SIO  133  -­‐  Marine  Mammal  Behavior,  and  Social  Systems:  Ma;ng  

       

John  Hildebrand,  Scripps  Inst.  Oceanography,  UCSD  

Ma;ng  Strategies      •  Individuals  behave  to  maximize  reproduc;ve  success  

•  Male  and  female  reproduc;ve  strategies  together  make  up  the  "ma;ng  system”    •  Female  (mammals)  invest  more  heavily  in  rearing  offspring      •  Males  in  maximizing  the  number  of  mates    

•  These  strategies  generate  structures  and  physiological  adapta;ons  ~  e.g.    sexual  dimorphism    •  The  sexes  do  not  necessarily  agree  and  may  some;mes    be  in  conflict.    

Cetacean  Reproduc;ve  PaVerns

Odontocetes    Calf  every  2-­‐8  years    Weaning  0.5  –10+yrs    Feeds  during  lacta;on    Ma;ng  over  extended  season  

Mys;cetes    Calf  every  1-­‐2  years    Weaning  5-­‐12  months    Fasts  during  lacta;on    Fixed  season  for  ma;ng/calving  

Both:  Rela;vely  high  level  of  investment  in  young  

Prolonged    Development  

Odontocete  Social  Groups  Low  adult  mortality  

High  juvenile  mortality  must  protect  offspring  to  increase    reproduc;ve  success    

Stolen  and  Barlow  2003  

Odontocete  Parental  Care  

Females  responsible  for  care    

Alloparental  care  taking  care  of  offspring    other  than  your  own    

 Tizzi  et  al.  ALLOPARENTAL  CARE  IN  TURSIOPS  TRUNCATUS:  A  CASE  REPORT    

Senescent  Females  in  KW  and  PW  

Female  life  history  paVerns      •  reproduc;ve  period  is    conserved  in  pilot  whales  and  Killer  whales  •  extended  post-­‐reproduc;ve  life  span    Infancy  is  defined  as  the    period  of  nursing.  Juvenile  period  includes  post-­‐  weaning  to  age  at  first  birth    Whitehead  and  Mann  2000  

Matriarch  as  repository  of  ecological  knowledge?  Hum

an  Pilot  Killer  

Primates  

Female  Reproduc;ve  Strategies      •  Females  maximize  their  reproduc;ve  success  …  by  being    

good  mothers  and  may  benefit  from  choosing  males  with  “good  genes”  (males  that  are  dominant,  older,  immunologically  Incompa;ble,  etc.)  …  given  the  energe;cs  and  other  constraints  of  searching  for  mates.    •  LiVle  is  known  about  female  choice.    Do  females  have    Preferred  companions?  Exert  cryp;c  female  choice?  

Male  Reproduc;ve  Strategies      •  Males  maximize  their  reproduc;ve  success  …  by    

ma;ng  with  as  many  females  as  possible  and  most  devote    the  bulk  of  their  energies  to  this  pursuit    •  No  known  male  parental  care  in  marine  mammals  

•  The  poten;al  for  males  to  mate  with  many  females    depends  on  temporal  &  spa;al  distribu;on  and  mobility    of  females    •  Males  compete  with  other  males  for  access  to  females  both  pre-­‐  and  post-­‐  ma;ng  

Pre-­‐ma;ng  Compe;;on      •  Contest  Compe22on  –aggressive  interac;ons    

to  limit  access  of  other  males  to  females    (size  and  weaponry)      •  Scramble  Compe22on  –compe;;on  to  disperse  and  find  sexually  recep;ve  females  (agility  and  speed)  

•  Mate  Choice  Compe22on  –compe;;on    in  courtship  to  be  chosen  by  the  female    (display)    

Weaponry    Beaked  Whales:    based  on  scarring  paVerns,  Males  appear  to  use  their  teeth  as  weapons  In  aggressive  encounters  with  other  males    (females  lack  teeth)    

Display    Display  may  take  several  forms    •  Modified  appendages  •  Pigment  paVerns  •  Acous;c  display    (song,  sperm  whale  clang)      

Male  Spinner  dolphin  

Sperm  Whale  Clang   Minke  Whale  Boing  

Odontocete  Ma;ng  Systems      Resident  Killer  Whale  –  ma;ng  during  mul;pod  

“gree;ng  ceremonies”  between  subpopula;ons  -­‐Bigg,  BarreV-­‐Lennard  and  others  

Sperm  Whale  –    Extreme  polygyny  with  roving  males  Whitehead  et  al.  

BoVlenose  Dolphins  –    sequen;al  female  defense  polygyny  –  with  male  alliances  sexual  coersion  and    polyestrous  females    –  Conner,  Mann  and  others  

Sperm  whale  groups  -­‐  Female  

Matrilineal groups (~10) Interact with other groups for short period Female bond based on cooperative care of young -  Leave calves at surface during feeding dives Emerging understanding of complexity

Sperm  whale  groups  -­‐  Male  

Males disperse (> 6 yrs)

Increasingly solitary

Form loose breeding associations

Roam between female groups

Sexual Dimorphism: Males > Females

Fusion  -­‐  Fission  System  

Fusion - Groups join for reproduction or feeding

Fission - Groups split to stable sub-units

Male Bottlenose Dolphin Grouping

- Strong, stable alliances (2-3 members) - Pairs join larger groups for mating - Super alliances = short term grouping - Aggressively separate females from

groups

Connor  et  al.  2006  Synchrony,  social  behaviour  and    alliance  affilia;on  in  Indian  Ocean    boVlenose  dolphins,  Tursiops  aduncus  

Female Bottlenose Dolphin Grouping

Not as strong as male alliances Vary by location Reproductive Status Typically 4-7 Individuals Mothers with most recent offspring

Mys;cete  Ma;ng  Solitary    Promiscuous    Body  size:    Females  >  Males  

 presumed  for  fetal  and  calf  development  Breeding  discrete  phase  of  each  year  Migrate  between  produc;ve  feeding  grounds  

 and  lower  la;tude  breeding  grounds  Best  data  on  humpback,  gray,  and  right  whales  More  data  on  males  than  females        

Pinnipeds  Amphibious:  •  Solitary  forager  at  sea  •  Return  to  land  or  ice  for  parturi;on    Aggrega;on  of  Females  on  Land    •  Avoid  harassment  by  males  •  Protect  pups    Ice  breeding  seal  dispersed  

Mating system Male parental care Sexual dimorphism Breeding substrate Mating substrate Lactation

Polygyny No High Land Land Long

Slight polygyny No Low Ice or land Water Short

Polygyny No High Land Land Short

Pinniped  Ma;ng  Systems  

Characteristic  No. of species Female density

Otariids  15 Gregarious

Most phocids  15 Solitary to Moderately Gregarious

H. grypus and Mirounga spp.  3 Gregarious

Cassini  1999  Behavioral  Ecology  

Sea  OVers  Live  close  to  coastal  forage  areas  •  Females  claim  year-­‐round  territories  •  Females  aggregate  in  small  groups  “raps”  •  Males  aggregate    outside  reproduc;ve  ;mes  •  Adult  males  establish  territories  that  overlap              with  one  or  more  female