Humpback whales, reproduction, migration, song, biology, age, etc.

From: Dagmar Fertl (dfertl@geo-marine.com)
Date: Mon Nov 24 2003 - 11:18:18 EST

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    Dear Dagmar,

        I had ask you those questions because I am interested. But yes, this is
    for a research project as well. I'm a senior this year at my high school and
    next year I plan on going to college. One of the majors I plan on taking is
    Marine Biology. Mostly on whales and mainly focused on Humpback whales. I'm
    sure you get these kind of e-mails all the time and some times you might
    feel like the person who e-mails you doesn't even care. But I can ensure
    that this is not the case with me. If you can answer my questions that would
    be great but if not how can I get contact with you to get the other e-mail
    addresses of other researchers who can answer my questions?

    Here are my questions:

    What is the reason for the one hair on every bump of the Humpback's head?

    Why do Humpback's have long fins for? They don't swim fast. Is it some kind
    of defense?

    Why are there so many barnacles on Humpback whales? Are there different
    kinds of barnacles on them?

    Do Atlantic and Pacific Humpback whales migrate together? Why or why not?

    How long can they live for and what was the longest living Humpback whale
    recorded?

    Have you ever seen Humpbacks use there eating technique with the Bubble net?
    Are there different forms of the Bubble net that they use to catch there
    food?

    Why do Humpback's migrate so far? I know some have said that it is probably
    because the calf has a better survival rate but isn't also dangerous for
    them not to eat healthy? There isn't al lot of food as there is in there
    distribution areas in the polar. And are they really better off in warm
    water?

    What is your thought and theory of the Humpback's migration behavior?

    Why is that all the Pacific and Atlantic Humpback whales sing the same song
    in there own region(Pacific and Atlantic) but differ between each other? Why
    don't they just all sing the same songs if they are incapable of producing
    there own unique songs? Why aren't they capable of creating there own songs?
    I thought Cetaceans were very bright?

    Do the male Humpback whales really sing there songs for mating?

    What is the purpose of the different patterns underneath the tail fluke of
    the Humpbacks? I know it helps us out to identify them but is there a
    reason? Was is it just a genetic thing or does it represent there family?

    How deep can they dive and for how long can they stay down there?

    Do female Humpbacks have delayed implantations?

    At what age do the calf leave the mother?

    Do Humpback's travel in groups? Why or why not?

    Do Humpbacks raise the calf together? Why or why not?

    How many Calf's can they have?

    That's all the questions I have. Thank you for your time and cooperation. I
    really appreciate it. Hope you have a great day.

    Sincerely,

    Jose Tapia
    ********************
    Jose,

    Oh my, this is like the humpback tutorial! Yes, I do very often get
    questions from people who appear to not really be interested in the answers,
    but just ask so they can get homework done. It's nice to have someone say
    thanks every once in a while and express a genuine interest. Gives me hope,
    and makes answering all the questions that I do, worth it. But, I do have to
    give you a hard time with some of the questions you've asked, since I know
    that the answers can easily be looked up within the WhaleNet archives or
    just a little elbow grease at the library. That said, here we go.

    1. The knobs that you are referring to are called tubercle. As you noted,
    each contains a hair which is 1-3 cm in length (ok, you didn't know the
    length before, but now you do!). The knobs (about the size of a tennis ball)
    are located along both the upper and lower jaws. The hair is considered to
    be sensory in nature; they may detect vibrations, water currents, or
    movements of nearby prey. We're just not absolutely sure.

    2. Ah, I see you are a little tripped up here with the long fins. First,
    whales do not use their flippers for forward movement or speed...that's the
    job of the tail (flukes). Flippers are used to steer. It's a good
    question...in fact, did you know that the humpback whale's scientific name
    means 'wings of the sea'. The flippers are about 1/3 the total body length.
    They may be used to maneuver, herd fish, guide calves, or pound the water to
    signal their location or position (when they are slapped on the water's
    surface, the sound travels far), show aggression (like whack each other), or
    stun fish. The logn flippers may also help to cool the whale during
    temperature extremes(remember they feed in cold waters and winter in warm
    waters) or after vigorous exertion.

    3. Yeah, a barnacle question. I did an article on barnacles for the
    Encyclopedia of Marine Mammals, which you might want to check out. There
    really are way less barnacles on humpback whales than on a gray whale.
    Barnacles appear to settle in greatest numbers on slow-moving cetaceans
    (whale vs a dolphin). Acorn barnacles (Coronula reginae and Coronula
    diadema) are the most common barnacle species on humpback whales. In fact,
    one humpback was reported to have as much as 450 kg of acorn barnacles
    attached to it. Humpback whale males scrape each other (often bloody) with
    their barnacle-encrusted flippers on the breeding grounds. There are over
    900 marine species of barnacles; at least 20 barnacle species have some
    association with marine mammal species (including seals!).

    4. Do humpbacks in the Pacific and Atlantic migrate together. This is kind
    of a wierd question. The obvious answer is no. They are separated by big
    land masses. To migrate together, side by side, they would have to meet near
    the Panama Canal or something like that to cross over. Do you mean do they
    migrate at the same time, but in different oceans, yes. Just remember that
    there are humpbacks in the Northern Hemisphere and Southern Hemisphere. With
    the seasons reversed, of course, humpbacks migrate at different times. Is
    there mixing between the 2 hemispheres. We don't think so.

    5. Life span, I have no idea, but probably around 35 years would be a good
    ripe old age for a humpback whale.

    6. I personally have not witnessed bubble feeding up close and personal, but
    yes, I would assume there are variations of it, depending on how many whales
    are present during the event.

    7. There are a number of popular explanations as to why whales migrate. The
    following article does a good job talking about this (I think this has also
    been addressed in WhaleNet archived questions). I recommend you get a copy
    of Corkeron and Connor's paper published in 1999 in the journal Marine
    Mammal Science entitled "Why do baleen whales migrate?" (vol. 15(4),
    1228-1245). The article reviews the various explanations and also suggests
    that a major selective advantage to migrating pregnant female baleen whales
    is a reduced riks of killer whale predation of their newborn calves in
    low-latitude waters (for example, Hawaii). I also want to remind you that
    whales do not feed on their breeding grounds, and if they do, it's not a
    lot, and they are not dependent on that food. It is the high concentrations
    of prey in the higher-latitude waters (e.g., Alaska) during the summer that
    supply the food that builds up that blubber layer upon which the whales
    depend during the migration and while on the breeding grounds.

    8. Not really sure what you're asking, except that it looks for my personal
    opinion. I think that all the reasonable explanations discussed by Corkeron
    and Connor are valid.

    9 and 10. I'm almost positive that the question regarding humpback whale
    song has been previously discussed. The primary function of the songs is
    resumbaly to attract females. All male whales in a given population sing
    essentially the same song, and although the form and content of all songs
    change over time, the whales somehow coordinate these changes. The reason
    they sing the same song, but just mildly tweak it with each iteration as
    well, is that it is a challenge that males put out to each other. It's a way
    to show off how physically strong they are (you know, boys showing off to
    boys, but also trying to impress the girls). The songs actually are complex,
    even if we don't pick up all the nuances, and are physically challenging to
    the males. They require some impressive breath holding capabilities, etc.
    Remember, this issue of geographic isolation comes into play. Pacific
    humpbacks don't mix with Atlantic humpbacks.

    11. Fluke patterns. They can range from white to all black. They are unique
    to each individual as you pointed out. Do the whales recognize each other
    from the fluke patterns. Who knows. Maybe, if they are close enough. More
    likely it is acoustically that they recognize one another. We don't
    recognize each other via our thumbprint, but each of us has a different one.

    12.Humpback whale diving behavior depends on the time of year. In summer,
    most dives last less than 5 min; those exceeding 10 min are atypical. In
    winter (December through March), dives average 10 to 15 min; dives of
    greater than 30 min have been recorded. Diving depth is likely dependent on
    how far down the bottom is and what the whale is trying to do underwater.

    13. There is no delayed implantation. Gestation is about 11 months.

    14. Basedon observations from the Gulf of Maine, most calves begin to feed
    independently at 6 months, however, apparent nursing behavior is observed
    for up to several months after this. Although the separation of calves from
    their mothers in the autumn of their birth year has been documented
    (remember, they are born in the winter), the great majority remain with
    their mothers until some point during the calves' second winter. Sightings
    of mother-calf pairs still together, or apart, during the second winter
    indicate that separation does not consistently occur at a particular time or
    stage of migration. None remain into the third year.

    15. Humpback whales are not really social, especially if compared to
    dolphins. Humpbacks are characterized by small unstable groups, and
    individuals typically associate with many companions on both feeding and
    breeding grounds...but they don't stay together.

    16. No cetacean males and females raise their calves together. The males are
    never assured of paternity, and also, food resources typically determine if
    males will stay with females to stay with calves. Also, remember that the
    calves are ready to hoof it as soon as they are born, as opposed to humans,
    canids, birds, ec.

    17. This wasn't clear if you meant how many are born or how many in a
    female's life time. I'm going to assume the former. Although multiple
    fetuses have been recorded in dead pregnant females, living twins or
    muliplets are unknown.

    Whew!
    Dagmar Fertl



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