1 - Animal Contests

Question 1

What are the factors influencing whether an animal will go into contest?

Answer 1

• The value of the resource to be won (V)
• The cost of competition/contest (C)
• The probability of winning the contest (p)

pay-off = pV - C

Question 2

When is fighting more likely?

Answer 2

When the value of resources is high in contrast to the cost of the fight

Question 3

When should you give up on a contest?

Answer 3

When your opponent is weighing the pay-off of a contest greater than you are

Eg. if your V/C is less than opponents V/C

Question 4

When are contests most costly?

Answer 4

If the competitors are more evenly matched in how they weigh the net benefit of the contest (competitors matched in fighting ability or value of resources high for both)

V1/C1 = V2/C2

This leads to prolonged contests

Question 5

How do animals assess each other non-violently (eg. in between bouts)?

Answer 5

• Visual displays (eg. shell size in hermit crabs)
• Behavioural cues (eg. head-on charge in african buffalo)

These displays/cues are evolved adaptations for the purpose of non-violent assessment, as fighting is costly.

Question 6

What are 3 problems with assessment signals?

Answer 6

• Signals too costly to fake (only animals in good condition can produce reliable signals, (eg. red deer roaring prevents them from eating so they have to be in good condition from the start - handicaps)
• Some signals can’t be faked (indices)
• Signals in which fakes are punished (status signals - eg. subordinate gets disciplined by dominant when producing faked status signal, social cost)

Question 7

What is sequential assessment?

Answer 7

A sequence or trade-off of behaviours that escalate from less to more costly signals (if it needs to)

Question 8

What are indices?

Answer 8

Signals that can’t be faked (eg. pitch of toad croak based on size)

Also known as revealing signals

Question 9

List three types of contest signals

Answer 9

• Handicaps (too costly to fake)
• Indices (can’t fake)
• Status signals (fakes are punished)

Question 10

List three qualities of bird song in order of aggression (least to most)

Answer 10

• Repertoire match
• Type match
• Stranger

Question 11

How can a bird signal that it’s ‘pissed off’ with bird song?

Answer 11

• A (focal) bird sings a certain song
• A neighbouring bird switches its song to match focal bird
• Focal bird persists with song, indicating aggression

If the focal bird switches to another song, they are signalling that ‘all is cool.’ If they stop singing, that is a further decrease in aggression.

Question 12

What is a strategy that birds take to settle in an area?

Answer 12

A bird learns songs from its neighbours, then settles in their area.

This can start a cascade of aggressive bird song (contest).