Predator Prey and Foraging

Question 1

What is predation?

Answer 1

The consumption of one organism (the prey) by another organism (the predator) when the prey is alive at the point of attack

Question 2

What are the costs associated with mobbing?

Answer 2

Injury / death of mobbers

attraction of additional predators

Question 3

Shared or improved vigilance leads to what?

Answer 3

Greater chance of spotting a predator

Question 4

Are sentinels at a greater risk than other members in the group?

Answer 4

There is no evidence to suggest they are at a greater risk.

Question 5

Sentinels are often what?

Answer 5

A subbordinate

Question 6

What are three passive social defences?

Answer 6

Dilution effect hypothesis
Selfish herd hypothesis
Confusion effect hypothesis

Question 7

What is dilution effect hypothesis?

Answer 7

Associating in a large group reduces the risk to an individual

Question 8

What is selfish herd hypothesis?

Answer 8

Individual in a group reduce risk by putting others in between themselves and a predator

Question 9

What is the confusion effect hypothesis?

Answer 9

Moving as a group reduces risk as predator can’t single out and attack an individual

Question 10

Give an example of dilution effect.

Answer 10

Mayflies emerge from water in vast numbers in spring
Aquatic nymph to flying adult
High density = lower individual risk

Question 11

Give an example of the confusion effect.

Answer 11

Decreased attack success with increased group size & density in three dimensional Starling flocks

Question 12

Give an example of the selfish herd effect.

Answer 12

Bluegill
Larger, more dominant fish occupy central positions
Subordinates occupy periphery – increased attacks by predatory fishes

Question 13

What are the advantages of blending in?

Answer 13

Aim to stay alive longer than average for their species as this translates to greater reproductive success
Camouflaged colour patterns along with behavioural tactics to enhance concealment

Question 14

Give an example of behavioural camouflage.

Answer 14

Majid crab decorates its body with algae
Survival of decorated crabs was higher than that of non-decorated crabs after 2 days in a rock pool
In the lab, crabs used more algae for decoration when puffer fish were present
(Thanh et al 2003)

Question 15

What did Fitzgibbon (1990) observe?

Answer 15

Observed the proportion of Gazelle fawns hunted by Cheetahs that were hiding, & those that were active, when the hunt began
Compared this to the proportion of time that Gazelles spent hiding / active
Gazelles were less likely to be detected when hiding than when active

Question 16

What did Daley et al. 1990 study/find?

Answer 16

He used subcutaneously implanted radio transmitters to monitor track the behaviour of 176 adult Merriam Kangaroo rats
50 were killed by predators during the study
More mobile individuals were more likely to be killed by predators than their less mobile counterparts

Question 17

What is Batesian Mimicry?

Answer 17

When an edible species resembles a distasteful or dangerous one

Question 18

What is MÜllerian Mimicry?

Answer 18

Two or more distasteful / dangerous species resemble each other
Multiple species who live in close proximity can benefit by converging on the same type of warning colouration
Mutualistic rather than exploitative arrangement

Question 19

What is the Signal detection hypothesis?

Answer 19

When a prey’s appearance or behaviour activate the escape behaviour on the part of the predator

Question 20

Give an example of Signal detection hypothesis.

Answer 20

Tephritid fly habitually waves banded wings

Wing markings resemble legs of jumping spiders

Question 21

Describe Green et al.’s 1987 study on Tephritid fly.

Answer 21

Switched clearwings from houseflies with patterned wings of tephritid flies
Flies behaved normally post surgery – flying around enclosure & waving (plain) wings
Modified tephritid flies readily eaten by jumping spiders
Controls – wings removed and replaced with their originals repelled predators (16/20)
Houseflies with new patterned wings gained no protection

Question 22

What is attack deterrence hypothesis?

Answer 22

A species will perform a behaviour to display their vigor to potential predators
Don’t appear to be the easy target in a group

Question 23

Given an example of attack deterrence.

Answer 23

Lizard Anolis cristaellus perform push up displays when a predatory snake is present

Question 24

Describe the study by Leal 1999.

Answer 24

Counted number of push ups by lizard Anolis cristaellus when model snake present
Individuals then encouraged to run – total time recorded
Total running time proportional to number of push ups

Question 25

What are the benefits of food?

Answer 25

Energy intake, ability to reproduce

Question 26

What are the costs of food?

Answer 26

Time & energy to locate and access it

Question 27

What were Zach’s observations of the Northwestern crow?

Answer 27

Select large whelks
Fly approx. 5m high
Repeat attempts until successful break

Question 28

What ere Zach’s predictions in regards to the Northwestern crow?

Answer 28

Large more likely to break than small at 5m
Drops <5m result in reduced breakage
Drops >5m do not greatly improve breakage
Probability of breakage independent of how many previous attempts