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BURROWING OWL NEST SITE USE AND PRODUCTIVITY
ON PRAIRIE DOG COLONIES IN THE SOUTHERN
HIGH PLAINS OF TEXAS
by
ANDREW TEASCHNER, B.S.
A THESIS
IN
WILDLIFE SCIENCE
Submitted to the Graduate Faculty of Texas Tech University in
Partial Fulfillment of the Requirements for
the Degree of
MASTER OF SCIENCE
Approved
Mark C. Wallace Chairperson of the Committee
Clint William Boal
Nancy E. McIntyre
James D. Ray
Accepted
John Borrelli Dean of the Graduate School
August, 2005
ACKNOWLEDGEMENTS
Funding for this project was provided by the United States Department of
Energy/National Nuclear Security Administration in cooperation with BWXT Pantex,
L.L.C., Texas Tech University, United States Geological Survey - Texas Cooperative
Fisheries and Wildlife Research Unit, and Texas Parks and Wildlife Department. I would
like to thank Dr. Mark Wallace for his encouragement, guidance and support throughout
this project. I would like to thank Dr. Clint Boal for his support and guidance, especially
in the trapping and banding methods for birds of prey. I thank Jim Ray, Monty
Schoenhals and Mike Keck for their assistance in field work and coordination on the
Pantex Plant. I also thank all of the private landowners in Carson and Lubbock Counties
who allowed me access to their property for the purposes of this project.
I am indebted to everyone who assisted me in collecting data in the field: Cole
Baack, Blake Beall, Lisa Belmonte, Tracy Boal, David Butler, Lawson Dennis, Matthew
Giovanni, Carey Haralson, Nicole Jaurequi, Tiffany Lyon, Alison Pruett, Ryan Stout,
Chris Taylor, Lindi Van Heuklon, and Ryan Ward. I would like to thank my fellow
graduate students for their support and advice throughout the project. Finally, I would
like to thank my family who have supported my education and interest from the
beginning.
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TABLE OF CONTENTS
ACKNOWLEDGMENTS………………………………………………..……………..ii
LIST OF TABLES……………………………………………………………………...iv
LIST OF FIGURES……………………………………………………………………..v
CHAPTER
I. GENERAL INTRODUCTION………………………………………… 1
II. BURROWING OWL NEST SITE USE AND PRODUCTIVITY IN THE SOUTHERN HIGH PLAINS OF TEXAS.…………………... 4
Abstract…………………………………………….…………... 4 Introduction…………………………………………………….. 5 Study Area.………………………..…………………………… 6 Methods…………………………………………….………….. 7 Results…………………………………………………………. 11 Discussion………………………………………….…………... 15 Management Implications………………………….…………... 19 Literature Cited…………………………………….……………21
APPENDICES
A. BURROWING OWL TRAPPING DATA…………………………….. 39
B. VEGETATION TRANSECT DATA………………………………….. 52
C. COLONY MAPS………………………………………………………. 55
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LIST OF TABLES
2.1 Study sites chosen and data known prior to 2003 field season...………………. 28
2.2 Burrowing owls marked and seen by season combined for all sites.…………...29
2.3 Burrowing owl nesting and productivity data given by site for Lubbock and Carson County, Texas in 2003 and 2004………………………....30
2.4 Number of prairie dogs estimated and holes marked by site for Lubbock and Carson Counties, Texas in 2004………………………………….31
2.5 Number of burrowing owl pairs per buffer area by site for Lubbock and Carson County, Texas in 2003 and 2004…………………………32
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LIST OF FIGURES
2.1 The maximum number of burrowing owls seen on prairie dog colonies correlated to prairie dog colony size for a 12 county area searched for a
prairie dog colony study in the Texas Panhandle……………………………… 34 2.2 The number of burrowing owls caught by trap type and season across
all sites in Lubbock and Carson Counties, Texas in 2003 and 2004…….….…. 35 2.3 Number of burrowing owls seen in 2003 and 2004, with and without
bands for the 6 study sites in Lubbock and Carson Counties, Texas………….. 36 2.4 The number of burrowing owl pairs recorded in relation to prairie dog colony area in hectares for the 6 study sites in Lubbock and Carson Counties, Texas for 2003 and 2004……………………………………………. 37 2.5 The number of burrowing owl pairs recorded in relation to the number
of prairie dog holes marked in 2004 for the 6 study sites in Lubbock and Carson Counties, Texas………………………………………………………... 38
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CHAPTER I
GENERAL INTRODUCTION
Western burrowing owls (Athene cunicularia hypugaea) are widely distributed
across the western portion of North America and can be found from deserts to
agricultural areas (Haug et al. 1993). Despite the wide distribution of this particular
species, Desmond et al. (2000), Korfanta et al. (2001), and Murphy et al. (2001) have
shown declines in the range and numbers of burrowing owls across the western U.S. and
Canada. Habitat destruction and land conversion are major causes for declines (Korfanta
et al. 2001, Martell et al. 2001, Murphy et al. 2001, Sheffield and Howery 2001).
Burrowing owls are considered a U.S. Fish and Wildlife Service regional conservation
priority (USFWS 2001).
In the Texas Panhandle, little research has been done on burrowing owls.
McIntyre (2004) indicated a long-term decline since the 1940’s of wintering owls
recorded in Christmas Bird Counts for this area, whereas Breeding Bird Survey data
suggested that summer burrowing owl populations may have remained stable since the
1960’s. Surveys of prairie dog colonies across 12 counties in the Southern High Plains of
Texas (Pruett 2004) showed that burrowing owl numbers were correlated to prairie dog
colony size. However, colony size explained very little of the up to 10-fold variation in
owl numbers that occurred over small colony sizes. This study was developed to assess
the use of prairie dog colonies as habitat by western burrowing owls (Athene cunicularia
hypugaea) in the Texas Panhandle. We wondered what factors might be responsible for
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some small prairie dog colonies having large numbers of owls while others had few.
While a potentially large number of variables could be involved, prairie dog density,
number of holes, vegetative composition or structure, and relative prey abundance were
measurable variables that we suspected were important.
The results of this research are presented in Chapter II. Chapter II assesses
burrowing owl presence on prairie dog colonies and related prairie dog colony parameters
to burrowing owl numbers and productivity and is formatted for submission to the
Wildlife Society Bulletin separately.
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6/9/2005
Andrew P. Teaschner Department of Range, Wildlife, and Fisheries Management Texas Tech University Lubbock, TX 79409 806-742-1981; E-mail: [email protected] RH: Burrowing Owl Nesting Southern High Plains • Teaschner et al.
Burrowing Owl Nest Site Use and Productivity in the Southern High Plains of Texas.
Andrew P. Teaschner, Department of Range, Wildlife, and Fisheries Management, P. O.
Box 42125, Texas Tech University, Lubbock, TX 79409, USA.
Mark C. Wallace, Department of Range, Wildlife, and Fisheries Management, P. O.
Box 42125, Texas Tech University, Lubbock, TX 79409, USA.
Clint W. Boal, Texas Cooperative Fish and Wildlife Research Unit, 218 Agriculture
Science, Texas Tech University, Lubbock TX 79409, USA.
Nancy E. McIntyre, Department of Biological Sciences, P. O. Box 43131, Texas Tech
University, Lubbock, TX 79409, USA.
James D. Ray, BWXT Pantex LLC, Pantex Plant, Bldg. T-9061, Amarillo, TX 79120,
USA.
Monty Schoenhals, BWXT Pantex LLC, Pantex Plant, Bldg. T-9061, Amarillo, TX
79120, USA.
Abstract
Large numbers of burrowing owls nest in the Texas Panhandle, yet very little is
known of their breeding ecology in the region. For this study we measured abundance of
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burrowing owls and attempted to assess the number of resident verses migrant burrowing
owls through color banding and the monitoring of marked individuals, at a sample of
study areas in the Texas Panhandle. Burrowing owl productivity and prairie dog colony
parameters that could influence burrowing owl nest selection and success were also
measured. The majority of burrowing owls in our area are breeding season migrants.
Noose carpet and Bal-Chatri traps were the most effective trapping methods during the
breeding season. Number of breeding burrowing owl pairs was positively correlated to
colony area (r2 = 0.5498, P = 0.0060), and to number of prairie dog holes in a colony (r2
= 0.7327, P = 0.0296). Our measures of vegetative composition and structure were not
related to burrowing owl numbers or productivity.
Introduction
Western burrowing owls (Athene cunicularia hypugaea) are widely distributed
across the western portion of North America and can be found from deserts to
agricultural areas (Haug et al. 1993). Despite the wide distribution of this species,
Desmond et al. (2000), Korfanta et al. (2001), and Murphy et al. (2001) have shown
declines in the range and numbers of burrowing owls across the western U.S. and
Canada. Habitat destruction and land conversion are major causes for declines (Korfanta
et al. 2001, Martell et al. 2001, Murphy et al. 2001, Sheffield and Howery 2001).
Burrowing owls are considered a U.S. Fish and Wildlife Service regional conservation
priority (USFWS 2001).
In the Texas Panhandle, little research has been done on burrowing owls.
McIntyre (2004) indicated a long-term decline since the 1940’s of wintering owls
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recorded in Christmas Bird Counts for this area, whereas Breeding Bird Survey data
suggested that summer burrowing owl populations may have remained stable since the
1960’s. Pruett (2004) recorded number of burrowing owls seen while surveying prairie
dogs in a 12 county area of the Southern High Plains of Texas. The number of
burrowing owls observed (Figure 2.1) was positively correlated (r2 = 0.0182, P = 0.0107)
to prairie dog colony size. However, there was >20-fold range in the number of owls
seen in smaller (2 to 20 ha) prairie dog colonies.
Information is lacking on all aspects of burrowing owl ecology that may be
unique to this area. Our objectives were to describe burrowing owl use of prairie dog
colonies and examine factors that might explain why some colonies are used more than
others. We were specifically interested in determining the relationship between numbers
of owls, prairie dog density, and colony size. We also examined related factors that could
affect burrowing owl use of prairie dog colonies, including relative prey abundance,
proximity to playas containing water, and vegetative structure associated with prairie dog
colonies.
Study area
We chose our study sites from a subset of sites surveyed for a companion study
on prairie dogs in relation to playas (Pruett 2004). We selected 3 sites on the Pantex
Plant in Carson County, TX, and 3 in the Lubbock area, Lubbock County, TX, for
burrowing owl trapping, banding, and observation. These sites were selected because we
knew, from previous surveys (McCaffrey 2001, Pruett 2004), that they provided nesting
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sites for burrowing owls and they represented prairie dog colony sizes 2.9 to 11.6 ha.
Study sites (Table 2.1) were chosen to have representative patterns of surrounding land
use and histories of on-site management activity. The Pantex Plant provided sites that
were relatively undisturbed (during our observation period) with a known history of
grazing and prairie dog control activities. Lubbock area sites provided agricultural sites
and abandoned areas within urbanizing landscapes.
Methods
We used Bal-Chatri traps, noose carpets (Mealy 1997, Millsap and Bear 1997),
walk-in traps (Botelho and Arrowood 1995, Banuelos 1997), and bow nets (Bloom 1987)
to trap burrowing owls. Captured owls were banded with one USFWS leg band and one
red alpha-numerically coded anodized aluminum band. We recorded captured
individuals as adult or juvenile based on plumage (Haug et al. 1993). To determine
whether individuals were migrants or residents, we attempted to relocate banded owls
weekly. We monitored burrowing owls with spotting scopes and binoculars from parked
vehicles, which we used as viewing blinds (Coulombe 1971). Walking through a prairie
dog colony to detect burrowing owls or observing a colony for ≥30mins from a vehicle
blind during any one day was defined as a search day for that site. Timing of migration
was assessed based on presence or absence of individually identifiable marked owls
during >3 monthly counts at each site. Identification of individual burrowing owls was
also used to determine individual nest sites, and between year area and pair fidelity.
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Nesting
Owls were not recorded as nesting pairs until we observed chicks at burrows.
Chicks have been recorded moving between nest burrows as young as 10 days old
(Henny and Blus 1981). Once a chick was observed above ground it was considered
“fledged.” Therefore, all pairs recorded as nesting were by definition successful nesters.
We recorded the number of burrowing owls, marked burrowing owls, nesting burrows
and maximum number of chicks seen per nest burrow (Martin 1973, Green and Anthony
1989, Desmond and Savidge 1996). We attempted to search all 6 main sites ≥1
time/week. We searched adjacent prairie dog colonies within 8 km of our 6 study sites,
opportunistically in an attempt to determine whether marked individuals moved between
prairie dog colonies or remained on the prairie dog colony on which they were marked.
To obtain relative measures of productivity, we monitored nesting burrows for 3
separate 10-minute periods within a 2-week period as nestlings began to emerge from
burrows (Gleason and Johnson 1985). We defined productivity as the maximum number
of young birds seen at any one period for each natal burrow.
We examined correlations between number of burrowing owl pairs and
productivity to prairie dog colony size, number of prairie dogs, and number of vacant
prairie dog holes. We determined perimeters of our study colonies by walking around the
exterior burrows with a handheld global positioning satellite (GPS) unit (Garmin model
12, Garmin Intenational Inc. Olathe, KS). The GPS track was then uploaded onto a
computer to determine colony area. Number of prairie dogs was estimated using 3 counts
following Pruett (2004). During 2004, we made a complete count of all holes on each of
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our sites. Location of each prairie dog hole at the 6 sites, including holes used as nesting
burrows by burrowing owls, was recorded using GPS. We derived an index of “vacant”
holes by dividing the number of holes counted at each site by the estimated (Pruett 2004)
number of prairie dogs present (Table 2.4). We reasoned that sites with a higher index
(more holes per prairie dog) should have more “vacant” holes available for burrowing
owls to use. If burrowing owls used parts of prairie dog colonies where holes were
more or less densely packed then the distance from nest burrows to holes should differ
from the distance between holes. We randomly selected an equal number of prairie dog
holes as there were burrowing owl nests on each site and compared distance from each
nesting burrow to its’ 5 closest prairie dog holes to the distance from the random holes to
their 5 closest prairie dog holes. We created 50-m buffers from prairie dog colony
centers using ArcView GIS and counted the number of owl nesting burrows per unit area.
Given the size of prairie dog colonies on our sites, all holes were within 3 of these 50-m
buffers from the colony center. We also compared the calculated distance from
burrowing owl nest burrows to the geographic center of the colony and to the nearest
colony edge.
Distance to playas containing water was used as an index of food availability,
since many amphibians and insects in this area use playas to complete their life cycle
(Anderson 1997). Local playas were identified from available GIS mapping (Fish et al.
1995, Pruett 2004). We checked for the presence of water during burrowing owl nesting
and recorded distances to nearest adjacent playas containing water to correlate distance to
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playas containing water to number of burrowing owl nests and nest success using
Pearson’s product moment correlation.
We assessed relative abundance of small mammals, another potential food source
for burrowing owls, by trapping on the 6 prairie dog colonies. Trapping grids consisting
of 100 Sherman live traps that were set for a period of 3 consecutive nights. All captured
mammals were identified to species and sex, weighed, measured, and marked for
identification upon recapture (Pruett 2004). Numbers of initial captures were compared
between sites for all species that are considered possible prey for burrowing owls to
assess relative abundance of foods in relation to burrowing owl nest density and success.
We also examined vegetative data to assess characteristics of burrowing owl
nesting sites and vegetative structure and composition. Two 25-m line intercept transects
were randomly placed in each prairie dog colony. Percent cover (intercept distance) of
vegetation along each transect was recorded by category: grass, forb, shrub, litter, bare
ground, or other (Bullock 1996). Visual obstruction was estimated using (n=6/transect)
Robel pole measures (Vermeire et al. 2002) taken at 5-m intervals along each 25-m
transect. We modified the lowest 2 decimeters of our pole marking off 2-cm intervals
with which to record heights of the commonly <1 decimeter tall vegetation on our sites.
We used Statistica (StatSoft, Inc. (2003). STATISTICA (data analysis software
system), version 6. www.statsoft.com) to calculate all statistical tests at the α = 0.05 level
of significance. All research was conducted following methods approved by the Texas
Tech animal care and use committee (protocol # 03014-02). Burrowing owl trapping and
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banding was conducted under the Federal Bird Marking and Salvage Permit (Permit #
22801-D).
Results
We captured burrowing owls (n=153; 137 adult, 16 juvenile) between January
2002 and July 2004 and banded them with USFWS No. 4 leg bands; n=130 of the 137
banded adults also received uniquely alpha-numeric coded red anodized aluminum leg
bands (Appendix A). Capture method success varied by season. Most owls (89%; 137 of
153) were captured during the summer breeding periods when Bal-Chatri and noose
carpet traps (87%; 119 of 137 total summer captures) were most successful (Figure 2.2).
Of the summer-banded owls, 14 (13 color banded adults and 1 juvenile) were captured
for a concurrent research project and were not monitored after capture for this project;
however, their trapping data are included in trap success and Appendix A. We baited
Bal-Chatri traps with domestic white mice (Mus musculus) and placed noose carpets
adjacent to burrow entrances occupied by a nesting pair of owls. Very few owls (n=7-18)
were observed on our 6 intensive sites during winter months. Therefore, we increased our
trapping and survey area by adding 3 sites on the Pantex Plant in Carson County during
winter 2004. Only 12% (n=16; 3 on the added sites) of all owls were captured during the
winter periods and most (81.3%; 13 of 16 captured) of these were captured with walk-in
traps placed over burrows that owls were observed entering.
We conducted searches (n=111) on our 6 intensive sites (mean + SE 3.5 ± 1.8
searches per month) per site between September 2003 and April 2005 and counted the
number of burrowing owls and marked burrowing owls observed. We attempted to assess
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timing of seasonal migrations by recording the total number of burrowing owls and the
number of marked owls seen each month throughout the year (Figure 2.3). Our sites had
3 to 7 times as many burrowing owls during the summer breeding period (between March
and September) as they did during the winter (October through February).
To determine whether burrowing owls were resident or migrant, we recorded the
number of birds marked in one season and re-sighted in another. Owls were designated
as known residents if they were observed in ≥3 consecutive seasons. There were more
(χ2 = 10.20; 1 d.f.; P = 0.0014) known resident winter-marked owls (44.4 %; 4 of 9) than
summer-marked (3.7%; 4 of 108) owls (Table 2.2). Some additional owls may have been
resident, including summer-marked owls that were observed the summer following the
summer in which they were marked (9.3%; 10 of 108). These owls may have over-
wintered in the region undetected at sites that we did not survey, or they may have
migrated south and returned to the same sites to breed the following summer.
Additionally, 2.6% of our marked owls (3 of 117) were seen in only 2 consecutive
seasons (1 seen winter and the following summer; and, 2 seen summer and the following
winter). We therefore determined that most burrowing owls in this area were summer
migrants, with only a small proportion (6.8%-18.0%; or 8-21 of 117 total marked owls)
likely resident (remaining over-winter between consecutive breeding seasons) in this
population. Furthermore, in over 406 days of searching our 6 intensive sites and 43 days
of searching adjacent sites within 8 km of the intensive sites, no marked owl was ever
observed at any site other than the one at which it was captured.
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Nesting
We identified 98 nesting pairs on our 6 sites during 2003 (n = 57) and 2004(n =
41). Number of nesting pairs/ha and productivity (maximum number of chicks seen per
breeding pair) did not differ (Wilcoxon matched pairs T > 4; P > 0.173) between years for
sites. Furthermore, the number of burrowing owl pairs/ha did not differ between years
among sites (χ2 = 5.691; 5 d.f.; P = 0.3374) and owl productivity did not differ between
years among sites (χ2 = 0.9523; 5 d.f.; P = 0.9663). Therefore, we pooled years for
analyses of nesting pairs and productivity. There were 1.02 ± 0.40 (mean + SE) nesting
pairs/ha on our sites. Productivity averaged 2.80 ±0.13 (mean + SE) chicks per pair
(Table 2.3). Mean distance between burrows of nesting pairs was 66.33 m ± 4.22. The
earliest date we recorded chicks seen was May 19, with the last observed emergence of
new chicks recorded on June 25.
The number of burrowing owl pairs (Figure 2.4) was positively correlated (r2 =
0.5498, P = 0.0060) to prairie dog colony size (n=12). In 2004 we also had counts of the
number of holes on each prairie dog town. The number of burrowing owl pairs was
positively correlated (r2 = 0.7327, P = 0.0296) to the number of prairie dog holes on our 6
sites in 2004 (Figure 2.5).
For our 6 intensive sites the number of prairie dog holes increased with colony
size (r2 = 0.7006, 4 d.f., P = 0.0377). However, number of burrowing owl pairs was not
related to either the density of prairie dogs (estimated prairie dogs/ha) (r2 < 0.3, P > 0.1)
or the index of vacant holes (holes/estimated prairie dogs) (r2 < 0.3, P > 0.1) for our 6
intensively monitored sites.
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We had measures of pairs of burrowing owls, owl productivity, and indices of
relative food abundance (distance to playas containing water and relative abundance of
small mammals) on all sites in both 2003 and 2004 (n=12 sites). However, our measures
of relative food abundance did not show significant relationships to burrowing owl pairs
or productivity (r2 < 0.1, P > 0.1). Measures of visual obstruction and vegetative
composition were not correlated to burrowing owl numbers or productivity (r2 < 0.4. P >
0.1) (Appendix B).
We plotted burrowing owl nest locations for 2003 and 2004 and prairie dog holes
for 2004 using ArcView GIS (Appendix C). We created 50-m buffers from prairie dog
colony centers and counted the number of owl nesting burrows per unit area. Given the
size of prairie dog colonies on our sites, all holes were within 3 of these 50-m buffers
from the colony center. There were more nesting burrows in zones farther from the
colony center (Table 2.5) but since buffers farther from the center also incorporated much
more area, the number of nesting burrows was not greater than expected if owls nested at
equal densities in each zone the from the center to the outer edges of prairie dog colonies
(χ2 = 2.401, 2 d.f., P = 0.3009). Average distance to the colony edge for burrowing owl
burrows (45 ± 3.8 Meters) was less than the average distance to the colony center (142 ±
6.9 meters, T = -12, 192 d.f., P < .001). To see whether burrowing owls were nesting in
specific orientations on the prairie dog colonies, we divided prairie dog colonies into 4
quadrants (based on cardinal directions) and compared aspects used for nesting burrows.
There was no difference in the number of nesting burrows (χ2 = 1.69, 3 d.f., P = 0.6483)
or nesting burrows per unit area (χ2 = 2.45, 3 d.f., P = 0.4850) by aspect.
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Burrowing owls did not use more or less dense areas of holes within the prairie
dog colonies. There was no difference (P > 0.10) between distances from burrowing owl
nests and total hole distances, or between the 5 closest holes to burrowing nests and the 5
closest to randomly selected holes.
Discussion
We found noose carpets and Bal-Chatri traps to be most successful for capturing
adult burrowing owls during the nesting season. Bal-Chatri traps with a live mouse were
often required to capture the male during the nest-provisioning period. Mealey (1977)
and Milsap and Bear (1997) also found noose carpets to be successful in Florida. During
the winter, walk-in or 1-way cage door traps placed on burrows after owls were observed
entering were almost the only methods that were successful on our sites. Both wintering
and breeding owls seemed to prefer flight to the shelter of burrows, making it difficult to
use walk-in traps. Clayton and Schmutz (1999) saw a similar pattern with owls in their
study in Alberta. We did capture 3 adult burrowing owls with bow-nets during winter by
placing the bow-net at a frequented burrow, then baiting it with a white mouse.
Most owls on our sites were summer migrants. Only 6.8%-18.0% of the owls we
marked were observed over-wintering or breeding on our sites in a second season. This
is much lower than reported returns of in Florida (68%; Millsap and Bear 1997) or in
California (20-25%; Coulombe 1971). A higher proportion of wintering owls than
summering owls were re-sighted again in another season in our study. Our returns are
similar, although somewhat higher, than those previously reported for other studies in the
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southern Great Plains. Butts (1976) reported less than 1% of the summer owl population
present in late July, returned to his Oklahoma Panhandle sites to breed in the following
year, whereas in Dallam County, Texas, 2.7% of the owl population from late July of the
previous year returned. However, all banded owls known to have over-wintered at his
sites remained to breed that following breeding season. Our higher numbers may reflect
a change since 1970’s with fewer owls using the northern parts of their continental range
(Clayton and Schmutz 1999) and more remaining or breeding in Texas.
To date we have had only 2 band recoveries from the 153 owls we banded. One
was killed by a car adjacent to the Lubbock site it was trapped at during the same season,
and the other was recovered in Apatzingan, Michoacán, México, in January of 2004, 7
months after it was banded in Lubbock County during June of 2003. This band return is
similar to Butts (1976) who reported one banded female from the breeding season in the
Oklahoma Panhandle, which was shot 17 months later during early winter in Zpaotlanejo,
Jalisco, México. Another similar record is from an owl captured and banded in this
region by Ross and Smith (1970) that was recorded in March of 1968 and 1969, captured
in Swisher County and recaptured the following year at El Paso, Texas.
We observed 2.80 ± 0.13 (mean + SE) chicks per pair, which is comparable to
reports from California (Thomsen 1971), Florida (Mealey 1997, Millsap and Bear 2000),
Montana (Restani et al. 2001), and New Mexico (Arrowood et al. 2001). However,
productivity on our sites was less than that reported in central Argentina (Bellocq 1997),
Saskatchewan (Haug and Oliphant 1990, James et al. 1997, Wellicome 1997), and North
Dakota (Konrad and Gilmer 1984).
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Distances between burrows may be representative of burrowing owl density or
territoriality. We compared mean distance between burrows at our sites to distances we
computed from data presented in Desmond et al. (1995). We used Desmond’s colonies
that were under 20 ha (comparable to ours), which averaged 68.23 m (Desmond et al.
1995). Other studies have reported much larger distances between burrows, particularly
for burrowing owls nesting in abandoned badger burrows (Green and Anthony 1989,
Haug and Oliphant 1990), squirrel burrows (Martin 1973) and those that dig their own
burrows in Florida (Millsap and Bear 2000).
Vegetative differences over all sites and years were not related to either
burrowing owl nests or productivity. Others have found burrowing owl nesting was
related to vegetative cover with owls selecting sites with lower visual obstruction
(Schmutz 1997, Trulio 1997, Clayton and Schmutz 1999). All 6 of our study sites were
located on prairie dog colonies, mostly on grazed shortgrass prairie or neglected sites in
an agricultural-suburban interface where there was minimal visual obstruction (2.7 ± 0.16
cm).
There is disagreement in the literature on whether burrowing owl numbers are
related to prairie dog colony size. Orth and Kennedy (2001) in Colorado and Restani et
al. (2001) in Montana found no relation between colony size and number of burrowing
owls whereas Desmond and Savage (1996) found a positive correlation between colony
size and number of burrowing owls in Nebraska. We found a positive relation between
prairie dog colony size and number of burrowing owl pairs. However, we believe this is
due more to the increased number of holes, hence, nesting opportunities than prairie dog
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colony size alone. It appears that the expectation of more burrowing owls is more
strongly related to the number of holes than the colony size. Although we do not know
how many holes were actually vacant, it did not appear that the number of “vacant” holes
in prairie dog colonies limited burrowing owls, as there were more holes with little or no
evidence of prairie dog activity than pairs of owls.
We did not detect specific spatial patterns of burrowing owl nesting in prairie dog
colonies. Desmond et al. (1995) assumed that burrowing owls in small (<35 ha) colonies
(such as ours) could not demonstrate spatial patterns due to size limitations, and that in
larger colonies they distributed a more clumped pattern. We suspect that use may be
based mostly on availability of vacant burrows; however, Powell et al. (1994) point out
that numbers of holes may not be directly related to number of prairie dogs or occupancy.
Our measure of vacancy was an indirect estimate with no spatial information. Vacant
burrows may be spatially clumped or widely scattered depending upon historical changes
in prairie dog occupancy within the colony. Established prairie dog colonies show
patterns of expansion, with older portions of the colony becoming less used or vacant
(Whicker and Detling 1988). This may result in clumped areas of vacant prairie dog
holes for burrowing owls. However, extrinsic disturbances (e.g., prairie dog control or
plague) may result in different patterns of hole availability for burrowing owls. Sidle et
al. (2001) found that burrowing owls appear to prefer prairie dog colonies in the Great
Plains National Grasslands that are active compared to those that are inactive; they cited
lack of burrow maintenance by prairie dogs and possible increases in predation as
potential reasons. With other prey (prairie dogs) absent, predators may focus more on
18
burrowing owls. We found burrowing owl numbers particularly high on the 12-36 site
even following prairie dog control with Phostoxin. However, treatments were conducted
during winter and this site was always rapidly recolonized by prairie dogs from nearby
untreated areas. So holes were seldom closed for very long.
Management Implications
Trapping of breeding burrowing owls appears to be more effective when nestlings
first emerge. Future breeding captures should be attempted immediately following
emergence of chicks using noose carpets and Bal-chatri traps when necessary. Winter
trapping should concentrate on walk-in traps and baited bow-nets.
More research is needed on burrowing owl ecology in our area. To better assess
potential burrowing owl food sources, we need data on where burrowing owls are
foraging and what prey items they are using in this area. Radio telemetry studies may
provide some of these answers in the near future, allowing for better sampling of
potential burrowing owl habitat use and prey base. Better estimates of burrowing owl
residency and timing of migration are needed with a more focused approach on one area
of the Panhandle where a more thorough sample of the population can be monitored.
Future band returns may lead to additional data on migration and fidelity of local
breeding populations of burrowing owls, as well as dispersal of chicks.
Prairie dogs are clearly important to burrowing owls in our area; however, the
characteristics that make one prairie dog colony more suitable than the next are largely
unknown. It does seem that the lack of visual obstruction provided by prairie dogs and
19
the large number of potentially vacant burrows are key elements in making good
burrowing owl habitat. Treatment of prairie dogs may initially reduce hole occupancy by
prairie dogs, leaving more available burrows for owls, although the quality of available
burrows may be lacking as well as the supply of future burrowing owl nest sites.
Additionally, the lack of prairie dogs in a colony can lead to an increase in visual
obstruction and potential loss of valuable nesting habitat.
20
Literature Cited
Anderson, A.M. 1997. Habitat use and diet of amphibians breeding in playa wetlands on
the Southern High Plains of Texas. Thesis, Texas Tech University, Lubbock,
Texas.
Arrowood, P.C., C.A. Finley, and B.C. Thompson. 2001. Analyses of Burrowing Owl
populations in New Mexico. Journal of Raptor Research 35:362-370.
Banuelos, G. 1997. The one-way door trap: an alternative trapping technique for
Burrowing Owls. Pages 122-124 in Lincer, J.L., and K. Steenhof, editors. The
Burrowing Owl, its biology and management: including the proceedings of the
first international symposium. Raptor Research Report Number 9.
Bellocq, M.I. 1997. Ecology of the Burrowing Owl in agrosystems of central Argentina.
Pages 52-57 in Lincer, J.L., and K. Steenhof, editors. The Burrowing Owl, its
biology and management: including the proceedings of the first international
symposium. Raptor Research Report Number 9.
Bloom, P. 1987. Capturing and handling raptors. Pages 99-123 in Raptor Management
Techniques Manual (B.A. Giron Pendleton, B.A. Millsap, K.W. Cline and D.M.
Bird, eds.). Port City Press, Baltimore, Maryland.
Botelho, E.E. and P.C. Arrowood. 1995. A novel, simple, safe and effective trap for
Burrowing Owls and other fossorial animals. Journal of Field Ornithology
66:380-384.
21
Bullock, J. 1996. Plants. Pages 111-138 in W.J. Sutherland, editor. Ecological Census
Techniques: A Handbook. Cambridge University Press, New York, New York.
Butts, K.O. 1976. Burrowing Owls wintering in the Oklahoma panhandle. Auk 93:510-
516.
Clayton, K.M. and J.K. Schmutz. 1999. Is the decline of Burrowing Owls Speotyto
cunicularia in prairie Canada linked to changes in Great Plains ecosystems? Bird
Conservation International 9:163-185.
Coulombe, H.N. 1971. Behavior and population ecology of the Burrowing Owl,
Speotyto cunicularia, in the Imperial Valley of California. Condor 73:162-176.
Desmond, M.J., J.A. Savidge, and K.M. Eskridge. 2000. Correlations between
burrowing owl and black-tailed prairie dog declines: a 7-year analysis. Journal of
Wildlife Management 64:1067-1075.
Desmond, M.J., J.A. Savidge. 1996. Factors influencing burrowing owl (Speotyto
cunicularia) nest densities and numbers in western Nebraska. American Midland
Naturalist 136:143-148.
Desmond, M.J., J.A. Savidge, and T.F. Seibert. 1995. Spatial patterns of burrowing owl
(Speotyto cunicularia) nests within black-tailed prairie dog (Cynomys
ludovicianus) towns. Canadian Journal of Zoology 73:1375-1379.
Fish, E.B., E.L. Atkinson, T.R. Mollhagafen, C.H. Shanks, and C.M. Brenton. 1995.
Playa lakes digital database for the Texas portion of the playa lakes joint venture
region. Unpublished report.
22
Gleason, R.L., and D.R. Johnson. 1985. Factors influencing nesting success of
burrowing owls in southeastern Idaho. Great Basin Naturalist 45:81-84.
Green, G.A., and R.G. Anthony. 1989. Nesting success and habitat relationships of
Burrowing Owls in the Columbia Basin, Oregon. Condor 91:347-354.
Haug, E.A., B.A. Millsap, and M.S. Martell. 1993. Speotyto cunicularia: Burrowing
Owl. The Birds of North America 61 (18pp).
Haug, E.A., and L.W. Oliphant. 1990. Movements, activity patterns, and habitat use of
burrowing owls in Saskatchewan. Journal of Wildlife Management 54:27-35.
Henny, C.J. and L.J. Blus. 1981. Artificial burrows provide new insight into Burrowing
Owl nesting biology. Journal of Raptor Research 15:82-85.
James, P.C., T.J. Ethier, and M.K. Toutloff. 1997. Parameters of a declining Burrowing
Owl population in Saskatchewan. Pages 34-37 in Lincer, J.L., and K. Steenhof,
editors. The Burrowing Owl, its biology and management: including the
proceedings of the first international symposium. Raptor Research Report
Number 9.
Konrad, P.M. and D.S. Gilmer. 1984. Observations on the nesting ecology of burrowing
owls in central North Dakota. Prairie Naturalist 16:129-130.
Korfanta, N.M., L.W. Ayers, S.H. Anderson, and D.B. McDonald. 2001. A preliminary
assessment of Burrowing Owl population status in Wyoming. Journal of Raptor
Research 35:337-343.
23
Martell, M.S., J. Schladweiler, and F. Cuthbert. 2001. Status and attempted
reintroduction of Burrowing Owls in Minnesota, U.S.A. Journal of Raptor
Research 35:331-336.
Martin, D.J. 1973. Selected aspects of Burrowing Owl ecology and behavior in central
New Mexico. Condor 75:446-456.
McCaffrey, R. 2001. Biodiversity associated with active and extirpated black-tailed
prairie dog colonies. Thesis, Texas Tech University, Lubbock, Texas.
McIntyre, N.E. 2004. Historical and current status of breeding and wintering Western
Burrowing Owls (Athene cunicularia hypugaea) in Texas. Journal of Raptor
Research 38:91-95.
Mealy, B. 1997. Reproductive ecology of the Burrowing Owls, Speotyto cunicularia
floridana, in Dade and Broward Counties, Florida. Pages 74-79 in Lincer, J.L.,
and K. Steenhof, editors. The Burrowing Owl, its biology and management:
including the proceedings of the first international symposium. Raptor Research
Report Number 9.
Millsap, B.A. and C. Bear. 1997. Territory fidelity, mate fidelity, and dispersal in an
urban-nesting population of Florida Burrowing Owls. Pages 91-98 in Lincer, J.L.,
and K. Steenhof, editors. The Burrowing Owl, its biology and management:
including the proceedings of the first international symposium. Raptor Research
Report Number 9.
Millsap, B.A. and C. Bear. 2000. Density and reproduction of burrowing owls along an
urban development gradient. Journal of Wildlife Management 64:33-41.
24
Murphy, R.K., K.W. Hasselblad, C.D. Grondahl, J.G. Sidle, R.E. Martin, and D.W.
Freed. 2001. Status of the Burrowing Owl in North Dakota. Journal of Raptor
Research 35:322-330.
Orth, P.B., and P.L. Kennedy. 2001. Do land-use patterns influence nest-site selection
by burrowing owls (Athene cunicularia hypugaea) in northeastern Colorado?
Canadian Journal of Zoology 79:1038-1045.
Powell, K.L, R.J. Robel, K.E. Kemp, and M.D. Nellis. 1994. Aboveground counts of
black-tailed prairie dogs: temporal nature and relationship to burrow entrance
density. Journal of Wildlife Management 58:361-366.
Pruett, A. 2004. Black-tailed prairie dog association with playa lakes in the southern
high plains and a new approach to estimating colony population sizes. Thesis,
Texas Tech University, Lubbock, Texas.
Restani, M., L.R. Rau, and D.L. Flath. 2001. Nesting ecology of Burrowing Owls
occupying black-tailed prairie dog towns in southeastern Montana. Journal of
Raptor Research 35:296-303.
Ross, P.V. and D.J. Smith. 1970. Notes on the ecology of the burrowing owl, Speotyto
cunicularia, in the Texas High Plains. Texas Journal of Science 21:479-480.
Schmutz, J.K. 1997. Selected microhabitat variables near nests of Burrowing Owls
compared to unoccupied sites in Alberta. Pages 80-83 in Lincer, J.L., and K.
Steenhof, editors. The Burrowing Owl, its biology and management: including
the proceedings of the first international symposium. Raptor Research Report
Number 9.
25
Sheffield, S.R., and M. Howery. 2001. Current status, distribution, and conservation of
the Burrowing Owl in Oklahoma. Journal of Raptor Research 35:351-356.
Sidle, J.G., M. Ball, T. Byer, J.J. Chynoweth, G. Foli, R. Hodorff, G. Moravek, R.
Peterson, and D.N. Svingen. 2001. Occurrence of Burrowing Owls in black-
tailed prairie dog colonies on Great Plains National Grasslands. Journal of Raptor
Research 35:316-321.
Thomsen, L. 1971. Behavior and ecology of Burrowing Owls on the Oakland Municipal
Airport. Condor 73:177-192.
Trulio, L. 1997. Burrowing Owl demography and habitat use at two urban sites in Santa
Clara County, California. Pages 84-89 in Lincer, J.L., and K. Steenhof, editors.
The Burrowing Owl, its biology and management: including the proceedings of
the first international symposium. Raptor Research Report Number 9.
U. S. Fish and Wildlife Service. 2001. Birds of Conservation Concern 2001. USFWS,
Division of Migratory Bird Management, Arlington, Virginia.
Vermeire, L.T., A.C. Ganguli, and R.L. Gillen. 2002. A robust model for estimating
standing crop across vegetation types. Journal of Range Management 55: 494-
497.
Wellicome, T.I. 1997. Reproductive performance of Burrowing Owls (Speotyto
cunicularia): effects of supplemental food. Pages 68-73 in Lincer, J.L., and K.
Steenhof, editors. The Burrowing Owl, its biology and management: including
the proceedings of the first international symposium. Raptor Research Report
Number 9.
26
Whicker A.D., and J.K. Detling. 1988. Ecological consequences of prairie dog
disturbances: prairie dogs alter grassland patch structure, nutrient cycling, and
feeding-site selection by other herbivores. BioScience 38:778-785.
27
Table 2.1. Six intensively monitored sites from Lubbock and Carson Counties, Texas, and data known prior to the start of the 2003-2004 field seasons.
Study Site County Historic Surrounding Area (ha) Owls
Treatment1 Land Use (2002) 2
School Lubbock None Urban 12.78 18
X-Fab Lubbock None/PT3 Industrial/Urban 37.15 14
L 103 Lubbock None Urban/fallow 14.37 27
12-36 Carson PT Industrial 11.61 15
Zone 4 Carson PT Agriculture 5.20 2
Pantex Lake Carson None Agriculture 22.63 10
1 PT denotes known (2000-2004) prairie dog control efforts using Phostoxin. 2 Numbers of burrowing owls counted during prairie dog surveys in 2002 (Pruett 2004). 3 Phostoxin treatments applied during winter 2004.
28
Table 2.2. Summary of burrowing owl captures and re-sightings by season for burrowing owls captured at 6 study sites in Lubbock and Carson Counties, Texas, between January 2003 and May 2005, including 3 additional winter owls captured on adjacent Carson County sites in February 2004.
Number Number Number Number Number Number Number
of owls color never seen season seen in ≥ 1 same season known
Season banded banded seen again banded1 other season next year2 resident3
Winter 16 9 3 4 1 0 4
Summer 123 108 51 57 2 10 4
29
1 Burrowing owls seen in season they were banded (includes late migrating owls that were no longer observed within 2 weeks of the end of the season of capture). 2 Burrowing owls seen, in this case, the summer after the summer that they were banded. These birds may have remained in the area but wintered at sites where we did not observe them. 3 Burrowing owls seen in ≥ 3 consecutive seasons.
Table 2.3. Burrowing owl nesting data for the 6 intensively monitored sites in Lubbock and Carson Counties, Texas, for 2003 and 2004. Site Year No. Pairs No. chicks/pair1 Area (ha) Spacing2
L103 2003 13 3.3 11.71 49.03 ± 7.86
School 2003 8 2.0 7.55 55.91 ± 21.75
X-Fab 2003 13 2.5 14.48 67.22 ± 12.94
12-36 2003 9 3.4 11.86 62.80 ± 16.06
Pantex Lake 2003 11 2.9 7.50 64.75 ± 10.67
Zone 4 2003 3 3.7 1.57 71.85 ± 7.96
L103 2004 8 2.5 11.71 81.62 ± 21.01
School 2004 6 3.0 7.55 91.56 ± 26.43
X-Fab 2004 5 3.0 11.12 77.78 ± 25.32
12-36 2004 13 3.2 11.86 59.85 ± 8.28
Pantex Lake 2004 5 1.8 7.50 85.00 ± 3.03
Zone 4 2004 4 1.5 3.08 44.59 ± 7.38
1 Mean maximum number of chicks seen above ground for successful nesting burrowing owl pairs. 2 Mean and standard error for distances between burrowing owl nesting burrows in meters.
30
Table 2.4. Number of prairie dog holes marked in 2004 and estimated number of prairie dogs for 6 intensively monitored sites in Lubbock and Carson Counties, Texas.
Colony Area (ha) Prairie Dogs1 Holes Density2 Vacancy3
L103 11.71 80 938 80.10 11.73
School 7.55 142 595 78.77 4.19
X-Fab 11.12 22 649 58.36 29.50
12-36 11.86 84 1179 99.39 14.04
Pantex Lake 7.50 145 810 107.93 5.59
Zone 4 3.08 28 266 86.44 9.50
1 Number of prairie dogs estimated using model based on 3 independent surveys (Pruett 2004). 2 Number of prairie dog holes per hectare. 3 Estimate of vacant burrows based on number of prairie dog holes per prairie dog.
31
Table 2.5. Number of burrowing owl pairs and area per 50-meter buffer on 6 intensively monitored sites in Lubbock and Carson Counties, Texas, in 2003 and 2004.
Buffer zone 1 Buffer zone 2 Buffer zone 3
No. Area No. Area No. Area
Colony Year Pairs (ha) Pairs (ha) Pairs (ha)
L103 2003 1 0.17 6 4.01 2 7.53
School 2003 0 0.21 1 2.20 4 6.89
X-Fab 2003 2 2.75 5 4.84 6 6.89
12-36 2003 0 1.45 4 3.99 4 6.43
Pantex Lake 2003 0 0.13 2 2.11 7 3.08
Zone 41 2003 3 3.08
L103 2004 0 0.17 2 4.01 6 7.53
School 2004 0 0.21 1 2.20 5 6.89
X-Fab 2004 0 2.75 4 4.84 1 6.89
12-36 2004 4 1.45 4 3.99 6 6.43
Pantex Lake 2004 0 0.13 2 2.11 4 3.08
Zone 41 2004 6 3.08
1Colony not wide enough for buffers.
32
LIST OF FIGURES
2.1 The maximum number of burrowing owls seen on prairie dog colonies correlated to prairie dog colony size for a 12 county area searched for a prairie dog colony study in the Texas Panhandle……………………………….. 34 2.2 The number of burrowing owls caught by trap type and season across all sites in Lubbock and Carson Counties, Texas in 2003 and 2004……………. 35 2.3 Number of burrowing owls seen in 2003 and 2004, with and without bands for the 6 study sites in Lubbock and Carson Counties, Texas…………… 36 2.4 The number of burrowing owl pairs recorded in relation to prairie dog colony area in hectares for the 6 study sites in Lubbock and Carson Counties, Texas for 2003 and 2004……………………………………………... 37 2.5 The number of burrowing owl pairs recorded in relation to the number of prairie dog holes marked in 2004 for the 6 study sites in Lubbock and Carson Counties, Texas…………………..………………………………… 38
33
Figure 2.1
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280
Colony Area (ha)
0
5
10
15
20
25
30
35
40
45
50
Max
Adu
lt B
UO
W
r2 = 0.0182 P = 0.0107
34
Figure 2.2
0
10
20
30
40
50
60
70
80
Bal-Chatri
Hand Walk-in NooseCarpet
Bow-net
No.
of b
urro
w o
wls
SummerWinter
35
Figure 2.3
0
20
40
60
80
100
120
June
July
Augus
tSep
tembe
r
Octobe
rNov
embe
rDec
embe
r
Janu
ary
Februa
ry
March
April
May
No.
of B
UO
W's
.
Banded 03Total 03Banded 04Total 04
1
2
36
1 We trapped and banded burrowing owls in this summer period (n = 63 in 2003; n = 32 in 2004) and these data include marks from the same season. 2 Adequate data was not collected for burrowing owls in August of 2003 or 2004; however, in 2004 5 banded and 13 total owls were observed on intensively monitored sites in Lubbock.
Figure 2.5
200 400 600 800 1000 1200 1400
Prairie dog holes
2
4
6
8
10
12
14BU
OW
Pai
rs
r2 = 0.7327 P = 0.0296
38
APPENDIX A
BURROWING OWL TRAPPING DATA
Table A.1. Burrowing owl trapping data for all burrowing owls captured in 2003 and 2004, including 13 adults and 1 juvenile captured for a concurrent project.
USFWS Date Code1 Age Sex Colony Weight Tarsus Tarsus Wing
(g) width depth2 Chord3
170538704 1/29/3 A X-FAB 172 3.3 4.5 168
80400627 2/7/3 A SCHOOL 190 3.6 4.8 177 39
80400628 2/11/3 A SCHOOL 172 3.4 4.7 164
80400629 2/12/3 A SCHOOL 176 3.5 4.8
80400630 2/16/3 A SCHOOL 162 3.2 5.0 166
80400630 4/30/4 79/H A M SCHOOL 141 3.2 4.9 169
80400631 2/22/3 A SCHOOL 163 3.6 4.9 172
80400632 2/22/3 A SCHOOL 180 3.9 4.7 172
80400633 2/23/3 A X-FAB 165 3.7 4.8 163
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
80400634 2/25/3 A X-FAB 155 3.4 4.7 174
80400634 6/5/3 16/H A M X-FAB 149 3.4 4.8 175
80400635 5/28/3 00/H A M L-103 143 3.6 4.9 186
80400636 5/29/3 01/H A L-103 152 3.4 5.1 174
80400637 5/29/3 02/H A F L-103 154 3.3 5.3 172
80400638 5/29/3 J L-103 88 4.0 4.4 40
80400639 5/29/3 J L-103 84 3.8 4.6
80400640 5/31/3 03/H A F L-103 143 3.6 4.7 176
80400641 5/31/3 04/H A M L-103 3.5 4.9
80400642 6/1/3 05/H A F L-103 142 3.5 4.5 166
80400643 6/1/3 06/H F F L-103 137 3.4 5.0 173
80400644 6/2/3 07/H A M L-103 134 3.3 4.5 171
80400645 6/2/3 08/H A F L-103 149 3.1 4.5 173
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
80400646 6/3/3 09/H A F L-103 136 3.7 4.8
80400647 6/4/3 10/H A F X-FAB 140 3.2 4.6 160
80400648 6/5/3 11/H A F X-FAB 147 3.4 4.6 183
80400649 6/5/3 12/H A F X-FAB 172 3.4 5.0
80400650 6/5/3 13/H A F X-FAB 3.0 4.9
80400651 6/5/3 14/H A M X-FAB 147 3.6 5.1 184 41
80400652 6/5/3 15/H A M X-FAB 146 3.7 4.9 173
80400653 6/6/3 17/H A M SCHOOL 150 3.3 4.8 173
80400654 6/6/3 J SCHOOL 122 3.8 4.5
80400655 6/6/3 18/H A F SCHOOL 143 3.4 4.8 172
80400656 6/9/3 19/H A F L-103 129 3.4 4.3 172
80400657 6/9/3 20/H A M L-103 145 3.5 4.5 186
80400658 6/9/3 21/H A F L-103 145 3.1 4.2 172
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
80400659 6/9/3 22/H A M L-103 143 3.5 5.1 175
80400660 6/11/3 23/H A M ZONE 4 156 3.6 4.6 176
80400661 6/11/3 24/H A F ZONE 4 146 3.4 4.7 162
80400662 6/11/3 25/H A F ZONE 4 125 3.2 4.5 162
80400663 6/12/3 26/H A F 12-36 149 3.4 4.7 173
80400664 6/12/3 27/H A M 12-36 142 3.2 4.3 173 42
80400665 6/12/3 28/H A F 12-36 146 3.3 5.0 169
80400666 6/12/3 29/H A F 12-36 165 3.3 4.9 184
80400667 6/12/3 30/H A F 12-36 145 3.3 5.3 172
80400668 6/12/3 31/H A F 12-36 135 3.2 4.3 172
80400669 6/12/3 32/H A M 12-36 150 3.6 4.6 178
80400670 6/12/3 33/H A F 12-36 155 3.8 4.7
80400671 6/12/3 34/H A M 12-36 155 3.6 5.0 164
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
80400672 6/13/3 35/H A F PLAKE1 140 3.4 4.7 173
80400673 6/13/3 36/H A F PLAKE 154 3.5 4.8 177
80400674 6/13/3 37/H A F PLAKE 163 3.2 4.6 168
80400675 6/13/3 38/H A F PLAKE 137 3.3 4.7 185
80400676 6/15/3 39/H A M X-FAB 145 3.5 5.0 171
80400677 6/15/3 40/H A M X-FAB 145 3.4 4.9 180 43
80400678 6/15/3 41/H A F X-FAB 141 3.9 5.2 175
80400679 6/15/3 42/H A F X-FAB 123 3.2 4.8 168
80400680 6/16/3 43/H A L-103 151 3.2 5.0 177
80400681 6/18/3 44/H A F X-FAB 137 3.2 4.8 168
80400682 6/18/3 45/H A F X-FAB 179 3.4 4.9 174
80400683 6/18/3 46/H A M X-FAB 141 3.6 5.0 173
80400684 6/18/3 47/H A M X-FAB 135 3.4 4.9 163
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
80400685 6/9/3 48/H A F L-103 155 3.2 5.1 176
80400686 6/23/3 49/H A M ZONE 4 150 3.5 4.7 165
80400687 6/23/3 50/H A F ZONE 4 152 3.2 4.9 177
80400688 6/24/3 51/H A F 12-36 144 3.4 4.7 160
80400689 6/25/3 52/H A F PLAKE 155 3.2 5.2
80400690 6/25/3 53/H A F PLAKE 151 3.3 4.6 172 44
80400691 6/25/3 54/H A F PLAKE 137 3.3 4.5 162
80400692 6/25/3 55/H A F PLAKE 148 3.6 5.2 179
80400693 6/25/3 56/H A F PLAKE 145 3.7 4.9 177
80400694 6/25/3 57/H A PLAKE 149 3.5 5.1 182
80400695 6/25/3 58/H A PLAKE 150 3.7 4.4 166
80400696 6/25/3 59/H A F PLAKE 146 3.3 4.6 168
80400697 6/25/3 60/H A F PLAKE 152 3.6 4.4 177
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
80400698 6/25/3 61/H A F PLAKE 141 3.3 5.3 169
80400699 6/26/3 62/H A ZONE 4 144 3.3 5.0 167
80400700 6/26/3 63/H A M 1236 180 3.6 4.9
84473501 6/11/3 J ZONE 4 49 3.9 4.2
84473502 6/18/3 J X-FAB 142 3.3 4.5 142
84473503 6/26/3 J ZONE 4 100 3.9 5.7 45
84473504 6/26/3 64/H A F PLAKE 135 3.2 4.8 162
84473505 6/28/3 J X-FAB 160 3.7 4.7
84473506 6/28/3 65/H A M X-FAB 143 3.6 5.0 172
84473507 6/30/3 66/H A F SCHOOL 151 3.4 5.2
84473508 6/30/3 67/H A SCHOOL 167 3.4 3.9 179
84473509 7/2/6 68/H A F SCHOOL 170 3.4 5.3 166
84473510 7/7/3 69/H A F 12-36 135 3.4 4.5 169
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
84473511 7/7/3 70/H A M 12-36 144 3.6 4.9 171
84473512 7/7/3 71/H A M 12-36 149 3.6 4.8 171
84473513 1/31/4 72/H A X-FAB 150 3.2 5.0 169
84473514 1/31/4 73/H A X-FAB 123 3.0 4.6 165
84473515 2/7/4 74/H A ZONE 82 157 3.4 4.8 168
84473516 2/11/4 75/H A PANTEX 160 3.5 4.9 179 46
84473517 2/11/4 76/H A PLAKE 187 3.7 5.0
84473518 2/17/4 77/H A SCHOOL 163 4.7 3.6 178
84473519 5/18/4 80/H A M L-103 141 3.4 4.8 173
84473521 6/4/4 81/H A F ZONE 4 132 3.3 4.4 174
84473522 6/5/4 82/H A F X-FAB 136 4.1 5.0 172
84473523 6/5/4 83/H A F SCHOOL 125 3.3 4.2 171
84473524 6/5/4 84/H A F L-103
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
84473525 6/5/4 85/H A F L-103 140 3.3 4.8 177
84473526 6/5/4 86/H A F L-103 152 3.5 5.7 176
84473527 6/8/4 87/H A M L-953 149 3.4 5.3 174
84473528 6/8/4 88/H A F L-95 192 3.3 4.9 178
84473529 6/8/4 89/H A M L-95 136 3.6 4.5 171
84473530 6/8/4 90/H A M L-95 152 3.5 4.6 175 47
84473531 6/8/4 91/H A M L-95 148 3.6 4.7 168
84473532 6/9/4 92/H A F ZONE 8 180 3.8 4.7
84473533 6/9/4 93/H A M ZONE 8 166 3.4 4.8 183
84473534 6/9/4 94/H A M ZONE 8 156 3.2 4.6 172
84473535 6/9/4 95/H A M ZONE 8 156 3.9 4.9
84473536 6/9/4 96/H A F ZONE 8 153 3.2 4.7
84473537 6/10/4 97/H A M ZONE 4 157 3.7 5.1
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
84473538 6/10/4 98/H A M ZONE 8 130 3.2 4.8 167
84473539 6/12/4 99/H A M L-103 137 3.4 5.0 173
84473540 6/12/4 00/K A M SCHOOL 142 3.3 4.9 176
84473541 6/15/4 01/K A M ZONE 8 137 3.7 4.8 162
84473542 6/15/4 02/K A F ZONE 8 142 3.2 4.4 164
84473543 6/15/4 J ZONE 8 104 3.5 4.1 48
84473544 6/17/4 03/K A F PLAKE 152 3.2 172
84473545 6/17/4 J PLAKE 113
84473546 6/17/4 04/K A M PLAKE 162 3.7 5.5 178
84473547 6/17/4 J PLAKE 84 3.8 4.9
84473548 6/17/4 05/K A M PLAKE 143 3.6 4.8 178
84473549 6/18/4 06/K A F ZONE 4 144 3.2 5.1 176
84473550 6/18/4 07/K A F 12-36 135 3.4 4.4 170
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
84473551 6/18/4 J 12-36 166 3.4 4.6 158
84473552 6/18/4 08/K A M 12-36 134 3.3 4.8 172
84473553 6/18/4 09/K A F 12-36 156 3.4 4.6 173
84473554 6/20/4 10/K A F SCHOOL 122 3.1 4.2 172
84473555 6/20/4 11/K A M SCHOOL 155 3.2 4.4 176
84473556 6/20/4 12/K A F SCHOOL 149 3.3 4.6 176 49
84473557 6/20/4 13/K A F SCHOOL 135 3.3 5.0 173
84473558 6/22/4 14/K A F ZONE 4 119 2.9 4.0 160
84473559 6/23/4 15/K A M 12-36 150 3.3 4.9 178
84473560 6/23/4 16/K A F 12-36 138 3.1 5.1 174
84473561 6/23/4 J 12-36 143 3.6 5.0
84473562 6/23/4 17/K A M 12-36 130 3.2 4.6
84473563 6/24/4 18/K A M PLAKE 149 3.2 4.7
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
84473564 6/23/4 J 12-36 139 3.8 4.8
84473565 6/24/4 19/K A F PLAKE 149 3.6 4.6 177
84473566 6/24/4 20/K A F PLAKE 140 3.2 4.7
84473567 6/27/4 21/K A M L-103 138 3.3 5.4 170
84473568 6/28/4 22/K A F SCHOOL 144 3.4 4.6 166
84473569 6/28/4 24/K A F X-FAB 149 3.4 5.1 149 50
84473570 6/28/4 23/K A M X-FAB 138 3.1 4.8 171
84473571 6/28/4 J X-FAB 3.4 4.2
84473572 6/30/4 25/K A F 12-36 155 3.7 5.3
84473573 7/2/4 26/K A M PLAKE 148 3.8 4.9
84473574 7/1/4 J ZONE 4
84473575 7/2/4 27/K A F PLAKE 131 3.7 4.8 165
84473576 7/6/4 28/K A M L-103 137 3.4 4.9 172
Table A.1. Continued.
USFWS Date Code1 Age Sex Colony Weight TW TL WC
84473577 7/10/4 J ZONE 4 145 3.9 5.9
84473578 7/17/4 29/K A M 12-36 141 3.4 4.7 176
1 Pantex Lake 2 Additional Pantex site for winter trapping, later used for concurrent study.
ed for concurrent study. 3 Additional Lubbock site us
51
APPENDIX B
VEGETATION TRANSECT DATA
Table B.1. RAW data from (n=2) transects per site. Percent cover of vegetative parameters measured on prairie dog colonies occupied by burrowing owls for intensively measured study sites in Lubbock and Carson Counties, Texas during July and August of 2003 and 2004. Site Year % grass % forbs % bare % litter % other Visual No. Burrowing Owl
Obstruction Pairs Productivity
L103 2003 26.16 16.20 8.48 49.16 0.00 1.3 13 3.3
0.00 51.44 14.28 34.28 0.00 1.0 52
School 2003 26.72 6.44 37.08 29.76 0.00 1.2 8 2.0
18.00 22.24 25.20 34.56 0.00 1.2
X-Fab 2003 0.00 19.04 8.92 72.04 0.00 1.2 13 2.5
0.00 12.56 29.64 57.80 0.00 1.0
12-36 2003 19.28 14.08 9.60 57.04 0.00 1.0 9 3.4
65.48 1.28 0.84 32.40 0.00 1.3
Table B.1. Continued.
Site Year % grass % forbs % bare % litter % other Visual No. Burrowing Owl
Obstruction Pairs Productivity
Pantex Lake 2003 22.44 10.12 13.36 54.08 0.00 1.0 11 2.9
47.44 7.28 1.60 43.68 0.00 1.0
Zone 4 2003 71.56 0.32 11.92 16.20 0.00 1.7 3 3.6
L103 2004 13.04 23.24 9.64 54.08 0.00 1.5 13 3.3
0.00 23.88 24.60 51.52 0.00 1.2 53
School 2004 4.04 14.12 67.28 14.56 0.00 1.0 6 3.0
16.32 25.72 23.56 34.40 0.00 1.3
X-Fab 2004 0.00 26.72 8.04 65.24 0.00 1.3 5 3.0
0.04 32.44 7.92 59.60 0.00 1.7
12-36 2004 35.12 17.20 12.76 34.56 0.36 1.3 13 3.2
34.72 13.28 3.44 48.56 0.00 2.2
Table B.1. Continued.
Site Year % grass % forbs % bare % litter % other Visual No. Burrowing Owl
Obstruction Pairs Productivity
Pantex Lake 2004 8.68 21.76 8.28 61.28 0.00 1.7 5 1.8
62.68 10.16 0.96 26.00 0.20 1.2
Zone 4 2004 78.36 6.20 3.04 12.40 0.00 1.4 4 1.5
54
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