The Wilson Journal of Ornithology 123 ( 2 ): 360 — 366 , 2011 
NON-BREEDING ECOLOGY OF LOGGERHEAD SHRIKES 
IN KENTUCKY 
ERIN OBRIEN' AND GARY R ITCH ISON 12 
ABSTRACT. Populations of Loggerhead Shrikes (Lcinius ludovicianus) across North America have been declining, 
and factors responsible for this decline remain unclear. Few studies have focused on the availability and use of wintering 
habitat. Our objectives were to ascertain the size and characteristics of Loggerhead Shrike territories, and examine the 
hunting behavior of shrikes during the non-breeding season. We observed 1.372 hunting attempts by 19 shrikes: arthropods 
(65.3%) and other invertebrates (23.3%) were the most common prey. Characteristics of habitat at used and randomly 
selected, apparently unused isolated and continuous perch sites differed (P = 0.023 and P = 0.021. respectively). Lied 
perches had less grass cover, more bare ground, and denser, shorter vegetation. We found no difference between 
characteristics of occupied and unoccupied areas (P = 0.34). Non-breeding territories in our study were larger (mean = 
85 ha) than those reported for shrikes during the breeding season. The availability of suitable winter habitat do^snoi appear 
to be limiting Loggerhead Shrike populations in Kentucky. However, most Loggerhead Shrikes winter south of Kentucky 
where densities are higher, and it is possible that availability of suitable habitat might be a limiting factor in some areas 
Received / / September 2010, Accepted 14 December 2010. 
Populations of Loggerhead Shrikes (Lcinius 
ludovicianus) have been declining over much of 
North America for the past several decades (Sauer 
et al. 2008). Factors potentially contributing to 
declines in populations of Loggerhead Shrikes 
include low reproductive success, habitat loss and 
degradation, and reduced over-winter survival. 
However, previous studies have revealed no 
evidence that declines in shrike populations are 
due to low reproductive success (Esely and 
Bollinger 2001. Yosef 2001). The availability of 
suitable shrike breeding habitat is apparently not a 
limiting factor, at least in some locations (Brooks 
and Temple 1990, Prescott and Collister 1993 
Fomes 2004). 
A possible factor in the decline of shrike 
populations is availability of suitable habitat 
during the non-breeding season. Gawlik and 
Bildstein (1993) examined seasonal habitat use 
and abundance of Loggerhead Shrikes in South 
Carolina and found no difference in habitat use 
between breeding and non-breeding seasons. They 
did not, however, compare the characteristics of 
occupied and unoccupied areas during the non- 
breeding season, and were unable to draw 
conclusions concerning the abundance or suitabil¬ 
ity of non-breeding habitat. Prey availability may 
also decline during the non-breeding season, 
particularly in the northern portion of their 
wintering range, and characteristics of territories 
Department of Biological Sciences, Eastern Kentucky 
University, 521 Lancaster Avenue. Richmond, KY 40475 
USA. 
2 Corresponding author; e-mail: gary.ritchison@eku.edu 
occupied by Loggerhead Shrikes during the non 
breeding season may differ from those occupied 
during the breeding season. For example, shrikes 
may defend larger territories in response to 
reduced prey availability during the winter. 
Previous work involving manipulation of prey 
availability suggests Loggerhead Shrikes increase 
territory size or perhaps even abandon territories 
when prey availability is reduced (Yosef and 
Deyrup 1998). 
The objectives of our study were to: (I) 
ascertain the size and characteristics of Logger- 
head Shrike territories in central Kentucky during 
the non-breeding season. (2) compare the charac¬ 
teristics of territories used by shrikes during the 
non-breeding season to those of areas not used by 
shrikes, and (3) examine the hunting behavior of 
Loggerhead Shrikes during the non-breeding 
season. 
METHODS 
Field Procedures .—We studied shrikes from I 
January to 31 March 2005 and 1 November 2005 
to 31 March 2006 in Garrard and Madison 
counties, Kentucky. Shrikes were located by 
surveying areas where they had been previously 
reported (Olson 2006. Peterson 2006) and search¬ 
ing areas ot apparently suitable shrike habitat 
We captured shrikes using modified bal-chatri 
traps (Clark 1968), and banded each with a USGS 
aluminum band and a unique combination ol 
or three colored plastic bands. Eight shrikes were 
also fitted with a tail-mounted transmitter (I - e- 
Model BD-2; Holohil Systems Ltd.. Carp. ON. 
Canada); transmitters were attached to three or 
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