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378 Southeastern Naturalist Vol. 10, No. 2
American Kestrel (Falco sparverius) Attacks Red-cockaded
Woodpecker (Picoides borealis) Fledgling
Abstract- A Falco sparverius (American Kestrel) was observed attacking and carrying away
a Picoides borealis (Red-cockaded Woodpecker) fledgling during observations associated with a
long-term monitoring program on Fort Bragg Military Installation, Fort Bragg, NC. The woodpecker
was released in mid-air approximately 100 m from the site of the attack and fell to the ground,
alive. It is unknown if the American kestrel returned to consume the fledgling, or if the fledgling
survived the encounter.
Picoides borealis (Vieillot) (Red-cockaded Woodpecker; hereafter RCWO) is a primary
cavity nester of the Pinus palustris P. Mill (Longleaf Pine) ecosystem and the only
woodpecker in North America to construct its cavities in living pine trees. The RCWO’s
cavity excavations in living pines provide a resource for numerous secondary cavitynesting
species (Blanc and Walters 2008). Populations of the endangered RCWO have
been studied and monitored for 3 decades in this ecosystem (Britcher and Patten 2004,
Brust et al. 2004, Carter et al. 1983), and the members of this species commonly raise
broods in cavities located in the same pine tree with secondary cavity nesters, including
avian predators such as Otus asio L. (Eastern Screech Owl) and Falco sparverius L.
(American Kestrel), which nest in enlarged RCWO cavities (Blanc and Walters 2008,
Gault et al. 2004, Hoffman and Callopy 1987).
The American kestrel is a small (97–150 g), sexually dimorphic falcon, which occurs
throughout the Americas. It can be considered an opportunistic-generalist (Callopy and
Koplin 1995), consuming insects, lizards, small rodents, and birds, depending on temporal
variability (Sarasola et al. 2003), energetic requirements during the breeding season
(Bohall 1984), and location (Rojas and Stappung 2004). The RCWO (42–52 g) falls
within the weight range of avian prey items (16–300 g) reported for American Kestrels
(Rojas and Stappung 2004); however, small lizards comprise the majority of vertebrate
prey consumed during the breeding season in open woodland habitat types (Smallwood
1990) like those on Fort Bragg. Alarm calls given by the RCWO when a kestrel is visible
infer a predatory relationship (Buchanan 1989); however both species raise broods
concurrently in nesting densities up to 4 pairs per square kilometer in the Longleaf Pine
ecosystem (Gault et al. 2004), and there are no previous records of an American Kestrel
preying on a RCWO.
The Fort Bragg Military Installation (FB) is located in the Sandhills region of southcentral
North Carolina, an area characterized by second-growth Longleaf Pine forests
previously described in detail by Carter et al. (1983). The site where the incident occurred
is located on the Overhills tract in the northeastern portion of FB. It is managed with
growing-season burns every 1–3 years in order to maintain an open midstory and diverse
groundcover dominated by Aristida stricta Michx. (Wiregrass).
At approximately 0830 on 20 June 2008 during routine RCWO-monitoring activities
at Cluster 470, we observed two 26-day-old color-banded fledglings. The 2 were vocalizing
and fighting with each other on a limb in the crown of a mature Longleaf Pine. One
of the fledglings was identified as a male because of his red crown patch, but we had not
*Directorate of Public Works, IMSE-BRG-PWE-E, 2175 Reilly Road Stop A, Fort Bragg, NC
Notes of the Southeastern Nat u ral ist, Issue 10/2, 2011
2011 Southeastern Naturalist Notes 379
determined the sex of the other fledgling. The adults (a breeding pair and 2 helper males)
were nearby and intermittently called and fed each of the fledglings. The squabbling
continued as the fledgling of unknown sex was repeatedly pecked and chased around the
bole of the pine tree by the male fledgling. The former flew to a large horizontal limb to
escape harassment, then moved to a smaller limb where it had a difficult time becoming
situated. At this time, an adult RCWO issued an alarm call and the other adult RCWOs
stopped vocalizing. An American Kestrel flew into the site, plucked the fledgling bird
from the limb, and flew off in a southwesterly direction. The captured fledgling began a
loud, raucous calling which continued as it was carried away.
We observed the direction the Kestrel flew carrying the fledgling and followed it to
determine the fledgling’s fate. At this time, we heard and identified several Kestrel fledglings
in the area. Approximately 100 m from the site of the attack, the Kestrel dropped the
RCWO to the ground and flew off. Due to the brownish plumage and call of the kestrel,
we believe it was an adult female.
The RCWO fledgling was alive on the ground, but appeared unable to fly, and was
identified as a female. We did not touch the bird and left the area. We returned several
hours later and found no evidence of the injured RCWO. The fledgling’s fate is unknown
as she was not seen in the FB population again. Her brother of the same brood was present
at his natal cluster in the 2009 breeding season.
It is well known among falconers that abnormal prey behavior is attractive to
predatory birds, as certain trapping techniques use distressed, harnessed pigeons or freemoving
mice and gerbils as bait. It has also been shown that kestrels and other falcons
select prey based on their activity level (Sarno and Gubanich 1995, Smallwood 1981),
rather than just body size (Bryan 1984, Smallwood 1989), and that the selection of small
to medium-sized (16–80 g) prey items could be influenced by high energy requirements
during the nesting season (Collopy and Koplin 1983, Sarasola et al. 2003). Additional
factors such as degree of hunger (Bryan 1984), temporal differences (Bohall-Wood and
Collopy 1986, Smallwood 1987), search image (Tinbergen 1960), and territory quality
(Smallwood 1987) may also influence prey-size selection and the relative representation
of such items in the diet (Collopy and Koplin 1983). The considerable amount of commotion
associated with the circumstances leading up to the attack support the idea that
American Kestrels are opportunistic and will expand their typical prey selection during
times of increased energetic demands (such as the post-fledging period), particularly
when a prey item is both conspicuous and vulnerable.
Acknowledgments. Special thanks to Brian Ball, Jacqueline Britcher, Dr. Jay H. Carter III,
and other, anonymous reviewers of this manuscript.
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