Reading 1: Adaptiveness of defence behaviour in peacock butterflies

Question 1

What were the three hypotheses being tested?

Answer 1

1. The relative importance of the peacock butterflies eyespots and sound, seperately and in unison for predator defence and survival when attacked by an avian predator (blue tit)
2. to simulate cold summer or spring conditions where butterflies have no option to fly away and a forced interaction ensued
3. to test whether butterflies were more unwilling to flick their wings open in the first interaction compared with subsequent interactions as they might not have been noticed

Question 2

How were butterflies raised etc?

Answer 2

• Larvae were raised on host stinging nettles and fed on 25% sucrose solution for two weeks to fill energy deposits
• They were then transferred to a cold storage room (6c)

Question 3

How were the butterflies manipulated?

Answer 3

Black permanent marker pens or scissors or both

Question 4

How many forms of butterfly were created?

Answer 4

Three with a control for each totalling 6

Question 5

Group 1 no eyespots

Answer 5

had eyespots painted over and the control had painted on the dorsal side but eyespots were left intact

Question 6

Group 2 no sound

Answer 6

had a part of the forewing removed to make no sound and the control had a large part of the hind wings cut but could still make sound

Question 7

Group 3 no sound or eyespots

Answer 7

had both eyespots and sound removed , control was painted and cut but could still produce sound and had eyespots

Question 8

How many birds involved in study?

Answer 8

54

Question 9

Where did the trials take place?

Answer 9

• The trials were conducted in a light room with a one way mirror for observations
  • They were all performed on a log of willow where two meal worms were provided to encourage bird to look for food and consequently find the butterfly
  • Trials were 30 mins but ended earlier if a butterfly was consumed
  • No bird or butterfly was used in >1 trial

Question 10

Was each butterfly or blue tit used in more than one trial?

Answer 10

No

Question 11

Results

Answer 11

• All butterflies remained motionless until blue tit was close or attacked
  • Peacocks flicked wings and birds retreated
  • Butterflies then either, kept wings open but motionless, continued flicking wings (48/54 also tilted body towards bird to increase eyespot effect) or closed their wings remaining cryptic
  • when a bird returned to attack the butterflies would begin to flick again
  • All butterflies were found and attacked
  • More with eyespots survived compared to no eyespots
  • No difference in survival with vs without sound
  • No interaction between eyespots and sound
  • more butterflies also survived in the eyespots and sound treatment compared with the no eyespots or sound treatment

Question 12

3 options of the butterfly after the bird retreated due to wing flicking?

Answer 12

Butterflies then either, kept wings open but motionless, continued flicking wings (48/54 also tilted body towards bird to increase eyespot effect) or closed their wings remaining cryptic

Question 13

Was there a difference in survival due to sound production?

Answer 13

No

Question 14

Was there an interaction between eyespots and sound?

Answer 14

No

Question 15

Impeding wing flicking behaviour

Answer 15

• To test if manipulations effected ability to flick wings the number of flicks performed relative to trial length was compared across treatments
  • Trend in no eyespot butterflies to show more intense wing flicking than butterflies with intact eyespots
  • covered eyespots and no sound flicked wings more than eyespots and sound
  • No difference between wing flicking in just sound treatments

Question 16

10cm to the blue tit

Answer 16

• Birds spent more time close to butterflies with no eyespots compared to eyespots
  • Distance to bird when wing flicking took place increased in distance in the second interaction

Question 17

When did distance to bird decrease with wing flicking?

Answer 17

the second compared to the first interaction

Question 18

What the results mean in relation to the hypotheses being tested?

Answer 18

The study investigates the relative importance of the peacock butterflies eyespots and sound, seperately and in unison for predator defence and survival when attacked by an avian predator (blue tit)

- In no eyespots versus eyespots and no eyespots or sound versus eyespots and sound, butterflies with eyespots survived more

- Only 1 of 34 butterflies with intact eyespots died 

- 13/20 with covered eyespots were killed

- No indication sound and eyespots is more effective

Question 19

How many butterflies with eyespots died?

Answer 19

1/34

Question 20

How many with covered eyespots died?

Answer 20

13/20

Question 21

Multimodal signals

Answer 21

• Multimodal signals eg eyespots and sound increases effects (Rowe and Guildford 1999,2001, Mohl and miller 1976)
  • Bats respond to sound even when butterflies are out of sight
  • Synergistic effects of eyespots and sound still needs investigating

Question 22

Further study could…?

Answer 22

• Synergistic effects of eyespots and sound still needs investigating
• Still needs deciphering whether multimodal signals act as better antipredator tactics
• Still unknown whether sound is important eg in the dark or to other species

Question 23

were butterflies more unwilling to flick their wings open In the first interaction compared with subsequent interactions as it may not have been noticed?

Answer 23

• Butterfly incorporates the possibility it has not been discovered on the first interaction
  • Brakefield 1992 peacock butterflies are leaf mimics when resting
  • the peacock butterfly appears to adjust its wing-flicking behaviour depending on its posture. The adaptive value of this seems obvious, but whether or not these differences confer any advantage to the butterfly in terms of increased survival remains to be investigated.

Question 24

How does the study compared to animal behaviour in general?

Answer 24

• Risk of remaining cryptic till late is that the predator gets closer and there is less of an escape chance
• Butterflies with wing patterns can afford to shift behaviour to wing showing more than a species relying solely on crypsis
• Study represents first strong evidence that a harmless prey can increase fitness by survival through bluffing intimidation

Question 25

Blest 1957

Answer 25

• Eyespots often mimic large avian predators that prey on the smaller passerines
• Eyespots can also be found near defensive organisms to provide an area of attack which will damage the predator

Blest suggested that butterflies with intact eyespots elicited higher numbers of escape responses from yellowhammers (E. citronella) compared with butterflies with removed eyespots.

Question 26

Ruxton et al 2004

Answer 26

However, although Blest’s results are suggestive, his conclusions are hampered by his experimental protocol which is characterized by low sample sizes and pseudoreplication

Question 27

Are all eyespots for scaring predators?

Answer 27

No eg Meadow Brown

• they provide a non-vital target for predators
• presumes its an eye and eats thw wing and not its eye
• if eye is lost that is deadly whereas partial wing loss is not