G ay squi el esponses o he e ospeci ic ala m calls o u ed i mice
Chloe A bogas & Ka hy n Sie ing
College o Ag icul u e and Li e Sciences, Uni e si y o Flo ida
Wildli e Ecology and Conse a ion Depa men
ABSTRACT
Mammals and bi ds ha e de eloped ala m calls o p o ec and wa n hei kin o p eda o s. Tu ed i mice
(Baeolophus bicolo ) in pa icula ha e de eloped p eda o -speci ic ala m calls. Many a ian species
lis en o u ed i mouse calls o gain in o ma ion o inc easing hei own sa e y, also known as
ea esd opping. Few s udies ha e looked a whe he mammal species ea esd op on a ian ala m calls, ye
small bi ds and mammals o en sha e he same p eda o species. In o de o b oaden unde s anding o
ea esd opping esponses among bi ds and mammals mo e gene ally, I es ed o Eas e n g ay squi el
(Sciu us ca olinensis) esponse o u ed i mice ala m calls. Audio playbacks o i mouse ala m calls,
gi en in 3 di e en speci ic isk si ua ions, and a con ol call we e used on squi els and hei beha io s
be o e and a e playbacks we e eco ded. The squi els exhibi ed s ong an ip eda o beha io s in
esponse o i mouse ala ms bu no con ols and hey disc imina e be ween ala m ypes. We conclude
ha Eas e n g ay squi els ea esd op on u ed i mice ala m calls o help a oid p eda ion.
Keywo ds: ala m call, ea esd op, an ip eda o beha io , g ay squi el, i mouse
INTRODUCTION
Mammals and bi ds ha e de eloped ala m calls (Hollen & Rad o d, 2009) known o ale hei own
kin o p eda o s (G eene & Meaghe , 1998). When o he species use such signals o a oid isks, his is
called ea esd opping (Wa e man & Mai, 2020). Tu ed i mice (Baeolophus bicolo ) make a ied and
eliable ala m calls o many di e en p eda ion isks (Sie ing e al., 2010) and nume ous species o
bi ds a e known o use hese calls o a oid dange (Huang e al., 2012). The u ed i mouse is a common
species wi h excep ional communica i e complexi y (a model o language e olu ion; K ams e al.,
2012). Mo eo e , many bi d species associa e wi h i mice in ime and space o gain in o ma ion abou
p eda o s (He ick & Sie ing, 2012), when hey should engage in isk sensi i e beha io s (Huang e al.,
2012) and enhance o aging e iciency (Sie ing e al., 2004).
Eas e n g ay squi els (Sciu us ca olinensis) a e ound in he same wooded habi a s h oughou
Eas e n No h Ame ica as u ed i mice making hem an excellen s udy species. Tu ed i mice and
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Eas e n g ay squi els also sha e simila p eda o s such as hawks and owls (Chow e al., 2021). Animals
ely hea ily on communica ion wi h simila and di e en species o adap i e decision-making, and his
has been demons a ed in eas e n chipmunks (Tamias s ia us) ea esd opping on u ed i mice ala m
calls (Schmid e al., 2008). Howe e , his opic emains la gely unexplo ed. The e o e, we explo ed i
Eas e n g ay squi els also use i mouse ala m calls o hei own p o ec ion. This s udy aims o es wo
hypo heses. Fi s , we expec ha i he squi els ea esd op on i mouse ala ms ha he beha io gi en o
ala m calls will be dis inc i e om hose exhibi ed when squi els a e exposed o con ols. Secondly, i
squi el ea esd opping is highly disc imina ing hen we expec ha he squi els should eac he
s onges o i mouse calls gi en o p eda o species ha ep esen he highes le el o dange o he
squi els.
METHODS AND MATERIALS
S udy A ea
This s udy mainly ook place in Gaines ille, Flo ida wi h a ew samples aken om Volusia Coun y,
Flo ida. Na u al a eas in Gaines ille se ed as he main places whe e samples we e collec ed as bo h
u ed i mice and eas e n g ay squi els occu he e. The sampling loca ions we e s anda dized as g assy
a eas wi h ees mainly on Uni e si y o Flo ida na u al a eas. Sampling loca ions include Na u al A ea
Teaching Labo a o y (LAT 29.6355553, LONG -82.3675674), Loblolly Woods (LAT 29.6599265,
LONG -82.3693071), McCa y Woods (LAT 29.6451553, LONG -82.3441510), Bi ens A m Na u e
Pa k (LAT 29.6199404, LONG -82.3328847), and G een Sp ings Pa k (LAT 28.8628194, LONG -
81.2488019). I is impo an ees we e p esen o e e y si e as ees a e a place o p o ec ion o
squi els o escape om p eda o s (Engelha d & Weladji, 2011).
Field P o ocol
To see i eas e n g ay squi els ea esd op on u ed i mice ala m calls, playbacks we e used as a
way o elici , obse e, and eco d his beha io . Th ee di e en u ed i mice ala m calls we e used as
playbacks, which a e he high see call, an eas e n sc eech owl (Megascops asio) ala m call, and a g ea -
ho ned owl (Bubo i ginianus) ala m call. A high see call is when a hawk ha is hun ing on he wing
passes close by, h ea ening a ack and is a high dange si ua ion. Playback o acous ic cues in ol es he
use o digi al eco dings b oadcas h ough a po able speake and a e commonly p ac iced in a ian
ecology (Bai, 2021). All h ee playback ypes used as ala m calls we e eco ded when i mice we e
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calling in esponse o li e p eda o s o each species (Sie ing and He ick 2012). A g een ee og call
(Hyla cine ea) was used as he con ol s imulus as hei call is common whe e eas e n g ay squi els and
u ed i mice occu and do no ep esen any dange (see Figu e 1). These playbacks we e s anda dized
h ough Adobe Audi ion acous ic so wa e o las 19 o 21 seconds and ea u ed h ee epe i ions o he
speci ic call wi hin he ime limi .
Fo his expe imen , a po able Blue oo h speake was placed abou 15 o 30 me e s away om an
eas e n g ay squi el o ensu e ha he squi el could hea he playbacks (Jackson e al., 1997). Videos
we e eco ded on a cellula de ice o he squi el’s baseline beha io o one minu e, hen a playback
ile was b oadcas h ough he speake and he beha io o he squi el was eco ded o one minu e
mo e. The ou di e en ea men playbacks we e selec ed andomly h oughou samples aken du ing
ield wo k a o al o nine indi iduals we e collec ed o each ea men (n=36). The dis ance be ween he
speake and he squi el was eco ded o each sample and calcula ed by using a ange inde . The
coo dina es o he squi el loca ions we e also no ed using a GPS and digi al map. All samples we e
independen in ha he e was su icien dis ance be ween hem ha one squi el ne e hea d he
playback o ano he squi el (250m). Any squi els ha we e ala med by my p esence we e no used o
da a analysis o a oid bias.
Da a Analysis
The beha io s obse ed om he ideos o he squi els we e cha ac e ized and quan i ied as coun
o du a ion me ics. The eac ion la ency o he playback ( ime be ween s imulus ini ia ion and i s
beha io change) and he ime spen exhibi ing igilance we e no ed om he ideos. Vigilance ime
was de ined as he ime squi els spen exhibi ing an ip eda o beha io s. A obi eg ession was used o
show a linea ela ionship o igilance ime and eac ion la ency based on ype o call and dis ance om
he speake . A obi eg ession was he bes o his calcula ion as analysis was es ic ed o 60 o al
seconds o obse a ion. Fo showing he p edic ed baseline and an ip eda o beha io s based on coun
da a, a mul ile el mixed-e ec model wi h poisson link unc ion was used in o de o see he mean o
he beha io s o each call and ail pe iod. All g aphs po ay p edic ed ma ginal means and 95%
con idence in e als. All analyses we e accomplished using S a a e sion 17.0 B/E.
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RESULTS
Squi el Vigilance and La ency
A o al o 36 di e en squi els we e eco ded o hei beha io s be o e and a e he playbacks. The
squi els had he longes p edic ed igilance ime o he g ea -ho ned owl and eas e n sc eech owl ala m
calls (Figu e 2A). The sho es p edic ed igilance ime was he g een ee og con ol call. All u ed
i mice ala m calls used had low eac ion la ency and he g een ee og call had e y high eac ion
la ency (Figu e 2B). The u ed i mice ala m call eac ions o igilance ime and eac ion la ency we e
all s a is ically di e en om hose obse ed o he g een ee og call (p=0.0003; p=0.0002).
Squi el Beha io
The p edic ed numbe o an ip eda o beha io s a e he playbacks we e g ea e in he g ea -ho ned
owl and eas e n sc eech owl ala m calls. The p edic ed an ip eda o beha io s dec eased a e he
p edic ed an ip eda o beha io s dec eased a e he og playback was b oadcas bu signi ican ly
inc eased a e all h ee ala m calls we e used (Figu e 3). This shows dis inc ly di e en eac ions o
ala m e sus con ol calls. The numbe o an ip eda o beha io s be o e he playbacks a e ela i ely
simila be ween all calls indica ing no biased esul s we e used. No e ha in all cases (Figu es 2 and 3),
eac ions o he wo owl ala m calls we e s onge han o he hawk a ack call.
DISCUSSION
Ou esul s sugges ha eas e n g ay squi els may also u ilize i mouse calls, es ablishing ha he
ea esd opping ne wo k o i mice includes a leas wo species o mammals (chipmunks also; Schmid e
al. 2008) and many bi ds species (Huang e al. 2012; Jones and Sie ing 2019), b oadening ou
unde s anding o he in e connec edness o animal communi y ne wo ks. Eas e n g ay squi els also had
dis inc eac ions o di e en ala m calls indica ing ha he squi els can unde s and which p eda o is
p esen om he call. In con as o bi ds, who a e much wa ie o he high see call owing o he ac
ha hawks on he wing a e much mo e dange ous o small bi ds han pe ched owls o any species
(He ick and Sie ing 2012), bo h squi els ( his s udy) and chipmunks (Schmid e al. 2008) exhibi
highe ala m s a es when i mice a e calling abou owls.
This s udy adds o he g owing demons a ion ha many axa sha e su i al in o ma ion wi h each
o he (Ridley e al. 2014) and unde s anding animal communica ion ne wo ks will ad ance knowledge
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o he d i e s o ecological communi y dynamics (Reiche e al. 2021). Gi en he impo ance o ocal
signals in animal communi ies, soundscape conse a ion is a high p io i y o p o ec ing animal
communi y dynamics in he ace o an h opogenic ac i i ies and in luence (e.g., Bu i olo a e al. 2021).
ACKNOWLEDGEMENTS
We would like o hank he s uden s in he Sie ing Lab o hei guidance h oughou his s udy. We
also wan o hank he Uni e si y o Flo ida and he Wildli e Ecology and Conse a ion Depa men .
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SUPPORTING FIGURES/TABLES
Figu e 1. Typical sonog ams o he 3 u ed i mouse calls used in his s udy. Calls pic u ed we e
eco ded when li e i mice we e exposed o he ollowing p eda o s imuli; (A) eas e n sc eech owl
(small owl), (B) g ea ho ned owl (la ge owl), and (C) a acking hawk. (D) Tu ed i mouse adul
(g aphic). Call o he ee og no shown.
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Table 1. Eas e n G ay Squi el Beha io s and Desc ip ions
Beha io Desc ip ion Beha io Class
Fo aging
Ac i ely ea ing o sea ching on g ound o ood
Baseline
G ooming
Fixing o cleaning u
Baseline
Laying Down
Body la on a su ace
Vigilan
Head Down
Head poin ed lowe han shoulde s
Baseline
Head Up
Head poin ed abo e shoulde s
Vigilan
Tail Twi ch
Ligh ail mo emen ha does no ully cu e he ail
Baseline
Tail Flag
Rapid ail mo emen ha ully cu es he ail
Vigilan
Climb Up
Going up a ee
Vigilan
Climb Down
Going down a ee
Baseline
Looking Up
Head poin ed up when on a ee
Vigilan
Si Up
Sa up on back legs and wo on legs o he g ound
Baseline
F eeze
Body is s ill and no mo emen occu s
Vigilan
Call
Any ocaliza ion
Vigilan
Run
Rapid mo emen whe e legs ully ex en
Vigilan
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Figu e 2. P edic ed igilance ime (Top) and eac ion la ency (Bo om) exhibi ed by squi els o each
call. “GHO” s ands o g ea -ho ned owl and “Z call” is he high see call.
050 100 150
P edic ed Reac ion La ency (60 sec = ul)
F og GHO Sc eech Z call
Type o Playback
-20 0 20 40 60 80
P edic ed Vigilance Time (60s = ul)
F og GHO Sc eech Z call
Type o Playback
