Lecture 11 Flashcards
Describe meerkat groups.
Consists of 3-30 individuals
Matriarch that mothers 75% of group.
In Meerkat groups there are 2-15 adult helpers that…?
help in guarding, carrying, feeding.
Describe meerkat foraging characteristics?
Forage for 5-8 hrs. in the open.
May dig up to 20cm below ground.
While digging, unable to detect predators.
What was the study done by Cluttonbrock?
Selfish sentinels in cooperative mammals.
Describe Cluttonbrock’s study.
Meerkats alternate guard duty.
Raised guard present 50% foraging time.
Guards announce presence with repeated calls.
Foraging animals are less __________ when a guard is present.
vigilant
In 2000 hrs. of observation no guards were killed by predators. Why?
Guards remained close to burrow.
Describe the observations in the Ranchland.
Raised guard 12% foraging time
Ind. spent 1.5% of foraging time on raised guard.
Guarding at ground level = to park
Describe the observations at Kalahari Park?
Raised guard 56% of time.
Ind. spent 10% foraging time on raised guard.
In meerkat groups ________ __________ spent more individual time in raised guard than individuals in larger groups.
solitary individuals
T/F: The amount of time a guard was present within the small group was significantly more.
false, less
What was observed about predation rates between the park and ranchland?
Predation rates on small groups in the park and ranchland increased equally with decreased group size.
Dominant females in meerkat groups do what?
Contributed less to raised guarding than any other group member (including immigrants)
How much time did unrelated immigrants spend in raised guard?
Spent and equal amount of time on raised guard as other individuals in the group.
What are some characteristics abt babysitters in meerkat groups?
Sitters stay with newborns for first 3 weeks in 24 hr. shifts.
Sitters lose 1-2% of body weight.
A study was done where meerkats were fed with hard boiled eggs. What were the findings?
Increased guarding time 30%
Long guarding bouts
3X likely to be raised guards
More likely to guard before forage.
What did Munn study in 1986?
Observed large flocks of mixed species birds in Peru rain forest.
What were the roles of the birds Munn studied?
Some were food finders and others were alarm callers.
What was true about the large mixed species flocks?
Appear to offer increased fitness in terms of improved vigilance and food discovery.
Within flocks there is a division of labor; what is it?
Alarm callers are the antshrike and tanager who give alarm calls majority and first to sound them. Other birds forage.
What do the sentinels do in these mixed species flocks?
Rely on insect flushing of other species within flock
They gather under foraging bird and collect insects
Never grabbed food frm foraging species.
What do sentinels do that is especially bitchy?
They freaking alarm call so foraging bird will fly away and they can take food. Or pursue the same flying insect.
Munn played recordings of true/false alarm calls. What was his hypothesis?
If calls are deceptive then false alarms should elicit the same response as true.
What did Munn find when he classified 106 alarm calls as true or false?
True calls were given when hawk model or if other flock species alarmed and froze for several minutes.
False calls were followed by sentinels flying into open to chase insects, or if no hawk was within 20m of calling bird.
False calls were given _______ percent of the time by sentinels.
50%
In Munn’s experiment, how do flock members react to true or false alarm calls.
They respond consistently to both true and false alarm calls, but not to control rattle call.
Tanagers sounded alarms less when foraging…?
alone than when another bird was involved.
When did the rate of responding increase?
When either sentinel species was feeding its young.
Sentinel species give a significant amount of _______ ______.
false alarms.
How can herding animals reduce their risk of predation?
Herding with diluting partners.
In herding group selection, larger bodied species may have a better what?
Have a naturally better vantage point.
Giraffes may provide an added benefit of what?
Increased vigilance and improved detection abilities for predators.
In the presence of predators, what do giraffes do?
Engage in a staring posture when in the presence of predators.
Mixed species herds will benefit from the ________ ________.
dilution effect
What areas to giraffes avoid?
woody areas, prefer savanna habitats.
In giraffe-zebra herds…?
Presence of giraffes lowered the average time zebras were vigilant by 65%.
T/F: Zebra spent 50% less time when herding with wildebeest than with giraffes.
False, switch giraffes and wildebeest.
When do zebras focus scan?
When herding alone they’re used proportionally more than general scans.
What scans do zebras use when herding with giraffe?
Used general scans more than focus scans.
