MARB 403 Lecture 7

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Begin Exam 2 Content

remember to ask about right whale story (something to do with right whales and mating... )

Videos

• Sei Whale feeding
• Flying penguins

Social and Reproductive Behavior in Baleen whales

(Biology's all about sex, isn't it?)

Feeding

Opportunity for sociality

Gray Whale

• bottom-feeders using suction
• Each feeding pit takes about a year to recolonize
• Each feeding dive is about 3—6 minutes long (tend to stay down longer for deeper dives; dive response?)
• Little meandering once they decide on a feeding spot
• Little sociality (like cows)
• Possibility of competitive exclusion (territorial/maritorial?)
• Can slurp from a cloud of food

Right Whales

• Skim feeders
• Echelon formation

Rorquals

• Lunge feeders
• Smaller rorquals (Minke and Bryd's whales)
  • Tend to feed on schooling fish and squid ("reliably" found at particular areas per season)
  • catholic feders = universal; all-inclusive (feed on everything)
  • form small groups (low sociality )
• Large rorquals (fin and blue whales)
  • feed on plankton, which is more randomly distributed
  • pay attention to each other to find food
  • form large groups (but not too many)
  • Humpback whale are more cooperative:
    • Bubble netting
    • Flick feeding — use flippers and tails to stun fish (also used by orcas)
    • Lunge feeding — all together now

Social-Sexual Behavior

Friendship bonds between partners ranging from hours to years; working together like odontocetes

More sociality on foraging grounds → more sociality at other times (migration and mating)

In general:

• Ovulation is winter/spring
• ~1 yr gestation
• Calves produced every few years
• Nursing usually a little over a year
• once mature, bye-bye (little attention to each other)

Blue Whale

• less than 1 year gestation
• Calf gains 80 kg/day
• Calves not born every year (long "resting period")
• nursing and weaned in 6–12 months
• sexual maturity at 4–10 years (very early for such a large creature)

Humpback Whale

Studied much, but we still don't know about mating. No one has seen humpback whales mating, but "little hummers" are born the next year

SAG: surface active groups (also in right whales and bowhead whales)

3 hypothesized mating strategies:

1. Male-male aggression: competition for access to females ("stove bolts" on rostrum), very aggressive
2. Male-male displays: singing
   • Other males come to singing males, brief social interaction, male might be displaced (in which case the "loser" gets pretty agitated about it)
   • Singing around the Hawaiian islands:
     • Start singing the same song they ended with last year)
     • Song evolves as more whales arrive
     • Everyone sings same song by end of mating season
3. "Escort Male": Alternate strategy
   • male stays with female
   • wait for estrus
   • serial monogamy: staying with one female for a short amount of time

In birds, males sing to warn other males (male-male communications). Is this the same in humpback whales?

Lots of sneaky males in polygynous environments

• allowed by females
• may be very important role in female selection
• making sure that she mates with a viable male

Note: In bottlenose dolphins, when male alliances force-mate with females, females do not have much choice in the matter

Balaenids

Lots of (very large) surface display... use imagination

No aggression; just a bunch of jostling around for position

• some males may even help to push the females under
• completely oblivious to anything going on while it's happening

Female plays difficult by rolling belly-up

• may have some choice in who mates with her

Polygynandrous: many males will mate with a given female, and then probably other females.

Sperm Competition

When testes are above the regression line (much larger in proportion to body size), animal happens to be polygynous

Rorquals are below the line, with blue being the farthest

Right whales are ridiculously above the line

Makes sense: More successful males need to produce a lot of sperm to displace those of other males

1. male-male conflict: prevent second matings, displace sperm
2. male-female conflict: selection on females to reduce costs of male paternity assurance mechanisms
3. female-male conflict: selection to avoid costs of male persistence and costs of remating

Whales Video

Ocean critters thrive on krill swarms

Blue Whale: 100+ ft and tons

• Heart larger than a car
• 1000 mile vocal communication range

Peninsula Valdez, Argentina

• winter
• right whales migrate from everywhere
• whales, penguins, and seals
• Colossities (white patches of hard skin on face) are unique and used

• 1 calf every 3 years
• 1/50 born white for limited time
• Drape themselves over mother's blowhole to get attention
• When one whale breaches, all start breaching (sequential sampling would be good to test this)

Sleep head down with tails in air positively buoyant

unknown destination after leaving

Humpback Whales

Hawaii: Breeding Grounds

Mysterious sounds

• incredibly loud

Calves weigh 2-3 tons

• Gain 100 lbs/day in first few weeks
• must come up for air every few minutes

Migration

• Feeding grounds near Alaska
• Shipping routes often encounter migration routes
• Lose 1/3 of weight before returning to Alaska
• predators: killer whales

Alaska: Feeding Grounds

Anecdote: a male humpback whale bow-riding?

Males arrive first

Om nom nom nom

Right Whale Story

Bowhead whales and right whales tend to be completely oblivious to everything else when they're mating.

Dr. Würsig jumed in the middle of a bunch of mating right whales, and got 3 ribs broken by a fluke

Scientist of the Day

Janet Mann

• Professor at Georgetown Univ. (Psychology and Biology)