Structure of a burrow of the fawn hopping-mouse Notomys cervinus (Rodentia: Muridae)

2010·1 MB·English

by  Dyck Van

Van Dyck, Janetzki &Sheridan
Structureofa burrowofthefawn hopping-mouse
Notomys cervinus (Rodentia: Muridae).
Atapproximately0030hrson4May2009,anadulthopping-
mouse, subsequently identified as Notomys cervinus, was
m
chased overa straight line distanceof100 (although the
actualpathfollowedwaszigzagged)untilitdisappearedinto
averticalburrow(23°46'08.9,fS,141°01'13.6"E,GDA94)on
atreeless,mostlygrassless,daypanbetweenLakeConstance
and Hunters Gorge, Diamantina National Park, south-
western Queensland. The3cm-diameter hole into which
itretreatedwasflushwiththedaypanandnotassociatedwitli
anvspoil from the burrow, however, anothersimilar-sized
hotelrSOcmawayhadanobviousplumeofgranulatedspoil
(silt)flaringnorth-westfrom theholebut notsurrounding
thehole toformaconicaldepression.
Before beginning the excavation (under torch light) at
thespoil-associatedhole,a butterfly netwasspread over
thesecond hole150cmaway. Drysiltwasthenshovelled FIG.1.Planviewofburrowcomplexwithflaggingtapehighlighting
from the inner side of the vertical exitshaft (i.e. the area tunnels.Scaledivisionsin1cmand10cmintervals(photo:HJ).
between the two holes) until, at a depth or 43 cm, the
burrow tooka right-anglebend toleadhorizontally in an
arc toward the otherexit. After20cm the burrow swung
outto takeon a semi-ellipticalorientation.Assuccessive
biscuits ofsiltwereshovelled offwhile following the3cm
wideburrow,ahopping-mouse(adultfemale)fledtheother
exitand wastrapped in, and immediately extracted from,
thebutterflynet. Atapprox.90cmalongtheburrow,four-
nestling mice were found in achamber thatexpanded to
12cm diameter. Theyoung, whoseeyeswere unopened,
were probably about14 days old (see Watts1983).They
werefoundonascantmattressofthin,chewedgrassstems,the
only vegetablematter tobefound inthe burrowcomplex.
Thechamberwaspalpablywarmand humid.
Twoburrowsledfromtinenestingchamber,a13cmblind
tunnelthatwasaperpendicularoffshoottothemainburrow
ellipseand anotherthatconstituted thenaturalextension
oftne main burrow. This led to thesecond vertical exit/
entrancetunnelapproximately40cmfurtheron.Thesecond FIG.2.Diagrammaticrepresentationofburrowcomplex.
verticalpipe(theoneintowhichthechasedmouseretreated
from theclay pan) was37cm long and 3 cm in diameter.
From thebaseof this pipe, the burrow continued on,but
swungaroundtoformtheotherarcofanellipsethatwould
eventually reconnected it with the entrance where the
excavationbegan(Figs1-3).
During excavation of the second half of the burrow
ellipse,anotherhopping-mouse(adultmale)erupted from
atunnelandbeganleapingaroundtheopendepressionofthe
excavation.This individualwaseventuallyhand-captured
when itjumped up the inside ofoneof our shirts. Using
a smallportableplasticmousecagefurnished with afew
calicocollectionbagsandwith theaddition oftheoriginal
nestingvegetation, the twoadultmicewere reintroduced
to the four young, which on capture had been provided
with a hotwaterbottle. Within minutes, the femalewas
sucklingtheyoung.
Mid-wayalongthereturningsweepoftheburrowellipse
weretwomoreblindtunnels:one,ashort(14cm)horizontal
drive into thecentre oftheellipse, and the other, a much
longer (at54cm) upward-inclined, tangential spur, that
beganasawide,smooth-walled galleryforapproximately FIG.3.Excavation(photo:JS).
98 MemoirsoftheQueensland Museum Nature • 2010 • 55(1)
Van Dyck, Janetzki & Sheridan
18 cm, but then continued as avery narrow (2cm) pass-
ageway.Fromthisspuralivesub-adultmalehopping-mouse
wascaughtwhiletryingtodigitswayout.
Later, after releasing this subadult and driving away
inourvehicle, anothersubadultwas spotlitrunningfrom
the opposite direction toward and eventually into the
excavationpitfromwhichitthenquicklyemergedandran
off. Within the15minutesittookus todriveapprox.2km
throughclaypanandgibberawayfromtheexcavation,we
recorded byspotlightingan additionaladultandajuvenile
N. ceivinus together, then a subadult, and finally two more
juveniles*.
Some physical features of this burrow complex would
appear to reduce the risk ofsnake predation. Firstly, it
was positioned in stark 'lunar' habitatmostly devoid of
vegetation or surfacecracks, and so perhapsless likely to
bevisitedbydiurnal snakesduetothedegreeofexposure.
Secondly, the horizontal elliptical natureofthe tunnelling FIG.4.SpoilplumefromanadjacentN.cervinusburrow(photoJS).
with theprovisionofpopholesateither'end' ofthe loop
could ensure escape from almost anywhere within the
system. Thirdly, thenesting'chamber' wasnotpositioned
aftheend ofablind tunnel but inanexpanded section of
the main burrow. Even if nestlings were too young to
escape, the reproducing adult(s) could. Blind galleries
maybemoreimportant in providingpointsfrom which
rapid-response exits canbedug when established exits
are suddenly blocked. In this regard, the very narrow,
upward risingtangential spurfrom whicha subadult was
collectedtowardthefinalsagesoftheexcavation,probably
representedtheongoingfranticexecutionofsuchatunnel.
Somefeaturesoftheconstructionare more puzzling. For
example,how,in thediggingprocess40cmunderground,
?o the miceconnect theends ofthehorizontal loop? How
ls burrow spoil (Fig. 4) moved up the vertical entrance/
escapeshaft? And why constructan all-horizontal system
whenstepping-upofburrowelementscouldprovideearly
Warningofincomingwateror,escapefromflooding?
PartsofDiamantinaNational Parkwereinundated by
uoodwaters betweenJanuary and April 2009. This site FIG.5.Northernviewfromexcavationsiteacrossclaypan(photo:HJ).
wasonly 1.5kmfromthemain Diamantina Riverchannel
and at the sameelevation (Fig. 6). Clearly, thesuperficial,
contorting crust on the claypan on which the burrow
excavationoccurred indicateditsrelatively recentreceipt
of substantial rain and/or inundatingfloodwaters (Fig.
o)- The ease ofexcavation (ipsofacto burrow construction)
throughthehomogeneoussiltsubstratemayhaveresulted
tom relatively recent inundation, and the generational
fccumulation of burrow spoil may contribute to the
establishmentofthe small raised hummocks thatdot the
cWlaatyeprafnrso.minetnitmreantcheesteunhneulmsm,obcuktsthmeiarycadpeaflceicttystuorftarcaep
wind-blownseedsamonggrasstuftsandscattered rubble,
‘haybemoresignificant.
Whilenotlabyrinthine inconstruction thisoneburrow
complex builds on earlier reports that N. cervittus con-
ducts 'very simple' burrows free of side galleries and
,,evojdofradiatingwarrens (Finlayson 1939). Itconfirms
inaf iWnadtitvsid&uaAlsslilniv1e98i1n).smWalelafcakmniolwylegdrgoeuphsow(eFvienrl,aytshoant FIG.6.EasternviewfromexcavationsitetowardDiamantinaRiver
tl1e buurrow system we describe here may have been still channel(photo:HJ).
Memoirsofthe Queensland Museum Nature • 2010 • 55(1) 99
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Van Dyck, Janetzki & Sheridan
TABLE1 Mammalstrapped(T),hand-caught(H),orspotlit(S)inthevicinityoftheexcavation(allcoordinatesareGDA94)between28
Apriland4May2009(975trap-nights;27hrsspotlighting).
urnw
Dasyuroidesbymei 23-.wiwrs, i n.«]uum>2/5/09
23*45'48.2"S,141*08'26.5"E(T,subadultF)3/5/09
Planigaletenuirostris 23*34'35.9"S,141*06'17.0"E(T)1/5/09
Sminthopsiscrassicaudata 23‘33'37.0"S,141*0745.7WE(H)30/4/09
1
23‘43'02.2"S,141*10'565"E(T.juv)4/5/09
Sminthopsismacroura 23*36*41.6"S,14r03T5.2''E(T)30/4/09
Notomyscervinus 23*39*44.2"S141*10'38.6"E(H)(28/4/09)
\ 23*41'393"S141*04'58.6"E(S)(29/4/09)
23*46'35.4-S141*09'08.5"E(H)(2/5/09)
23*45'34.4"S141*08'25.2~E(H)(2/5/09)
23'46'08.9"S141*01'13.6"E(H,2adull,4juv,1subadult)(S,1subadult)4/5/09
*23*45'50.0"S,141*0V20.0"E(S,1adult,1juv)4/5/09
•23*45'31.6"S,141*01'29.6"E(H,subadult)4/5/09
•23*45T0.0"S,141'0T50.0"E(S,2juv)4/5/09
Leggndinafbrresti 23*33'37.0"S,141*07'45.7"E(H,juv)30/4/09
23*44'22.2”S,141*10'30.6"E(H)2/5/09
underconstruction,ormayhavebeenmodifiedbyreptiles Watts,C.H.S. (1983). FawnHopping-mouseNotomyscervinus. Pp
ofironraotsehmneusrcumhraiamnsmgtachliosso.lexDhceuasvmeairttdibocnuoronrcdociwutsriroaenrdseoignnenhaeorvtaelrclylyiccmoealltdeebsnriabgtuhettd,, 4M3a2m-m4a3l3.s.InAnR.guSstraanhdanRo(beed.r)tsTohne:CSoymdpnleeyt.eBookofAustralian
hituhmiighdlciognhdtietdioanbsufrorroawd'usltcsapaancditnyesttolianlgsosdpurroviindgepewrairomd,s Watts,aCn.dH.RSo.be&rtHs.oJn.:ASsyldinne(y1.981).TheRodentsofAustralia. Angus
oflow ambienttemperature.
LiteratureCited SteveVanDyck,HeatherJanetzkiandJohnSheridan,Queensland
Finlapysaornt,IHV.HT.he(19M3o9n)o.dOelnphmiaam.mTaralnssafctrioomnstohfetLheakReoyEalyrSeocBiaestiyno,f Museum, POBox3300South Brisbane, 4101, Qld, Australia.
SouthAustralia63:88-117(asNotomysaistoni). [email protected];5August2009.
100 MemoirsoftheQueensland Museum Nature • 2010 • 55(1)
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