ArticlePDF Available

Monitoring Northern Bobwhite (Colinus virginianus) Populations in the Rolling Plains of Texas: Parasitic Infection Implications

Authors:

Abstract and Figures

The Northern bobwhite quail (Colinus virginianus) is an important gamebird among hunters that has been experiencing a nationwide decline for N 50 yr. In West Texas, one of the last regions to experience this downward trend, research on bobwhite populations has focused on habitat variables and, increasingly, on parasitic infection. In bobwhite, two of the most common parasites are the caecal worm (Aulonocephalus pennula) and eyeworm (Oxyspirura petrowi). To better document the state of bobwhite populations in the Rolling Plains Ecoregion, trapping , summer rooster counts, fall covey counts, and parasitic infection assessments were conducted in three counties during 2018. These efforts were compared with previous years for a longitudinal perspective. In 2018, bobwhite populations experienced a widespread decline, although some counties surveyed fared slightly better than others. More effort was required to trap fewer total bobwhite, and fewer roosters and coveys were counted than in previous years. In addition, in 2018, parasitic infection levels of caecal and eyeworms were higher than or similar to levels in previous years. Additional research is necessary to understand which factors influence bob-white populations in allopatric locations and over time.
Content may be subject to copyright.
Monitoring Northern Bobwhite (Colinus virginianus) Populations in the
Rolling Plains of Texas: Parasitic Infection Implications
Kelly A. Commons, Kendall R. Blanchard, Matthew Z. Brym, Cassandra Henry, Aravindan Kalyanasundaram,
Kalin Skinner, Ronald J. Kendall
Wildlife Toxicology Laboratory, Texas Tech University, Lubbock, TX 79409-3290, USA
abstractarticle info
Article history:
Received 20 December 2018
Received in revised form 5 April 2019
Accepted 24 April 2019
Available online xxxx
Key Words:
Aulonocephalus pennula
bobwhite quail
die-off
Oxyspirura petrowi
population trend
The Northern bobwhite quail (Colinus virginianus) is an important gamebird among hunters that has been
experiencing a nationwide decline forN50 yr. In West Texas, one of the lastregions to experiencethis downward
trend, research on bobwhite populations has focused on habitat variables and, increasingly,on parasitic infection.
In bobwhite, two of the most common parasites are the caecal worm (Aulonocephalus pennula) and eyeworm
(Oxyspirura petrowi). To better document the state of bobwhite populations in the Rolling Plains Ecoregion,trap-
ping, summer rooster counts, fall covey counts, and parasitic infection assessments were conducted in three
counties during 2018. These efforts were compared with previous years for a longitudinal perspective. In 2018,
bobwhite populations experienced a widespread decline, although some counties surveyed fared slightly better
than others. More effort was required to trap fewer total bobwhite, and fewer roosters and coveys werecounted
than in previous years. In addition, in 2018, parasitic infection levels of caecaland eyeworms were higher than or
similar to levels in previous years. Additional research is necessary to understand which factors inuence bob-
white populations in allopatric locations and over time.
© 2019 The Author(s). Published by ElsevierInc. on behalf of
The Society for Range Management. This is an open access
article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
The Northern bobwhite quail (Colinus virginianus; hereafter bob-
white), a gamebird highly sought after by hunters (Hernández et al.,
2002; Johnson et al., 2012), has been experiencing a nationwide decline
since the 1960s (Sauer et al., 2013). In Texas, specically the Rolling
Plains Ecoregion, the nationwide pattern of decline for bobwhite was
not documented until the 1980s (Brennan, 1991; Rollins, 2002). Bob-
white are a species known to have irruptive population growth
(Rollins, 1999a), but additional factors may exacerbate these natural
boom and bustcycles. Possible explanations for this continued decline
in the Rolling Plains Ecoregion have ranged from the loss of habitat and
decreasing habitat quality (Brennan, 1991; Hernández et al., 2013)to
predators (Rollins, 1999b; Rollins and Carroll, 2001)andre ants
(Allen et al., 1995). Although other factors, such as parasitic infection,
have been hypothesized to have a low impact on quail populations
(Olsen et al., 2016), the continued decline of quail in favorable habitats
has led to a reevaluation of this hypothesis. As such, an increasing
number of studies have been done to determine the potential
impact of parasites (Dunham et al., 2017a; Henry et al., 2017;
Bruno et al., 2018).
Two of the mostcommon parasites of bobwhite in the Rolling Plains
Ecoregion, the caecal worm (Aulonocephalus pennula) and eyeworm
(Oxyspirura petrowi), have been known to occur in bobwhite for nearly
50 years (Kellogg and Ca lpin, 1971; Olsen et al., 201 6; Dunham and Ken-
dall, 2017; Bruno et al., 2018). While prevalence of caecal and
eyeworms has been shown to vary by time of year (Villarreal et al.,
2016), they are still among the most prevalent parasites found in bob-
white (Bruno et al., 2018). In some areas of Texas, bobwhite have had
80100% prevalence of caecal and eyeworms (Dunham et al., 2017a;
Henry et al., 2017). In a survey by Kubečka et al. (2017) of bobwhite
in 9 states, those individuals sampled from the Rolling Plains of Texas
had the highest prevalence and intensity of eyeworm infection.Despite
their high prevalence, it is currently not completely understood how
these parasites affect the survival of bobwhite. It has been proposed
that heavy infection by caecal worms couldlead to malnutrition in bob-
white (Dunham et al., 2017b), which may hinder survival, whereas
eyeworms, which are found in the tissues around the eye, can cause cel-
lular damage to the eye tissues, as well as scarring and interstitial kera-
titis of the cornea (Bruno et al., 2015; Dunham et al., 2016). Bobwhite
Rangeland Ecology & Management xxx (xxxx) xxx
Correspondence: Professor Ronald J. Kendall, The Wildlife Toxicology Laboratory,
Texas Tech University, Box 43290, Lubbock, TX 79409-3290, USA.
E-mail address: Ron.kendall@ttu.edu (R.J. Kendall).
RAMA-00408; No of Pages 7
https://doi.org/10.1016/j.rama.2019.04.004
1550-7424/© 2019 The Author(s). Published by Elsevier Inc. on behalf of The Society for Range Management. This is an open access article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/4.0/).
Contents lists available at ScienceDirect
Rangeland Ecology & Management
journal homepage: http://www.elsevier.com/locate/rama
Please citethis article as: K.A. Commons, K.R. Blanchard, M.Z. Brym, et al., Monitoring Northern Bobwhite (Colinus virginianus) Populations in the
Rolling Plains of Texas: Parasitic Infec..., Rangeland Ecology & Management, https://doi.org/10.1016/j.rama.2019.04.004
infected with eyeworms have therefore been hypothesized to have im-
paired vision, which is supported by anecdotal reports of abnormal be-
havior like bobwhite ying into large structures (Brym et al., 2018a).
As such, these parasites have the potential to impactindividualbob-
white, but their ability to impact bobwhite populations has only re-
cently been addressed. For example, Henry et al. (2017) found
evidence of a die-off among bobwhite that corresponded to higher in-
fection levels of caecal and eyeworms than seen in previous years. Fur-
thermore, drought is suggested to exacerbate caecal worm intensity in
bobwhite (Lehmann, 1984), and high caecal worm intensities have
been reported in bobwhite during periods of drought (Brym et al.,
2018a; Brym et al., 2018b). These high intensities may have negative
impacts on bobwhite populations considering drought has increased
in the past decade and will continue to increase in the Rolling Plains
(Modala et al., 2017).
This studyexpands on the narrative of Henry et al. (2017), by includ-
ing more study locations, analyzing trapping effort between these loca-
tions, and using additional metrics to monitor bobwhite populations.
Although the number of individuals trapped can be a useful metric,
measuring the amount of effort required to trap those individuals pro-
vides necessary context (McDonald and Harris, 1999). Likewise, moni-
toring populations at any one time of year, or using any one method,
will not be completely representative of their population dynamics.
This is especially true for bobwhite as their social organization varies de-
pending on their breeding cycle (Williams et al., 2003). To better under-
stand bobwhite population dynamics in the Rolling Plains Ecoregion of
Texas on a qualitative level, trapping effort, summer rooster counts,
fall covey counts, and parasite intensity data were collected and com-
pared among three counties in the Rolling Plains in 2018, as well as
compared with data collected between 2014 and 2017 from one of the
counties to assess potential population changes over time.
Methods
Ethics Statement
All work wasperformed under Texas Parks and Wildlife Department
(TPWD) permits SPR 1098-984 and SPR-0715-095 and consistent with
Texas Tech University Animal Care and Use Committee protocols
13066-08, 14027-04, and 16071-08.
Study Areas
This study was performed at three sites within the Rolling Plains
Ecoregion of West Texas (Fig. 1). In Mitchell County (32°745N
100°596W), a 120000-ha privately owned cattle ranch has been
trapped for bobwhite since 2014. In 2018, trapping was performed in
two additional counties. These included the Matador Wildlife Manage-
ment Area (MWMA), an 11400-ha public land operated by the TPWD
in Cottle Co. (34°73N, 100°2041W) and a 6880-ha privately owned
cattle ranch in Garza Co. (33°1232N, 101°1525W). In 2017, weather
stations at or near the sites all reported annual rainfalls between 50.8
and 55.8 cm, average July temperatures between 28.3°C and 29.4°C,
and average January temperatures between 6.1°C and 7.2°C
(Lawrimore, 2018). The sites are dominated by honey mesquite
(Prosopis glandulosa), juniper (Juniperus pinchotti), sand shinnery oak
(Quercus havardii), and prickly pear (Opuntia spp.), which is character-
istic to the Rolling Plains Ecoregion (Rollins, 2007).
Trapping
Bobwhite were typically trapped between March and October from
2014 to 2018. Bobwhite trapping followed procedures outlined in
Dunham et al. (2014). This included the use of wire, walk-in, double
funnel traps (91.4 × 60.9 × 20.3cm) baited with milo (Sorghum bicolor).
Traps were also covered with nearby vegetation to decrease the chance
of bobwhite mortality due to weather and temperature. In addition,
bobwhite have a low mobility (b0.4 km; Hernández et al. 2007), and
in Mitchell Co. traps were set in the samelocations within and between
years and at distances between 0.4 km (Dunham et al., 2014)and
0.1 km apart (McGrath et al., 2017). In Cottle and Garza Co., traps
were placed in areas where bobwhite were reportedly seen or heard
with traps spaced at a minimum distance of 0.1 km to increase success
of trapping bobwhite in this area (McGrath et al., 2017). In all years,
traps were typically only moved when ants were present or the trap
was repeatedly disturbed by other animals. Upon capture, bobwhite
were tted with an aluminum leg band, weighed, aged, sexed, and
given a body condition score on the basis of visual assessment. Individ-
uals were either kept for assessment of parasite intensity or released at
the location of capture. While trapping objectives over the years varied
between nesting success and parasite assessments, the aims of all stud-
ies involved the same systematic trapping methods to appropriately as-
sess bobwhite populations in the Rolling Plains Ecoregion.
Trapping effort in this study is dened as the quotient of trapping
sessions and number of birds captured (Henry et al., 2017). In other
words, trapping effort is the number of trapping sessions necessary to
catch one bobwhite. Trapping sessions are dened for each site as the
number of times each trap was checked in a given period of time
(e.g., morning, afternoon, and evening; Henry et al., 2017). Although
Dunham et al. (2014) checked traps two times per day, an afternoon
check was added in 2018 to increase chances of bobwhite capture, as
well as to prevent mortality from weather and temperature. This re-
sulted in three trapping sessions per day in 2018: in the morning
(10:00 ± 30 min), afternoon (15:30 ± 30 min), and evening (20:30
± 90 min). In addition, the number of days in which trapping occurred
each month varied between and within years, and in 2018, each sitewas
visited for 5 consecutive d of trapping. On average (±SE), 61.4 ± 1.0,
31.0 ± 2.2, and 30.1 ± 1.5 traps were set in Mitchell, Cottle, and Garza
Co., respectively, each month in 2018.
Trapping effort was estimated in Mitchell Co. for 20152017 from
the number of traps set, the number of checks per day, and the number
of trappingdays in a given month. In 2015, 48 traps were used through-
out the year. An average of 41 ± 6.2 traps were used in 2016 with num-
ber varying by month. In 2017, 35 traps were used throughout the year.
Figure 1. Location of studysites (from north to south) in Cottle,Garza, and Mitchell Co. in
West Texas. Stars designate study site locations in each county.
2K.A. Commons et al. / Rangeland Ecology & Management xxx (xxxx) xxx
Please cite this article as: K.A.Commons, K.R. Blanchard, M.Z. Brym, et al., Monitoring Northern Bobwhite (Colinus virginianus) Populations in the
Rolling Plains of Texas: Parasitic Infec..., Rangeland Ecology & Management, https://doi.org/10.1016/j.rama.2019.04.004
The number of trapping days was estimated from dates in the banding
record, with both the day before and after recorded bandings being in-
cluded to ensure that trapping sessions were not omitted. At most, this
method added 3 d of trapping to a given month. These banding records
were also used to determine the number of new bobwhite caught for
each trapping month from 2015 to 2017.
The trapping effort estimates from 2015 to 2017 may have inconsis-
tencies in the estimates for several reasons. First, a static number of
traps are assumed for up to an entire yr (i.e., 2015 and 2017); however,
exact trap numbers likely varied slightly at a ner scale due to eld con-
ditions such as livestock and wildlife disturbing traps. Using the criteria
described earlier, the actual number of days in which trapping occurred
may have been higher if multiple consecutive days occurred with no
bobwhite trapped. There were also additional studies occurring in
March and April from 2015 to 2017and in July 2016 that gave additional
bobwhite trapping effort data. Also, a small portion of bobwhite in 2015
and 2016 were not recorded in the banding record due to multiple bob-
white being trapped in the same location when a representative sample
(i.e., ~510) had already been achieved. Finally, in 2015, trapping be-
came difcult afterMarch and necessitated additional methods for trap-
ping bobwhite that are not comparable with other years or locations
and therefore are not presented here.
Rooster Counts
From 30 May to 7 June 2018, rooster counts were conducted at each
of the three sites. Each site consisted of three transects totaling 6 to 10
points that were chosen following similar guidelines to rooster counts
covered in Hernández and Guthery (2012). Transects were placed on
the basis of availability of ranch roads and appropriate lengths and dis-
tances apart. Points within each transect were at least 0.7 kmapart, and
transects were separated by at least 1.6 km to prevent double counting
individuals. A designated operator wasassigned to each transect so that
counts were conducted on each transect over 3 consecutive d. In Cottle
Co., inclement weather prevented a third day of counts. Beginning
30 min before sunrise, operators began listening following the rst
bob-white call heard. Operators listened for 5 min at each point, record-
ing the number of roosters heard by using a spot map to prevent double
counting. Rooster counts in Mitchell Co. in June 2017 used identical
methods, transects, and points as those used in 2018.
Covey Counts
From 11 October to 16 November 2018, covey counts were con-
ducted at each site. Transects were identical to those used for rooster
counts but only contained three stations per transect. Stations were sep-
arated by at least 1.6 km and were chosen in such a way that transects
were separated by at least 2.3 km. As per Hernández and Guthery
(2012), three operators listened at one station per transect per day
over 3 consecutive d. Therefore, there were no repeat observations per
station. Beginning 45 min before sunrise, operators listened for 20 min
after the rst koi-lee covey call heard or for 40 min if no calls were
heard (Stokes, 1967). Operators recorded the number of independent
coveys heard. After listening, operators drove the transect and recorded
the number of coveys ushed, as well as the number of quail in those
coveys. Covey counts in Mitchell Co. in October 2017 used identical
methods, transects, and points as those used in 2018.
Parasite Intensity Assessment
To assess bobwhite for the presence of caecal and eyeworms, up to
nine live birds were collected from each site each month in 2018. If
dead bobwhite were found, they were also collected and assessed for
parasites. Typically, the rst six bobwhite were kept, with no more
than ve taken from the same trap each month. Birds were held in
crates (66.0 × 43.2 × 12.7 cm) for 14 d, depending on their time of
capture,and provided milo and water ad libitum.Attheendoftrapping,
bobwhite were transported to The Institute of Environmental and
Human Health Aviary at Texas Tech University. Bobwhite were held
for no more than 3 d in individual 25 × 61 cm cages and fed milo and
water ad libitum before euthanasia via a carbon dioxide chamber.
After euthanasia, bobwhite were immediately necropsied following
procedures from Dunham et al. (2016, 2017b). Caecal and eyeworms
were identied via morphological traits (Dunham et al., 2016;
Kalyanasundaram et al., 2017). Caecal worms were collected from
both arms of the caecum and a portion of the ileum. Eyeworms were
collected from tissues in and around the orbital cavity. The number of
both caecal worms and eyeworms were counted and recorded for
each bird. Parasite intensity assessment methods from 2014 to 2017
followed the same procedure.
From 2014 to 2017, additional bobwhite were collected from an area
in Mitchell Co. designated for parasite assessment. These bobwhite
were not included in trapping effort estimates. Therefore, the number
of bobwhite trapped may differ from the number of bobwhite sampled
for parasitic infection. In addition, juvenile bobwhite were included in
the trapping effort but were not included in the parasite assessment.
This is because it has been demonstrated that juveniles are less infected
than adults (Dunham et al., 2017a; Bruno et al., 2018) and would have
lowered the parasite intensity for the last half of the trapping season.
Data Analysis
Mean and standard error were calculated for trapping effort
(Table 1), rooster counts (Table 2), covey counts (Table 3), and parasite
intensities (Table 4) for comparison. The number of bobwhite trapped
does not include recaptured bobwhite, of which there were 10 in
2018, 11 in 2017, 77 in 2016, and 52 in 2015. Recaptured bobwhite
were not included in the comparisons.
Results
Trappingin 2018 required the highest amount of effort of years sam-
pled (see Table 1). For all three counties in 2018, 102.3 trap checks were
necessary to trap a single bobwhite, an order of magnitude higher than
previous years in Mitchell Co. Even when broken down by county and
year, the effort required to trap one bobwhite was higher for each
county in 2018 than in any previous year (see Table 1). Overall, Mitchell
Co. in 2018 required themost effort with 16 bobwhite caught over 4906
sessions, while Mitchell Co. in 2017 required the least effort (115 bob-
white trapped over 1 820 sessions). Cottle Co. had the highest trapping
success in 2018 with 52 bobwhite trapped over 2287 trapping sessions
but still required more effort than Mitchell Co. did in any year from 2015
to 2017. While Garza Co. fared better than Mitchell Co. in 2018 with 27
bobwhitetrapped over 2525 sessions, the amount of effort required was
still double that of the most effortrequired in Mitchell Co. from 2015 to
2017.
Second, anaverage of 3.4 ± 0.9 roosters were heard over 255 counts
for all three counties in 2018, which is lower than the 6.8 ± 0.9 roosters
heard over 78 counts in 2017. Each county in 2018 had fewer roosters
per count than that of 2017 as well (see Table 2). Cottle Co. had the
highest average, followed by Garza Co., and then Mitchell Co. In addi-
tion, far fewer coveys were counted in 2018 from all three locations
than from a single county in 2017. A total of 25 coveys were counted
from all threelocations in 2018 compared with 56 coveys from Mitchell
Co. in 2017 (see Table 3). Again, there were fewer coveys in each county
when compared with 2017. Cottle Co. averaged the highest number of
coveys counted while Mitchell and Garza Co. were similarly low in
their average numbers for 2018 (see Table 3). There were also no c oveys
ushed in 2018, so a comparison of average covey size cannot be made
(see Table 3).
Finally, parasitic infection burdens varied with parasite, year, and
county. Average caecal worm counts were similar between all 3
3K.A. Commons et al. / Rangeland Ecology & Management xxx (xxxx) xxx
Please citethis article as: K.A. Commons, K.R. Blanchard, M.Z. Brym, et al., MonitoringNorthern Bobwhite (Colinus virginianus) Populations in the
Rolling Plains of Texas: Parasitic Infec..., Rangeland Ecology & Management, https://doi.org/10.1016/j.rama.2019.04.004
counties in 2018 and Mitchell Co. in 2017, but more worms were
counted in all counties in 2018 than Mitchell Co. from 2014 to 2016
(see Table 4). Caecal worm infection ranges from mild (150 worms),
to strong (101200 worms), to extreme intensities (N300 worms;
Dunham et al., 2017a). Bobwhite averaged between strong and extreme
caecal worm infection intensity in both 2018s 3 locations (235.7 ±
24.2) and Mitchell Co. in 2017, while strong infection intensity was re-
corded for Mitchell Co. from 2016 to 2014 (see Table 4). Bobwhite aver-
aged an extreme intensity of caecal worm infection in Mitchell Co.,
between a strong and extreme intensity of infection in Cottle Co. and a
strong intensity of infection in Garza Co. in 2018 (see Table 4). In
2018, the average number of worms counted in Mitchell Co. was higher
than any other county or yr (Fig. 2a). In 2018, Cottle and Garza Co. had
similar caecal worm counts. However, when compared with Mitchell
Co. from 2014 to 2017, both counties were similar to 2017 and 2016
but had higher averages than in 2015 and 2014 (seeFig. 2aandTable 4).
Average counts of eyeworms for the three locations were higher in
2018 than in Mitchell Co.s 2017 and 2016 counts but were similar to
2015 and 2014 in Mitchell Co. Eyeworm infection ranges from mild
(110 worms), to strong (2140 worms), to extreme intensities (N
60 worms; Dunham et al., 2017a). Bobwhite averaged strong eyeworm
infection intensity in 2018 over three locations (22.5 ± 3.1), as well as
in Mitchell Co. in 2015 and 2014 (see Table 4). In 2017 and 2016 infec-
tion intensity was between mild and strong for Mitchell Co. (see
Table 4). In 2018, the average number of wormscounted was not similar
between any county (see Fig. 2b). In 2018, bobwhite in Mitchell Co. had
between strong and extreme infection intensities, while Cottle and
Garza Co. had between mild and strong intensities (see Table 4). In
2018, Mitchell Co. had higher average worm counts than any other
county or yr (see Fig. 2b). Cottle Co. had slightly higher infection inten-
sities than in 2017, andGarza Co. had lower intensities than any other yr
(see Fig. 2b).
Discussion
All the data presented here are in congruence with TPWD (2018) re-
ports of reduced bobwhite in the Rolling Plains Ecoregion. On the basis
of roadside surveys, TPWD (2018) reported the third lowest number of
bobwhite heard since 1978. This is a stark contrast given that 2 years
ago TPWD reported the highest number of bobwhite in the same time
period. Although this decline has been attributed to reduced breeding
(TPWD, 2018), the trapping efforts presented here suggest that bob-
white began to decline before the 2018 breeding season. In fact, the de-
cline likely began before trapping started in March 2018 based on
hunter-shot bobwhite data by Brym et al. (2018b) from Mitchell and
Garza Co. Of those hunter-shot bobwhite, 57% had extreme caecal
worm infection intensities (300 + worms) and 74% had strong
eyeworm infection intensities (2160 worms) (Dunham et al., 2017a;
Brym et al., 2018b). Hunters also reported fewer and smaller coveys
during the 20172018 hunting season (Brym et al., 2018b). When
Table 1
Bobwhitetrapping effort fromMarch to October in MitchellCounty, Texas, from2015 to 2018 and in Cottle and Garza Co.in 2018. Trapping effort(TS/B) is the number of trappingsessions
necessary to catch one bobwhite. NA values represent months where no trapping occurred.
Yr County Effort Mar Apr May June July Aug Sept Oct Average Total
2015 Mitchell Sessions 1248 864 672 288 192 NA NA NA 652.8 3264
Bobwhite 65 7212NANANA15.4 77
TS/B 19.2 123.4 336.0 288.0 96.0 NA NA NA 42.4
2016 Mitchell Sessions 2984 550 280 140 950 NA 70 70 720.6 5044
Bobwhite 108 27 7 5 18 NA 7 10 26.0 188
TS/B 27.6 20.4 40.0 28.0 52.8 NA 10.0 7.0 27.7
2017 Mitchell Sessions 350 420 210 210 210 70 140 210 227.5 1820
Bobwhite 34 20 4 4 17 9 17 10 14.4 115
TS/B 10.3 21.0 52.5 52.5 12.4 7.8 8.2 21.0 15.8
2018 Mitchell Sessions 480 712 682 609 660 600 598 565 613.3 4906
Bobwhite 13 10010102 16
TS/B 36.9 712.0 ——660.0 598.0 306.7
2018 Cottle Sessions NA 305 317 238 418 351 330 328 326.7 2287
Bobwhite NA 3 18 3 12 12 3 1 7.4 52
TS/B NA 101.7 17.6 79.3 34.8 29.3 110.0 328.0 44.1
2018 Garza Sessions 324 439 232 304 277 330 329 290 315.6 2525
Bobwhite 2 13 5 5 0 1 0 1 3.4 27
TS/B 162.0 33.8 46.4 60.8 330.0 290.0 92.8
Average Sessions 2 222.2 777.3 510.1 317.3 584.8 324.2 334.5 303.8
Bobwhite 45.4 20.9 11.6 6.7 8.5 9.6 9.2 7.0
TS/B 48.9 37.2 44.0 47.4 68.8 33.8 36.4 43.4
Table 2
Bobwhite rooster counts from May to July in Mitchell County, Texas from 2017 to 2018
and in Cottle and Garza Co. in 2018.
Yr County Transect Total counts Average ± SE Total average ± SE
2017 Mitchell 1 145 8.1 ± 0.5 6.8 ± 0.9
2 219 7.3 ± 0.5
3 152 5.1 ± 0.2
2018 Mitchell 1 42 2.3 ± 0.3 1.8 ± 0.4
2 57 1.9 ± 0.3
3 34 1.1 ± 0.2
2018 Cottle 1 135 4.5 ± 0.5 4.7 ± 0.4
2 126 4.2 ± 0.4
3 165 5.5 ± 0.5
2018 Garza 1 118 3.9 ± 0.3 3.7 ± 0.2
2 99 3.3 ± 0.3
3 106 3.9 ± 0.3
Table 3
Bobwhite covey counts in October in Mitchell County, TX from2017 to 2018 and in Cottle
and Garza Co. in 2018. The number of coveys ushed and the covey count are summed
across points in each transect. The number of quail per covey are averaged.
Yr County Transect Coveys
ushed
Quail per
covey
Covey
count
Total average covey
count ± SE
2017 Mitchell 1 5 10.0 14 18.7 ± 5.7
2 0 0.0 30
3 3 11.0 12
2018 Mitchell 1 0 0 0 0.7 ± 0.7
20 0 0
30 0 2
2018 Cottle 1 0 0 8 6.3 ± 0.9
20 0 5
30 0 6
2018 Garza 1 0 0 2 1.3 ± 0.7
20 0 2
30 0 0
4K.A. Commons et al. / Rangeland Ecology & Management xxx (xxxx) xxx
Please cite this article as: K.A.Commons, K.R. Blanchard, M.Z. Brym, et al., Monitoring Northern Bobwhite (Colinus virginianus) Populations in the
Rolling Plains of Texas: Parasitic Infec..., Rangeland Ecology & Management, https://doi.org/10.1016/j.rama.2019.04.004
Dunham et al. (2017a) trapped bobwhite in 2014 and 2015, it was
found that only 4% and 43% of bobwhite had similar infection intensities
of caecal and eyeworms, respectively. Given that the probability of host
survival decreases as parasite intensity increases (Wilber et al., 2016),
Dunham et al. (2017a) suspected that higher proportions of highly par-
asitized individuals would suffer attrition. Consequently, the high para-
site intensities found both during (Brym et al., 2018b) and just after the
hunting season may have contributed to the decline of bobwhite in
early 2018.Although infection in Garza and Cottle Co. appeared compa-
rable with previous years in Mitchell Co., those areas may have had
lower infection overall and/or the birds with higher infections had al-
ready dropped out during the winter, particularly given the high level
of infection reported from Garza Co by Brym et al. (2018b).
Furthermore, parasites are known to negatively interact with envi-
ronmental stressors (Lafferty and Kuris, 1999). In the winter of
20172018, some areas of the Rolling Plains experienced 100
consecutived with no precipitation, limiting food availability (TPWD,
2018). Although drought could not be considered in this study, caecal
worm infection has been documented to intensify with drought
(Lehmann,1984), which may correlate with the persistently high caecal
worm burdens observed in 2018. High caecal worm intensities may
have also increased nutrient stress on bobwhite given that caecal
worms are suspected to impede caecal function and absorb nutrients
from their hosts (Dunham et al., 2017b). The high parasite loads ob-
served in 2018 may have compounded with the drought and scarcity
of food to impact overwinter survival of bobwhite. If these factors did
Table 4
Average (±SE) numberof caecal worms (Aulonocephalus pennula) and eyeworms (Oxyspirura petrowi) found in adult northernbobwhite quail (Colinus virginianus) in Mitchell County in
20142018 and in Cottle and GarzaCo., Texas, in 2018.The sample size of bobwhite may differ from thetotal number caughtfor that month and istherefore listed below the avera ges. For
monthsand locations with onlyone bobwhite sample,the count is given withoutSE. NA values representmonths where no trappingoccurred; “—” valuesrepresent monthswhere data for
both parasites was not collected.
County Species March April May June July August September October Average
Mitchell 2014 Caecal worm NA 121.5 ± 31.1 155.5 ± 36.1 158.3 ± 54.3 135.0 ± 14.0 145.3 ± 26.4 117.1 ± 21.2 155.5 ± 49.5 136.5 ± 11.9
Eyeworm NA 19.6 ± 5.4 26.8 ± 7.3 32.3 ± 6.3 34.5 ± 7.5 35.0 ± 8.2 31.3 ± 4.1 25.0 ± 4.0 29.0 ± 2.7
Bobwhite NA 8 6 3 2 9 9 2
Mitchell 2015 Caecal worm 138.8 ± 34.8 223.0 ± 36.0 131.6 ± 20.0 115.5 ± 18.1 93.0 ± 14.5 132.0 ± 68.9 89.2 ± 16.8 136.2 ± 11.5
Eyeworm 29.0 ± 5.9 23.2 ± 9.1 27.6 ± 3.7 22.6 ± 3.2 22.6 ± 6.5 67.5 ± 7.3 41.2 ± 12.4 28.1 ± 2.5
Bobwhite 9 9 16 13 5 2 5
Mitchell 2016 Caecal worm 146.5 ± 18.3 216.0 ± 17.7 110.9 ± 20.1 237.2 ± 44.0 143.0 ± 28.5 NA 164.0 ± 54.5 223.0 ± 47.5 166.9 ± 12.1
Eyeworm 9.9 ± 3.0 11.7 ± 3.7 16.4 ± 7.4 15.0 ± 5.2 13.6 ± 2.2 NA 26.0 ± 10.4 17.2 ± 7.6 14.3 ± 1.8
Bobwhite 15 10 7 5 17 NA 6 5
Mitchell 2017 Caecal worm 262.0 ± 28.4 321.3 ± 49.2 264.5 ± 46.5 243.3 ± 53.6 207.3 ± 71.5 339.0 ± 60.6 173.0 ± 45.0 260.3 ± 19.5
Eyeworm 14.8 ± 2.7 14.1 ± 4.0 20.2 ± 4.9 19.3 ± 4.6 11.1 ± 2.2 27.3 ± 5.0 31.0 ± 6.6 17.5 ± 1.7
Bobwhite 12 8 6 3 7 34
Mitchell 2018 Caecal worm 369.9 ± 93.5 562 ——258 244 366.1 ± 72.5
Eyeworm 49.3 ± 8.8 2 ——49 441.6 ± 8.3
Bobwhite 9 1 ——11——
Cottle Caecal worm NA 510.7 ± 182.7 213.8 ± 51.0 138.0 ± 60.9 206 ± 63.5 234.6 ± 33.5 249.3 ± 43.4 160 197.3 ± 69.7
Eyeworm NA 16.3 ± 8.0 32.3 ± 9.5 12.7 ± 11.2 19.3 ± 7.4 22.2 ± 3.9 10.7 ± 7.3 51 20.3 ± 9.9
Bobwhite NA 3 8 3 8 3 3 1
Garza Caecal worm 83.8 ± 30.4 144.0 ± 31.5 186.6 ± 47.1 276.2 ± 84.0 90 ——171.1 ± 27.8
Eyeworm 2.8 ± 2.1 11.7 ± 6.6 14.2 ± 14.0 19.6 ± 9.1 0——11.9 ± 4.3
Bobwhite 4 6 5 5 1-
Average Caecal worm 272.3 ± 40.3 220.0 ± 24.2 193.8 ± 17.5 179.8 ± 19.5 157.5 ± 18.7 136.4 ± 18.7 179.6 ± 23.7 160.2 ± 21.5
Eyeworm 25.3 ± 5.0 17.1 ± 2.3 22.8 ± 3.6 23.1 ± 2.6 18.3 ± 2.0 27.2 ± 5.1 28.8 ± 4.2 30.1 ± 5.0
Figure 2. The average number of a, caecal worms (Aulonocephalus pennula) and b, eyeworms (Oxyspirura petrowi) found in northern bobwhite quail (Colinus virginianus) caught in
Mitchell County, Texas from 2014 to 2018 and in Cottle and Garza Co. in 2018. Error bars represent SE. Sample sizes are given for each column.
5K.A. Commons et al. / Rangeland Ecology & Management xxx (xxxx) xxx
Please citethis article as: K.A. Commons, K.R. Blanchard, M.Z. Brym, et al., MonitoringNorthern Bobwhite (Colinus virginianus) Populations in the
Rolling Plains of Texas: Parasitic Infec..., Rangeland Ecology & Management, https://doi.org/10.1016/j.rama.2019.04.004
indeed compound, increased mortality of bobwhite in general and, spe-
cically females, as adult female survival is a key driver of bobwhite
population dynamics (Sandercock et al. 2008), during the winter of
20172018 would have had a profound effect on overall bobwhite
numbers.
For those bobwhite that survived, drought conditions and high par-
asite intensities may have further negatively impacted their breeding.
Bobwhiteare known tohave lower reproductive effort and success dur-
ing dry periods (Hernández et al., 2005), and the drought that hit the
Rolling Plains in October 2017 peaked during the breeding season in
May 2018 (National Integrated Drought Information System, 2018).
Heavily parasitized red grouse (Lagopus lagopus scoticus; Hudson,
1986) and house martins (Delichon urbica; De Lope et al., 1993)havere-
duced reproductive output and clutch size. House martins have further
reduced clutch sizes when conditions are unfavorable (De Lope et al.,
1993). As such, it is plausible that a similar scenario occurred in bob-
white due to unfavorable conditions and high parasite loads. Indeed,
during 2018 fewer males were heard giving the bobwhite call during
summer rooster counts. This call represents sexual vocalization, typi-
cally given by unmated males seeking female mates (Stokes, 1967). It
is possible that low counts indicate a high proportion of mated males
at the time of counting. However, given the reports of low breeding
and small broods by TPWD (2018) and the data presented here, it
seems more likely that breeding was poor. In fact, only 11% of bobwhite
trapped in 2018 were juveniles, which is far below the 70% required to
prevent population declines (Hernández et al., 2005). Consequently,
the reduction in breeding would have hindered the recovery of already
low bobwhite populations and furthered the decline rst noted by
Henry et al. (2017).
Although the data presented here suggest a general decline in bob-
white populations in the Rolling Plains during 2018, it is also important
to consider the potential for bias in this data set due to site differences
that were not accounted for in the analysis and results. For example,
while habitat across the Rolling Plainsis reported to be relatively consis-
tent (Rollins, 2007), specic habitat metrics were not recorded in this
study. The incorporation of habitat metrics would have allowed for
more precise inferences regarding bobwhite population dynamics and
better comparisons between locations. However, these considerations
were beyondthe scope of this study asthe purpose was to provide a rel-
ative comparison among study sites and not an absolute metric of pop-
ulation size. Nevertheless, trapping success was reduced in all three
locations during 2018 despite consistent trapping effort in areas that
provide quail hunting and a designated wildlife management area.
This corresponds with TPWD (2018) reports of decreased bobwhite
abundance throughout the Rolling Plains, as well as signicant reduc-
tions in bobwhite populations on the intensively managed Rolling
Plains Quail Research Ranch (Rollins, 2018). Thus, it is plausible that
the inference of decreased bobwhite populations reported here is gen-
erally representative of quail abundance in the Rolling Plains during
2018. These data are also useful in bringing attention to other factors
potentially affecting bobwhite population dynamics, as well as encour-
aging more comprehensive future studies.
Given the drought, reduced food availability, and high parasite loads
documented in 2018, it is not surprising that trapping effort was ele-
vated, fewer males were heard in summer, and fewer coveys were
heard in fall; considering these things, breeding may have been insuf-
cient to offset a population decline. Though it is likely that parasites had
some direct effect on bobwhite populations in 2018, their ability to in-
teract with and be compounded by a variety of factors likely also inu-
enced bobwhite population trends in the Rolling Plains. For instance,
there were discrepancies between sites in 2018. Bobwhite populations
at MWMA in Cottle Co. fared the best ofthose studied in 2018, especially
when compared with Mitchell Co., which had the highest parasite bur-
dens, lowest trapping success, and lowest call counts. These discrepan-
cies may be due to intense and regular land management conducted at
MWMA, as is done with other public lands. Not only would
management improve overall conditions for bobwhite, but practices
such as prescribed burning could reduce endoparasites (Scasta, 2015),
which could potentially ameliorate the impact of parasites on bobwhite
populations in these areas. However, it is unknown whether landscape
factors, climate, increased parasite intensities, or a combination of these
were responsible for the differences in bobwhite metrics reported in
this study. Therefore, in addition to traditional landscape metrics, such
as rainfall and vegetative cover (Rollins, 2007), researchers should
also consider the effect of parasites and how land management prac-
tices interact with infection intensities.
Implications
Although the denitive causes remain unknown, it is undeniable
that bobwhite populations in the Rolling Plains have experienced a de-
cline in 2018. Systematically documenting trapping effort offers the
most detailed record of the decline, as effort is a more comparable met-
ric than number of bobwhite trapped alone. In addition, the level of un-
derstanding that was achieved by using supplementary population
metrics, such as summer and fall counts, further emphasizes the need
to use multiple methods when generalizing population trends. Re-
searchers must also consider the impacts of parasites, like caecal and
eyeworms, on bobwhite populations. Achieving a more comprehensive
understanding of bobwhite populations would require sampling over
both a wider geographic area and longer time period. However,
expanding the means and scope of sampling will increase the resources
and time needed to collect data. Therefore, the future of sustainable
bobwhite populations in the Rolling Plains Ecoregion of West Texas
will depend on continued collaborative efforts between researchers
and land managers while also considering additional understudied fac-
tors, such as parasites.
Acknowledgements
We thank Park Cities Quail (Grant ID: 24A125-B53795-200) and the
Rolling Plains Quail Research Foundation (Grant ID: 23A527-B53811-
200) for their funding and continued support of our efforts necessary
to conduct this research. We also thank the staff at the Matador Wildlife
Management Area, Cross H Ranch in Garza Co., and additional private
landowners for their assistance and access to their lands. Without the
interest and support of dedicated land owners and managers, this re-
search would not be possible. We also thank the Wildlife Toxicology
Laboratory eld and laboratory personnel for their assistance in
this study.
References
Allen, C.R., Lutz, R.S., Demarais, S., 1995. Red imported re ant impacts on Northern bob-
white populations. Ecological Applications 5, 632638.
Brennan, L., 1991. How can we reverse the Northern bobwhite population decline? Wild-
life Society Bulletin 19, 544555.
Bruno, A., Fedynich, A.M., Smith-Herron, A., Rollins, D., 2015. Pathological response of North-
ern bobwhites to Oxyspirura petrowi infections. Journal of Parasitology 101, 364368.
Bruno, A., Fedynich, A., Rollins, D., Wester, D., 2018. Helminth community and host dy-
namics in Northern bobwhites from the Rolling Plains Ecoregion, U.S.A. Journal of
Helminthology, 17https://doi.org/10.1017/S0022149X18000494.
Brym, M.Z., Henry, C., Kendall, R.J., 2018a. Potential parasite induced host mortality in
Northern bobwhite (Colinus virginianus) from the Rolling Plains Ecoregion of West
Texas. Archives of Parasitology 2, 14.
Brym, M.Z., Henry, C., Kendall, R., 2018b. Elevated parasite burdens as a potential mecha-
nism affecting northern bobwhite (Colinus virginianus) population dynamics in the
Rolling Plains of West Texas. Parasitology Research 117, 16831688.
De Lope, F., González, G., Pérez, J.J., Møller, A.P., 1993. Increased detrimental effects of ec-
toparasites on their bird hosts during adverse environmental conditions. Oecologia
95, 234240.
Dunham, N.R., Kendall, R.J., 2017. Eyeworm infections of Oxyspirura petrowi, Skrjabin,
1929 (Spirurida: Thelaziidae), in species of quail from Texas, New Mexico and Ari-
zona, USA. Journal of Helminthology 91, 491496.
Dunham, N.R., Soliz, L.A., Fedynich, A.M., Rollins, D., Kendall, R.J., 2014. Evidence of an
Oxyspirura petrowi epizootic in No rthern bobwhites (Colinus virg inianus), Texas,
USA. Journal of Wildlife Diseases 50, 552558.
6K.A. Commons et al. / Rangeland Ecology & Management xxx (xxxx) xxx
Please cite this article as: K.A.Commons, K.R. Blanchard, M.Z. Brym, et al., Monitoring Northern Bobwhite (Colinus virginianus) Populations in the
Rolling Plains of Texas: Parasitic Infec..., Rangeland Ecology & Management, https://doi.org/10.1016/j.rama.2019.04.004
Dunham, N.R., Reed, S., Rollins, D.,Kendall, R.J., 2016. Oxyspirurapetrowi infection leads to
pathological consequences in Northern bobwhite (Colinus virginianus). International
Journal for Parasitology: Parasites and Wildlife 5, 273276.
Dunham, N.R., Peper, S.T., Downing, C., Brake, E., Rollins, D., Kendall, R.J., 2017a. Infection
levels of the eyeworm Oxyspirura petrowiand caecal worm Aulonocephalus pennula in
the Northern bobwhite and scaled quail from the Rolling Plains of Texas. Journal of
Helminthology 91, 569577.
Dunham, Nicholas R., Henry, C., Brym, M., Rollins, D., Helman, R.G., Kendall, R.J., 2017b.
Caecal worm, Aulonocephalus pennula, infection in the northern bobwhite quail, Colinus
virginianus. International Journal for Parasitology: Parasites and Wildlife 6, 3538.
Henry, C., Brym, M.Z., Kendall, R.J., 2017. Oxyspirura petrowi and Aulonocephalus pennula
infection in wild Northern bobwhite quail in the Rolling PlainsEcoregion, Texas: pos-
sible evidence of a die-off. Archives of Parasitology 1, 2.
Hernández, F., Guthery, F.S., 2012. Beef, brush, and bobwhites: quail management in cat-
tle country. Texas A&M University Press, Kingsville, TX, USA.
Hernández, F., Guthery, F., Kuvlesky, W., 2002. The legacy of bobwhite research in South
Texas. The Journal of Wildlife Management 66, 18.
Hernández, F., Hernández, F., Arredondo, J.A., Bryant, F.C., Brennan, L.A., Bingham, R.L.,
2005. Inuence of precipitation on demographics of northern bobwhites in southern
Texas. Wildlife Society Bulletin 33, 10711079.
Hernández, F., Perez, R.M., Guthery, F.S., 2007. Bobwhites on the South Texas Plains. In:
Brennan, L. (Ed.), College Station, Texas. Texas quails: ecology and management.
Texas A&M University Press, USA, pp. 273296.
Hernández, F., Bren nan, L., DeMaso, S., Sands, J., Webster, D., 2013. On reversing the
Northern bobwhite population decline: 20 years later. Wildlife Society Bulletin 37,
177188.
Hudson, P.J., 1986. The effect of a parasitic nematode on the breeding production of red
grouse. The Journal of Animal Ecology 55, 85.
Johnson,J., Rollins, D., Reyna, K., 2012. Whats a quail worth? A longitudinal assessment of
quail hunter demographics, attitudes, and spending habits in Texas. National Quail
Symposium Proceedings 7, 294299.
Kalyanasundaram, A., Blanchard, K.R., Kendall, R.J., 2017. Molecular identication and
characterization of partial COX1 gene from caecal worm (Aulonocephalus pennula)
in Northern bobwhite (Colinus vi rginianus) from the Rolling Plains Ecoregion of
Texas. International Journal for Parasitology: Parasites and Wildlife 6, 195201.
Kellogg, F., Calpin, J., 1971. A checklist of parasites and diseases reported from the bob-
white quail. Avian Diseases 15, 704715.
Kubečka, B., Bruno, A., Rollins, D., 2017. Geographic survey of Oxyspirura petrowi among
wild Northern bobwhites in the United States. National Quail Symposium Proceed-
ings 8, 311315.
Lafferty,K.D., Kuris, A.M.,1999. How environmental stressaffects the impacts ofparasites.
Limnology and Oceanography 44, 925931.
Lawrimore, J. 2018. Global summary of the month, version 1.0. Subset for 2017 in Padu-
cah, Post, and Roscoe, TX. NOAA National Centers for Environmental Information.
Available at: https://doi.org/10.7289/V5QV3JJ5. Accessed August 2018.
Lehmann, V.W., 1984. The bobwhite in the Rio Grande Plain of Texas. College Station. TX.
Texas A&M University Press, USA, pp. 207209.
McDonald, R., Harris, S., 1999. The use of trapping records to monitor populations of
stoats Mustela erminea and weasels M. nivalis: the importance of trapping effort. Jour-
nal of Applied Ecology 36, 679688.
McGrath, D.J., Terhune II, T.M., Martin, J.A., 2017. Northern bobwhite habitat use in a food
subsidized pyric landscape. The Journal of Wildlife Management 81, 919927.
Modala, N.R., Ale, S., Goldberg, D.W., Olivares, M., Munster, C.L., Rajan, N., Feagin, R.A.,
2017. Climate change projections for the Texas high plains and rolling plains. Theo-
retical and Applied Climatology 129, 263280.
National Integrated Drought Information System. 2018. Southern Plains drought update:
October 26,2018. Available at: https://www.drought.gov/drought/documents/south-
ern-plains-drought-update-october-26-2018.AccessedDecember2018.
Olsen, A.C., Brennan, L.A., Fedynich, A.M., 2016. Helminths and the Northern bobwhite
population decline: a review. Wildlife Society Bulletin 40, 388393.
Rollins, D., 1999a. A pattern to quail irruptions in the Rolling Plains of Texas. Preserving
TexasQuail Heritage into the 21
st
Century. San Angelo, TX. Texas Agricultural Exten-
sion Service, USA, pp. 3336.
Rollins, D., 1999b. Is there a place for predator control in quail management? Preserving
TexasQuail Heritage into the 21
st
Century. Abilene. TX. Texas Agricultural Extension
Service, USA, pp. 4548.
Rollins, D., 2002. Sustaining the quail wavein the Southern Great Plains. National Quail
Symposium Proceedings 5, 4856.
Rollins, D., 2007. Quails on the Rolling Plai ns. Brennan, L. [eds.]. Texas quails: ecology
and management. College Station, Texas. Texas A&M University Press, USA,
pp. 117141.
Rollins, D. 2018. Roadside counts conrm poor quail outlook. Rolling Plains Quail Re-
search Foundation. Available at: http://www.quailresearch.org/roadside-counts-con-
rm-poor-quail-outlook/. Accessed April 2019.
Rollins, D., Carroll, J.P., 2001. Impacts of predation on northern bobwhite and scaled quail.
Wildlife Society Bulletin 29, 3951.
Sandercock, B.K., Jensen, W.E., Williams, C.K., Applegate, R.D., 2008. Demographic sensi-
tivity of population change in Nothern bobwhite. Journal of Wildlife Management
72, 970982.
Sauer, J., Link, W., Fallon, J., Pardieck, K., Ziolkowski, D., 2013. The North American breed-
ing bird survey 19662011: summary analysis and speciesaccounts. North American
Fauna 79, 132.
Scasta, J.D., 2015. Fire and parasites: an under-recognized form of anthropogenic land use
change and mechanism of disease exposure. EcoHealth 12, 398403.
Stokes, A. W. 1967. Behavior of the bobwhite, Colinus virginianus. The Auk 84:133.
Texas Parks and Wildlife Department. 2018. Texas Quail Forecast 2018-19. Available at:
https://tpwd.texas.gov/huntwild/hunt/planning/quail_forecast/forecast/index.phtml.
Accessed December 2018.
Villarreal, S.M., Bruno, A., Fedynich, A.M., Brennan, L.A., Rollins, D., 2016. Helminth infec-
tions across a Northern bobwhite (Colinus virginianus) annual cycle in Fisher County,
Texas. Western North American Naturalist 76, 275280.
Wilber, M.Q., Weinstein, S.B., Briggs, C.J., 2016. Detecting and qu antifying parasite-
induced host mortality from intensity data: method comparisons and limitations. In-
ternational Journal for Parasitology 46, 5966.
Williams, C.K., Lutz, R.S., Applegate, R.D., 2003. Optimal group sizeand northern bobwhite
coveys. Animal Behaviour 66, 377387.
7K.A. Commons et al. / Rangeland Ecology & Management xxx (xxxx) xxx
Please citethis article as: K.A. Commons, K.R. Blanchard, M.Z. Brym, et al., MonitoringNorthern Bobwhite (Colinus virginianus) Populations in the
Rolling Plains of Texas: Parasitic Infec..., Rangeland Ecology & Management, https://doi.org/10.1016/j.rama.2019.04.004
... While these helminths have been documented in bobwhite from the West Texas Rolling Plains before (Jackson and Green, 1965), the high prevalence reported during OID led to calls for more study into the impacts of parasites and resulted in a surge of research into the topic (Bruno et al., 2015;Dunham et al., 2017;Henry et al., 2017). Recent studies suggest that helminth prevalence in bobwhite from the Rolling Plains continues to be high (Commons et al., 2019), especially in Texas, where eyeworm infection is higher than other regions (Kubecˇka et al., 2017) and where cecal worms are consistently reported in 100% of sampled individuals (Henry et al., 2017;Brym et al., 2018). As such, high cecal worm and eyeworm infection are likely endemic in bobwhite from the West Texas Rolling Plains, and researchers suspect that these infections may play an important role in affecting regional bobwhite population dynamics (Commons et al., 2019). ...
... Recent studies suggest that helminth prevalence in bobwhite from the Rolling Plains continues to be high (Commons et al., 2019), especially in Texas, where eyeworm infection is higher than other regions (Kubecˇka et al., 2017) and where cecal worms are consistently reported in 100% of sampled individuals (Henry et al., 2017;Brym et al., 2018). As such, high cecal worm and eyeworm infection are likely endemic in bobwhite from the West Texas Rolling Plains, and researchers suspect that these infections may play an important role in affecting regional bobwhite population dynamics (Commons et al., 2019). Contemporary research is also expanding our knowledge into the pathological consequences of eyeworm and cecal worm infection, as well as their potential impact on bobwhite populations (Bruno et al., 2015;Dunham et al., 2016;Henry et al., 2020). ...
Article
Full-text available
The Northern bobwhite quail (Colinus virginianus) is a popular game bird that has been experiencing a well-documented decline throughout Texas since the 1960s. While much of this decline has been attributed to habitat loss and fragmentation, recent studies have identified other factors that may also contribute to decreasing quail populations. Parasites, in particular, have become increasingly recognized as possible stressors of quail, and some species, particularly the eyeworm (Oxyspirura petrowi) and cecal worm (Aulonocephalus pennula) are highly prevalent in Texas quails. Eyeworm infection has also been documented in some passerines, suggesting helminth infection may be shared between bird species. However, the lack of comprehensive helminth surveys has rendered the extent of shared infection between quail and passerines in the ecoregion unclear. Thus, helminth surveys were conducted on bobwhite, scaled quail (Callipepla squamata), Northern mockingbirds (Mimus polyglottos), curve-billed thrashers (Toxistoma curvirostre), and Northern cardinals (Cardinalis cardinalis) to contribute data to existing parasitological gaps for birds in the Rolling Plains ecoregion of Texas. Birds were trapped across 3 counties in the Texas Rolling Plains from March to October 2019. Necropsies were conducted on 54 individuals (36 quail and 18 passerines), and extracted helminths were microscopically identified. Nematode, cestode, and acanthocephalan helminths representing at least 10 helminth species were found. Specifically, A. pennula and O. petrowi had the highest prevalence, and O. petrowi was documented in all of the study species. This research adds to the body of knowledge regarding parasitic infections in quail and passerines of the Rolling Plains ecoregion and highlights the potential consequences of shared infection of eyeworms among these bird species.
... However, there has recently been increased research regarding O. petrowi due to its prevalence in a declining game bird, the Northern bobwhite quail (Colinus virginianus; hereafter bobwhite), within the Rolling Plains ecoregion of Texas and Oklahoma (Dunham et al., 2016a;Commons et al., 2019). Oxyspirura petrowi was first reported in bobwhite from Texas in 1961, with a prevalence of 49% (Jackson, 1969), but since then this parasite has frequently been found with a prevalence of 90-100% in bobwhite of the Rolling Plains Henry et al., 2017;Commons et al., 2019). ...
... However, there has recently been increased research regarding O. petrowi due to its prevalence in a declining game bird, the Northern bobwhite quail (Colinus virginianus; hereafter bobwhite), within the Rolling Plains ecoregion of Texas and Oklahoma (Dunham et al., 2016a;Commons et al., 2019). Oxyspirura petrowi was first reported in bobwhite from Texas in 1961, with a prevalence of 49% (Jackson, 1969), but since then this parasite has frequently been found with a prevalence of 90-100% in bobwhite of the Rolling Plains Henry et al., 2017;Commons et al., 2019). Researchers have also documented O. petrowi in songbirds , conducted phylogenetic analysis (Kalyanasundaram et al., 2018), and demonstrated pathological changes in the eye of birds infected with this parasite (Bruno et al., 2015;Dunham et al., 2016b). ...
Article
Full-text available
Recently, the heteroxenous eyeworm, Oxyspirura petrowi, has gained attention due to its prevalence in the declining game bird, Northern bobwhite (Colinus virginianus), but the intermediate hosts of many nematodes remain unknown. However, identifying the intermediate host of O. petrowi with traditional techniques would be difficult and time-consuming, especially considering there are more than 80 potential orthopteran hosts just in Texas. To screen a large number of samples quickly and effectively, primers for nested PCR (nPCR) were developed using the internal transcribed spacer 1(ITS1) region. Then the nPCR was used to identify which of the 35 species collected from the Order Orthoptera were potential intermediate hosts of O. petrowi. With this technique, 18 potential intermediate hosts were identified. Later, we collected live specimens of species that tested positive to confirm the presence of larvae, but larvae were not found in the live specimens, nor in the extra tissue of the species that had tested positive for O. petrowi DNA. Despite this, this study demonstrated that nPCR is more sensitive than traditional techniques and can be a valuable tool in determining the intermediate hosts of parasites.
... Wild bobwhite were collected during April 2018 from private ranches using trapping procedures as described in Commons et al. (2019) for glycoprotein collections of eyeworms and caecal worms. Adult eyeworms were extracted from the eyes and associated tissues as described in Dunham et al. (2014). ...
Article
Full-text available
Helminth parasites have been a popular research topic due to their global prevalence and adverse effects on livestock and game species. The Northern bobwhite (Colinus virginianus), a popular game bird in the USA, is one species subject to helminth infection and has been experiencing a decline of > 4% annually over recent decades. In the Rolling Plains Ecoregion of Texas, the eyeworm (Oxyspirura petrowi) and caecal worm (Aulonocephalus pennula) helminths are found to be highly prevalent in bobwhite. While there have been increasing studies on the prevalence, pathology, and phylogeny of the eyeworm and caecal worm, there is still a need to investigate the bobwhite immune response to infection. This study utilizes previously sequenced bobwhite cytokines and toll-like receptors to develop and optimize qPCR primers and measure gene expression in bobwhite intramuscularly challenged with eyeworm and caecal worm glycoproteins. For the challenge experiments, separate treatments of eyeworm and caecal worm glycoproteins were administered to bobwhite on day 1 and day 21. Measurements of primary and secondary immune responses were taken at day 7 and day 28, respectively. Using the successfully optimized qPCR primers for TLR7, IL1β, IL6, IFNα, IFNγ, IL10, and β-actin, the gene expression analysis from the challenge experiments revealed that there was a measurable immune reaction in bobwhite in response to the intramuscular challenge of eyeworm and caecal worm glycoproteins.
Article
West Nile virus (WNV) has been implicated in regional declines of numerous North American bird species, although its potential impact upon many species, including some game birds, remains unknown. Specifically, information about susceptibility to infection and infection outcome are crucial to assessing health risks. Northern bobwhite quail (Colinus virginianus) are a popular and common game bird across much of the United States, as well as in captive breeding programs and as backyard birds. Two age groups of bobwhites were subcutaneously inoculated with WNV and euthanatized on 15 days postinoculation (DPI). Three of 10 inoculated 5-wk-old and 4/10 inoculated 15-wk-old birds developed detectable viremia titers during 1–5 DPI, with low peak titers (101.7–103.0 plaque-forming units [PFU]/ml). Three of 10 inoculated 5-wk-old and 1/10 inoculated 15-wk-old birds shed low viral titers (peak 100.7–101.8 PFU/swab) either orally or cloacally or both for limited periods from 2 to 6 DPI. All inoculated birds (n = 20) remained apparently healthy and seroconverted by 15 DPI. No infectious virus was detected in select tissues: heart, kidney, brain, skeletal muscle, spleen (15-wk-old group only), and feathers from any of the bobwhites. No sham-inoculated, contact control birds (n = 8) became viremic or had virus isolated from tissues or swabs. The most consistent microscopic lesion was minimal to mild, lymphoplasmacytic myocarditis (6/10 in 5-wk-olds; 5/10 in 15-wk-olds). Immunohistochemical labeling was most often in macrophages in spleen and bone marrow, likely reflective of clearance of infection. There were no statistically significant differences in the peak viremia and shedding titers between age groups and no differences in the development of WNV-associated lesions between the two age groups. These results suggest that WNV is unlikely to pose a health risk to bobwhites and that bobwhites likely are an incompetent reservoir host species in WNV transmission.
Article
Full-text available
The potential of parasites to affect host abundance has been a topic of heated contention within the scientific community for some time, with many maintaining that issues such as habitat loss are more important in regulating wildlife populations than diseases. This is in part due to the difficulty in detecting and quantifying the consequences of disease, such as parasitic infection, within wild systems. An example of this is found in the Northern bobwhite quail (Colinus virginanus), an iconic game bird that is one of the most extensively studied vertebrates on the planet. Yet, despite countless volumes dedicated to the study and management of this bird, bobwhite continue to disappear from fields, forest margins, and grasslands across the United States in what some have referred to as “our greatest wildlife tragedy”. Here, we will discuss the history of disease and wildlife conservation, some of the challenges wildlife disease studies face in the ever-changing world, and how a “weight of evidence” approach has been invaluable to evaluating the impact of parasites on bobwhite in the Rolling Plains of Texas. Through this, we highlight the potential of using “weight of the evidence” to better understand the complex effects of diseases on wildlife and urge a greater consideration of the importance of disease in wildlife conservation.
Article
Full-text available
Northern bobwhite quail (Colinus virginianus) are a highly sought-after game bird in the Rolling Plains of West Texas. Unfortunately, bobwhite populations in this area are subject to dramatic fluctuations and have been steadily decreasing over the past several decades. While many factors have been investigated as potential mechanisms of cyclic and declining bobwhite numbers, the effect of parasites on bobwhite populations has historically been undervalued. Between December 2017 and February 2018, we received 21 hunter-shot bobwhite from Garza and Mitchell counties in Texas and found peak caecal worm (Aulonocephalus pennula) and eyeworm (Oxyspirura petrowi) burdens averaging 599 and 44, respectively. These represent the highest average parasite loads we have documented in bobwhite from the Rolling Plains thus far and are coincident with widespread reports of declining bobwhite abundance. These elevated infections also followed a high point in bobwhite populations in the Rolling Plains, and our observations of infection dynamics during this time reflect other instances of potential parasite-induced host mortality. While the sample discussed in this communication is small, our findings highlight the need for additional research into how parasites may affect bobwhite population fluctuations in this region.
Article
Full-text available
Anecdotal reports of Northern bobwhite quail (Colinus virginianus) exhibiting strange behavior have raised suspicions of parasite induced host mortality (PIHM) in the Rolling Plains of West Texas. In 2017, we received 11 bobwhite carcasses associated with such reports and found parasites in all of these specimens. While further research is needed to evaluate the impact of parasites on bobwhite, these reports provide a valuable supplement to on-going investigations of PIHM in bobwhite from the Rolling Plains of West Texas.
Article
Full-text available
We have been monitoring wild Northern bobwhite quail (Colinus virginianus) on a research transect in Mitchell County, Texas. We captured a total of 51 bobwhites in March-May of 2016 and 2017 and examined them for eyeworm (Oxyspirura petrowi) and caecal worm (Aulonocephalus pennula) infections. In March 2017, bobwhites averaged 15 ± 10 eyeworms and 269 ± 90 caecal worms, and by mid-April averages had increased to 18 ± 13 eyeworms and 372 ± 144 caecal worms. These averages were much higher than those observed in March 2016 (11 ± 13 eyeworms and 160 ± 57 caecal worms) and April 2016 (12 ± 12 and 216 ± 56, respectively). We observed a precipitous decline in quail numbers by late April 2017, and average infection had dropped to 7 ± 2 eyeworms and 252 ± 109 caecal worms. The number of trapping sessions needed to capture one bobwhite also increased from 14.26 in 2016 to 36.46 in 2017. These observations warrant further investigation into the effects these helminth parasites may have on bobwhites and their populations within the Rolling Plains.
Article
Full-text available
Aulonocephalus pennula is a nematode living in the caeca of the wild Northern bobwhite quail (Colinus virginianus) present throughout the Rolling Plains Ecoregion of Texas. The cytochrome oxidase 1 (COX 1) gene of the mitochondrial genome was used to screen A. pennula in wild quail. Through BLAST analysis, similarity of A. pennula to other nematode parasites was compared at the nucleotide level. Phylogenetic analysis of A. pennula COX1 indicated relationships to Subuluridae, Ascarididae, and Anisakidae. This study on molecular characterization of A. pennula provides new insight for the diagnosis of caecal worm infections of quail in the Rolling plains Ecoregion of Texas.
Article
Full-text available
Parasitic nematodes that infect quail have been understudied and long been dismissed as a problem in quail management. Within the Rolling Plains ecoregion of Texas, an area that has experienced quail population “boom and bust” cycles and ultimately a general decline, the need to determine why Northern bobwhite (Colinus virginianus) populations are diminishing has increased in priority. Previously, caecal parasites have been documented to cause inactivity, weight loss, reduced growth, inflammation to the caecal mucosa, and even death. The caecal worm Aulonocephalus pennula is an intestinal nematode parasite that is commonly found within the caecum of quail, as well as many other avian species. In the Rolling Plains ecoregion, A. pennula has been documented to have as high as a 98% prevalence in bobwhite quail samples; however, the effect it has on its host is not well understood. The present study documents A. pennula causes no pathological changes within the caeca of the Northern bobwhite. However, there is concern for disruption of digestion and the possible implications of infection for wild bobwhite quail survival are discussed.
Article
Full-text available
Debilitating ocular diseases are often reported in avian species. By and large, helminth parasites have been overlooked in avian diseases and regarded as inconsequential. The decline of Northern bobwhite quail (Colinus virginianus) in the Rolling Plains ecoregion of Texas has prompted an investigation of the factors influencing their disappearance. Infection by the eyeworm (Oxyspirura petrowi) has been documented in many avian species; however, the effect it has on its host is not well understood. Heavy eyeworm infection has been documented in Northern bobwhites throughout this ecoregion, leading to eye pathology in this host species. The present study further documents and supports the pathological changes associated with O. petrowi in bobwhites.
Article
Full-text available
Northern bobwhite (Colinus virginianus) and scaled quail (Callipepla squamata) have experienced chronic declines within the Rolling Plains ecoregion of Texas. Parasitic infection, which has long been dismissed as a problem in quail, has not been studied thoroughly until recently. A total of 219 northern bobwhite and 101 scaled quail from Mitchell County, Texas were captured and donated from 2014-2015, and examined for eyeworm (Oxyspirura petrowi) and caecal worm (Aulonocephalus pennula) infections. In 2014, bobwhites averaged 19.6±1.8 eyeworms and 98.6±8.2 caecal worms and 23.5±2.1 eyeworms and 129.9±10.7 caecal worms in 2015. Scaled quail averaged 4.8±1.0 eyeworms and 50±6.8 caecal worms in 2014 and 5.7±1.3 eyeworms and 38.1±7.1 caecal worms in 2015. This study expands the knowledge of parasitic infection in quail inhabiting the Rolling Plains of Texas. A significant difference was documented in O. petrowi infection between species but there was no significant difference in A. pennula between quail species. No significant difference was detected in parasite infection between the sexes of both northern bobwhite and scaled quail. This study also documented the highest reported O. petrowi infection in both species of quail. Additional research is needed on the life history and infection dynamics of O. petrowi and A. pennula infections to determine if there are individual and/or population level implications due to parasitic infection. .
Article
One hundred and sixty-one northern bobwhites ( Colinus virginianus ; hereafter ‘bobwhite’) were examined from the Rolling Plains ecoregion of Texas and western Oklahoma from 2011 to 2013. Complete necropsies yielded 13 species, of which two are new host ( Gongylonema phasianella ) and region ( Eucoleus contortus ) records and three ( Dispharynx nasuta , Tetrameres pattersoni and Oxyspirura petrowi ) are known to cause morbidity and mortality. Of the species found, Aulonocephalus pennula commonly occurred, Oxyspirura petrowi was intermediate in prevalence, and the remaining species were rare. Species richness was similar compared to studies from the southeastern U.S., but higher than studies from the same region. In addition, 12 of the 13 species were heteroxenous helminths, supporting the theory that heteroxenous helminths in semi-arid regions are more successful than monoxenous helminths. Prevalence and abundance of A. pennula and O. petrowi were higher in adult bobwhites than in juveniles. Abundance of A. pennula and O. petrowi was higher at southern locations compared to northern locations in the study area. Our study is the first to provide a current assessment of the bobwhite helminth community across the Rolling Plains ecoregion of the U.S.
Article
Animals inhabiting disturbance-prone systems, such as the northern bobwhites (Colinus virginianus) in pine (Pinus spp.) savanna, are adapted to certain intensities of disturbance (e.g., frequency, spatial extent, seasonality). Management practices attempt to mimic these natural conditions. Even though northern bobwhites are known as the firebird, most fire-related management is currently based on tradition and limited peer-reviewed literature. We studied habitat selection of northern bobwhites on private property in Georgetown County, South Carolina, USA, managed with fire, winter disking, and supplemental feeding. We radio-tagged 338 individual bobwhites and monitored them 3–4 times weekly via very high frequency (VHF) telemetry for 2 years. We used hierarchical habitat selection functions in a Bayesian framework to model the data. We considered 2 spatial scales: the study site (second-order) and within home ranges (third-order). Bobwhites selected for small burns during the breeding season but had the highest selection for areas intermediately distant from burn edges during winter (i.e., 67 m). Bobwhites had the strongest selection for fire return intervals of 2–3 years during winter but 1–2 years during the breeding season. Use of supplemental feed was strong across seasons but not selected for by brooding birds within their home range. Use of fallow fields was strongest for brooding birds. Our results are useful for bobwhite managers, especially those in subtropical climates, because they provide scientifically defensible information supporting the use of prescribed fire, winter disking, and supplemental feeding in the context of habitat use.
Article
Northern Bobwhite (Colinus virginianus) populations in Texas have been declining during the past several decades. Declines have been attributed to habitat loss, but other causes and potential contributing factors (e.g., parasites, disease) have been posited. Little is known about helminth parasites in bobwhites from Texas. Previous studies often used bobwhites collected during the hunting season, which only samples individuals that survive after the summer breeding season. Our objectives were to (1) assess the prevalence, intensity, and abundance of helminths in bobwhites from Fisher County, Texas, during an annual cycle; (2) identify which species are known to be pathogenic; and (3) determine whether infections are related to host age, sex, and season of collection. We collected 142 bobwhites during February-March 2010 (n = 37), August 2010 (n = 51), and December 2010-January 2011 (n = 54). We found 7 helminth species, of which 3 (Oxyspirura petrowi, Tetrameres pattersoni, and Dispharynx nasuta) are known to cause tissue damage to bobwhites. Aulonocephalus pennula was the most common (82% prevalence) and numerically abundant species (96% of all specimens). Prevalence and mean abundance of A. pennula, O. petrowi, and T. pattersoni were higher in adults than juveniles. Prevalence of A. pennula, O. petrowi, and T. pattersoni did not vary with host sex. Mean abundance of T. pattersoni was higher in females than males. Prevalence of A. pennula, O. petrowi, and T. pattersoni was lower in summer than early and late winter and was related to low infections in young juveniles. Our findings provide insight into helminth infection dynamics of Northern Bobwhites across an annual cycle.