The Wilson Journal of Ornithology 124(4):750-757, 2012 
HISTORIC PRESENCE AND ABSENCE OF PREDATOR AFFECTS CAII 
STRUCTURE OF BLACK-CAPPED CHICKADEES 
JACOB A. SABORSE 1 AND IAN J. RENNE 1,2 
{P r U ' U,riCaPil,US) ^ CaP ' Urcd presented 
Populations („ = 4 and 8 chickadee,!“to^s^hr /‘"t “T* - * “■* ***** «** 
thls dangerous, regionally sympatric predator These learned vo-al Ch,C . k ' d ' dec c “ l,s have a site-specific structure for 
context is to denote information about predator threat level with nurnem! * T !" Van ° US circums >ances and one 
threat. Average number of D notes per call was 4 4 where chi k t ' ' IS ShW I an< lrcqueDt D no,es designating high 
then, the average was 2.3. Dun,.ion of the f", D note and ime b u " """ * CTC *'™* ^ in — ** 
m areas without screech-owls. Diminution of Dred ator J ■ ^ !* notes Were - respectively. 36% and 44 % longer 
chickadees elicit a threat-inappropriate present evidence that suggest' 
repertoire for this predator and that nuances in ‘chick-a-dcc* e- 41 !"? SCreech ' owls because they have not learned the vocal 
20/2. Accepted 14 June 2012. ‘ s LOnve > predator-specific identity. Received 2 February 
Many animals produce variable calls in response 
to potential predators (Bayly and Evans 2001 
Yorzinski and Patricelli 2010). Some calls arc 
structured to recruit individuals to harass predators 
tom , he area via mobbing (Hurd 1996, Templeton 
‘ id Greene 2007, Nolen and Lucas 2009) and 
contain specific information important to survivor- 
'h,p .such as predator type, location, or level of 
threat (Gnesser 2008 , Bartmess-LeVasseur et al 
-010 Courier and Ritchison 2010). For example 
Black-capped Chickadees (Poecile alricapillus] 
feveUBak" "‘"hT ‘° designa,c Predation risk 
A r ccker 2002 ' "Templeton et al 
m“ed floT' * ?!' ’• Thcse “«* ■*l«~d by 
Greene 2007). Tem P ,clon a "d 
The Black-capped Chickadee is a small non 
Ame'ri ° SOngb,rd COmmon throughout its North 
b trT w s i tt e i„ produce,oud ^ 
^Ms^o'recru 198 ^ 
Predator Hurt 
et al. 20 fts . . 1 J9f) - Templeton 
pi . ~ ’ empleton and Greene ^ 007 ) 
important to survival. Templeton e, a”~ 
indicate number, rate, and duration of D notes by 
chickadees correlate with the threat level posed by 
particular predators (Avey et al. 2011): -50 
species are known to respond to ‘chick-a-dee' 
calls and join in mobbing (Gunn el al. 2000). 
Eastern Screech-Owls {Megascops asio) in 
northeast Ohio have historically been ahseni 
t loughout large regions but a few areas main¬ 
tain persistent populations (R. C. Jones and R. J. 
ovoiny, local park managers, pers. comm.: 
Pc ter job n 2001). We assessed whether presence 
oi absence ol the Eastern Screech-Owl, a small, 
dexterous and dangerous predator of Black- 
capped Chickadees and other small songbirds 
(Smith 1947, VanCamp and Henny 1975. Ritch¬ 
ison and Cavanagh 1992), corresponded to 
alterations in the ‘chick-a-dee* call structure. Pro¬ 
duction of the ‘chick-a-dee’ call appears mostly 
learned by conspecifics and not innate (Hughes 
cl al. 1998), and loss of structural components 
resulting from predator absence may occur in as 
hnle as one generation (Blumstein et al. 2004). 
Screech-owls are a predatory threat to chickadees 
ut their patchy distribution may locally relax 
maintenance ot otherwise important vocalizations. 
Uur objective was to test whether elements of the 
chick-a-dee’ call structure differed in areas 
istoncally lacking and harboring screech-owls, 
c captured chickadees from each type of area 
and analyzed components of their calls when 
presented with a stuffed screech-owl model. 
' Department of Biological Science v 
University. Youngstown. OH 44555 - ^ ,H,n SM°wn Slate 
■ Corresponding author; e- m ail7ij re nne@y si ,e du 
750 
methods 
... ^ eto> Calls ,—-Twelve unhanded Black 
c-m! X . PV ckadees °* unknown sex and age wen 
re 1,1 ^rec counties in northeast 0hit 
