MOVEMENTS OF AUSTRALIAN FLYING FOXES
(PTEROPODIDAE: MEGACHIROPTERA)
By J. E. NELSON*
[Manusc ip ecei ed July
20,
19641
Summa y
E idence is p esen ed o show ha he coas al species
P e opus poliocephalus
and
P. gouldi
cong ega e in la ge camps om ea ly un il la e summe . In hese la ge summe
camps he young a e bo n and aised, he sexes become associa ed, and concep ion
occu s. The numbe s wi hin hese camps a e in luenced by he a ailabili y o blossom
in he su ounding a ea.
The adul s a e no mally dispe sed du ing he win e while he imma u e o m
win e camps. These camps con ain a la ge pe cen age o adul s in hose win e s in
which blossom is mo e abundan .
The inland species
P. scapula us
o ms la ge camps in ea ly summe bu he young
a e bo n in au umn when he popula ion is dispe sed. Since he ood supply
o
P.
scapula us
is less dependable and unde goes g ea e luc ua ions han ha o he coas al
species,
P.
scapula us
is mo e nomadic han
P.
poliocephalus
and
P. gouldi.
Flying oxes ( ui ba s) hang du ing he day in ees wi hin an a ea called a
"camp", and a nigh mo e in o he su ounding coun yside o eed on nec a ,
blossoms, and ui . These daily mo emen s a e well documen ed (Willey 1904;
Jameson 1909; Allen, Lang, and Chapin 1917; Ra cli e 1932; Fe a 1934; McCann
1934; Sanbo n and Nicholson 1950; Kulze 1961) bu li le is known o he seasonal
mo emen s o Megachi op e a. Seasonal pa e ns o mo emen ha e been in e ed
om he p og essi e occupa ion o camps o e he ange o he species, bu ha e no
been s udied by he eco e y o ma ked indi iduals.
These seasonal mo emen s ha e been associa ed wi h ood and clima e. Jameson
(1909) co ela ed mo emen s o Epomopho us wahlbe gi wi h he ipening o ce ain
A ican ui s; Allen, Lang, and Chapin (1917) sugges ed ha he hea y seasonal
ains may cause Eidolon hel um o mo e om he a ea. Sanbo n and Nicholson
(1950, p. 316) conside ed ha luc ua ion in numbe s wi hin camps o P e opus o na us
in New Caledonia "does no indica e a ue mig a ion; a he , simply a seasonal
mo emen ins iga ed by he p esence o absence o ood".
Ra cli e (1 93 1, p. 26); a e examining he Aus alian species, concluded
:
"The
ex ensi e mig a ions o he li le ed ox,
P.
scapula us, a e almos ce ainly go e ned
by he blossoming o he so-called ha dwood ees. As his is no o iously unce ain,
he mo emen s o his species show a conside able i egula i y"; and again on p. 24
"P.
poliocephalus ca ies ou e y egula , seasonal mig a ions, mo ing sou hwa d in
he sp ing in o sou he n Queensland and New Sou h Wales
.
.
.
Beyond he ac (made
appa en by he pe iodic dese ion and e-occupa ion o well-known camps) ha his
seasonal mig a ion does ake place, he a ailable in o ma ion is scan y".
*
Zoology Depa men , Uni e si y o Queensland; p esen add ess
:
Depa men o Zoology
and Compa a i e Physiology, Monash Uni e si y, Clay on,Vic.
Aus .
J.
Zool., 1965,
13,
53-73
54
J.
E.
NELSON
The summe ange o
P.
poliocephalus
ex ends om Rockhamp on (cen al
Queensland) o Vic o ia. Ra cli e ound win e camps o he species only be ween
Rockhamp on and he Ma y Ri e 200 miles sou h o Rockhamp on. Thus, he
egula mig a ion o
P.
poliocephalus
would esul in a e y dense popula ion being
es ic ed each win e o a ac ion o he summe ange and would necessi a e an a ea
whe e blossom and ui we e abundan . P elimina y obse a ions indica ed ha
blossom and ui p oduc ion h oughou he ange o P,
poliocephalus
was a a low
le el a his ime. The mig a ion, he e o e, may in ol e only a small sec ion o he
popula ion. This possibili y was in es iga ed by examining he no he n po ion o
he ange o
P.
poliocephalus
in he win e mon hs, and by obse ing he changes
h oughou he yea wi hin camps in sou h-eas e n Queensland.
11.
MATERIALS
AND
METHODS
Du ing his s udy, obse a ions we e made on h ee species o
P e opus
which
occu in sou h-eas Queensland:
P.
poliocephalus
Temminck 1825,
P. gouldi
Pe e s
1867, and
P.
scapula us
Pe e s 1862.
In an a ea wi hin 100 miles o B isbane he e a e a leas 10 camps each con-
aining in mid-summe abou 20,000 indi iduals. Camps a Eagle Heigh s, Fishe man
I., Beenleigh, Slacks C eek, and Cu umbin C eek in Queensland, and Mu willumbah
in New Sou h Wales (Fig. 1) we e isi ed e e y 2-3 weeks du ing 1961, and a leas
e e y mon h du ing 1959, 1960, and 1962. Rough es ima es o numbe s wi hin he
camps we e made a e walking a ound he edge o he camp and obse ing changes
in he occupied a ea and a e a e sing he camp and no ing numbe s in ma ked ees.
A emp s o es ima e numbe s by pho og aphing lying oxes in he ai a e
i ing a sho gun we e unsuccess ul as many did no ake o he ai .
I egula isi s we e made o camps ou side he s udy a ea and ques ionnai es
we e sen o cen es h oughou he s a e o ob ain in o ma ion on he ime o
occupa ion and he luc ua ions o numbe s wi hin he camps.
The mo emen s o lying oxes could no be s udied by ca ching and ma king
lying oxes indi idually since he chances o eco e y o he small numbe s ha could
be caugh in he ain o es canopy would be e y small. In an a emp o s udy he
sho - e m mo emen s o he animals, he camp a Fishe man I. was sp ayed wi h
he dye hodamine ed om a c op-dus ing plane in No embe 1961.
The apidi y wi h which ood passes h ough he simple alimen a y canal o
lying oxes has been commen ed on by se e al au ho s (Dobson 1878; Allen, Lang,
and Chapin 1917; Ra cli e 1932). In labo a o y animals he passage o ood ook
40 min. Since solid ma e ials such as seeds and s amens a e only sligh ly damaged in
he gu , he ela i e impo ance o ui and blossom a any pe iod could be asce ained
by he pe cen age o aecal pelle s on he loo o he camp which con ained seeds o
s amens.
Fo in o ma ion on ma u i y and he ep oduc i e s a e, 719 specimens (384$,
3359) o
P.
poliocephalus
we e ob ained h oughou he pe iod Decembe 1958-June
1961, and 560 specimens (2213, 3399) o
P.
scapula us
we e ob ained du ing he
pe iod om Decembe 1958 o Ap il 1959.
P.
gouldi
occu s in e y small numbe s
MOVEMENTS OF AUSTRALIAN FLYING FOXES
55
(50-200) wi hin he la ge
P.
poliocephalus
camps (5000-20,000), and so only occasional
specimens we e ob ained.
MOORE
0
WARRIL BANK
CHEVELLUM
.
GLASSHOUSE
::
0
SAMFORDO
FISHERMAN I.
0
BRISBANE
GOODNA
C
SLACKS CK
*)
GILBERTON
BEENLEIGH
%?
EAGLE HEIGHTS*
ALLORA
0
LEGUME
0
MURWILLUMBAH*
20
MILES
I
Fig.
1.-Map o he s udy a ea showing he loca ion o camps men ioned in he ex .
The ep oduc i e o gans and scapula glands we e emo ed as soon as possible
a e shoo ing, and placed in Bouin's luid. All sec ions we e cu a
7
p
and s ained
in haemo oxylin and eosin.
Body weigh s we e measu ed o he nea es g am, es es weigh o he nea es
0.1
g,
u e us weigh s o he nea es g am, and o ea m leng hs o he nea es millime e.
The bacula o 91 males we e dissec ed ou and measu ed o he nea es 0.1 mm.
J.
E.
NELSON
BLAIR
ATHOL.
Fig.
2.-Map o eas e n Aus alia showing he known dis ibu ion o
P.
poliocephalus
(close ha ching)
and
P,
gouldi
(wide ha ching). The dis ibu ions in his and in Figu e
3
a e based on he au ho 's
obse a ions, Queensland Museum, Aus alian Museum, and Na ional Museum o Vic o ia eco ds,
and on local epo s.
MOVEMENTS
OF
AUSTRALIAN
FLYING
FOXES
57
In a se ies o expe imen s designed o es he e ec o he ambien empe a u e
upon he descen o he es es, lying oxes we e placed in wi e mesh cages, 50 by 50
by 100 cm, in a cons an empe a u e oom whe e he ambien empe a u e could be
a ied o e he ange 20-35°C (10.5 degC).
Tempe a u e measu emen s we e made o he nea es 0.1 degC using a
he mis o uni assembled o he design o McLean (1954).
111. DISTRIBUTION
OF
SPECIES
The dis ibu ions o
P,
poliocephalus and
P.
gouldi a e shown in Figu e 2, and o
P.
scapula us in Figu e
3.
Camps a e e y common in he coas al a eas and a e
occupied egula ly. In he wes e n hal o he s a e camps a e a e and in some a eas
ha e been o med only once in li ing memo y.
Ra cli e (1932) ga e he Ma y Ri e as he sou he n limi o dis ibu ion o
P.
gouldi, and oday his is he sou he n limi o camps in which
P.
gouldi is he
dominan species. Bu i is also ound in small numbe s (50-500) in
P.
poliocephalus
camps om Nambou in Queensland o Mu willumbah and Legume in New Sou h
Wales. Only small numbe s o
P.
poliocephalus a e ound in
P.
gouldi camps om
Ma ybo ough o Rockhamp on.
In he coas al a eas,
P.
scapula us may be ound in camps o o he species, o
i may o m i s own camps. In hose camps whe e wo o mo e species occu , each
species ends o be seg ega ed om he o he species.
Camps o all species occu in ain o es s, mang o e o es s, Melaleuca swamps,
alongside i e banks o wa e holes (in weeping willows, Salax babylonica, Casua ina
spp., e c.), and occasionally in open o es s.
IV. RESULTS
(a)
P.
poliocephalus
(i) Fluc ua ions o Numbe s in Camps
The gene al pa e n o he mo emen s h ough he camps in he s udy a ea can
be seen om Figu e
4.
The e a e wo ypes o camps-summe camps and win e
camps.
(1) Summe Camps.-A i s , he summe camps con ain small numbe s o
lying oxes which emain o only a ew days. Fo example, a Eagle Heigh s in 1961
he e we e none on Augus 31, abou 200 on Sep embe 15, and none on Sep embe 17.
In any one yea he e was some a ia ion in he ime om which he camps we e
occupied con inuously. Usually Fishe man I. was occupied om ea ly Sep embe ,
Mu willumbah om ea ly o mid-Sep embe , Eagle Heigh s om mid-Sep embe , and
Cu umbin C eek om mid o la e Sep embe . La i ude hen did no appea o
in luence he ime o a i al.
Du ing No embe and Decembe he e a e la ge luc ua ions wi hin all camps.
The dec eases a Che ellum and Fishe man
I.
indica e a mo emen om hese camps
whe eas he inc eases in he o he summe camps sugges mo emen in o hese camps.
These mo emen s a e i egula , a ying sligh ly om yea o yea . In 1959, o
example, Cu umbin C eek was dese ed om Oc obe 24 o Decembe 6, and no
J.
E.
NELSON
--
Fig. 3.-Map showing he dis ibu ion o
P.
scapula us
in eas e n Aus alia.
MOVEMENTS OF AUSTRALIAN FLYING FOXES
59
occupied con inuously un il Decembe 15 onwa ds. O he examples can be seen
om Figu e
4.
In 1958, wo camps which had no been occupied o 6-7 yea s (acco ding o
local esiden s) we e each occupied o 2 weeks. The one a Moo e was occupied o
he i s 2 weeks o No embe and he one a Wa il Bank was occupied o he las
2 weeks o No embe . This indica es ha he e a e mo emen s in o he s udy a ea,
as well as mo emen s om camp o camp in he a ea.
AF
I
I
Y
FISHERMAN I. SLACKS CK. BEENLEIGH EAGLE CURRUMBIN
CK.
MURWILLUMBAI-
HEIGHTS
LOCATION OF CAMP
Fig. 4.-Ki es illus a ing he a ia ion wi h ime in he popula ion size o he
a ious camps in he s udy a ea. Ho izon al lines indica e he ime o isi s o he
a ious camps.
As
seen in Figu e
4,
he maximum numbe s in he majo summe camps a e
a ained in Decembe o Janua y. The dec ease in numbe s in la e Janua y a Eagle
Heigh s, Cu umbin C eek, and Mu willumbah indica es ha he lying oxes a e now
lea ing he camps. A e Ma ch-Ap il he e is a u he dec ease. In 1960, all summe
camps we e dese ed by mid-Ap il whe eas in 1962, al hough some camps we e
dese ed o a sho pe iod abou his ime, mos we e no dese ed un il June.
In con as , Fishe man I. showed an inc ease in Ma ch-Ap il 1961 and 1962,
and in Feb ua y 1961. Two indi iduals ma ked wi h hodamine ed a Fishe man I.
on No embe 29, 1961,'we e eco e ed a Mu willumbah in mid-Feb ua y 1962.
60
J.
E.
NELSON
No
P.
poliocephalus we e ound a ound Bundabe g in Augus 1958 (la e win e )
no in he a ea be ween Bundabe g and Rockhamp on in June 1961. Some
P.
poliocephalus we e p esen in he
P.
gouldi camp a Bundabe g in Feb ua y 1961.
P.
poliocephalus camps a G a on and Imbil (see Fig. 2) we e occupied om
la e Sep embe -ea ly Oc obe o ea ly Ap il, wi h he popula ion peak occu ing in
No embe , Decembe , and Janua y. Legume isi ed only on Ma ch 5, 1960, con ained
la ge numbe s, and he Bunya Moun ains isi ed on May 23, 1961, con ained only
200-400.
Thus, om he small amoun o in o ma ion a ailable, camps ou side he s udy
a ea appea o be simila o hose inside.
The gene al pa e n hen appea s o be a g adual inc ease in he camp popula ion
size om Sep embe o he maximum o Decembe and Janua y. In la e Janua y
lying oxes begin o lea e he camps, o possibly mo e lea e han en e . F om Feb ua y
o Ap il he numbe s emain ai ly s eady, while in Ap il he e is a ma ked dec ease.
In some yea s he camps a e dese ed a his ime (i.e. 1960) bu in o he s he numbe s
dec ease a his ime, may inc ease again in May, and hen dec ease again so ha hey
a e dese ed by la e June. Fishe man
I.,
which has i s minimum popula ion while
o he summe camps a e ha ing hei maximum, appea s o be a camp en ou e o some
o he camp o camps. One o hese camps is Mu willumbah; he camps a Moo e
and Wa il Bank, and possibly Che ellum, we e simila camps. This sugges s ha
he la ge popula ions o Decembe and Janua y in such camps as Mu willumbah
a e composed o lying oxes om a numbe o small camps which a e occupied only
in ea ly o la e summe o bo h. One empo a y camp o
P.
poliocephalus was p e-
sen a Sam o d o 2 weeks in ea ly Feb ua y 1958.
(2) Win e Camps.-Two win e camps we e ound in he s udy a ea. One a
Slacks C eek was i s occupied in Ap il 1960, when he summe camps we e being
dese ed; his camp was dese ed in Sep embe 1960 when he summe camps we e
o ming, was occupied again in Janua y 1961 when he summe camps dec eased,
and was inally dese ed in la e June 1961 as we e he summe camps in he a ea. The
o he win e camp was a Beenleigh and was occupied con inuously om Oc obe 1961
o Sep embe 1962 when he s udy e mina ed. This camp inc eased in size in Ap il
1962 when he summe camps dec eased. Bo h win e camps had no been occupied
(acco ding o he land owne s) o 5 o 6 yea s.
(ii) Male Rep oduc i e Cycle
(1)
Ma u i y.-When es es weigh s and bacula dimensions a e plo ed agains
body weigh , bo h show a sudden inc ease be ween 540 and 650 g body weigh ,
indica ing ha ma u i y in
P.
poliocephalus occu s a a body weigh o 595i-55 g
(Fig. 5). This co esponds wi h a o ea m leng h o 145&5 mm (Fig. 6) and an age o
abou 18 mon hs (Fig.
7).
The maximum body weigh eco ded was 1016 g, and he
maximum o ea m leng h seco ded was 164 mm.
(2) Seasonal Changes in Male Rep oduc i e Sys em.-The seasonal a ia ion
in es es weigh is shown in Figu e
8.
The semini e ous ubules and duc s o he
epididymis a e solid a bi h and ha e a diame e o 12
p.
Typical meio ic and mi o ic
nuclei a e no seen un il abou he i een h mon h, when spe ma ocy es and spe ma ids
MOVEMENTS
OF
AUSTRALIAN
FLYING
FOXES
61
a e seen in he lumen o he duc s o he epididymis. A his ime o he yea (Janua y)
he es es o he ma u e males a e app oaching hei maximum de elopmen . By he
age o
17
o 18 mon hs he duc s o he epididymis a e illed wi h spe ma ozoa.
BODY
WEIGHT (G)
Fig. 5.-The ela ion o body weigh and es es weigh o 307 male
P,
poliocephalus
collec ed om Janua y 1959 o June 1961. The symbol
0
ep esen s mean o class
wi h an in e al o 100 g (e.g. om 101 o 200). The e ical line shows one
s anda d de ia ion on ei he side o he mean.
Fig. 6.-The ela ion o body weigh o leng h o o ea m in 315 male
P.
poliocephalus
collec ed om Decembe 1958 o June 1961. Symbols as
in
Figu e 5.
50
Spe m we e p esen in he epididymis o he ma u e male du ing e e y mon h
o he yea al hough hei abundance a ied wi h he es es weigh being g ea es
du ing Feb ua y and leas in he pe iod om June o Sep embe . Dec eased
spe ma ogenesis in he la e pe iod was indica ed by he dec eased diame e o he
I I
I
I
I
!
I
0 100 200 300 400 500 600 700 800 900
BODY
WEIGHT
(G)
68
J.
E.
NELSON
Kogan (No embe ), Eids old (Decembe -Janua y), Cha e s Towe s, and Chinchilla
(Oc obe ). 1961 was a e y d y yea a Kooloo ah (7.5 in. ain ell compa ed wi h
he a e age annual ain all o 40 in.) and o he i s ime on eco d no
P.
scapula us
appea ed.
In d y yea s indi iduals we e commonly ound en angled in ba bed-wi e ences
o d owned in wa e anks in he wes e n a eas o he species' ange, and we e epo ed
o be mo e common in he coas al a eas.
Small g oups (1-500) o
P.
scapula us
we e ound a Cha le ille (Ma ch-Ap il
1962), Hunge o d (Ap il 1962), Ta oom, Sp ingsu e (1959), Mi chell, Cle mon , and
A amac. These small g oups we e ound nea lowe ing ees o wa e holes, and
emained in he a ea om 1 day o 3 weeks.
0
i
I
I I
I
250 300 350 400 450 500
BODY
WEIGHT
(G)
Fig. 11.-The ela ion be ween body weigh and es es weigh o 182 male
P.
scapula us
collec ed om Decembe 1958 o Ap il 1960. The symbol
0
indica es
mean o class wi h an in e al o 50 g (e. g. 451-500). The e ical 1i.ne shows one
s anda d de ia ion on ei he side o he mean.
(ii)
Male Rep oduc i e Cycle
Male
P.
scapula us
a e ma u e a a body weigh o 355
25 g (Fig. 1
I),
a o ea m
leng h o 12315 mm (Fig. 12) and an age o 18 mon hs. The maximum body weigh
measu ed was 604 g and he maximum o ea m measu ed was 141 mm.
The a ia ion in es es weigh o e he pe iod Decembe -Ap il is shown in
Figu e 13. Maximum es es weigh occu ed in Decembe bu he weigh may ha e
been g ea e in he p eceding mon hs when no eco ds we e ob ained. The accesso y
sex glands we e la ge du ing Decembe and small om Janua y o Ap il.
(ii)
Female Rep oduc i e Cycle
Ma u i y in he emale
P.
scapula us
occu s a a body weigh o 325&25 g, a
o ea m leng h o 120 4 mm (Fig. 14), and an age o 18 mon hs. Maximum body
weigh measu ed was 560 g and he maximum o ea m leng h ob ained was 137 mm.
Ma e ial was no adequa e o de e mine he ime o concep ion accu a ely.
Concep ion p obably occu ed in la e No embe and ea ly Decembe when males
we e seen ma king and de ending e i o ies.
Pa u i ion occu s om la e Ap il o ea ly May as all o he emales sho on
Ap1il25, 1962 had ull- e m emb yos and one animal ga e bi h in he labo a o y on
Ap il 27, 1962 (young was s illbo n), and ano he ga e bi h on May 2, 1962.
MOVEMENTS
OF
AUSTRALIAN
FLYING
FOXES
69
(iii)
Co ela ion o B eeding wi h Mo emen s
Al hough he mo emen s o his species a e i egula he e is usually a mo emen
in o camps .abou he No embe -Decembe pe iod when copula ion and concep ion
occu . A e concep ion he sexes seg ega e and may emain in he camp o a sho
pe iod o mo e (in smalle numbe s) o new camps o in o he camps o o he species.
300
350 400 450 5W
BODY
WEIGHT
(G)
Fig. 12.-The ela ion be ween body weigh and leng h o o ea m in 218 male
,
collec ed om Decembe 1958 o Ap il 1960. Symbols as in
P.
scapula us
Figu e 1 1.
7
6
5
S
-
k
i
4-
$
i
3-
ill
k
2
0
1
I
I
I
I
JAN
FEE.
MAR.
APR.
MONTHS
-
-
-
-
1-
Fig. 13.-Showing he seasonal a ia ion in es es weigh o 92 male
P.
scapula us
collec ed om Decembe 1958 o Ap il 1960. Symbols as in Figu e 11.
Since only small g oups ha e been ound om Feb ua y un il Sep embe ,
pa u i ion in his species, in con as o
P.
poliocephalus
and
P.
gouldi,
occu s when
he popula ion is dispe sed.
70
J.
E.
NELSON
(i )
Die
The Fo es y Depa men o Queensland has kep eco ds o he lowe ing imes
o he spo ed gum,
E.
macula a,
in he Dalby dis ic whe e i is a dominan species
and a good indica o o gene al blossoming condi ions in he locali y. In Decembe
1950 and Oc obe -No embe 1955 he e was e y hea y gene al lowe ing, and in
1959 he e was a good lowe ing anging om Augus o Decembe . Ligh and
sca e ed lowe ings occu ed in he be ween yea s. The gene al lowe ings o 1950,
1955, 1959 co espond wi h he la ge numbe s o
P.
scapula us
ound a Chinchilla
(and in o he a eas) in he summe s o hose yea s. As in
P.
poliocephalus,
he
maximum numbe s o
P.
scapula us
occu when blossom is mos abundan , i.e. in
he summe .
0%
PREGNANT
O
33.3%
PREGNANT
0
97.7%
PREGNANT
0
100%
PREGNANT
300 400 500
BODY
WEIGHT
(GI
Fig.
14.-The ela ion be ween body weigh and o ea m leng h in
160
emale
P.
scapula us
collec ed on Janua y
18,
1959.
Ve y small numbe s we e ound in he s udy a ea in he poo blossom pe iod
1960-61, whe eas in he good pe iod o 1961-62,
P.
scapula us
was p esen in mos
camps and o med a la ge camp a Esk om No embe o Janua y, and a Glass
House in Janua y. The e we e la ge numbe s in he s udy a ea in 1958-59 and none
in 1959-60, a good blossom yea in he s udy a ea bu also a good pe iod h oughou
he s a e. F om he li le e idence a ailable,
P.
scapula us
appea s in la ge numbe s
in he coas al a ea o sou h-eas Queensland e e y 2 o
3
yea s, and has been epo ed
in he G a on camp e e y 2 o
3
yea s. Many co esponden s s a ed ha
P.
scapula us
was mo e common in he coas al a eas in d y yea s, sugges ing ha hey appea on
he coas (whe e blossom is egula ly a ailable, hough in a ying amoun s) when
blossoming is poo inland.
Since no camps o
P.
poliocephalus
we e ound a ound Bundabe g in Augus
1958 o in he a ea be ween Bundabe g and Rockhamp on in June 1961, he hypo hesis
ha he e is a egula mass win e mo emen in o he no he n pa o he species
ange mus be ques ioned. Fu he , he e is no e idence o a p og essi e occupa ion
o camps om Gympie in he no h o G a on in he sou h; and he a ia ion in he
MOVEMENTS OF AUSTRALIAN FLYING FOXES
7
1
imes o a i al in camps in he s udy a ea was as g ea as hose obse ed by Ra cli e
o e he en i e ange o he species; (Ra cli e epo ed ha
P.
poliocephalus
appea ed
in Oc obe in he no he n a eas, and in Decembe in he sou he n pa s o New
Sou h Wales). Fo example, Cu umbin C eek was no occupied un il mid-Decembe
1958, while all o he camps in he s udy a ea we e occupied in Oc obe .
While he e idence sugges s ha he e is no egula seasonal mig a ion, he
luc ua ion in numbe s wi hin camps du ing a yea indica e ha local mo emen s a e
common. Mo eo e , he ma king expe imen p o ides di ec e idence o a mo emen
be ween Fishe man
I.
and Mu willumbah. The g adual inc ease and dec ease in
numbe s in he summe camps indica e ha hese local mo emen s in ol e small
g oups a he han la ge sec ions o he popula ion.This is suppo ed by he p esence
o small numbe s in he camps o b ie pe iods du ing he ea ly and la e s ages o
occupa ion.
I he animals which lea e he camps a he end o summe do no mig a e no h,
we a e aced wi h he ques ion o wha happens o hem. Obse a ions on o he
species o
P e opus
p o ide some clues as o wha p obably akes place.
Bake and Bake (1936, p. 126) e e ing o he mo emen s o
P. geddiei
o he
New Heb ides s a ed: "When emales become p egnan abou Feb ua y, hey lea e
hese camps, and i becomes di icul o a ime o ob ain emale specimens. Fo a ime,
he males con inue o lead a social li e
. . .
La e in he yea , abou June, when
p egnancy is a ad anced, he emales may be ound in inland camps which con ain
ew o no males. A his season, males ha e gi en up hei social li e and li e
sepa a ely". And ews (1900) discussing
P.
na alis
om Ch is mas I. s a ed: "A his
season, mos o he emales seemed o li e in he deepe pa s o he o es , and nine
ou o en o he specimens sho on he coas we e males".
These obse a ions sugges ha he animals ha e a non-g ega ious phase o
season, s a ing soon a e concep ion wi h a seg ega ion o he sexes, and culmina ing
in a dispe sed and agmen ed popula ion.
As he e can now be li le doub ha he g ea majo i y o he adul popula ion
o
P.
poliocephalus
(and also o
P.
gouldi
and
P.
scapula us)
do no emain agg ega ed
in camps du ing he win e , i seems almos ce ain ha hey dispe se, li ing ei he as
indi iduals o in small g oups. I he adul s emained g ega ious du ing he win e ,
hei camps would ce ainly ha e been disco e ed, whe eas a dispe sed popula ion o
an animal wi h he lying ox's noc u nal habi s would eadily escape no ice. I is
no su p ising, he e o e, ha he e a e e y ew obse a ion which h ow ligh on he
loca ion o he animals when he adul s disappea om he camps. No ele an
obse a ions came o ligh on
P. poliocephalus
in he s udy a ea bu some highly
signi ican eco ds o indi iduals and small g oups o
P.
gouldi
and
P, scapula us
we e
ob ained om many pa s o Queensland, as has al eady been men ioned. Fu he -
mo e, Ra cli e (pe sonal communica ion) has epo ed ha on 2 successi e yea s
wi hin he pas decade indi iduals o
P.
poliocephalus
ha e u ned up in Canbe a in
he ea ly win e . Hea y nigh os s ( o which he lying oxes had appa en ly
succumbed) we e being expe ienced on bo h occasions.
As he educ ion in size and he b eaking up o he main summe camps can be
co ela ed wi h a dec ease in he abundance o blossom, i seems sa e o assume ha
72
J.
E.
NELSON
he s imulus o dispe sion and he adop ion o a non-g ega ious exis ence is ood
sho age. I also seems sa e o assume ha he dispe sed popula ion is o ced o
become e y la gely nomadic. While mos o he animals will p obably s ay wi hin
he b oad egion ha included hei summe camps, i is no unlikely ha in he mos
sou he n pa s o he species ange, whe e he win e clima e would be un a ou able
and he ood sho age se e e, he mo emen s would end o be no hwa d and
(augmen ed by a ai ly high mo ali y) migh esul in he equi alen o a seasonal
mig a ion.
I he hi he o accep ed idea o
P.
poliocephalus e aining i s g ega ious beha iou
and ca ying ou egula seasonal mig a ions is disca ded in a ou o he hypo hesis
ha has jus been ou lined, he annual sequence o e en s alls in o he ollowing
pa e n. Summe camps a e o med when blossom is abundan , and hence when la ge
popula ions can main ain hemsel es wi hin es ic ed a eas. In he ea ly pa o he
season when blossom is s ill ela i ely sca ce he camps a e no as la ge as in mid-
summe and consis mainly o p egnan emales and emales wi h young. By Decembe
and Janua y blossom is abundan and he popula ion wi hin mos camps is a i s
maximum. Va ia ions in he size o he summe camps du ing he pe iod o hei
occupancy sugges s ha he e a e con inuous mo emen s o lying oxes be ween hem.
Some o he lying oxes ound in he la ge summe camps du ing he pe iod o peak
popula ion come om smalle b eeding camps (e.g. Mu willumbah om Fishe man
I.,
as indica ed in he ma king expe imen ).
The young, which a e bo n in he ea ly s age o he occupancy o he camps,
begin o ly in mid-summe and hus can lea n o end o hemsel es a he ime o
he yea when blossom is no mally mos abundan . The young mo e om he summe
camps in Ma ch-Ap il and o m win e camps (in which a a ying bu usually small
numbe o adul s will also be ound).
Some adul s s a lea ing he camps in la e Janua y and Feb ua y when he ood
supply is dec easing and e i o iali y is being es ablished. The main exodus begins
a e concep ion in la e Ma ch-ea ly Ap il when he sexes seg ega e, soon o mo e
o sepa a ely o in g oups. The pe cen age o adul s leading a dispe sed and nomadic
li e du ing he win e a ies acco ding o he season. I is leas in good blossom yea s
when many will be ound associa ed wi h he young in he win e camps.
P.
gouldi and
P.
scapula us appea om he e idence a ailable o ha e he same
basic pa e n o beha iou as
P.
poliocephalus, hough he b eak-up o he summe
camps o
P.
gouldi is no comple e. A small numbe o animals con inue o occupy
hem du ing he win e mon hs.
P.
scapula us, whose ange includes much o he
lowe - ain all inland, has had o adap i sel o a much mo e e a ic and p eca ious
ood supply han he o he wo species, and shows e idence o being nomadic a imes
while emaining g ega ious.
The mo emen o lying oxes in o camps when ood is plen i ul, and hen a
dispe sal o he popula ion when ood is sca ce would be a mo e e icien me hod o
u iliza ion o ood supply han a concen a ion o he popula ion wi hin a small a ea
o i s ange a he la e ime. The abili y o adjus hei beha iou o he luc ua ions
in
he ood supply is one ac o con ibu ing o he success o he species.
MOVEMENTS
OF
AUSTRALIAN
FLYING
FOXES
7 3
VI.
ACKNOWLEDGMENTS
The au ho would like o hank D . M. C. Bleakly, Depa men o Zoology,
Uni e si y o Queensland, o his guidance and suppo du ing his s udy; M .
F.
N.
Ra cli e, Di ision o En omology, CSIRO, o his many sugges ions du ing he
p epa a ion o his manusc ip ; M s.
J.
Lee o assis ance in p epa a ion o he
igu es; and M . Hen y, Fo es y Depa men , B isbane, o in o ma ion upon he
lowe ing o a ious species.
The p ojec was suppo ed by a Wal e and Eliza Hall Fellowship in Economic
Biology in 1960 and 1961, by a Commonweal h Pos -g adua e Fellowship in 1962,
and by Uni e si y o Queensland Resea ch Funds. P epa a ion o he pape was
aided by Na ional Science Founda ion G an No. 23737.
VII.
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