Activity of Post-fledging Peregrine Falcons in Different
Rearing and Habitat Conditions
Matthew R. Dzialak, Kristina M. Carter, Michael J. Lacki,
David F. Westneat, and Katie Anderson
Southeastern Naturalist, Volume 8, Number 1 (2009): 93–106
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2009 SOUTHEASTERN NATURALIST 8(1):93–106
Activity of Post-fl edging Peregrine Falcons in Different
Rearing and Habitat Conditions
Matthew R. Dzialak1,*, Kristina M. Carter2, Michael J. Lacki3,
David F. Westneat4, and Katie Anderson5
Abstract - To assist with recovery of Falco peregrinus (Peregrine Falcon) in the
southeastern United States, we compared pre-dispersal activity budgets between
falcons reintroduced at sites chosen for their contrasting habitats (agriculture vs
forest). We also compared behavior of our hacked birds with nearby wild-produced
juveniles. We classified pre-dispersal behavior into nine activities depicting fl ight
and non-fl ight. We logged 901 hr of observation and found that wild-produced
falcons spent more time in low fl ight, soaring, and mock combat during a 4-wk postfl
edging period (mean ± 95% CI) than hacked birds. Peregrine Falcons hacked in
mixed agricultural habitat spent more time soaring and perching alertly than those
hacked in forest habitat; falcons in forest habitat perched inactively with higher
frequency. Dispersal time (mean ± SD) differed among groups (F2,31 = 11.4, P <
0.001). Falcons hacked in forest habitat spent 15.2 ± 12.2 days on the post-fl edging
areas before dispersing, whereas those hacked in agricultural habitat spent 31.0 ± 3.3
days and wild-produced birds spent 35.9 ± 10.1 days. It appeared that transitional
habitat supporting available prey and the presence of adults during the post-fl edging
period were important in the expression of key behavior repertoires including hunting,
defense, and social fl ight activity. Our results suggest that further recovery of
the Peregrine Falcon in the southeastern United States would be poorly served by
additional hacking, particularly in forest habitat. Rather, managers should continue
to monitor and encourage productivity in existing occupied habitat; eventually offspring
from occupied habitat may occupy adjacent habitats.
The transition from fledging to independence is an important lifehistory
stage for many bird species. In raptors, the post-fledging period
provides stimuli that contribute to development of behavior such as social
interaction among conspecifics, prey recognition, pursuit, and defense
(Newton 1979). Understanding the factors that affect post-fledging behavior
in raptors can inform their management, particularly for species
of conservation concern that might be subject to manipulations in rearing
conditions (e.g., hacking [housing juveniles in enclosures at the release
site from several days to up to four weeks before release] or cross-fostering)
during recovery efforts. Attention to the events that lead to formation
1Hayden-Wing Associates LLC, 2308 South 8th Street, Laramie, WY 82070. 2Kristina
Carter Photography, Aurora, IL 60504. 3Department of Forestry, University of Kentucky,
Lexington, KY 40546. 4Department of Biological Sciences, University of
Kentucky, Lexington, KY 40546. 5Department of Biology, Northern Michigan University,
Marquette, MI 49855. *Corresponding author - email@example.com.
94 Southeastern Naturalist Vol. 8, No. 1
of fully functional adults could make the difference between success and
failure in raptor management for recovery.
Falco peregrinus Turistall (Peregrine Falcon) has been the focus of several
conservation-oriented studies that examined behavior. A comprehensive
description of the transition to independence in hacked and wild-produced
Peregrines Falcons has been completed (Sherrod 1983). Many facets of behavior
developed similarly in these two groups despite the absence of adult
infl uence on hacked birds, which suggests that instinct and sibling interaction
among hacked falcons were key factors in this similarity. This finding
had important conservation implications for development and refinement of
recovery efforts because it characterized the resilience of Peregrine Falcons
to alternate rearing strategies. Behavior in the Peregrine Falcon has since
become well known, particularly as it relates to managing eyries (Carlier and
Gallo 1995, Hovis et al. 1985, Palmer et al. 2003). Knowledge gaps remain,
however, including information on factors affecting behavior in areas where
this falcon is still considered to be at risk of extirpation.
The Peregrine Falcon has recovered throughout much of North America.
In the Arctic, it was removed from the endangered species list in 1994, and
the population in the lower 48 United States was removed from the endangered
species list in 1999. Recovery has progressed more slowly in the
southeastern United States (Southeast: US Fish and Wildlife Service [FWS],
Region 4). Up to 70 eyries may have occurred historically in the Southeast,
but at present, the region supports approximately 18 breeding pairs—the
fewest among regions designated by FWS (Dzialak et al. 2005a). Given the
extent of apparently suitable habitat, several states in this region still list this
falcon as endangered.
We hacked peregrines in Kentucky as part of an effort to augment Peregrine
Falcon recovery in the Southeast. Typically, hacked raptors remain
in the vicinity of the hacking station for several weeks after release and
then disperse after a post-fl edging period. Our objectives were to compare
pre-dispersal activity time budgets among Peregrine Falcons hacked at
sites specifically chosen for their contrasting habitat configurations and to
compare time budgets and time to dispersal of hacked groups with nearby
wild-produced juveniles to develop insight into relative infl uences of rearing
and habitat on Peregrine Falcons in the Southeast.
We hacked 33 Peregrine Falcons at Red River Gorge Geologic Area in
Daniel Boone National Forest (DBNF) and at Tom Dorman State Nature Preserve
(TDSNP), KY. Cliffs at these sites are 60–80 m in height. These sites
were chosen, in part, for their contrasting habitat features. DBNF, located in
the Cumberland Plateau physiographic region, provided non-forest corridors
within a forest matrix. TDSNP, about 75 km to the west in the Bluegrass
region, provided forest corridors within a largely non-forest matrix (Fig. 1;
Dzialak et al. 2005b). We summarized several key differences in habitat
2009 M.R. Dzialak, K.M. Carter, M.J. Lacki, D.F. Westneat, and K. Anderson 95
between these regions (Dzialak et al. 2005a; Table 1). We released 28 falcons
at DBNF during 2001–2003 at two hacking stations 1.5 km apart, and
Figure 1. (A) The Red River Gorge Geologic Area, Daniel Boone National Forest,
KY. Numerous massive sandstone outcrops within a largely forested matrix characterize
the region; photo by J.L. Larkin (B). Aerial views of largely nonforest corridorlike
landscape features increasing in spatial extent from Cumberland Plateau into
Bluegrass physiographic regions near Daniel Boone National Forest; photo by M.R.
Dzialak (C) and (D). Aerial views of the largely forested Kentucky River drainage
near Tom Dorman State Nature Preserve within a mixed agricultural landscape; photos
by M.R. Dzialak. Figure adapted from Dzialak et al. (2005b).
Table 1. Characteristics of cliffs in the Bluegrass and Cumberland Plateau physiographic regions,
KY. Nine Cumberland Plateau cliffs were located in Red River Gorge, with two used
as hack sites. One Bluegrass cliff was in Dorman Preserve. Table modified from Dzialak et al.
(2005a). Data presented as mean ± SD.
Variable (units) Bluegrass (n = 3) Cumberland Plateau (n = 26)
Height (m) 50 ± 20 34 ± 21
Estimated horizontal extent (m) 1269 ± 1300 204 ± 131
Elevation (m) 208 ± 34 323 ± 50
Nearest agriculture >2 ha (m) 244 ± 77 2089 ± 1455
Nearest developmentA (m) 825 ± 101 13,190 ± 4920
Nearest open water (m) 19 ± 5 1192 ± 2795
Land use: forest (%)B 50 ± 1 92 ± 4
Land use: agriculture (%)C 47 ± 1 6 ± 2
Land use: development (%)D 1 ± 0 0 ± 0
Land use: total non-forested (%)E 50 ± 1 8 ± 4
ARestricted to incorporated city, town, borough, or locality.
BPercentage of landscape (20,096 ha) primarily forest within 8-km radius of the cliff.
CPercentage of landscape (20,096 ha) primarily agriculture within 8-km radius of the cliff.
DPercentage of landscape (20,096 ha) primarily developed/residential within 8-km radius of
EPercentage of landscape (20,096 ha) non-forest within 8-km radius of the cliff.
96 Southeastern Naturalist Vol. 8, No. 1
five at TDSNP in 2003 following methods of Sherrod et al. (1982). Data on
22 of 28 falcons hacked in DBNF were available for this study in addition
to data on the five falcons hacked from TDSNP. We fitted each bird with a
tarsal-mounted RI-2CM transmitter (Holohil Systems, Ltd., ON, Canada)
and gave it a unique identification marking on the dorsal humeral region using
nontoxic paint. Prerelease veterinary evaluation and health certification
of all falcons was coordinated through the University of Minnesota College
of Veterinary Medicine Raptor Center. All methods used were approved by
the University of Kentucky Animal Care and Use Committee (protocol #
We observed eight wild-produced Peregrine Falcons in 2002–2003 at
two breeding locations along a 60-km segment of the Ohio River in northern
Kentucky where adults used nest boxes affixed to smokestacks of coal-fired
power plants. Four breeding pairs occupied the smokestacks along a 175-km
segment of the Ohio River in the Bluegrass region. We used a geographic
information system and Mid-American Remote Sensing Center data (Murray
State University, Murray, KY) to characterize four habitat classes within 8
km of Ohio River eyries and hacking stations; we arcsine-transformed the
data and used the Fisher exact test (Zar 1996) for analysis.
We observed Peregrines Falcons from 18 June–14 August at a distance
of 200–400 m using 10 x 30 binoculars and a 20 x 60 mm spotting scope
(Fujinon®, Wayne, NJ). Observation began immediately following fl edging
and ended with dispersal. We visited a site for two consecutive days before
switching to a different one. The experimental unit was a fl edgling; we
observed each fl edgling for a 1-hr block. When a fl edgling moved beyond
survey range for ≥15 min, we selected a different fl edgling for observation
and began a new 1-hr block. Observation sessions were 10-hr blocks, with
start times staggered to encompass daylight hours (0630–2100). We classified behavior into nine types (Table 2; Cade 1960, Harris and Clement
1975, Herbert and Herbert 1965, Sherrod 1983). We converted data into
activity budgets calculated as percent frequency of time spent in a behavior
by a fl edgling divided by total time in view per day. We averaged these data
among fl edglings over 1-wk intervals and evaluated a 4-wk post-fl edging period
(Sherrod 1983, Varland et al. 1991). The dataset was unbalanced across
groups (hereafter, groups refers to wild-produced, DBNF, and TDSNP),
rendering a two-factor (group and week) repeated measures ANOVA unreliable.
We present the data graphically and discuss results in terms of central
tendency and associated precision (i.e., mean ± 95% CI). Non-overlapping
95% CI is a conservative estimate of significance (i.e., likely has a lower
type I error rate and higher type II error rate at α = 0.05; Schenker and
Gentleman 2001). There are techniques to correct for bias in error rates (type
I error-averaged confidence intervals; Goldstein and Healy 1995) but, given
the small sample size and probable deviations from underlying assumptions
of equal variance and normality, we opted to present the more conservative
results. We also compared the proportion of Peregrine Falcons achieving
2009 M.R. Dzialak, K.M. Carter, M.J. Lacki, D.F. Westneat, and K. Anderson 97
independence among sites using the Fisher exact test (Zar 1996). Data on
the proportion of wild-produced young that achieved independence during
2001–2003 were from Vorisek and Carter (2004). Beginning at fl edging, we
tabulated the number of days elapsed before each peregrine dispersed and
used a single-factor ANOVA to compare dispersal time among groups. Differences
for the Fisher exact test and ANOVA were considered significant at
P ≤ 0.05. All analyses were performed using SAS® software (SAS Institute,
We logged 901 hr of observation. It appeared that the activity types we examined
adequately characterized behavior among sites (Table 2); we observed
no behavior unique to a particular site. Habitat composition at TDSNP and two
Ohio River eyries was similar in terms of percent forest (0.48, 0.44, and 0.47,
respectively), agriculture (0.48, 0.48, and 0.46, respectively), open water
(0.02, 0.06, and 0.06, respectively) and development (0.02, 0.02, and 0.01,
respectively). The proportion of forest, agriculture, open water, and development
at DBNF was 0.94, 0.05, <0.01, and 0.01, respectively. Habitat attributes
were different among sites (Fisher exact test; df = 3, P < 0.001), refl ecting the
contrast between the heavily forested DBNF and the mixed forest-agricultural
TDSNP and Ohio River eyries.
Peregrine Falcons achieved independence similarly among sites: 5 of 5 at
TDSNP, 17 of 22 at DBNF and 10 of 26 at the Ohio River sites (Fisher exact
test; df = 2, P = 0.30). Dispersal time differed among groups, with DBNF
falcons leaving the post-fl edging area at 15.2 ± 12.2 days, TDSNP at 31.0
± 3.3 days, and wild-produced falcons at 35.9 ± 10.1 days (F2,31 = 11.4, P <
0.001). Time-activity budgets differed among groups and with week-sincefl
edging based on mean ± 95% CI criteria (Figs. 2, 3, and 4).
Table 2. Nine predispersal activities identified for hacked and wild-produced Falco peregrinus
(Peregrine Falcons) in Kentucky, June to August, 2001–2003.
Non-fl ight activity
Alert perching Active visual surveying, head-bobbing, or movement while perched.
Inactive perching Sunning, resting, lying down, or other stationary perching.
Movement Flapping, walking, hopping, stationary play with inanimate objects,
preening, feaking, or scratching.
Simple fl ight Perch to perch fl ights, short fl ight with high wing-stroke frequency.
Low fl ight Low altitude fl ight restricted to areas adjacent to hacking stations or
eyries, moderate wing-stroke frequency.
Soaring Prolonged high-altitude fl ight, infrequent or no wing-stroke.
Mock combat Social aerial activity including stooping, chasing, vocal protest, or
Hawking Effort to capture fl ying invertebrates.
Direct pursuit Effort to capture vertebrate prey.
98 Southeastern Naturalist Vol. 8, No. 1
Figure 2. Predispersal activity budgets for non-fl ight behavior including inactive
perching (A), alert perching (B), and movement (C) among hacked (Daniel Boone
National Forest and Tom Dorman State Nature Preserve) and wild-produced Falco
peregrinus (Peregrine Falcon) in Kentucky, June to August, 2001–2003. Sample
sizes shown in Figure 2A apply to 2B and 2C.
2009 M.R. Dzialak, K.M. Carter, M.J. Lacki, D.F. Westneat, and K. Anderson 99
Non-fl ight activity
Week effects within groups. Wild-produced Peregrine Falcons spent considerable
time perching inactively during weeks one and two (27–38%), but
reduced inactive perching in weeks three and four (5–6%) (Fig. 2). Falcons
at TDSNP also perched inactively with high frequency in week one (31%),
but then reduced their inactive perching through time (9–11%). In contrast,
DBNF falcons perched inactively throughout the study (18–36%). All
groups generally maintained a consistent frequency of alert perching; the
only notable effect was more frequent alert perching at DBNF in week one
(52%) compared to week three (27%). Movement activity was most frequent
in all groups in week one (6–7%) compared to weeks two to four (0.4–4%).
Figure 3. Predispersal activity budgets for fl ight behavior including simple fl ight (A),
low fl ight (B), and soaring (C) among hacked (Daniel Boone National Forest and
Tom Dorman State Nature Preserve) and wild-produced Falco peregrinus (Peregrine
Falcon) in Kentucky, June to August, 2001–2003. Sample sizes shown in Figure 3A
apply to 3B and 3C.
100 Southeastern Naturalist Vol. 8, No. 1
Comparison of wild-produced and hacked falcons. Hacked Peregrine
Falcons at DBNF perched inactively more frequently than wild-produced
birds (≈30% vs ≈5%) during weeks three to four (Fig. 2). Similarly, hacked
falcons generally perched alertly more frequently than wild-produced falcons;
differences existed between TDSNP (67–79%) and wild-produced
(33–51%) Peregrine Falcons in weeks two and four. Movement activity
generally was more frequent in hacked falcons; differences existed between
wild-produced and DBNF birds in week four (1% vs 3%).
Comparison of hacked falcons by habitat. DBNF falcons perched inactively
more frequently than ones at TDSNP during all weeks, but differences
existed only in week three (31% vs 9% inactive perching). Peregrine Falcons
at TDSNP perched alertly more frequently than at DBNF, but differences
Figure 4. Predispersal activity budgets for pursuit behavior including mock combat
(A), direct pursuit (B), and hawking (C) among hacked (Daniel Boone National Forest
and Tom Dorman State Nature Preserve) and wild-produced Falco peregrinus
(Peregrine Falcon) in Kentucky, June to August, 2001–2003. Sample sizes shown in
Figure 4A apply to 4B and 4C.
2009 M.R. Dzialak, K.M. Carter, M.J. Lacki, D.F. Westneat, and K. Anderson 101
were only significant in weeks two to four (≈70% vs ≈30%). Movement
activity was similar between hacked groups (Fig. 2).
Week effects within groups. Simple fl ight was consistently infrequent
throughout the study (Fig. 3). Low fl ight peaked in frequency in week three
and was lowest in week one, but this difference was significant only in wildproduced
falcons (0.5% vs 13%). Frequency of soaring exhibited the same
trend as low fl ight by peaking in all groups in week three; the most apparent
week effect was less frequent soaring in all groups in week one (≈0.5%)
compared to week three (≈6%).
Comparison of wild-produced and hacked falcons. We found no difference
between wild-produced and hacked Peregrine Falcons in simple
fl ight (Fig 3). Wild-produced falcons exhibited low fl ight more frequently
than hacked Peregrines during weeks two and four (≈8% vs. ≈1%). Wildproduced
birds generally spent more time soaring than hacked ones, but
differences were apparent only between wild-produced and DBNF falcons in
week two (14% vs 2%) and between wild-produced and both hacked groups
in week four (7% vs ≈1%).
Comparison of hacked falcons by habitat. We found no difference between
hacked groups in frequency of simple fl ight or low fl ight (Fig. 3).
TDSNP birds soared more frequently than those at DBNF, but differences
were significant only in weeks three (8% vs 2%) and four (2% vs 0.1%).
Week effects within groups. No week effect existed for direct pursuit,
mock combat or hawking activities; however, wild-produced falcons
engaged in mock combat, more frequently in weeks two and four (≈9%)
compared to week one (≈2%) (Fig. 4).
Comparison of wild-produced and hacked falcons. Direct pursuit was
observed infrequently in hacked birds, but was seen with comparatively high
frequency in wild-produced ones in weeks two to four (Fig. 4). Hawking was
rarely observed during the study. Mock combat was more frequent in wildproduced
falcons in week four (9% vs. ≈0.4%).
Comparison of hacked falcons by habitat. We found no differences between
hacked groups in direct pursuit, hawking, or mock combat activities
Changes in the frequency of activities that we monitored were consistent
with what is known about the post-fledging period in raptors,
especially for young Peregrine Falcons during development from fledging
to dispersal (i.e., Balbontin and Ferrer 2005, Newton 1979, Sherrod
1983). For example, Peregrine Falcons generally exhibited perching activities,
movement, and simple flight with relatively high frequency soon
after fledging. Concurrent with a decrease in these activities with age
102 Southeastern Naturalist Vol. 8, No. 1
(week effect) was an increase in frequency of more complex flight behavior
such as mock combat and soaring.
Wild-produced falcons spent more time in mock combat, pursuit, soaring,
and low fl ight activities than hacked birds, although these differences
were not always apparent because of low sample sizes. Wild falcons also
remained on the post-fl edging area longer than hacked birds. More conspicuous
social behavior and a longer post-fl edging period in wild-produced
versus hacked Peregrine Falcons has been reported previously (Sherrod
1983). The activities we identified as more frequent among wild-produced
falcons often occurred as part of adult-juvenile interaction, including aerial
food transfers, family hunting events, mimicking adult defensive behavior,
and adult-juvenile antagonism (Sherrod 1983). We have corroborated many
previous findings, particularly those on the infl uence of adults in conspecific
interaction and defense (Sherrod 1983). Research on hacked fl edgling Haliaeetus
leucocephalus Linnaeus (Bald Eagle) that had been captive-reared or
removed from active nests at about seven weeks of age (wild-reared) indicated
that wild-reared eagles generally dispersed sooner than captive-reared
ones and also sooner than eagles fl edged at wild nests (Meyers and Miller
1992). However, none of the Bald Eagles was reared in a setting with adults
as was the case with wild Peregrine Falcons in this study.
We found differences in pre-dispersal activity between Peregrine Falcons
hacked in two different habitats. Falcons at TDSNP (mixed forest-agriculture)
spent more time in alert perching and soaring behavior and less time
perching inactively than falcons at the forested DBNF. Timing of dispersal
also differed considerably between hacked groups, with those at TDSNP
remaining on the post-fl edging area for an average of 31 days compared to
only 15 days for birds at DBNF. It is important to note the similarity between
TDSNP and wild-produced falcons, which while reared differently, shared a
Did habitat differences cause behavioral differences between falcons
at DBNF and TDSNP? Inferring cause and effect would require replicated
landscapes and perhaps manipulation of habitat, which we could not investigate.
Also, several factors associated with variation in hacking protocol can
confound these observations including health condition, sex, release age, and
release cohort size. We controlled for such factors as much as possible. All
Peregrines received pre-release veterinary evaluation and appeared healthy
at release. Some limited variation occurred in other factors, but given the
conservation objective of restoration, it was in our interest to follow hacking
protocol (Dzialak et al. 2006). For example, all falcons were 43–54 days old
at release, with males generally released slightly younger than females. Consistency
in rearing conditions (hacking protocol) was generally maintained
between sites, so we suggest that it is worthwhile to consider how habitat
might play a role in the behavioral differences between hacked groups (sensu
Bélisle et al. 2001, Evans et al. 2003, Lima and Zollner 1996). The value of
exploring this is in developing further hypotheses on the infl uence of habitat
2009 M.R. Dzialak, K.M. Carter, M.J. Lacki, D.F. Westneat, and K. Anderson 103
on raptor development and in offering insight into factors affecting the success
of Peregrine Falcon hacking and recovery in the Southeast.
Habitat affects the falcon’s activity by infl uencing prey availability, the
presence of competitors, the risk of predation, mating opportunities, and
microclimate. From previous work, we knew that preferred prey were significantly more abundant at TDSNP compared to DBNF (Carter et al. 2003,
Dzialak et al. 2005a). More abundant prey at TDSNP appeared to result in
a higher frequency of alert perching, and also appeared to trigger pursuit.
Once in fl ight, pursuit often gave way to soaring. In contrast, falcons at
DBNF had to move several km from the hack site to encounter edge habitat
and associated prey species (Dzialak et al. 2005b). Most falcon prey in the
immediate vicinity of DBNF hack sites were inconspicuous forest birds,
so visual stimulus associated with prey abundance was limited; therefore,
falcons at DBNF tended to rest (perched inactive). The importance of prey
resources has been observed previously, particularly in terms of breeding
success or movement behavior in raptors (Barclay and Cade 1983, Hickey
1942, Holroyd and Banasch 1990, Kopimärki and Norrdahl 1991). It is important
to have abundant and available prey in close proximity to hacking
stations. Yet, the importance of prey abundance and availability in the development
of behavior critical to hunting, defense, and perhaps conspecific
interaction has received little attention because the effects of prey resources
at hack sites have focused on physical requirements rather than behavioral
development (Holroyd and Banasch 1990, Sherrod et al. 1982).
An alternative hypothesis is that differences in activity between hacked
groups refl ected differences between sites in predation (by owls) or competition.
Previous work suggested that risk of predation by raptors (i.e., Bubo
virginianus Gremlin [Great Horned Owl]) was greater at TDSNP (Dzialak
et al. 2005a). However, no mortality occurred at TDSNP; in contrast, five
deaths occurred at DBNF, all from unknown causes (Dzialak et al. 2007).
Competition for food may also have been greater at DBNF. Species observed
at DBNF but not at TDSNP that scavenged on dead quail (Coturnix sp.) we
provided as food for falcons, included Urocyon cinereoargenteus Schreber
(Gray Fox), Crotalis horridus Linnaeus (Timber Rattlesnake), and Lynx rufus
Schreber (Bobcat). Reduced alertness and activity (observed at DBNF),
however, is not supported in the literature as an adaptive response to predation
or competition in raptors.
A post-fl edging period of 23–30 days has been observed for hacked
Peregrine Falcons (Fyfe 1988, Powell et al. 2002). Hypotheses on resource
competition, physical condition, and density-dependent social interaction
have been offered in investigations of dispersal timing in raptors (Balbontin
and Ferrer 2005, Belthoff and Dufty 1998, Willey and van Riper 2000). We
found no evidence that hacked groups in the two locales differed in physical
condition or access to resources, and our data do not support the notion of
density-dependent social confl ict (i.e., more falcons were released at DBNF,
but there was less activity there). Also, week of dispersal was highly variable
104 Southeastern Naturalist Vol. 8, No. 1
at DBNF; some individuals dispersed in the first week of fl edging, while others
remained on the post-fl edging area for 39 days and defended territories
there in subsequent years. Peregrine Falcons in other regions occupy forest
habitat (Corser et al. 1999), but an association between forest and a short
post-fl edging period has not been reported, and so it seems questionable that
simple preference for non-forest habitat explains the short and highly variable
post-fl edging period at DBNF. Rather, individual experiences among
these falcons in release conditions, successful food acquisition, or conspecific
interaction post-release may better account for this variability (S. Sherrod,
G.M. Sutton Avian Research Center, Bartlesville, OK, pers. comm.).
What factors limit Peregrine Falcon recovery in the Southeast? An absence
of resident reproductive adults following extirpation, limited foraging
habitat near cliffs, or frequent recreational use of cliff habitat might contribute
to an aversion to these areas among potential colonizers. To these
considerations should be added the possibility that a diminished social repertoire
in the absence of abundant prey can infl uence choices of habitat over
the long term. To our knowledge, no additional Peregrine Falcon releases are
scheduled in the Southeast in the foreseeable future. This shift away from
falcon introductions in the Southeast is appropriate as further recovery there
may be poorly served by additional hacking in forest habitat. Perhaps the
best option biologically and financially would be to monitor and encourage
productivity at existing strongholds of Peregrine Falcon activity such as
western North Carolina or coastal regions of Virginia and Maryland. Some
of these offspring may eventually adapt to contemporary selective pressures
in the Southeast and begin to occupy inland portions of the Appalachian
Plateaus (Mengel 1939) and Mississippi River bottomland forests (Bellrose
1938, Spofford 1943).
Funding and other support for this project was provided by the Kentucky Department
of Fish and Wildlife Resources; the University of Kentucky, College of
Agriculture; and the US Department of Agriculture, Daniel Boone National Forest.
We thank S. Sherrod for his comments and suggestions, which improved the
manuscript. This research (KAES 03-09-065) is associated with a project of the
Kentucky Agricultural Experiment Station and is published with the approval of
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