Introduction to Animal Behavior

1
Introduction to Animal Behavior
2
What is behavior? Why study it?

• Behavior
• Everything an animal does how it does it
• Innate inherited or developmentally fixed
• Learned developed during animals lifetime
• Why study behavior?
• Acted upon by natural selection
• Does it lead to greater fitness?
• Greater reproductive success?
• Greater survival?

3
Proximate and Ultimate Questions

• Two basic types of questions asked in animal
  behavior
• Proximate causes
• Immediate stimulus mechanism
• how questions
• Ultimate causes
• Evolutionary significance
• why questions

4
Proximate Questions

• How do beewolves find their way home?
• Type of wasp that nests in sandy areas

5
Beewolf Homing

• When leaving the nest to hunt bees, female
  beewolf covers entrance with sand?
• How does she relocate it later?
• Behavior Beewolf circles the nest after covering
  with sand
• Hypothesis Beewolves remember landmarks

6
Niko Timbergens Experiment

• Timbergen cleared objects from around nest after
  beewolf left
• Beewolf struggled to relocate nest
• Timbergen then set up landmarks around nest for
  wasp to use

7
(No Transcript)
8
When the landmark moved, wasps searched where
landmarks suggested nest should be.
9
Ultimate Questions

• Why do black-headed gulls remove eggshells from
  their nest?

10
Gull Egg Removal

• Timbergens Hypothesis
• Broken eggshells draw attention to the nest and
  attract predators
• Removing eggshells should remove predation risk

11
Experiment

• Place broken eggshells at different distances
  from intact gull eggs.
• Does presence of egg shells affect the likely
  hood of intact gull eggs being found by
  predators?
• YES!
• Distance from eggshell to egg eaten
• 15 cm 42
• 100 cm 32
• 200 cm 21

12
Conclusion

• Black-headed gulls remove egg shells because this
  behavior reduces predation
• Ultimately leads to increased reproductive
  success
• Genetic mutation made a gull more likely to
  remove egg shells from its nest
• Led to inc. reproductive success
• Gene inc. in population

13
Infanticide in Hanuman Langurs

• Langurs live in groups of one male, several
  females
• Males fight to control groups of females

14
When a new male takes over group, infants are
killed by male
15
Why does infanticide take place?

• Why does male risk serious injury from females to
  kill babies?
• How can this behavior be favored by natural
  selection?
• Shouldnt it be selected against since babies are
  killed?

16
Possible Explanations

• Overcrowding
• Males in high density populations become
  hyperaggresive and then attack babies
• Observation infanticide occurs in low density
  populations too
• Darwinian
• Males kill infants so that females become fertile
  sooner
• Increases males reproductive success
• Favors the spread of infanticide genes, though it
  may harm the langur population

17
Other animals that practice infanticide

• Lions males take over pride and kill all males
  lt 9 months old
• 25 of cubs killed in some populations

18

• Jacanas polyandrous (female mates with several
  males)
• Female taking over territory kills any chicks of
  previous female
• Frees up males to tend to new females eggs