~J..IP'Ol~HA
S'.l'ATE UNIVERSI'l'Y r NORTHRIDGE
Hct•l.E. P.J\..NGE, HOMING 21l-7D OR!:ENTl:.'l'.ION IN
ll
i':
A thesis submitted in partial satisfaction of t..he
requirements for t.he degreP. of Master of Science in
by
Brian
Jerc~e
Hill
The 'thesis of Brian Jerome Hill is
approvec~
Califoruia S'tz;:te University 1 Nort:J.1r.idge
'1,
.f\..CKNO?lLEDGEMENTS
I am sincerely grateful to Dra Jim Dole for his
guidance and many helpful suggestions in the performance
of this study and preparing the manuscript.
Dr. George
Fisler and DJ:'. Anthony Gaudin also read the manuscript and
'
offered many helpful comments.
I would. also like to thank
Ron Koller, Jan r..ewis and Charles Mike for their valuable
help in the field.
TABLE OF CONTENTS
ACKNOWLEDGE!-1ENTS
• • • • e • • ~ • • •
TABLE OF CONTENTS
~
• o •
o • • • •
•
•
•
•
•
•
~
•
•
•
•
~
•
•
•
CHAPTER
3--H~{E
AR&~
Discussion
•
•
$
•
•
•
•
•
o • • •
•
$
•
•
•
•
•
•
•
•
•
8
~
••••••
~
~
9
•
~
• •
G
•
•
•
• _• • • #
~ •
•
•
e •
0
• •
9
~
s • • o • •
*• • •
~
•
o
~
~
e •
~
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
~
•
•
•
$
•
•
•
•
•
•
•
9
~
~
•
1
8
• o o
•
•
•
•
v
•
•
•
•
~
•
~
~
•
•
•
~
•
•
•
"
~
•
~
•
•
•
~
•
•
4
~
Discuss.i.on.
•
•
19
•
•
•
•
~
•
~
•
•
•
•
•
•
4
•
~
•
•
•
w •
•
•
•
•
~
•
•
•
19
•
•
•
•
•
0
•
•
•
•
•
•
•
•
~
•
•
•
•
•
-
•
•
•
•
•
•
•
•
21
~
~
•
~
~
~
41
48
• •
~ ~
e
48
•
•
~
e
o
49
• • • • • • • •
~
~
•
53
••""•e••~~s••,.••••••"'"'
63
••••'"'•""~••••&.•••••).e·~a•••o•••~•••s••••
65
~
•
~
•
~ 4
•
•
•
$
•
•
*
u
e
•
•
$
e
~
~
•
•
~ •
•
~
~ -
•
~
~
e • •
~
8
•
e e
•
*
Q
•
•
•
e •
•
~
•
~
•
Q
e a •
CfTAPTER 5--SlJM.t-1..\EY AND CONCLUSION
LI'!'El<A'YJ.RE CITED
11
•
OF SENSES ON HOMING .l>.ND Ol"U.BNTATION
~
vi
o o o • o
• o • • • • • o & e •
•
v
••
o •
Materials and Methods
c
•
•
• •
•
~
3
•
~
5~-ROLE
Results
iv
.... .. . ...... .. .... . ... ...........
Discussion
CHAPTER
•
• • • • a • • o • e e • •
~
••••••••• 9
a • • • • • • • e •
Materials and Methods
•
iii
e • • • • • • • • •
o • • • • • • • • • • • • • • • • • • a
CHAPT:ER 4--HOMING AND OR!E.NTlt.TION IN QTh
Results
A •
~ o •
•••••••••••••,.••••••••tJ~o•••o•
RANGE
o • • o •
•.• •
~
Materials and Methods
Results
• • • • •
e • o e •
... ............ ....... .....
CHAPTER !--INTRODUCTION
CHAPTER 2--STJDY
•
'
...........................
LIST OF TABLES AND FIGURES
ABSTRACT
o • •
• •
•
• •
~
• •
o •
v •
•
•
•
•
•
~
~
•
• •
s e •
•
LIST OF T.\BLES
~···••••••••••a••••••••
4
••••••••••
22
1.
Meteorlogical data ••••
2.
Homing success in adult and
3.
Homing success among adul·t males and females •••
4.
Haning success among sensorily deprived lizards ....
8
.....
juvenile~~
c • •
23
50
LIST OF FIGURES
Major features and vegetation of study area •••••••
6
2. 'Distribution of home ranges .. ~ ..................... ~.~
13
1.
i
3.
Locations of lizards after 50 m displacement
.......
26
4.
Locations of lizards after 60 m displacement
.......
28
s.
orientation in open arena
6.
Orientat.ion of adult males and females in open
arena ..... ~ ..
7.
~ ~
"' ....
Ill
•
,.
$
,..
•
...
..:.
•
•
~
•
$
•
•
•••••••
•
~
•
•
•
•••
~
~
•
Cl
0
•
30
~
33
a.~ ...~.
35
·····G····
38
•
•
•••
•
,.
•
.,
•
•
••
•
•
•
o ••
Influence of displacement distance and visibility
of landmarks en orientation
0
................. ".
8.
Orientation of lizards in enclosed arena
9.
Orientation following displacement. to opposite
10.
Orientation in enclosed arena undt;:.c shade .......... ,.
11..
Directional choices of lizards displaced 50 and
60 ru ···~·········3~·······~···········•••c••··~··
12.
45
Locations of displaced lizards with t,he parie·ta.l
e
52
Locations of anosmic lizards aft.er displa.cen\ent • •
55
8lf6
13.
43
cov.ered ..
&
.....
Locations of blind
0
....
!(;-
t9
t;,
;:.,
~
•••
liz~rds
<':'
•
"
•
after
~
e
tOo
...
1.' • • • • • • • • • 6
d.isplac~ment
•
57
59
ABSTRACT
HOME RANGE, HOMING
YTA
At~D
ORIENTATION IN
~ANSBURIANA
by
Brian Jerome Hill
Master
of
Science in Biology
June, 1974
Heme ranget homing and orientation in a population of
~~~buri~
r found
months.
were studied over a period of thirteen
t.:.he home ra.nge sizes (males 36.8 m2,
2
fernales 30.7 m and
j'~veniles
16b4 re 2 } to be smaller than
those reported in previous studies, with no significant
difference betwe€;n adult male and female home range size.
Thr::re was considerable o·•Jerla.p among the home ranges of
both adult males and females&
About
25~'
of the adults of both sexos whlch were
displaced 50 to GO m homed..
hc:m~.
we:t:~J
not observed t.o
Anosmic adult li:e;ards, those with the pariet:al eye
cov~red,
well~
Jtt.veniles
and normal animal::; oriented and homed equally
Blind adults did not cr.ient cr home.
~?.:..
relE.;ased in an
op~m
arena :tn the field shewed
td.gnif:tc,m·t orientation to\A:o.rd their original capture
.in
their home range area \vere visible c
I.iza,rds fart.h er than
40 m from their home area, or which could not see landmarks
within their home area from the arena center, failed to
sh~~
significant orientational abilityQ
Lizards tested in enclosed arenas exhihit:ed behavior
related to thermoregulation rather than orientation to'>'llard
home.,
vii
CHAPTER 1
INTRODUCTION
Homing and the mechanisms required for homing have
been studied in many verte·brates representing several
classes.
Salmon return to the mouth of their home s·traam
by use of a sun compass and t.hen find their natal tributary
by olfaction (Hasler 1966).
TWitty (1966) found that newts
can home by using olfactory cues also.
Frogs are able to
orient using celestial cues perceived by the eyes or the
parietal eye (Taylor and 11"erguson 1970).
There are many
studies on homing among birds which indicate that eyesight
is the principle sense used although other senses may be
involved in sorneo
Homing and orientation among various rept.iles have
also been studied.
Bo::s: turtles
6
~e,M .saro}~f!,
using celestial cues {Gould 1957).
crotal'!:ll!,
,Y.,.iridi.~o
and
~~J!.ticophi~
orient
Two species of snakes,
taen;!.,P.tus_, have been found
to :r.eturn to a hibernaculum after displacement, apparently
~E~:12~~
orients by use of olfaction (Fraker 1970).
1 izards homing has been observed for
Among
.2.9~::J..S~...§. 1-'a.~~-~
eyesight of familiar landmarks appea:ci.ng t.o be the mechanisn.\
used~
No evidence of. ha.r.ting ability was found in
1
~l:.QE:-
2
'
Previous studies on homing of Uta
~~
include
Spoecker (1967) who found homing among members of this
species and suggested that visual perception of familiar
landmarks was the mechanism used, and Tinkle (1967) who
found no evidence of homing ability.
Although homing and orientation ability hae been found
among some reptiles, ·compared ·to most other vertebrate
groups they hava been little studieda
This is especially
true among lizards, since homing and orientation have been
studied in only five species with varying results.
In no
case has an attempt been made to block any of the senses to
determine if homing or orientation were impaired as has
been done with several other vertebrates.
The primary purpose of my study was to determine if
homing ability existed in U:SS.. st.ansbqriana and, if soe to
analyze the role of certain senses.
Before the nature of
homing or orientation could be determined, the home range
characteristics of this particular population of lizards
had to be ascert.ained.
cerned with
this
th~
species~
Thus part of this paper is cona•
npatia.l relationships among individuals of
CHAPTER 2
STUDY AREA
The study area was an irregular polygon which measured
approximately 290 x 40 m and enclosed 11,600 m2.
The plot
was located 2 km east of Pepperdine University, Malibu,
california, along t.he west bank of Malibu Creek ( 33.9° N
latitude, 118.7° W longit.ude) within one mile of the Paci,,,,
fie Ocean and approximately 12 m above sea
level~
The
region is characterized by mild, dry summers and mild,
moist winters (Table 1).
Rainfall is largely confined to
the winter months, beginning in November and extending
through April, with little precipitation from May to october.
The presence of the'ocean moderates the temperature var~
iances during the year, and often low clouds or fog form
during the
mo~~1ing
weather conditions,
hours.
u~
Because of these general mild
are active in all months of the
year on those days when the temperature is sufficiently
high.
The nat.ure of the study area is variable (Figure 1).
Approximately 157:; of the area is bare sand.
Ano·ther 25% is
covered sparsely by various herbs and shrubs such as mustard
(,~.rlf~
thistle
whil~:o
sp), sage (Artemisia californica)
(~la ,Eestif~)
and cocklebur
6
(~nthium
Russian
sp)
an•::>ther 20% supports a dense plant cover of willow
Piled
rocks~
4
Table 1--Meteorlogical data for Santa Monica, California,
twelve miles south of the study area.
Data were taken in
1972 at a weather station operated by the Santa Monica
Harbor Department.
Mean Temperatures
Montq
January
February
March
April
May
June
July
August
September
October
November
December
Mean
Ma~
17.3
19 .. 1
17.8
16.7
17.6
19.3
20.7
20.8
21.3
20.3
19.1
17.3
Mean Miq
9~7
10.3
10.7
10.1'
11.9
14.7
16.4
16.1
15.0
14.0
12 .. 3
8 .. 9
0
P,aily
c
Avg Monthly
Mean~ Ita~~~all
13.5
14.6
14.2
13 .. 4
14.8
17.1
18.6
18.5
18 .. 2
17 .. 2
15 .. 7
13.1
1.27
5.52
4.02
1.42
0.03
o.oo
o.oo
o.oo
o.oo
0.03
12.89
11.90
(em)
5
Figure 1--Study area
sh~~ing
major features and vegetation.
6
.X
u
0
0::
"CC
.X
u
0
...
....
"CC .
Vi
a:
G)
G)
rGu
£t:
..!
<\!
·;;
'£§
Ill
'2
•t;
~
'
I<
~
tl)
·:'t
.....
G)
"':J
i
<(
I
en
~
g
...
1\:
it<
::1
ro
(.!}
~ []
.
...
Ill
:z
A
oil
....,
ij)
:.E
~1
1
briC'.ks and broken concrete (duinped construction :materials)
cover
appl.~oximately
scattered rocks.
15% and another 200-" consis·ts o£
CHAPTER 3
HOME
RANGE
Materials and Methods
The study area was divided into a grid of 10 x 10 m
quadra·ts with stakes marking the intercepts.
Lizards wi th.:tn
the area were captured either in pit traps or by noosing.
Noosing was accomplished with a lizard gun patterned after
f,
that described by Bertram and Cogger (197l)Q
Traps consis-
ted of tin cans, each at least 10 em in diameter and 14 em
deep, placed in the ground with tops flush \'lith the surface ..
The arrangement of traps was haphazard, their locations
being dictated by the nature of the terrain.
Each
~
captured was marked for future identification
by toe clipping but in no case were more than two toes cut
frcm any one foot.
Each animal was also painted on its
back with a diRtinctive combination of colored stripes so
that !t could be visually identified.
Lizards with such
marks were identifiable for up to two months and were not
recaptured
~,til
the marks became
im~ossible
to reada
At
tr..a t time they were retaken and the pain ted marks rene1rted.
After each capture all r•oosed animals were released ;vhe.re
first observed immediately prior to noosing.
&~imals
taken
in pit traps V&'ere released adjacent to the can into which.
they had fallen ..
9
animal's location with respect to the nearest stake was
noted.
Sex, snout-vent length and any obvious abnormalities
were recorded.
Sex was determined by the size of the
femoral pores and post anal scales.
Snout-vent length was
measured with a millimeter rule while holding the
anj~al
vertically with the head upward and the body and tail
alla_,ed to fall of ·their own weight.
Animals shorter than
45 mm were considered juveniles (Stebbins 1954).
Fraa 17 February to 17 August 1973 the study area was
I'I
visited from 2 to 5 days per week.
At each visit about
four hours were spent searching the entire area for animals,
capturing unmarked animals seen and releasing any tx·apped
animals.
Dimensions of home ranges for all lizards observed at
least four times over a period of two weeks or more were
computed.
This was done by plotting all capture points for
each animal on scale maps of the study area and connecting
the outside points (minimum home range method of Mohr,
19~7)~
The area of the resulting polygon was then deter-
mined with a compensa·ting polar planimeter.
Results
Between 17 February and 17 August 1973, 301
~were
marked and 1056 observations of these animals made.
Of,
thcset 661 were identifications without capture, 235 were
noos ings and 160 were pit tra.ppings.
T'he area.s c£ hane ranges of 41 adult males averaged
36.,8 m2 (range l.,7«•1HL.07 SD=23 .. 9) based on a mean of 6.4
10
observations per lizard· (ranger 4-14).
Home ranges of 35
adult females averaged 30.7 m2 (range 1.7-154.8 m2 ; SD=34.4).
The average number of observations per fe-..male was 7. 7
(range 4-19).
For 35 juveniles, the average home range
area was 16.4 m2 {range 0.3-83.9 m2 : SD=l7.2) based on an
average of 5.1 observations per animal (range 4-10).
As
tested with Student's t, the adult male home ranges averaged
significantly larger than those of juveniles Ct=4.09 with
74 df; Pc::. OS) but did not differ significantly from those
of adult females (t=Oo9l with 75 df: P>elO).
The home
ranges of adult females also were significantly larger than
those of juveniles ('t=2.11 with 67 df; P<.OS).
Correlation coefficient tests were applied to ·the heme
range data comparing home range area to ntll-nber of observa-
tions.
tion
Among adult males there was a significant correlawith 41 df: P<.OS), the size of home range
(r=0~34
tending to increase with an increase in the number of
observations.
~uong
adult females (r=O.lS with 33 df;
P>.lO) and juveniles {r=O.ll with 34 df: P>.lO) no such
correlati~n
could be found.
Correlation coefficient tests of body
~ize
vs home
range area. revealed no significant correlation among adult
males (r=O.OS with 38 df: P>.lO} or adul·t females
(r~O .. ll
with 29 df; P>.lO).
Juveniles showed a significant negat.ive
cort;elation {r=-0. 36
-y,;i th
decrease,
33 df; P<. 05), indicating that as
11
To determine if there
'~as
any relationship beb1een
location of a home range and its size, the home ranges of
lizards known to have utilized the piled-rock area were
compared to the home ranges of lizards captured exclusively
outside that area.
Student's t test showed no significant
difference between the mean home range areas of adult males
(t=9.19 with 39 df; P>.lO), adult females (t=-1.55 with 33
df; P>.lO) or juveniles (t=O.l4 with 33 df; P>.lO) occupy-
ing the two zones.
Furthermore, no obvious relation
between the location of a lizard's
h~~e
range and the sex
or age of the animals could be discerned (Figure 2).
The
majority of animals of both sexes, both juvenile and adult,
were concentrated in the area of piled reck or sparse plant
cover.
No tendency for any of these groups to preferen-
tially occupy the outlying bare sand or dense plant covered
areas was noted.
Discussion
My home range data differed somewhat from that of
other studies (Tinkle et al. 1962).
~ne bQ~e
range areas I
obtained are considerably smaller than previously reported
(290m2, 100 m2 and 50m2 for adult males, adult fen1ales
and juveniles respectively).
ence of a more favorable
This may be due to the pres-.
~habitat
in my study area so tha·t
the animals were able to meet their needs within a smaller
<!lrea.
Tinkle 1 s (1962) study area was desex·t where temper·-
at.ures ''a.ry greatly and where there rnay have been less food
and cover availableo
12
Figure 2--Distribution of home ranges of adult males (a),
adult females (b) and juveniles (c).
Ranges of individuals
are outlined in narrad lines; some are shaNn as broken or
dotted lines for clarity.
piled-rock areas.
Heavy dashed line outlines
Thet:e are no lizard home ranges indica-
ted in central portion as lizards in this area were used
for orientation study rather than ho.'lle range.
(.
13
----,
.... '
'\
I
I
\
l
'• ',
'I
' '\
I
I
J
I
I
I
:
\
\ \
0
\ I
II
I I
II
It)
rI ' a
I S
\s
' a
'\\
\
z
ll
I
14
Tinkle et ala (1962) detennined t.hat
most~
heme
ranges could be fairly accurately estimated after four
observations~
He found that the home ranges tended to get
larger as the number of observations increased beyond four.
I found this to be true only among adult males, suggesting
that home range areasof the adult fem.ales and juveniles
are more accurately calcula.ted on the basis of four captures
than are those of adult males which would tend to be underestimated.
In this case, raising the minimum number'of
observations to determine home ranges among adult males·
gives 1nore accurate results.
•
J
Tinkle et al. (1962) reported that adult males defin-
itely shOW"ed a larger home range
than~
did adult fe1llal'es,
whereas my results show the range sizes of the two sexes
not to be signific<:.nt.ly different.
that his observations of
·~
Spoecker (1967) 'Stated
indicated the adult hame range
of males and females may in fact, be similar'but due to
behavioral differences between, the sexes,· the home range·
area of males may appear to be larger.
He suggested males
are terri toriaJ.. C)Ver their en tire .heme rc.nge ancl.conse-..
quently cover their home range
more
frequent:ly as they· ...
patrol for intruders ·than do the non-territorial females.
Thus t because males are mo:r·e likely to be a.een near the
pez·iphery of their heme ranges, these· areas, a.a determined
using the minimum polygon method would appear larger than.
those of females which presumably restrict. most o.f their
activity to a small portion of t.heir heme
c:;.:r.·ea.~
If,
15
h~ever,
a greater number of observations were made of the
females, this difference in estimated home range size
should be negated.
This may explain my failure to detect a
significant difference in size, since female home ranges
were based on more observations per animal than were those
of, the males.
Other factors also may be involved in producing these
similar heme range sizes.
For example, if :males,are ter-
ritorial, their home ranges might be expected to be smaller
where there is a great density, as was the case in my study
The home ranges of the non-territorial females would
areae
be less affected by this canpression effect.
Also, as
mentioned earlier, since ,mal-e home ranges based- on four
captures tend to be underestimated whereas those of females
are more accurate when based on
fou1~
captures, my usa of
areas based on four captures for males may have equalized
tb,e comparison between the two sexes.
Tinkle et al. (1962) found
that~
living in sparsely
vegetated and completely open areas had the largest home
ranges~
Hcr-N"evcr, when I compared home rangesof lizards
associated
\'ii th
the favored piled-·rock area to those
exclusively in open or sparsely vegetated areas, I fow1d
no significant differences.
These contrasting results are
probably due to the differences in the climate of the two
study areas.
u~y
The sparsely vegetated sections in my area
have provided a very good environment with moderate
texuperatxu:e at all times whereas a similar region in a
16
harsh desert climate as used by Tinkle would have great
extremes in temperature, forcing the animals t.o move elsewhere in the heat of the day.
I found no correlation betw·een the home range size and
the body length of the resident animal among either adult
males or females.
Thus
it appears that, once adulthood is
reached, the size of the area occupied does not vary
appreciably with age.
The inverse correlation between body
length and home range area among juveniles may indicate
that among very young animals I was not observing a specific
bane range but free wandering.
However, as they near adult-
hood, a home range is established as they wander less and
begin to restrict their activities to a fixed site.
,,
Spoecker (1967) also recorded long movements of juvenile
lizards before they established permanent home ranges ..
Although individual male
~
have been shown to be
territOrial over their. entire home range ( Tinlc:le et al.
1962), and I observed territorial behavior (head bobbing,
,.
cb.asing) as well, the home ranges of males as plotted in
Figure 2a O"'J'erlapped a great deal.
Some of the O"'.rerlap is
only apparent as there cam be up to a 90% turnover in a Uta
population ('I'inkle 1967}, so that the males did not all
inhabit these areas at the same
time~
However, twenty
males were noted to occupy overlapping areas during t.he
same time periods.
Since nearly all observed overlap
occurred in the pi.led-rock. areas where the densi·ty of !Jli
was at. it.s greatt:"tst. and where the best cover W'as available,
17
the lizards, although very close spatially, may not have
been able to see each other, thus per-mitting them to exist
in much closer proximity than is posslble in an open area.
It is also possible that in this area the actual territory
is only a small part of the home range so that most of the
bane range is not defended and is subject to overlap.
Tinkle's studies did no1;: present any evidence on this point.
From outlined home ranges in Figure 2, it is apparent
t'hat the areas of sparse plant cover, scattered rock and
piled-rock are the most inhabited, whereas the dense plant
cover and bare sand areas are scarcely utilized.
The
preferred areas provide escape refuges and egg laying sites
under or among rocks and vegetation.
These areas support
many insects which are the main food for Qta.
These areas
I
i'
a~~P
provide basking sites and shade, both of which are
important for lizards since they depend on behavioral body
temperature control.
The areas covered densely with plants
are scarcely utilized although they do provide refuges, egg
laying sites, food and shade.
suitable basking sites
~rhich
They, however, usually laCk
may be necessary to raise a
lizard's body temperature sufficiently for the animal to
be
active~
Bare sand areas are the least utilized.
They
provide·ample area.s for basking6 butthere are no refuges
from predator&, no egg laying sitesand no
shade~
The
amolli,t of food ie also reduced in these areas.
No obv:tous .t:'olation bet\'leen location of ho:ne r-ange and
stm: or age of
~'ln:i.1uals
was found.
Adul ·t males a!.'1d females
18
occupied similar
areas~
Juveniles tended to occupy the
same areas as adults, as was also found by Tinkle et al.
(1962).
Since there is such a large turnover of adults
each year, most juveniles will occupy the vacated areas
when they reach maturity.
Should no vacated areas be
immediately available, the juveniles will presumably disperse to another area (Spoecker 1967).
CHAPTER 4
HOMING AND ORIENTATION .IN
~
Materials and Methods
To determine homing ability, individual normal
~
were displaced 50 to 60 m from their original site of
capture~
For displacement, animals were first placed in
ti.n cans covered with aluminum foil so that no light could
:'\
enter and then carried to the release point..
All lizards
were released in t.he central part of the study
At
area~
release, the animals always moved quickly to the nearest
cover or into the nearest burrow available.
An animal was
considered to have homed if later found within 10 m of its
original capture site.
'l\llo
methods were used to determine if these lizards
are able to orient. toward home immediately after displacement.
In the first a flat arena, 10 m in diameter, laid
ol.1t 5.o. a. sandy area adjacent to the study area, was used •
.Four 80 x 80 em blinds of black plastic were placed 5 m
frcm the aren.a center at the: cardinal compass points.
Liza.rds cap·tured less than 60 m fr.or11 the arena center \'.•ere
tlre clipped, painted with identifying marks and placed i.n
tin cans covered. with aluminum foil for transport to the
arena.
Each ani.'!llal was then placed one at a time in the
c1ent.er of the arena tmde:r. another tin can. which
\'la~;
att.ached
20
opposite blinds.
Then, while out of sight behind one of
the blinds, I released the lizard by pulling the line and
thus raising the can.
The lizard r s movements a.fter release
were observed through a pin hole in the blind..
The rnnimal's
activities and the point at which it left the arena were
I'ecorded.
This departure direction \li'as then compared with
the expected direction toward the original capture point.
Another attempt to determine the ability of Yls. to
orient was also tried using a smaller, glass-enclosed arena.
This arena, 70 em in diameter, consisted of a wood base
surrounded by eight clear glass plates, 18 em high, arranged in an. octagon.
During use it was mount.ed on a stand
75 em high and placed 10 to 15 m from the original capture
point of the animal to be tested.
was divided into eight
tri~~gles,
The floor of the arena
each having its apex at
the center of the arena and one of the arena sides as its
base.
The midpoint of one side of the arena was faced
toward a li.zard • s original capture site.
The o1:iginal
capture site was always visible to the lizard from the
arena.
Ind.ividual liza.rds were capturedc carried t.o t.he a.rena
in light-tight cans and :r:·eleased in its center so that. the
animal faced away fro.""!!
home~
Fifteen minutes 'VTere allowed.
for the lizard to explore the a.renar dur.tng which time I
left the area.
After this adjustment period
location was noted once every ten minute a a
tlu~
animal's
()bserv-.a t.ione.:
were made with binoculars from behing t:;over so t..hat..
t.h~~
21
animal was not disturbed.
In cases where the animal ex-
tended across two or more sections, the triangle in which
the animal's head was situated was deaignatedc
From 12 to
16 points were recorded per animal over a period of
hours.
2-2~5
The results were compared to the expected homeward
direction.
In some cases, in order to determine if sun position
or temperature had an effect on the orientation results, a
circular, fl. at piece of cardboard \'ias placed on top of the
arena after the lizard had been placed into it.
In this
way the whole arena was kept in the shade during the
experiment and the animal was precluded from seeing the sun
directly.
To determine if the directions taken-correspond to the
.expected homeward direction in these orientation studi.es,
the
v test was used ( Bat.chalet 19?2).
r.oe 5% level of
significance was chosen as the critical value.
Results
Some normal adult lizards were able to home when
displaced 50 m and 60 m fran their capture site.
In each
group the percentage which.returned was similar {25 and
28%), howeverf a greater percentage o£ those-displaced the
shorter distance was observed again somewhere in the study
area after
displac~mer.rt.
observed to ho.11e
(Tabl<~
suveniles dit-oplaced 50 m were not
2) ..
Homi.ng success of male and female
gr.eat.ly ('fable 3)
~
Jft~.
d:td not dlf.fer
Of r.-tir.teteen l!t:tles displaced/ 26;iG
22
Table 2--Homing success in normal adult
y~~
displaced 50
and 60 m and juveniles displaced 50 m.
Adults
§..0 m
50 m
Number of animals displaced
Number and percent of
displaced animals which
returned to within 10 m of
their original ca,pture
site (home)
25
7
(2~~)
J~t.iles
20
10
5 (25%)
Number and percent of
displaced animals later
observed in study area but
which did not hane
13 (52%) S (25%)
4
(40"~)
23
Table 3--Homing success of .Y.t-J!. by sex, irrespective of
distance displaced.
Malef!.
Number of animals displaced
Females
_'!'ota.l,
45
19
26
5 (26%)
7 (27%)
12 (27%)
5 (26%)
13 (50%)
lS ( 400~)
Number and percent of
displaced animals which
returned to within 10 m of
their original capture site
(hotue)
;I
11umber and percent of
displaced animals later
observed in study area but
,which did not home
returned to 'ill thin 10 :m of their original capture sites
whereas 27% of the 26 displaced females were later found in
thei.r home areas.
'l'o assess the directness of homing among normal liz-
ards, all locations fer each displaced animal which was
later observed ai:. least once were plotted with respect to
the original capture sites and the release sites {Figures 3
and 4) •
T'iiel ve animals homed successfully.
Eleven of
these when first seen after displacement were already
within 10 m of their original capture site.
Another
in.itially moved in the opposite direction but 159 days
later was observed haae.
Eighteen others apparently failed
to heme, in some cases establishing new home ranges..
Three
o.f these had moved less them 5 m from the displacement site
when next. seen 2, 4 and 5 days after release.
Another
which moved in the wrong direction established a new home
range~ for it vras seen fourteen times in an area of 35 m2
over a period of 61 days.
in a new
area~
One animal was seen eight times
one \\fas seen five times, two were seen three
times and one '\'las seen twice
0
Of nine lizards seen only
once after release and v-.rhich failed to home, alJ. but one
went in a correct direction.
Using the fla.t sand arema, 38 pta were tested for
t.he.ir ability
to orient homeward.
The direct.ion each
a11im.cal left the arena was compared to the homeward direction (Figtu:e 5)..
When all animals are treated t.oget.hex the
probability t.h.ut the choict:ls of direction were random
';,:iii-t;~
25
Figure 3-·-Loca.tions of all seventeen normal l.i.zards which
were seen after displacement of 50 m.
An x indicates
observation points with respect to home (A) and the release
site (B).
Lines connect release site and consecutive
capture points.
Numbar next to some points indicates num-
ber of times animal was seen at or within 5 m of that point.
For simplicity of presentation, the release sites of all
animals have been plotted to coincide: all other locatio."ls
have been rotated around t.his point so that the original
capture sites of all animals also correspond.
Heavy line
indicates seven c<.nimals had already homed when first seen
af.ter release.
Three additional lizards wh:.tch were
observed not to move a·t least 5 m from the release site ·are
not show-n.
.
.
26
\ ,, 14
\
.
\
l
\.
27
Figure 4--Locations of all nine normal lizards which·were
seen after displacemen·t of 60 m.
An x indicates observa-
tion points with respect to home (A)
{B)6
andt.he-:t"e~ease
site
Lines connect release site and consecutive capture
pqints.
l:?umber next to so.--ne points indicates number of
·tim.es animal was seen at or within 5 m of that point.
For
simplicit.y of presentation, the release sites and original
. cap~ure sites have been rotated to correspond as previously
,described.
Heavy line indicates four animals had already
homed when first seen·after release.
One additional lizard
(not shown) did not move at least 5 m from the release site.
4
3'l\
\\
'
-'<3
\
29
Figure 5--0rientation in relation to homeward direction
(arrOW') of 38 lizards tested in open sand arena (u=2.04
with 38 df: P<.OS).
Length of lines extending from circle
indicate number of lizards leav·ing arena in each 10° seg-
ment of circleo
Shortest lines equal one animal.
30
less than 5% as tested with the V t.est.
Thus there was a
significant tE;lndency for the departure points to be clustered around the expected homeward direction.
when each sex was considered
al~ne,
However,
neither males or fe-
males shc:Med significant orientation ta11ard heme {Figure 6).
Among females the distribution of ·the departure points more
closely approached significance (P':.05) than among males
(P>.lO).
The failure to achieve significance in either sex
alone, whereas significant orientation is indicated when
they are considered together i.a due to the small sample
£ize ..
A further analysis was made with the above animals
grouped as to distance of displacement and ability to see
l·a.ndmarks from. the arenas
The 26 anir.-tals displaced less
---
. tha.u 40 m demonstrated significant orientation toward home
(P<.05) whereas
~hose
twelve displaced more than 40 m did
not ( P.;-.10; Figures 7A, B)..
When grouped on the basis of
;r.rhether or not la&Admarks within the anintal • s home range
were visible frc.rn the arenas- the v test was significant for
those animals that could p.resumably se\!'.' home landmarks
(P<0::05) and insignificant for those t.hat could not
Figures 7C, D).
(P>~lO:
Although this a.nalysls was made wit.h ·the
same 39 lizards tested for orientation vs distance from
h<)me, those animals captured closer t.o the arena did net
cor:ce~pond
~~xactly
to those that. could. see home landmarks ..
In test.h,.g six·teEm animals for orientation ability
32
Figure 6--C'noice of directions among seven-teen male and 21
female lizards released. in the flat sand arena plot.ted
respect to homeward direction (arrow).
(u=l.06 with 17 df:
21 df :· P:>. 05) •
P>~lO),
'~'.lfi th
(A) Male lizards
(B) female lizards (u=l.60 'i'iith
Length of lines extending from circle
indicate number of animals leaving ~rena in each 10° segment of circle..
Short.est lines equal one animal.,
(A)
'""'~I
.
(B}
::; '
_::(
I
t -·--
_/
I
34
Figure 7--Cholce of directions among 38 lizards released in
the flat sand arena plotted wi·th respect to homeward direc-
tion (arrCM).
(A) I,izards displaced less than 40 m (u=2.33
with 26 df: P<.OS), (B) lizards displaced more than 40 m
(u:;;0.20 with 12 df: P>-10), (C) lizards for which landmarks
within hane range were visible from release point ( u=2 .. 31
with 23 df: P<":05) and (D) lizards for which landmarks
within home range were not visible from release point
(u=0.39 with 15 df; P>.lO).
Leng·th of lines extending from
circle indicate number of antmals leaving arena in each 10°
segment of circle .. · Shortest lines equal one animal.
35
(A)
(B)
(C) .
·~·
i
t
I
L
)
/
,..,__
appeared to ir1dicate a significant tendency to orient in
the homeward direction (P<.05; Figure 8A)e
However,
whP~
these same data were tested with the direction toward the
aun as the expected direction the tendency for clumping wa.s
found to be even more significant (P<. 05: Figure 8B). · A
careful check also revealed a 3° C temperature difference
within the arena, coolest on the side toward the sun.
This ·
finding prompted a further test to determine if the animals
were in fact orienting to the temperature gradient.
For
this test five animals were each used twice but with the
arena in a different position on each run.
The arena was
set so that twelve observations (one every five minutes)
were made while the cooler temperature and home were ira t.he
same direction.
~-
The arena was then moved so that the ·cooV3r
t.empera ture and horileward directlons were as close to op-
posite as possible and twelvemors observations were made
asybe:Eore.
The directions taken :in these 120 observations
sh6wed no significant clumping in the homeward direction ·
(P>.lO; Figure 9A).
However, when.the coolest reg;ion in.
the arena -v1as .designated the expected
observations are significant (P< .. OS;·
direction.~
F.igure.~.9B),
,t.hese -
indicating
that the animals in the previous tests \'/ere probably
orien·t.ing to the tempera tu;re gradien:t ~ not to tlu:dr home
di.recticm.
In an attempt to
eli~inate
the temperature factor, six
addi't.ional lizards were tast.ed wh.:i.l.e the arena was com-
pletely shao.ed.
1>1i th cardboar~ s~·;:)
, t.ha t t.h.e r;;un vms not.
37
Figure a--Numbers of observations of sixteen liza.rds in
each 45° segment of the enclosed arena, (A) plott.ed with
ho.'tteward direction as expected direction -(u=4.08 with 229
df1 P<.OS) and (B) plotted with coolest segment as expected
direction (u=6.23 with 229 df: P<.OS).
38
(A)
39
Figure
9-~Nmnbers
of observations of five lizards in each
45° segment of the enclosed arena.
Arena position relative
to home was shifted midway through the observation period
so that homeward direction was
away from sun in other half.
t~~ard
sun for one half and
Data in (A) are plotted with
homeward direction as expected direction (u:::0 .. 48 with 120
df: P>.lO)
o
In (B) data are plotted with coolest Sf3gment
as expected direction (u=6.85 with 120 elf; P<.OS).
40
(A)
(B}
41
visible from any spot in the arena.
the arena was therefore uniform.
The ·temperature within
Figure 10 shows the dis-
tribu·tion of the eighty points observed.
The V test w·ith
homeward as the expected direction proved to be insignificant (P> .. lO).
As a further test of orientation, an analysiswas made
of the directions taken by animals displaced during the
homing study.
For each lizard the direction from its
release site to the last point at which it was observed
,.
after being displaced from home and released was compared
with the expected homeward direction.
move
at
least 5
1n
Animals that did not
from the release site were.not considered ..
This group of 27 lizards showed significant orientation
toward hC'..me ( P<. 05 1 Figure 11) •
Discussion
Homing among ad\.11 t
~ stans~.rj,_~_s.
is ·probably Type I
(Grifful 1953), that is, hauing is dependent upon release
ir• an area ·with which the animal has had prior experience ..
This conclusion is suggested by the fact
which in
l"il.Y
t~~t
the adult
~.'
study ax-ea. have small heme ranges,_ do not .homa
well from a distance as short as 50 m.
The finding
th~~------------
adult male and female lizards, which have similarly sized
heme ranges an.d are presu."'!ably familiar wit;h comparably
sized. areas, do n-ot dif£er e.ig.nifica.ntly in their horo.ing
success further supports this conclusion.
Other studies
baaing.
t.il'.i th
lizards also suggested Type I
Spoecker { 196 7) _dete.:r::ro.ined that JJ:!f.a haued with
42
Figure 10--Numbers of observations of six lizards in each
45° segment of the enclosed arena under complete shade and
uniform temperature throughout.
Arr~r
direc·tion (u=-1.30 w·ith 80 d£1 P>.lO).
indicates homeward
43
44
Figure 11--Directional choices of 26 normal lizards which
were displaced 50 to 60 m.. · Lines sha-A direction from
release site to last observed location after displacement,
plotted relative to expec£ed homeward direction (arraw).
Probability of achieving such a distribution by chance is
less than 5% (u=4.56 with 27 df).
Lizards which were seen
after displacement and did not move at least 5 m from
release site are not
animalo
sh~~~
Shortest lines equal one
45
46
some success after displacements of up to 122 m and with
lOOO.;b success for 80 m displacements.
He believed lizard.s .
in his study area to be familiar with an area of at least
150 m in its smallest dimension, although he did not actual-
ly determine home range size.
This presumed familiar area
is much greater t.han displayed by .ill;.a in my- study area.
If
homing is of Type I, it would be expected t.hat lizards in
Spoecker' s area would home from gr·eater displacement distances and with be·t:.ter success.
mined homing to be of Type I in
Weintraub (1970) deterScelopor~
orcutti, as
those lizards released where the original capture site
could be seen homed significantly better than those released out of sight-of-their home area.
The finding that orientation toward the original
capture site in .!!.E! is apparently influenced by visibility
of familiar areas further supports the idea that homing is
'l.ype I.
In testing 38 lizards from the open arena, a sig-
nificant orientation was shown, with those animals which
could see landmarks ttd thin their home range fran the arena
center psrforming much better than thr.>se which could notType I homing is also sug-gested by the finding that the
ability to orient appears to be influenced by distance from
the home ranger since individuals whose original captu:r:e ·
site was less than 40 m from the arena center
sha~ed-
ve1:y
significant orientation whereas those captured moz·e than
40 m away s'how'ed ( none~
'l~hese .;resul. t.s suggest
JJ!:.C!.
can
orient toward home if fau'tilia:r w1t:h l,:mdmarks .i:n ·the area
47
but these do not necessarily have to be in the animal's
actual home range since those animals captured closer to
the arena did not correspond to those that could see heme
landmarks.
My attanpt to demonstrate homeward orientation in
~a
using the glass enclosed octagonal arena proved unsucces- sful.
1'he results w·i th this method shewed that .!:!!:.2. orients
· significantly in relation to tempe:r:·atnre differences in the
arena.
After completely shading the arena, random move-
ments were observed.
This method was similar to that used
by Weintraub ( 1970) with s_gelo,E_orll..[i_ orc_!.ltti.
He also found
that lizards orient with refez:ence- to_ the sun and concluded .
that this behavior was due to a thermoregulatory mechanism.
CHAPTER 5
ROLE OF THE SE...~SES ON HOMING AND ORIENTATION
Materials and Methods
To ·determine if iot was necessary for homing, the
parietal eyes of twenty lizards were covered with black
paint before the animals were displaced.
The paint dried
within thirty minutes, after which the animals were carried
,,
f!
in covered tin cans 50 m from the original capture point
·and released.
TWe~ty
lizards were rendered anosmic before displace-
·ment to determine if olfaction was essential forhoming.
These animals were taken to the laboratory in tin cans
covered with aluminum foil on the day of
animals "'lere refrigerated at 5°
c
capture~
Here the
and then kept on crushed
ice while 10% formaldehyde was perfused through the nasal
chamber with a rounded needle as done by TWitty (1966).
~his
method was chosen after attempts tc) sever the olfac-
tory nerves proved unsatisfactory.
In !!:!2! these nerves are
very short, thus difficult to cut without damaging the
brain..
After the injection of formaldehyde the animals
were allc:Med sixteen hours to recover in the laboratoryb
The following day they were returned to the study area in
the
sa1il<!:1
cans and released 50 m from their original capture
'!.V~(") det.ei-min~ if
eyesight. was necessaxy for homing 6 21
49
lizards were blinded.
Immedia.tely after capture these
animals wers taken to the laboratory in covered tin cans.
Here they were blinded by first refrigerating ·them at 5° C
a~d
then keeping them on ice while both eyes were removed
with a sharp probe.
After the operation the lizards were
allowed sixteen hours to recover- and the ne.xt day w·ere
returned" to the s-tudy area w·here they were released 50 m
_,.
--- from their original capture point.
Results
1.-;f
Heming success among anosmic lizards and those with
the parietal eye covered was comparable to that among nor- mal animals ( 25%) •
(Table 4)
No blind lizard was observed to home
$
To assess the directness of homing among these
li~ards,
a:11 locations of animals s-een after displacement. were plotted with respect to the original capture site and the
release site as ·was previously done for normal lizards
(Figures 3 and 4).
Among those lizards with the parietal
eye covered, fi,re were first seen within 10 m of their
'original capture point after displacement
(Figure-c~2~,.
Five others vn1ich apparently failed to home were seen elsewhe:t·e in the study area.
one initially moved in the correct
home\"ard direction but was later seen four times in a
diffel~ent.
place '11here it had apparently established a new
home range.
Another was seen twice in a new area, and
tbree others 'W'ere seen once,.
'IIJ:tese latte:t'. three
.each gcln-
50
Table 4--Homing success among anosmic and blind lizards as
well as those with the parietal eye covered compared to
normal lizax·ds.
Covered
X..a...£.ietal JiY.Et
Number of animals
displaced
20
liD.Q,_~
20
Bli,ng,
~orrqg,!_
21
45
a <3SO"}
1s ( 4~")
Number and percent of
displaced animals
which retun1ed to
withi.n 10 -m of their
original capt.ur.e
_point (home)
5 (25%)
5 (25%)
Number and perc~nt of
displaced animals
later observed in
study area but which
.did not home
-
5 ( 25:1')
1 (35%)
Figure 12--Locations of all ten lizards w·ith the parietal
eye covered \'Thich were seen after displacement of 50 m.
An x indicates observation points with respec·t to home (A.)
and the release site (B).
consecutive capture points.
Lines connect release site and
Number next t.o some points
indicates nwUber of times animal was seen at or within 5 m
of that point.
For simplicity of presentation, the release
sites of all animals have been plotted to coincide; all
other locations have been rotated around this point so that
the original capture sites of all animals also
correspond~
Heavy line indicates five animals had already homed when
first seen after release.
5
\
\
\
known to have homed.
Among anosmic lizards (Figure 13), five when first
seen after displacement were already within 10 m of their
original capture point.
obse~ved
Seven others which were not
to home were seen in the study area.
One animal
was still within 5 m of the release site fourteen days
after release.
Three were seen twice each in the area
following release and three others were seen once.
No blind lizard was observed to home although eight
were seen in the study area as late as 24 days after their
release (Figure 14).
One was still within 5 m of thereAnother one was
lease site five days after displacement.
seen three times in the area.
TWo lizards were seen twice
each and four others once ..
When the di:rections taken by displaced ..Y..§_, as determined by connecting the release site and their last known
location,. are plotted with respect to home, the data show
clear, statistically significant, evidence of Qomeward
orientation at the 5% level for the ten
li~ards
with the
parietal eye covered (Figure 15A) and the eleven anosmic
anin~ls
(Figure lSB).
The seven blind lizards shad no
evidence of homeward orientation (P>.lO; Figure 15C).
Discussion
Neither olfaction nor the parietal eye alone appear to
be necessary for homing and orientation in
~
since anos-
mic lizards and those with the parietal eye covered homed
as well as normal animals from the same displacement
Figure 13--Loca·tiona of eleven an.osmic liza.rds which were
seen after
displact:~ment.
An x indicates observation points
with respect to home (A) .and the release site (B).
connect release site and consecu·tive capture points.
Lines
Num-
ber next to sorae points indicates number of times animal
was seen at or within 5 m of that point.
For
sL~plicity
of
presentation, the release sites and original capture sites
have been rotated to correspond as previously describedo
single lizard (not shown on figure) was still at release
site fourteen days after release.
A
5
2
Figure 14--Locat.ions of all seven blind lizards \IThich were
seen after displacement of 50 m.,
An x indicates observa-
tion points with respect to home (A) and the release site
(B).
Lines connect release site and consecutive capture
points.
Number next to same points indicates number of
times animal was seen at or within 5 m
1;,f that
point.
For
simplicity of presentation, the release sites and original
capture sites have been rotated to correspond as previously
describ.ed.
One additional lizard which ""as observed not to
move at least 5 m from the release site is not shown.
.SB
Figure 15--Directional choices of lizards which were displaced 50 m with respect to home (arrow).
(A) Those
lizards with the parietal eye covered (u=-.:3.09 with 10 d£;
P<.OS),
blind
(B) anosmic Uta. (u=2.36 with 11 df; P<.05) and (C)
Uta (u=0.40
with 7 df: P>.lO).
Lizards which were
seen after displacement and did not move at least 5 m from
the release site are not included.
one animal.
Shortest lines equal
(B)
(A)
(C)
6C
distance.
Likewise, the analysis made of directions taken
by the homing lizards demonstrated significant orienta·t.ion
t~~ard
home for anosmic animals and those with the parietal
eye covered.
~hese
data do not conclusively show that the
parietal eye or olfaction are not used, only that homing
and orientation are possible without
them~
There have been no other studies on the role of the
parietal eye or olfaction on homing and orientation among
lizards.
Hoewver, these senses have been implicated in
homing and orientation in other vertebrates.
The parietal
eye has been found to be involved in Y axis orientation
among frogs, enabling the animals to determine compass
bearings even if blind.
However, this structure is not
absolutely necessary, for frogs with the parietal eye
removed can orient using eyesight as well (Taylor and Ferguson
1970)~
Olfaction, on the other hand, has been found
to be the necessary sense for successful homing and orien-.
tation among salmon (Hasler 1966) and newts (Twitty 19661
Grant et ala 1968).
My evidence indicates that sight may be necessary for
relocating the home area after displacement in
yta~
Eight
blind lizards were later observed after displacements of
50 m from their original capture sites and none homed successfully.
An analysis made of the directions taken by
these animals showed no significant orientation toward home
as had been the case among normal and anosmic lizards and
those with the parietal eye covered.
However, since removing the eyes is a serious operation
and no sham opera.tions were run, there are other possible
interpretations of this lack of homing success.
The opera-
tions may have been traumatic to the lizards so that their
behavior toward homing was changed even though. they still
had the capacity to home.
There is no evidencec however,
of severe trauma as a result of the operation.
Three blind
lizards were observed in the lab for 65 days and during
this time remained active and healthy.
Of the 24 animals
blinded, none died as an immediate result of the oper::tt.:ton
and two were observed to survive at least 24 days in the
field after displacement.
Homing ability may not have been
shown simply because the blind lizards did not survive as
well as normal animals.
Lack of protection from predators
and inability to obtain sufficient food are the most probable mortality factors.
This seems unlikely, however, for
the eight blind lizards observed after displacement were
known to have survived an average of
days) after release.
13~7
days (range 2-24
This should have been enough time for
at least some of them to home had they been able# since
eleven of the 22 total lizards (normal, anosmic and with
the parietal eye covered) that homed were near their original capture site in an average of 6.8 days (range 2-13)
after displacement.
There is no previous literature on homing or orientation among blind lizards.
However, evidence that eyesight
is an important factor in homing has been found.
Weintraub
(1970) observed that in
Sce~oporus orcu~~,
displaced liz-
ards which could see their original capture point fran the
release sit.e showed a significantly better degree of homing
success than those which could not.
~
Li'kewise my tests with
in the open sand arena demonstrated that those lizards
which could see landmarks located in their home range from
the arena center displayed the most significant orientation
tow-ard home of all animals run.
The role of these three senses (parietal eye, olfaction and eyesight) on homing and orientation in Uta \'las
studied~
I
found homing and orientation were possible
without the use of olfaction or the parietal eye since
lizards deprived of these two senses performed similarly to
nor.mal animals.
There is evidence that homing and orien-
tation are dependent on eyesight as blinded lizards showed
none.
However, since no sham operations were run there are
still other possible interpretations of these results.
CHAPTER. 6
SUMMARY AND CONCLUSION
From my studies on home range, homing and orientation
in a population of Uta stansburiana I found:
1..
The home range size within this population is c.x;nsider-
ably smaller than those reported in previous st:udies and is
probably due to a higher density of animals in my study
arer:t.
2.
There is no significant difference in home range size
among adult. males and females in this populati,on, indic.ating
that both are familiar with comparably sized areas.
All
adults have significantly larger home ranges than j;.;:ven:i.J.es.
3.
Among both adt!l t males and females considerable OVI?:rlap
exists in the home ranges.
Since males have been reported
to' be territorial, this overlap may be due to the
fac~t
that
the lizards in my study area are able to avoid confrontations as a result of the great amount of cover.
It is also
possible that they are territorial over only a small part
of their home range.
4.
Homing success among adults of both sexes is about 25%
after displacement of 50 to 60 m.
Homing is probably of
Type I.
5.
Juveniles do not home from displacements of 50 m pos-
sibly because they are not familiar with as large an area
as.are adults.
63
6s
Adults which were renderfJd anos:nuc or
whi(~h
had their
parietal eye covered homed ;:.:,.nd orien:t.ed as well as nonnal
lizards.
Blind animals did not. home.
Thus, eyesight may
be necessary for homing, but since no sham operations were
run, other
7.
~uterpretations
are possibleo
Individuals tested close to home or which were able to
see home landmarks from release site showed the most significant orientation, suggesting that orientation toward. home
is influenced by visual perception of familiar landmarks.
8.
Individual
~
bellavior related to
orientation.
tested in an enclosed arena showed
thermoregulation~
rather than homeward
LI'I'ERATURE CITED
Batschelet., E,. 1972. Recent statistical methods for
orientation data. .In.: Animal orientation ~tnd. navigation§ S. R .. Galler, IC Schmidt-Koenig, G. J~ ~ra.c:obs
and R. 1<~. Belleville (eds), NASA Publ. 262, Washington8
D.C. P~ 61-91.
Bertram, B. P. and H. G. Cogger. 1971. A noosing gun for
live captures of small lizards. Copeia, 1971:371-373o
Fitch, H. W~ 1940. A field study of the growth and behavior of the fence lizard. Univ. Calif. Publ. Zool.,
44:151-172.
Fraker, M. A. 1970. Home range and homing in the watersnake, ]Latrix ~~Qedon. Copeia, l970:665-673e
Gould, E. 1957. Orientation in the box turtle, yerrapene
carolina. Biol. Bull., 112:336-348.
Grant, D., o. Anderson and v. Twitty. 1968. Homing orientat.ion by olfaction in newts (Taricha rivularis)
Science 160:1354-1356.
------s
Griffin, D. R. 1953.
tion of animals.
Sensory physiology and the orientaAmer. Scientist, 41:209-245.
Hasler, A. D. 1966. Underwater guideposts: homing in
salmon. Univ8 Wise. Press, Madison 155 p.
Hirth, H. F. 1966. The ability of two species of snakes
to return to a hibernaculum after displacement.
Southwestern Naturalist, 11(1):49-53 ..
Mayhew,
w. w.
1963. Biology of the granite spiny lizard,
oreutti. Am. Midl. Nat., 37:223-249.
§.£~.2EOl:Jd:~
Mohr,
c. o. 1947.. Table of equilavent populations of
North American small mammalsM Am. Midl. Nat., 37:223249.
Noble, G. K. 1934. Experimenting with the courtship of
lizards. Natural History, 34:5-15.
Rand, A. s. 1967. Ecology and social organization in the·
•
iguanid lizard Anolis lineatopus. Proc. u.s. National
Mus., 122:1-79.
65
66
Spoecker, P. D. 196'7. Movements a.nd seasonal B.ctivi·ty
cycles of the lizard p~q st~ppuri~qo P~n. Midl. Nat.
77~484-494.
Stebbins, R$ C. 1954. Amphibians and reptiles of Wt1stern
North America. McG:t·aw~·Hill Book Company., New York~
Taylor, D. H. and Do E~ Ferguson. 1970. Extraoptic
celestial orientati9n in the southern cricket frog
Acri-1!. qryllus. Sci.ence, 168;390-392.
Tinkle, D. w. 1967. The life and. demography of the sideblotched lizard, Uta stansburiana. Misc. Publs Mus.
Zool. Univo Mich.--r3~
'J:linkle , D. W~ , D. McGregor and s. Dana. 1962 • Horue rang--a
ecology of ~ !,!ansburiana stejneger_!. Ecology 4a
(2):223-229.
Twitt.y, v. c. 1966. Of scientists and sala."llanders..
Freeman, San Francisco, 176 p.
Weintraub, J. D. 1970. Homing in the lizard
orcutti. Animal Behavior, 18:132-137.
W6 H.
lL~elQEOI~~