BIO3052 Lecture Notes - Lecture 7: Waggle Dance, Web Decoration, Leafcutter Ant
30 May 2018
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FORAGING BEHAVIOUR I
• Prey selection by pike cichlids:
o Preys on guppies
o Do they prefer male or female guppies?
o Experimental design: has choice between male and female
o Results: ends up choosing female because they are larger
• Optimal foraging theory: animals should forage in a way that maximises net energy gain
-> going for the larger prey
o Aial dot alas forage i a a that aiises et eerg gai as oth osts ad
benefits need to be taken into account
o Eg. optimal foraging by north-western crows
Eats whelks
Selected larger whelks and flew to height of 5m to drop until whelk broke
If behaving optimally larger whelks should be easier to break and 5m should
yield the best breaking distance
Probability of breaking whelk increased with height to about 5m
chance of breaking whelk did not depend on number of previous drops (1 in 4
chance)
• Mussel selection in oyster catchers
o Is bigger always better?
o Profitability of mussel is based solely on energy intake (the bigger the mussel, the more
flesh)
o However profitability takes into account of wasted handling time (bigger mussels are
harder to pry open)
o Birds go for medium sized mussels (50mm? -> no, 50mm are comprised with barnacles,
hard to open)
find more resources at oneclass.com
find more resources at oneclass.com
• Risk avoidance in foraging leaf-cutter ants
-ants cultivate fungi by cutting leaves and bringing back to nest
o Different ants in day/night, bigger ants prefer night time
o Flies that lay eggs in ants head prefer larger ants/certain height
-> ignore ants heads 1.8mm diameter
• Trading food for safety in garden skinks
o Can optimal foraging have long term consequences?
o Predator avoidance is often traded against foraging opportunities
-> negative relationship between predator avoidance and resource gain
-> the more time you spend avoiding predators, the less time you forage
o What implications does this have on long term fitness?
o Eg. garden skink preyed upon by yellow face whip snake
Experimental set up: 20 skinks caught in wild put into a large outdoor enclosure
with wood then 2 treatments; predator scented or unscented. 330 crickets are
put into each treatment and unconsumed crickets are recorded using sticky trap
to catch them
Results:
▪ Lizards exposed to predator scent were less active
▪ Also less likely to be found in open habitat
▪ As a result they also ate less
Long term consequence:
▪ Smaller body size and reduced growth rate (by looking at hatchlings)
▪ Fewer eggs per clutch
▪ Lighter post-lay mass (females themselves were much smaller after
laying eggs)
▪ Lighter clutch mass (because offspring were also smaller for predator
scented)
▪ Smaller offspring size
• Foraging and the ideal free distribution:
o Assuming that an individual aims to achieve highest pay off, with no competitors, an
individual should go to the better habitat
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
> going for the larger prey: a(cid:374)i(cid:373)al do(cid:374)(cid:859)t al(cid:449)a(cid:455)s forage i(cid:374) a (cid:449)a(cid:455) that (cid:373)a(cid:454)i(cid:373)ises (cid:374)et e(cid:374)erg(cid:455) gai(cid:374) as (cid:271)oth (cid:272)osts a(cid:374)d benefits need to be taken into account, eg. optimal foraging by north-western crows. Selected larger whelks and flew to height of 5m to drop until whelk broke. If behaving optimally larger whelks should be easier to break and 5m should yield the best breaking distance. Probability of breaking whelk increased with height to about 5m chance of breaking whelk did not depend on number of previous drops (1 in 4 chance: mussel selection in oyster catchers. > no, 50mm are comprised with barnacles, hard to open: risk avoidance in foraging leaf-cutter ants. Ants cultivate fungi by cutting leaves and bringing back to nest: different ants in day/night, bigger ants prefer night time, flies that lay eggs in ants head prefer larger ants/certain height.
