Brood Care

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Brood Care
Goslings
Ducklings
Cygnets
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Life-History Tradeoffs

• Precocial young still require care
• Weeks to a year
• Current Reproduction vs. Future Survival or
  Reproduction
• Parents should invest least amount to assure
  survival of young
• Abandon young when costs outweigh benefits

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Male/Female Choice

• Male abandon Mate and Young, if
• Remating possible
• Male presence does not enhance survival of young
  or
• Increases risk of mortality of male (future
  survival)
• Female
• Presence does not enhance survival of young and
  increase risk of future survival of female
• Opportunities for additional reproduction in
  current or future season

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Length of Care

• Anserini, Cygnini, Dendrocygninae
• Biparental care
• To fledging or up to a year
• Superfamilies in swans and geese (large bodied)
  last beyond a year
• Body sized related within and among tribes
• Why this length of Care?
• Benefit to young and adults
• Competitive advantage during non-breeding season

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Anatinae - Male

• Males abandon female during incubation and
  sometimes during brood rearing
• Northern latitudes
• Does bright plumage of males attract predators?
• Tropical or southern hemisphere latitudes
• Pair maintained through year
• Plumage dimorphism lacking
• Irregular breeding

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Anatinae - Female

• Generally remain with young until fledging
• Ruddy duck before fledge
• Why?
• Length of Care AythyiniltMerginiltAnatini
• Consequences for migration?
• Brood recesses

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Types of Care

• Brooding
• Thermoregulation
• Parental feeding
• Direct Musk Duck and Magpie Goose
• Indirect
• Locating food
• Predator Protection
• Alarm calls
• Aggressive postures and attacks
• Geese, swans, and whistling ducks
• Injury feigning
• Anatinae
• Less common in Aythyini and Mergini

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Types of Care

• Competition
• Dominance related to body size
• Brood Amalgamation
• Adoption a single female or pair accepting
  foster young
• Creche a brood with any number of adults and at
  least 2 unrelated young
• Adults may be unrelated
• Adults attending young may not have their own
  young in creche

• Gang Brooding Several females or mating pairs
  joining together with their broods
• Kidnapping dominant female or pair aggressively
  kidnap young of subordinate parents

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Why amalgamate broods?

• Why be a donor?
• Reduce predation risk
• Host or foster offspring
• Increase compettitive advantage for food
• Accidental mixing
• Salvage
• Energetics, age, experience

• Why be a recipient?
• Constraints
• Neutral effects
• Benefit
• Parenting experience
• Reciprocal altruism

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Opportunity and Viability
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Factors Affecting Care

• Season Date
• Time to acquire nutrients for migration
• Young and adults

• Time of day (food availability)
• Age of adults predictions?
• Age of brood
• Brood Size - ?
• Habitat