1. Parental Care

2. Cost vs benefit of parental care
Birds that are likely to live long protect themselves (have smaller clutches of eggs, know they can probably mate again).
Birds that are short lived have more to gain by protecting their young because they may not get another chance. In B, the short lived robins reduced their nest visits more than the thrushes. Opposite for an adult predator.

3. Why maternal more than paternal?
Egg investment is the obvious answer but, in many species females leave the eggs in the care of the male

4. Cost benefit ratio Female maternity is 100%
Male paternity might be 80%
If the cost of parental care is the same for both females and males in terms of energy and inability to find new mates, the ratio is clearly in the female’s favor
Explains why females provide more parental care than males
Costs may also NOT actually be equal

5. Exceptions to this rule…
Male sticklebacks care for up to 10 clutches of eggs at a time, females could only do one
Less cost for males
Both male and female cichlids may mouth brood
Also, females can’t forage while guarding eggs, so they don’t grow as big, and egg quality suffers
Male parental behavior may be especially attractive to females, so benefit is greater for that reason too

6. Parental discrimination
Mothers are very adept at picking out and caring for only their offspring even in very crowded conditions
Bats, seals, rodents
Why even have these communal nests?
What signals might aid the discrimination?

7. Recognizing Kin Production Perception Action
Offspring produce a cue that signals their identity
Perception
Parents are able to detect the cue and recognize it through comparison to some reference
Self-referent phenotype matching
Template stored or online processing
Action
Parental action depends on matching outcome
Affiliative, feeding, grooming, chasing, killing, etc

8. Auditory cues
Clear species discrimination amongst closely related birds but those who nest in large colonies together have young that emit highly distinctive sounds (left), while those that nest singly sound more similar to each other.
Also the baby fur seals use their distinctive calls to reunite with their mothers after weeks separation.

9. Other cues
Olfactory/Pheromone
Body Size
Coloration, Patterning …

10. DQ
Occasionally, female Mexican free-tailed bats make mistakes and feed an infant that is not their biological offspring. This mistake surely would have been avoided if they nested alone. -Does this mean that the parental behavior of this species is not adaptive? -Use cost-benefit analysis to develop alternative hypotheses to account for the “mistakes”.

11. Adoption of genetic strangers
Colonial, ground-nesting gull chicks not being fed by their parents may leave the nest and seek adoption by other parents
They beg, act submissive, and usually are taken in
Why? If discrimination is so important, why do parents ever adopt?

12. Brood Parasites Lay eggs in another species’ nest Why is it tolerated?
Can’t differentiate eggs shape, size, color
“Mafia” hypothesis