1
00:00:00,080 --> 00:00:01,790
The following
content is provided

2
00:00:01,790 --> 00:00:04,030
under a Creative
Commons license.

3
00:00:04,030 --> 00:00:06,880
Your support will help MIT
OpenCourseWare continue

4
00:00:06,880 --> 00:00:10,740
to offer high quality
educational resources for free.

5
00:00:10,740 --> 00:00:13,360
To make a donation or
view additional materials

6
00:00:13,360 --> 00:00:17,258
from hundreds of MIT courses,
visit MIT OpenCourseWare

7
00:00:17,258 --> 00:00:17,883
at ocw.mit.edu.

8
00:00:22,670 --> 00:00:25,160
PROFESSOR: We have
just this topic

9
00:00:25,160 --> 00:00:28,250
to cover before
the midterm exam.

10
00:00:28,250 --> 00:00:31,780
So we'll probably have a little
bit of it to cover on Friday,

11
00:00:31,780 --> 00:00:33,940
but I'm working on
a review for you.

12
00:00:33,940 --> 00:00:37,670
And I won't answer everything
on the review, of course.

13
00:00:37,670 --> 00:00:38,870
We won't have time for that.

14
00:00:38,870 --> 00:00:42,730
But I will try to go
over some of the points

15
00:00:42,730 --> 00:00:45,980
that students have asked
me about in the past

16
00:00:45,980 --> 00:00:50,830
before the midterm, points that
seem to cause more confusion.

17
00:00:50,830 --> 00:00:52,700
And I'll give you a
few clues to the kind

18
00:00:52,700 --> 00:00:54,320
of things I put on the exam.

19
00:00:54,320 --> 00:00:56,267
But it's basically
a short-answer exam.

20
00:00:56,267 --> 00:00:57,475
There might be some matching.

21
00:01:01,570 --> 00:01:07,660
We got started with
this last time,

22
00:01:07,660 --> 00:01:11,816
primary and secondary
defense mechanisms.

23
00:01:14,450 --> 00:01:17,410
We talked a little bit about
countershading in camouflage.

24
00:01:23,850 --> 00:01:25,570
And this is where we left.

25
00:01:25,570 --> 00:01:30,260
Many predators developed search
images by perceptual learning,

26
00:01:30,260 --> 00:01:35,250
and then they learn to
search for their prey,

27
00:01:35,250 --> 00:01:37,865
remembering what they've been
successful with in the past.

28
00:01:40,990 --> 00:01:44,200
And I asked what
octopus and squid do.

29
00:01:44,200 --> 00:01:49,060
And for that, I would
like to show a video.

30
00:01:49,060 --> 00:01:51,190
Let me see if I'm online here.

31
00:01:54,790 --> 00:01:58,812
Some of you may not
be familiar with this.

32
00:01:58,812 --> 00:02:02,177
The mimic octopus.

33
00:02:02,177 --> 00:02:03,635
I'll only take a
couple of minutes.

34
00:02:06,250 --> 00:02:10,169
This content has been removed
due to copyright restrictions

35
00:02:10,169 --> 00:02:13,080
see the readings and
feelings page for information

36
00:02:13,080 --> 00:02:18,660
about this material

37
00:02:18,660 --> 00:02:21,690
PROFESSOR: Anyway, you
can find a little more

38
00:02:21,690 --> 00:02:22,770
online if you want.

39
00:02:30,510 --> 00:02:34,910
So that behavior of the
octopus-- and there's

40
00:02:34,910 --> 00:02:40,780
another example right here
in the cover of your book--

41
00:02:40,780 --> 00:02:46,330
another octopus that can change
color patterns on its surface.

42
00:02:46,330 --> 00:02:48,060
It can mimic predators.

43
00:02:48,060 --> 00:02:51,390
Actually, this animal
can create a thing that

44
00:02:51,390 --> 00:02:53,705
looks like two big
eyes facing you,

45
00:02:53,705 --> 00:02:55,770
so it looks like a predator.

46
00:02:55,770 --> 00:02:58,630
Most predators have
forward-facing eyes.

47
00:03:01,230 --> 00:03:04,690
It's related to
mimicry, and I want

48
00:03:04,690 --> 00:03:07,220
to talk here about the
different kinds of mimicry.

49
00:03:07,220 --> 00:03:11,170
There's two kinds:
Mullerian and Batesian.

50
00:03:11,170 --> 00:03:18,780
With Mullerian, different
species that are all poisonous

51
00:03:18,780 --> 00:03:20,930
evolved to look
similar to each other,

52
00:03:20,930 --> 00:03:24,430
because then they all benefit,
like the vespid wasps.

53
00:03:24,430 --> 00:03:31,335
So, an animal learns by
trying to eat one vespid wasp.

54
00:03:31,335 --> 00:03:31,960
They taste bad.

55
00:03:31,960 --> 00:03:34,270
They're poisonous.

56
00:03:34,270 --> 00:03:37,330
The animal, the
predator, learns to avoid

57
00:03:37,330 --> 00:03:40,070
not just at one species,
but other vespids,

58
00:03:40,070 --> 00:03:42,070
too, because they
look fairly similar.

59
00:03:42,070 --> 00:03:45,580
They all have the bands--
yellow and black bands--

60
00:03:45,580 --> 00:03:48,030
on her abdomen.

61
00:03:48,030 --> 00:03:55,130
And that's the evolution
of Mullerian mimicry.

62
00:03:55,130 --> 00:03:59,680
With Batesian mimicry,
animals that are not poisonous

63
00:03:59,680 --> 00:04:02,670
will evolve to look
like a poisonous one.

64
00:04:02,670 --> 00:04:05,710
The best-known is the
monarch butterfly,

65
00:04:05,710 --> 00:04:08,990
which is poisonous
and bad tasting.

66
00:04:08,990 --> 00:04:11,970
Animals learn to avoid it.

67
00:04:11,970 --> 00:04:15,740
Birds will generally
not attack monarchs.

68
00:04:15,740 --> 00:04:17,529
And this is an
example right here

69
00:04:17,529 --> 00:04:19,519
the viceroy butterfly
that's evolved

70
00:04:19,519 --> 00:04:21,399
to look very much
like the monarch.

71
00:04:21,399 --> 00:04:24,120
Here's a female monarch.

72
00:04:24,120 --> 00:04:27,990
Here's a male monarch butterfly.

73
00:04:27,990 --> 00:04:29,945
And there's several
species that have

74
00:04:29,945 --> 00:04:31,335
evolved to look like a monarch.

75
00:04:34,580 --> 00:04:38,040
Now, let's talk about other
ways to avoid predation.

76
00:04:38,040 --> 00:04:43,970
The ground-nesting birds: why
do some birds nest in the open,

77
00:04:43,970 --> 00:04:46,050
on the ground?

78
00:04:46,050 --> 00:04:48,620
They must have some advantages.

79
00:04:48,620 --> 00:04:51,610
And you can see one
clear advantage:

80
00:04:51,610 --> 00:04:54,330
they can see any
approaching predator,

81
00:04:54,330 --> 00:04:57,070
because there's no concealment.

82
00:04:57,070 --> 00:05:00,020
But, of course, their nest
isn't all that well concealed,

83
00:05:00,020 --> 00:05:01,700
either.

84
00:05:01,700 --> 00:05:07,820
So, what do they do
to protect their nests

85
00:05:07,820 --> 00:05:12,530
from an approaching predator,
like a fox or a polecat?

86
00:05:12,530 --> 00:05:17,080
And one of the best known
examples that's usually cited

87
00:05:17,080 --> 00:05:20,500
is the way the plovers behave.

88
00:05:20,500 --> 00:05:23,460
Here's a couple: the
black-headed plover

89
00:05:23,460 --> 00:05:25,550
and a Piping Plover.

90
00:05:25,550 --> 00:05:28,990
They both nest on the ground,
so they have that problem:

91
00:05:28,990 --> 00:05:32,720
what to do if there
is a predator.

92
00:05:32,720 --> 00:05:36,790
They want to protect their eggs.

93
00:05:36,790 --> 00:05:38,680
They, of course, can
flay away, but that

94
00:05:38,680 --> 00:05:39,885
leaves the eggs unprotected.

95
00:05:43,900 --> 00:05:47,650
One of the things they
do is reminiscent of what

96
00:05:47,650 --> 00:05:50,030
we saw in that
very first video we

97
00:05:50,030 --> 00:05:53,020
showed in class of
the stickleback.

98
00:05:53,020 --> 00:05:55,620
Remember, the male
stickleback can

99
00:05:55,620 --> 00:05:58,290
have his nest attacked
by female sticklebacks,

100
00:05:58,290 --> 00:06:03,060
and he'll behave like he's
got a nest some other place.

101
00:06:03,060 --> 00:06:06,276
He creates a false nest, and
he attracts them to that.

102
00:06:09,530 --> 00:06:12,660
So they, then, are led
away from his real nest.

103
00:06:12,660 --> 00:06:16,400
And that's what these birds do.

104
00:06:16,400 --> 00:06:20,270
They'll pretend they're
nesting in the wrong place,

105
00:06:20,270 --> 00:06:24,130
attract the predator, and,
of course, they fly away,

106
00:06:24,130 --> 00:06:28,090
and then the predator
doesn't get their eggs.

107
00:06:28,090 --> 00:06:32,010
Another method is to
approach the predator,

108
00:06:32,010 --> 00:06:36,650
if there's tall grass
where he can do it.

109
00:06:36,650 --> 00:06:38,800
And then, suddenly,
they'll duck down,

110
00:06:38,800 --> 00:06:40,740
so they're hidden in
the grass, and they'll

111
00:06:40,740 --> 00:06:44,020
scurry away, squeaking
like a rodent.

112
00:06:44,020 --> 00:06:46,410
And the predator finds
that irresistible.

113
00:06:46,410 --> 00:06:48,200
He chases after the rodent.

114
00:06:51,970 --> 00:06:56,720
And, of course,
that rodent mimic,

115
00:06:56,720 --> 00:07:01,910
the Plover is leading the
animal away from their nest.

116
00:07:01,910 --> 00:07:06,070
And there's another couple
of methods they can use.

117
00:07:06,070 --> 00:07:08,375
Especially if the predator's
already pretty close,

118
00:07:08,375 --> 00:07:10,040
they can run directly at it.

119
00:07:10,040 --> 00:07:12,570
They can run or fly towards it.

120
00:07:12,570 --> 00:07:13,870
They'll call very loudly.

121
00:07:13,870 --> 00:07:18,230
They turn away the last second,
and move away from the nest.

122
00:07:18,230 --> 00:07:22,760
That way, they attract the
predator to attack them.

123
00:07:22,760 --> 00:07:26,920
But they're quite
able to get away.

124
00:07:26,920 --> 00:07:29,730
Another well known
one-- and a few of you

125
00:07:29,730 --> 00:07:33,720
may have occasionally
seen this in the wild--

126
00:07:33,720 --> 00:07:36,920
if you like to observe birds'
nests, the broken-wing display.

127
00:07:36,920 --> 00:07:39,510
This animal that's
being attacked

128
00:07:39,510 --> 00:07:44,550
can flee along
the ground, acting

129
00:07:44,550 --> 00:07:47,500
like he can't fly,
looking exactly

130
00:07:47,500 --> 00:07:49,960
like he's got an injured wing.

131
00:07:49,960 --> 00:07:53,550
And, again, predators
can't resist that.

132
00:07:53,550 --> 00:07:59,170
An injured bird is their
best chance, catching a bird.

133
00:07:59,170 --> 00:08:00,890
Normally, they
can't catch birds,

134
00:08:00,890 --> 00:08:04,340
but they can catch them
if they're injured.

135
00:08:04,340 --> 00:08:07,750
That way, the plover
can lead the animal away

136
00:08:07,750 --> 00:08:08,485
from their nest.

137
00:08:11,080 --> 00:08:13,710
So all of that's kind
of secondary defense:

138
00:08:13,710 --> 00:08:21,620
reduces the success
of an attack,

139
00:08:21,620 --> 00:08:23,990
reducing the
probability of attack.

140
00:08:23,990 --> 00:08:25,960
Its, sorry, primary.

141
00:08:25,960 --> 00:08:30,510
Now, secondary defense is
when an animal is actually

142
00:08:30,510 --> 00:08:32,409
caught by the predator.

143
00:08:32,409 --> 00:08:35,169
What does he do to
reduce the chances

144
00:08:35,169 --> 00:08:37,190
he's going to be killed?

145
00:08:37,190 --> 00:08:39,779
They're not totally helpless,
even if they're caught.

146
00:08:43,570 --> 00:08:46,840
Scott describes the
behavior of a chick.

147
00:08:46,840 --> 00:08:52,790
Chicks, of course, are a lot
less able than adult chickens.

148
00:08:52,790 --> 00:08:56,700
They can't fly yet.

149
00:08:56,700 --> 00:08:58,530
They can't even run very fast.

150
00:08:58,530 --> 00:09:00,380
They're much more
likely to get caught

151
00:09:00,380 --> 00:09:01,910
in the jaws of a predator.

152
00:09:01,910 --> 00:09:03,920
What do they do?

153
00:09:03,920 --> 00:09:08,537
Well, they have this
physiological change

154
00:09:08,537 --> 00:09:09,120
in their body.

155
00:09:09,120 --> 00:09:11,970
It's called tonic immobility.

156
00:09:11,970 --> 00:09:15,340
We call it "playing dead."

157
00:09:15,340 --> 00:09:19,350
But it's a
physiological response.

158
00:09:19,350 --> 00:09:20,920
It's a fixed action pattern.

159
00:09:23,470 --> 00:09:26,390
Other animals, I ask
here whether mammals

160
00:09:26,390 --> 00:09:29,640
have such response, and
many small mammals do.

161
00:09:32,860 --> 00:09:37,240
I still remember, when
I was keeping hamsters

162
00:09:37,240 --> 00:09:40,800
in a basement-- I kept
pet hamsters for awhile

163
00:09:40,800 --> 00:09:43,780
before I started
studying them in a lab--

164
00:09:43,780 --> 00:09:45,420
and I remember
coming down there,

165
00:09:45,420 --> 00:09:52,610
and a female had gotten out
of the nest, or the cage

166
00:09:52,610 --> 00:09:55,270
that I had.

167
00:09:55,270 --> 00:09:58,560
But when I turned the
light on and made movement,

168
00:09:58,560 --> 00:10:03,910
that animal just froze,
became totally immobile.

169
00:10:03,910 --> 00:10:06,490
And I thought, as soon
as I walk over here,

170
00:10:06,490 --> 00:10:08,050
she's just gonna
run and get away.

171
00:10:08,050 --> 00:10:13,410
I'm gonna have to trap her with
food or something, or water.

172
00:10:13,410 --> 00:10:16,320
And if you know these animals
well, that's fairly easy to do,

173
00:10:16,320 --> 00:10:17,460
but it takes a lot of time.

174
00:10:17,460 --> 00:10:22,130
But instead, the animal
was totally immobile.

175
00:10:22,130 --> 00:10:24,950
I could even touch the
animal and move a limb,

176
00:10:24,950 --> 00:10:27,960
and it would just stay that way.

177
00:10:27,960 --> 00:10:30,580
It was a tonic
immobility response,

178
00:10:30,580 --> 00:10:35,140
and they maintain it
for quite a few minutes.

179
00:10:35,140 --> 00:10:39,810
Hamsters also have that as a
response to specific odors.

180
00:10:39,810 --> 00:10:42,440
For example,
polecat-like animals

181
00:10:42,440 --> 00:10:45,180
and certain species of dog.

182
00:10:45,180 --> 00:10:49,160
I had it happen with
visitors who had dog,

183
00:10:49,160 --> 00:10:53,090
but all dogs didn't elicit
that, just certain ones.

184
00:10:53,090 --> 00:10:55,960
And I never tracked
down exactly which

185
00:10:55,960 --> 00:11:01,760
ones were more related to
the polecat, their odor.

186
00:11:01,760 --> 00:11:04,660
But anyway, these
chicks are responding

187
00:11:04,660 --> 00:11:09,610
to the vision of those two
predator eyes facing 'em.

188
00:11:09,610 --> 00:11:11,475
That triggers the
tonic immobility.

189
00:11:15,830 --> 00:11:20,480
said Generally, the predator, if
he doesn't struggle and doesn't

190
00:11:20,480 --> 00:11:26,870
move, just keeps him
in its nest area,

191
00:11:26,870 --> 00:11:29,410
and doesn't
immediately kill them.

192
00:11:29,410 --> 00:11:33,660
I, mean he doesn't
need to, unless he's

193
00:11:33,660 --> 00:11:37,240
competing with other animals,
in which case he might.

194
00:11:37,240 --> 00:11:40,300
This method doesn't
always work for the chick.

195
00:11:40,300 --> 00:11:42,790
But the chick lying
there will occasionally

196
00:11:42,790 --> 00:11:45,580
peek to find out if the
predator is still there.

197
00:11:45,580 --> 00:11:49,810
And it looks, and it
still gets that stimulus,

198
00:11:49,810 --> 00:11:55,480
he'll continue in that
state of tonic immobility.

199
00:11:55,480 --> 00:11:59,550
But if it doesn't see the
eyes-- so the innate releasing

200
00:11:59,550 --> 00:12:04,390
mechanism is missing-- he will
lose the tonic immobility,

201
00:12:04,390 --> 00:12:05,180
and run away.

202
00:12:08,560 --> 00:12:12,650
Now, we know the opossum
does something similar there.

203
00:12:12,650 --> 00:12:14,570
We talk about
opossums playing dead.

204
00:12:14,570 --> 00:12:18,830
You don't hear about hamsters,
but I can assure you,

205
00:12:18,830 --> 00:12:20,950
they also can do that.

206
00:12:20,950 --> 00:12:24,470
And many other small
mammals with certain kinds

207
00:12:24,470 --> 00:12:28,500
of stimulation-- rabbits, for
example-- can enter that state.

208
00:12:31,670 --> 00:12:34,890
We talked about anti-predator
benefits of group foraging

209
00:12:34,890 --> 00:12:37,850
by birds before.

210
00:12:37,850 --> 00:12:41,310
You should be able to tell
what the major benefits are,

211
00:12:41,310 --> 00:12:43,220
and the costs.

212
00:12:43,220 --> 00:12:45,800
I can count at least
three benefits.

213
00:12:45,800 --> 00:12:48,400
One is dilution effect.

214
00:12:48,400 --> 00:12:51,350
We call it the selfish herd.

215
00:12:51,350 --> 00:12:55,080
The more animals are
there, the less chance

216
00:12:55,080 --> 00:12:56,880
that any one animal's
going to be caught.

217
00:12:56,880 --> 00:13:00,300
And for that reason, in
the period of reproduction,

218
00:13:00,300 --> 00:13:03,220
many animals
reproduce in a colony,

219
00:13:03,220 --> 00:13:05,440
because if the
colonies attacked,

220
00:13:05,440 --> 00:13:08,920
the chances that it will be
their nest and their young that

221
00:13:08,920 --> 00:13:11,630
are attacked are reduced.

222
00:13:11,630 --> 00:13:14,860
It also, of course,
reduces the demands

223
00:13:14,860 --> 00:13:18,500
for vigilance on an individual,
because there's many more eyes

224
00:13:18,500 --> 00:13:20,030
to see the predator.

225
00:13:20,030 --> 00:13:22,290
So the chances of their
detecting a predator

226
00:13:22,290 --> 00:13:23,650
are much greater.

227
00:13:23,650 --> 00:13:27,000
As one animal
responds, it's quickly

228
00:13:27,000 --> 00:13:29,290
communicated to all of them,
either because they fly,

229
00:13:29,290 --> 00:13:33,470
or they emit alarm
calls, or both.

230
00:13:33,470 --> 00:13:37,690
And, of course, if they
all fly up at once,

231
00:13:37,690 --> 00:13:40,550
it confuses the predator,
and very often the predator

232
00:13:40,550 --> 00:13:44,000
doesn't get any of them.

233
00:13:44,000 --> 00:13:47,570
It has costs, of course.

234
00:13:47,570 --> 00:13:50,550
You're competing with a lot
of other animals for food.

235
00:13:54,675 --> 00:13:56,660
Other animals that
are interfering

236
00:13:56,660 --> 00:13:58,720
can interfere with
your activities.

237
00:13:58,720 --> 00:14:01,230
It's, of course, a lot
worse if you're not

238
00:14:01,230 --> 00:14:07,025
a dominant individual
in the flock.

239
00:14:09,610 --> 00:14:12,110
We talked about the
optimal group size,

240
00:14:12,110 --> 00:14:15,400
which was not specifically
rated related to predation,

241
00:14:15,400 --> 00:14:18,460
but to food gathering ability.

242
00:14:18,460 --> 00:14:21,250
So I won't go back
over that now.

243
00:14:21,250 --> 00:14:23,940
I will mention mobbing here.

244
00:14:23,940 --> 00:14:29,820
We've talked about mobbing
in jackdaws and in geese.

245
00:14:29,820 --> 00:14:34,050
You saw examples of that,
of the geese in the video.

246
00:14:34,050 --> 00:14:38,110
You read about it in Lawrence's
description of jackdaws.

247
00:14:38,110 --> 00:14:43,960
We saw it in the
meerkat video, as well.

248
00:14:43,960 --> 00:14:46,870
Scott discusses the
black-headed gulls,

249
00:14:46,870 --> 00:14:50,450
which will show
mobbing of predators.

250
00:14:50,450 --> 00:14:54,390
And he cites data
from a study where

251
00:14:54,390 --> 00:14:59,460
they looked at
colony-nesting gulls,

252
00:14:59,460 --> 00:15:02,500
and how frequently
they engaged in mobbing

253
00:15:02,500 --> 00:15:06,210
as a function of where their
nest was in the colony.

254
00:15:06,210 --> 00:15:08,680
If they were near the
center of the colony,

255
00:15:08,680 --> 00:15:12,950
the rate of mobbing in
most animals in most nests

256
00:15:12,950 --> 00:15:15,290
was the highest.

257
00:15:15,290 --> 00:15:20,840
The rate at which they lost eggs
to a predator was the lowest.

258
00:15:20,840 --> 00:15:24,950
And then, if you went to the
edge of the colony, further

259
00:15:24,950 --> 00:15:29,120
he got from the
center, then they

260
00:15:29,120 --> 00:15:33,120
were less likely to engage
in the mobbing behavior,

261
00:15:33,120 --> 00:15:37,890
but they were much more likely
to have their nests predated,

262
00:15:37,890 --> 00:15:39,220
and they would lose eggs.

263
00:15:42,020 --> 00:15:47,400
So mobbing is an effective
kind of anti-predator behavior.

264
00:15:47,400 --> 00:15:51,270
So what they do besides
these kinds of behaviors,

265
00:15:51,270 --> 00:15:53,700
or just running away?

266
00:15:53,700 --> 00:15:56,900
Of course, that's the main
defense an animal has.

267
00:15:56,900 --> 00:15:59,640
If he's by himself, he's
attacked by a predator,

268
00:15:59,640 --> 00:16:01,285
he has to run.

269
00:16:04,230 --> 00:16:06,455
And the trick is simply
not getting caught.

270
00:16:09,450 --> 00:16:11,100
But they can do
other things, too.

271
00:16:11,100 --> 00:16:17,880
For example, some mollusks,
they have these tentacles.

272
00:16:17,880 --> 00:16:20,280
Some of these chemicals are
actually are pretty meaty,

273
00:16:20,280 --> 00:16:22,210
and animals will
often-- because they're

274
00:16:22,210 --> 00:16:24,250
moving-- are more
likely to attack

275
00:16:24,250 --> 00:16:26,390
that part of the mollusk.

276
00:16:26,390 --> 00:16:30,010
But these things can be shed.

277
00:16:30,010 --> 00:16:33,070
Similarly, lizards.

278
00:16:33,070 --> 00:16:34,514
They'll move their
tail much more

279
00:16:34,514 --> 00:16:35,680
than the rest of their body.

280
00:16:35,680 --> 00:16:40,220
And they will do that purposely,
because if the animal attacks

281
00:16:40,220 --> 00:16:45,600
them, grabs the tail, the
lizard just sheds the tail,

282
00:16:45,600 --> 00:16:49,550
and the tailless
lizard will get away.

283
00:16:49,550 --> 00:16:51,610
And, sometimes, the
tail will be shed

284
00:16:51,610 --> 00:16:53,080
and it keeps
wiggling and wiggling

285
00:16:53,080 --> 00:16:55,267
and the predator
keeps going after it.

286
00:16:58,070 --> 00:17:00,445
The movement is irresistible
to the predator.

287
00:17:04,089 --> 00:17:06,910
We talked about this a little
bit, about alarm calls.

288
00:17:06,910 --> 00:17:10,859
You should know that there's
both altruistic and selfish

289
00:17:10,859 --> 00:17:13,410
uses of alarm calls.

290
00:17:13,410 --> 00:17:17,060
We know it can be altruistic,
it can help others.

291
00:17:17,060 --> 00:17:19,240
But, of course, the
animal doing the calling,

292
00:17:19,240 --> 00:17:22,290
his position is betrayed
to the predator.

293
00:17:22,290 --> 00:17:23,194
So that's a cost.

294
00:17:26,260 --> 00:17:30,390
And of course, the animal
can elicit a mass escape

295
00:17:30,390 --> 00:17:34,020
and benefit from the dilution
and confusion effects,

296
00:17:34,020 --> 00:17:35,120
and he can do that.

297
00:17:35,120 --> 00:17:41,460
He's benefiting perhaps
more than others,

298
00:17:41,460 --> 00:17:44,650
because they head start he gets.

299
00:17:44,650 --> 00:17:47,680
And, sometimes, he will do that
even if there's not a predator,

300
00:17:47,680 --> 00:17:49,670
just so he gets access to food.

301
00:17:49,670 --> 00:17:52,570
So that's another selfish
use of the alarm calls.

302
00:17:56,120 --> 00:18:00,170
[? Cresswell ?] in '94
is reviewed by Scott.

303
00:18:00,170 --> 00:18:02,940
Collected data on
that, these animals

304
00:18:02,940 --> 00:18:04,620
that wade around
the shallow water

305
00:18:04,620 --> 00:18:09,645
and eat fat worms that they
find in the bottom of the ponds.

306
00:18:13,570 --> 00:18:20,860
He found that the
ones that didn't call,

307
00:18:20,860 --> 00:18:25,620
and the ones that flew up the
latest, were the most likely

308
00:18:25,620 --> 00:18:26,750
to be attacked.

309
00:18:26,750 --> 00:18:28,950
So those animals that
were doing the calling

310
00:18:28,950 --> 00:18:31,350
weren't the most likely to
be caught, even though they

311
00:18:31,350 --> 00:18:34,170
did betray their position.

312
00:18:34,170 --> 00:18:38,200
The calling might attract
the predator to the region,

313
00:18:38,200 --> 00:18:41,580
but it doesn't make him
select the animal to attack.

314
00:18:41,580 --> 00:18:43,410
In fact, if the
animal's calling,

315
00:18:43,410 --> 00:18:45,430
he's probably the one
you don't want to attack,

316
00:18:45,430 --> 00:18:48,550
because he's the vigilant
one that saw you first.

317
00:18:48,550 --> 00:18:50,670
They want to attack an
animal that's less aware,

318
00:18:50,670 --> 00:18:53,600
and that's exactly what they do.

319
00:18:53,600 --> 00:18:56,160
The late-flyers
and the non-callers

320
00:18:56,160 --> 00:18:57,670
were the most likely
to be attacked.

321
00:19:00,400 --> 00:19:02,620
And, of course, I
mention here at the end

322
00:19:02,620 --> 00:19:05,550
that alarm calls
can also attract

323
00:19:05,550 --> 00:19:08,530
predators of the predator.

324
00:19:08,530 --> 00:19:13,075
So it's another occasional
benefit of the calling.

325
00:19:17,520 --> 00:19:23,220
Redshanks actually have two
distinct ways of escaping.

326
00:19:23,220 --> 00:19:28,120
Some animals even have
very distinct calls.

327
00:19:28,120 --> 00:19:30,350
It gives away which way
they're going to escape,

328
00:19:30,350 --> 00:19:35,850
and that's because they can
be attacked in different ways.

329
00:19:35,850 --> 00:19:42,330
And for the redshanks, they
have two major predators.

330
00:19:42,330 --> 00:19:45,810
The peregrine falcons
attack from above,

331
00:19:45,810 --> 00:19:49,760
in a rapid-diving
attack, so they

332
00:19:49,760 --> 00:19:53,080
need to crouch low
and remain still,

333
00:19:53,080 --> 00:19:58,700
so they're not attracting
the vision of that falcon.

334
00:19:58,700 --> 00:20:01,780
Whereas the sparrow
hawk attacks flying

335
00:20:01,780 --> 00:20:05,030
in just above the ground, low.

336
00:20:05,030 --> 00:20:07,590
So their best bet-- if
he's already been detected

337
00:20:07,590 --> 00:20:10,580
and that hawk is coming towards
him-- the best thing he can do

338
00:20:10,580 --> 00:20:12,980
is fly up.

339
00:20:12,980 --> 00:20:16,930
Those are two very
distinct methods of escape,

340
00:20:16,930 --> 00:20:21,530
and they each work best
for one these predators.

341
00:20:24,250 --> 00:20:28,270
And then we come to a really
weird one: stotting behavior.

342
00:20:28,270 --> 00:20:31,490
It's caused a lot of confusion
in studies of animal behavior.

343
00:20:31,490 --> 00:20:33,110
Do know what it is?

344
00:20:33,110 --> 00:20:37,860
These little gazelles will
be fleeing from a predator,

345
00:20:37,860 --> 00:20:43,780
and as they flee, they're using
extra energy and extra time

346
00:20:43,780 --> 00:20:47,380
to leap up high so
they can be seen.

347
00:20:47,380 --> 00:20:50,710
They make themselves
visible to the predator.

348
00:20:50,710 --> 00:20:52,630
And this is the
way they look like.

349
00:20:52,630 --> 00:20:57,100
And when you're looking at them,
as you see in the drawing here,

350
00:20:57,100 --> 00:21:01,580
here's a cheetah pursuing one
of these Thomson's gazelle.

351
00:21:01,580 --> 00:21:05,450
And the cheetah sees him
from behind, and what he sees

352
00:21:05,450 --> 00:21:10,220
is this, like a white
flag, every time

353
00:21:10,220 --> 00:21:12,010
the gazelle leaps up.

354
00:21:12,010 --> 00:21:12,970
Why would they do that?

355
00:21:16,050 --> 00:21:18,306
There's been
multiple hypotheses.

356
00:21:21,720 --> 00:21:26,490
The book mentions that there
are 11 different hypotheses.

357
00:21:29,790 --> 00:21:31,870
He summarizes just
three of them,

358
00:21:31,870 --> 00:21:34,830
and uses data from Carrol.

359
00:21:34,830 --> 00:21:38,320
This is from 1986.

360
00:21:38,320 --> 00:21:44,340
He found that
attacks by cheetahs

361
00:21:44,340 --> 00:21:46,820
appeared to be deterred
by the stotting.

362
00:21:46,820 --> 00:21:51,360
It does work, and
the interpretation

363
00:21:51,360 --> 00:21:53,990
is that it's
communicating this: I'm

364
00:21:53,990 --> 00:21:57,480
far enough away that I have
a high probability of escape,

365
00:21:57,480 --> 00:21:59,720
so why waste your
time and energy?

366
00:21:59,720 --> 00:22:03,635
And, of course, if it does deter
the attack of the cheetah, then

367
00:22:03,635 --> 00:22:08,060
the animal himself
will use less energy.

368
00:22:08,060 --> 00:22:11,720
He will not have
to flee as long.

369
00:22:11,720 --> 00:22:14,970
And, in fact, they've collected
data that is summarized

370
00:22:14,970 --> 00:22:19,310
in the book about the frequency
of success of these attacks

371
00:22:19,310 --> 00:22:22,270
in animals that engage in
stotting and those that don't.

372
00:22:22,270 --> 00:22:25,880
And those that show
the stotting behavior

373
00:22:25,880 --> 00:22:29,655
are not caught as often.

374
00:22:34,850 --> 00:22:40,700
So, I want to show this
video called Great Escapes.

375
00:22:40,700 --> 00:22:42,580
Some of you have
seen Marty Stouffer

376
00:22:42,580 --> 00:22:45,000
on the TV and public television.

377
00:22:48,930 --> 00:22:51,350
I don't know if I'll
show all of these things,

378
00:22:51,350 --> 00:22:53,380
but this is a
summary of a number

379
00:22:53,380 --> 00:22:59,480
of the things in the
earlier part of the video.

380
00:22:59,480 --> 00:23:01,190
So let me pull up here.

381
00:23:20,150 --> 00:23:26,170
It'll start out with a bobcat,
the most common big cat

382
00:23:26,170 --> 00:23:29,310
in the USA.

383
00:23:29,310 --> 00:23:33,390
Not a real huge cat,
but a common predator.

384
00:23:39,880 --> 00:23:43,800
This content has been removed
due to copyright restrictions

385
00:23:43,800 --> 00:23:46,672
see the Readings and
Viewings page for information

386
00:23:46,672 --> 00:23:47,505
about this material.

387
00:23:54,692 --> 00:23:56,400
PROFESSOR: Why didn't
the bobcat kill it?

388
00:23:59,560 --> 00:24:03,660
We've met this before, when we
talked about predatory behavior

389
00:24:03,660 --> 00:24:07,135
and the work of
Layhuasen and Lawrence.

390
00:24:10,060 --> 00:24:12,330
What's your interpretation?

391
00:24:12,330 --> 00:24:15,230
Good exam question.

392
00:24:15,230 --> 00:24:17,524
Interpret what just
happened there.

393
00:24:23,461 --> 00:24:23,960
Yes.

394
00:24:23,960 --> 00:24:24,912
AUDIENCE: [INAUDIBLE]

395
00:24:33,280 --> 00:24:35,120
PROFESSOR: If I'm
hearing you right,

396
00:24:35,120 --> 00:24:37,710
I think you what
you said is correct.

397
00:24:37,710 --> 00:24:43,370
He had exercised his
killing by pretty recently,

398
00:24:43,370 --> 00:24:45,110
and killed prey.

399
00:24:45,110 --> 00:24:48,540
His motivation for
executing the killing bite

400
00:24:48,540 --> 00:24:52,190
was reduced below
the level where

401
00:24:52,190 --> 00:24:55,030
it could be triggered
by that prairie chicken.

402
00:24:55,030 --> 00:24:59,090
But his motivation to
stalk, and even attack,

403
00:24:59,090 --> 00:25:03,430
was still high enough that
when the stimulus was strong,

404
00:25:03,430 --> 00:25:09,440
like that prairie chicken taking
off, it elicited the attack.

405
00:25:09,440 --> 00:25:11,630
But he wasn't
sufficiently motivated

406
00:25:11,630 --> 00:25:15,530
to finish that
last step, because

407
00:25:15,530 --> 00:25:18,800
the action-specific
potential, the motivation

408
00:25:18,800 --> 00:25:23,620
to do the killing bite,
doesn't build up as fast

409
00:25:23,620 --> 00:25:25,810
as the motivation
for those earlier

410
00:25:25,810 --> 00:25:27,615
parts of predatory behavior.

411
00:25:30,320 --> 00:25:35,300
So there's other examples of
that in the work of Leyhausen.

412
00:25:35,300 --> 00:25:38,880
He wasn't playing
with it, but that

413
00:25:38,880 --> 00:25:40,450
seems to be what it amounts to.

414
00:25:40,450 --> 00:25:45,310
And in fact, these big cats will
do that when they themselves

415
00:25:45,310 --> 00:25:48,380
have killed and
eaten and so forth.

416
00:25:48,380 --> 00:25:52,710
They will still actually
catch prey without killing it,

417
00:25:52,710 --> 00:25:56,195
and bring it to their young,
which then can practice.

418
00:26:02,610 --> 00:26:03,790
We're going to see a coyote.

419
00:26:06,960 --> 00:26:10,870
This content has been removed
due to copyright restrictions

420
00:26:10,870 --> 00:26:13,702
see the Readings and
Viewings page for information

421
00:26:13,702 --> 00:26:14,535
about this material.

422
00:26:20,912 --> 00:26:23,370
PROFESSOR: There was only one
other thing I could show you.

423
00:26:23,370 --> 00:26:25,540
It's just a bobcat
attacking a lizard,

424
00:26:25,540 --> 00:26:30,770
and the bobcat ends
up chasing a tail.

425
00:26:30,770 --> 00:26:33,970
OK, so I will see you on Friday.

426
00:26:33,970 --> 00:26:35,870
And we will just have
a little bit more

427
00:26:35,870 --> 00:26:37,660
on anti-predator
behavior, and then we'll

428
00:26:37,660 --> 00:26:39,840
do us some reviewing.