Predator Prey and Foraging Flashcards
What is predation?
The consumption of one organism (the prey) by another organism (the predator) when the prey is alive at the point of attack
What are the costs associated with mobbing?
Injury / death of mobbers
attraction of additional predators
Shared or improved vigilance leads to what?
Greater chance of spotting a predator
Are sentinels at a greater risk than other members in the group?
There is no evidence to suggest they are at a greater risk.
Sentinels are often what?
A subbordinate
What are three passive social defences?
Dilution effect hypothesis
Selfish herd hypothesis
Confusion effect hypothesis
What is dilution effect hypothesis?
Associating in a large group reduces the risk to an individual
What is selfish herd hypothesis?
Individual in a group reduce risk by putting others in between themselves and a predator
What is the confusion effect hypothesis?
Moving as a group reduces risk as predator can’t single out and attack an individual
Give an example of dilution effect.
Mayflies emerge from water in vast numbers in spring
Aquatic nymph to flying adult
High density = lower individual risk
Give an example of the confusion effect.
Decreased attack success with increased group size & density in three dimensional Starling flocks
Give an example of the selfish herd effect.
Bluegill
Larger, more dominant fish occupy central positions
Subordinates occupy periphery – increased attacks by predatory fishes
What are the advantages of blending in?
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
Give an example of behavioural camouflage.
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)
What did Fitzgibbon (1990) observe?
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
What did Daley et al. 1990 study/find?
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
What is Batesian Mimicry?
When an edible species resembles a distasteful or dangerous one
What is MÜllerian Mimicry?
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
What is the Signal detection hypothesis?
When a prey’s appearance or behaviour activate the escape behaviour on the part of the predator
Give an example of Signal detection hypothesis.
Tephritid fly habitually waves banded wings
Wing markings resemble legs of jumping spiders
Describe Green et al.’s 1987 study on Tephritid fly.
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
What is attack deterrence hypothesis?
A species will perform a behaviour to display their vigor to potential predators
Don’t appear to be the easy target in a group
Given an example of attack deterrence.
Lizard Anolis cristaellus perform push up displays when a predatory snake is present
Describe the study by Leal 1999.
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
What are the benefits of food?
Energy intake, ability to reproduce
What are the costs of food?
Time & energy to locate and access it
What were Zach’s observations of the Northwestern crow?
Select large whelks
Fly approx. 5m high
Repeat attempts until successful break
What ere Zach’s predictions in regards to the Northwestern crow?
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
