on several of them, including a female named Nile (who is a favorite of whalewatchers).  As it turns out, the other whales appeared to be doing all of the work and Nile just appeared to lunge through their bubble clouds at the last moment.  Perhaps whales and humans are not so far removed evolutionarily.  It should be pointed out that the tags were designed to stay on the whales for only a day and there is not information as to what was going on with Nile or that group on previous or on subsequent days.