Wildlife Visitation on a Multi-unit Educational Livestock
Facility in Northwestern Georgia
Susanna E. Kitts-Morgan, Reneé E. Carleton, Stuart L. Barrow,
Katharine A. Hilburn, and Amanda K. Kyle
Southeastern Naturalist, Volume 14, Issue 2 (2015): 267–280
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22001155 SOUTHEASTERN NATURALIST 1V4o(2l.) :1246,7 N–2o8. 02
Wildlife Visitation on a Multi-unit Educational Livestock
Facility in Northwestern Georgia
Susanna E. Kitts-Morgan1, Reneé E. Carleton2,*, Stuart L. Barrow3,
Katharine A. Hilburn4, and Amanda K. Kyle5
Abstract - Wildlife visitation of livestock facilities results in economic losses through feed
consumption and a potential for disease transmission through fecal contamination of feeds
and associated facilities. In order to assess wildlife visitation among livestock-management
teaching units on a college campus, we monitored feeding and feed-storage areas via direct
observations, live-trapping, and motion-detecting cameras. We also examined visitation
patterns and fecal contamination and consumption of grain-based feed and hay. Nine species
of wildlife visited the livestock units during the course of the study. Birds and Odocoileus
virginianus (White-tailed Deer) were the most frequent visitors in less-enclosed facilities,
and rodents, Didelphis virginiana (Virginia Opossum), and Procyon lotor (Raccoon) were
mostly documented in more-enclosed facilities. Birds visited daily throughout the year, but
documented visitations by Raccoons, Virginia Opossums, and White-tailed Deer occurred
only during summer months. Marmota monax (Groundhog) were present each month except
for January, February, and March. Of 827 feed samples examined, 16.8% were contaminated
by wildlife feces, primarily from birds. Grain-based feed was consumed or removed more
frequently than hay, and loss declined during the winter and increased in spring and summer.
Introduction
Peridomestic wildlife species are attracted to livestock-feeding and feed-storage
facilities because of the readily available and easily accessible food resources these
areas offer (Daniels et al. 2003). Wildlife visitation and associated consumption and
fecal contamination of livestock feed not only results in economic losses to producers
(Johnson and Timm 1987, Pimental et al. 2000), but has the potential to increase
disease transmission risks between wildlife and both humans and livestock animals
(Carlson et al. 2011, Corn et al. 2005, Daniels et al. 2003, Kirk et al. 2002, Tolhurst
et al. 2009, Ward et al. 2006).
Sturnus vulgaris L. (European Starling) are frequent visitors to feedlots and
other animal-feeding operations and have been shown to carry pathogens such as
Salmonella enterica (ex Kauffmann & Edwards) Le Minor & Popoff. This situation
is of great concern because their droppings have been shown to contaminate
cattle feed and water and have the potential to cause disease in humans and cattle
(Carlson et al. 2011, Kirk et al. 2002). Likewise, birds, deer, and other mammalian
1Department of Animal Science, Berry College, Mount Berry, GA 30149. 2Department
of Biology, Berry College, Mount Berry, GA 30149. 3Kolomoki Mounds Historic State
Park, Blakely, GA 39823. 4College of Veterinary Medicine, Auburn University, Auburn,
AL 36849. 5UGA/Clinical Pharmacy Program, Georgia Regents University, Augusta, GA
30912. *Corresponding author - rcarleton@berry.edu.
Manuscript Editor: Andrew Edelman
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pests frequenting feedlots and other livestock areas may promote transmission of
diseases, such as paratuberculosis (also known as Johne’s disease; Corn et al. 2005,
Davidson et al. 2004), bovine tuberculosis (Böhm et al. 2009, Schmitt et al. 2002,
Ward et al. 2006), and rabies (Chipman et al. 2013, Dyer et al. 2013), to domestic
animals and humans.
Certain wildlife species are commonly reported on livestock operations such as
dairies and feedlots: Procyon lotor L. (Raccoon; Corn et al. 2005, Ikeda et al. 2004),
Odocoileus virginianus Zimmerman (White-tailed Deer; Berentsen et al. 2013,
Johnson and Timm 1987, Philips et al. 2012, VerCauteren et al. 2008), small rodents
(Johnson and Timm 1987), European Starlings (Johnson and Timm 1987, Linz et al.
2007), and other grain-feeding birds (Palmer 1976).
An understanding of factors promoting wildlife visitation is useful when considering
means of reducing wildlife–livestock and wildlife–human interactions or
minimizing feed losses due to wildlife consumption. Our objectives were to 1) document
wildlife presence within livestock-management teaching units on a college
campus and 2) investigate their patterns of visitation, consumption, and associated
fecal contamination of livestock feed. We expected grain-feeding birds and small
rodents to be regular visitors within all of the feeding and feed-storage areas. We
also expected these species would be the most common source of deposited feces.
Because of the proximity of the livestock units to wildlife habitats, we also expected
visitation, to a slightly lesser degree, by medium-sized wild mammals, such as Raccoons.
For all wildlife species, we expected a higher rate of visitation during winter
months, when natural food sources would be reduced, than in summer months.
Field-Site Description
We conducted this study (June 2011–April 2012) within 3 livestock-management
teaching units at Berry College (34º17'43.82"N, 85º11'12.6"W) in
northwestern Georgia. The college property is expansive and consists of approximately
10,500 ha, including a wildlife management area and wildlife refuge
located adjacent to the livestock units (Fig. 1). Mixed Quercus (oak)/Carya
(hickory) and Pinus (pine) spp. forests dominate the land tract and border livestock-
grazing pastures and concentrations of campus buildings. All of the units had
been actively housing livestock for more than 10 years at the time the study was
conducted. Each unit, located on separate areas of the campus, featured different
livestock (horses, dairy cattle, and beef cattle), supportive feeding and feed-storage
areas, and feedstuffs of differing composition. The units also differed in the
design of associated buildings (i.e., fully enclosed by 4 complete walls and a roof,
partially enclosed having at least 2 walls and a roof, or open-air with less than 2
solid walls but under roof), type of feed used, and method of livestock feeding. The
equine unit consisted of 2 partially enclosed and connected barns containing multiple
stalls, 2 adjoining partially enclosed 10 m × 4 m hay sheds, and surrounding
paddocks. Grain-based equine feed was stored in fully enclosed bunks. Horses
were fed grain from individual buckets and hay from racks in their stalls. A
working dairy, dairy-cattle feeding and holding areas, feed and hay storage, and
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adjacent pastures comprised the dairy unit. The feeding and holding barn for milking
cows was of an open-air design. Dairy cows were fed Total Mixed Ration
(TMR; Purina Mills, Gainesville, GA) and hay exclusively. The TMR, which was
constantly available and replenished frequently, was deposited in a 20-m long, linear
row in the feeding area. Hay was stored in the barn and fed to dairy cows in the
holding area. In addition to beef cattle grazing pastures, a fully enclosed 30 m × 17
m feed- and hay-storage barn and open-air cattle pens made up the beef cattle unit.
Corn gluten pellets were the only grain-based ration fed to the beef cattle. The
pellets were distributed into troughs placed within beef-cattle pastures and stored
within an open bunk inside the barn. Hay was distributed in beef-cattle pastures
during winter months to supplement available pasture grasses. Amount and timing
of human activity also varied by unit, ranging from near-constant daylight-hour
activity in the equine barn to peaks of activity for milking and feeding activity at
the dairy or a limited twice-per-day visit at the beef-unit storage building.
Methods
Wildlife documentation
We employed various methods to document wildlife presence in order to
maximize the likelihood of detecting species of differing sizes and habits. These
methods included remote-imaging, live-trapping, direct visual observation, and fecal
evidence. For each instance of visitation, we noted the species, the livestock unit
in which it was observed, the design of facility, and feed type used at that unit in
addition to the date of visitation. We used motion-detecting game cameras (Moultrie
DGS-200, Global Point Products, Farmington, NY) as our most-constant means
Figure 1. Map of study site in northwest Georgia (Berry College) showing location of livestock
units and adjacent wildlife refuge and wildlife management areas (WMA).
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of monitoring to remotely record medium- to larger-sized animals that we expected
would visit the units when human activity was minimal. Six cameras were deployed
from mid-June 2011 through April 2012 for a total of 302 days (mean = 27.5 days
per month). We placed 2 cameras at each unit; 1 within a livestock-feeding area and
1 within a feed-storage area. Based on trials we conducted beforehand, the cameras
were aimed at feeding areas or stored feed in a position to take maximal advantage
of the cameras’ 42° field of view. Cameras were active for 24 hr/day throughout the
study, except for short periods when we retrieved them to replenish their batteries
and download images. We programmed the cameras to take still photographs at 30-
sec intervals during activation.
For 31 nights between 11 July and 10 August 2011, when the college’s student
population was minimal, we set live traps at each unit, in addition to the cameras,
to capture and document elusive small- to medium-sized wildlife, such as rodents,
Raccoons, and Virginia Opossums. We placed a Havahart 82.28-cm, single-door
trap (Woodstream Corporation, Lititz, PA) baited with sugar-coated apple pieces
and fermented cantaloupe in each of two areas at the dairy and equine units for a
combined total of 124 trap nights. Four 7.6 cm × 8.9 cm × 22.8 cm folding traps
(H.B. Sherman, Tallahassee, FL), baited with rolled oats to target small rodents,
were placed at least 4 m apart but adjacent to feeding or within feed-storage areas
at each unit for a combined total of 372 trap nights. Traps were open approximately
dusk to dawn. Since we could not be certain of how many unique individuals of a
particular species were recorded by camera each day, we compared mammal visitations
among units in terms of numbers of detection/no detection. Captured rodents,
Raccoons, and Virginia Opossums were humanely killed following American Society
of Mammologists guidelines (Sikes et al. 2011) because they were considered
nuisance animals, i.e., those causing damage to the facilities or capable of spreading
disease to livestock or personnel. Relocation was not considered an option per
United States Department of Agriculture recommendations (USDA APHIS 2011).
Tissues from these animals were collected for a separate, regional pathogenprevalence
study currently in progress. We also documented wildlife presence
by recovering and identifying feces deposited in samples of feed (methodology
described below). Our protocol for manipulation of live animals was approved by
the Institutional Animal Care and Use Committee of Berry College and carried out
under a State of Georgia Scientific Collecting permit.
Evaluation of feed contamination and consumption
We used 50 cm × 40.5 cm × 2.5 cm fast-food restaurant-style trays to hold
feed or hay samples to evaluate fecal contamination and feed removal by wildlife.
Before placing feed samples into the trays, we thoroughly examined fresh
quantities of feed or hay for feces or other contaminants and removed any if
found. After weighing each tray to the nearest 0.01 g, we completely filled them
with the sample and then reweighed the tray. At the equine unit, we randomly
placed 4 trays adjacent to or on stored Cynodon sp. (Bermuda grass) hay bales.
In the beef unit, corn gluten pellets were stored in an enclosed building but on the
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floor of an open bunk consisting of a 6.5 m × 6 m concrete pad bounded by low
concrete block walls on 3 sides. We placed 1 tray containing pellets adjacent to
and 1 tray on the pile of stored pellets, and 2 trays filled with hay were placed on
and adjacent to Bermuda grass square bales. At the dairy barn, we placed 2 trays
containing TMR at either end of the feeding area and 2 trays containing Bermuda
grass hay on square bales stored at one end of the barn. With the exception of the
TMR samples, we left trays exposed to wildlife for approximately 1 week before
collecting them. Due to its water content and propensity to develop mold, we
recovered the TMR samples each day after 12 hrs (17:00–05:00) and replaced
them with fresh samples at the beginning of another 12-hr period. After retrieving
the samples from their respective locations, we reweighed them and performed
a thorough visual examination for fecal material. Feces were removed and later
visually identified (by S.L. Barrow or A.K. Kyle) based on appearance as having
been produced by a bird (small size of irregular shape and possibly containing
white urates), small rodent (small-sized oblong pellets), or other mammal (larger
in size). We determined the amount of feed presumably removed or consumed by
calculating the difference between weight before placement and after recovery.
For a small number of samples, there was an increase in weight, probably due to
incidental addition of feed caused by animal movement, unit worker interaction,
or urination into the tray by Felis catus L. (Domestic Cat), and we did not include
those in our analysis of feed removal. To compensate for temperature-associated
water evaporation from TMR samples, we used dry-matter weight to determine
the weight lost from each sample.
The differing nature of each unit in terms of building design, type of feedstuffs
used, manner of feed storage or distribution, human activity, and number of sample
trays we could place without disrupting feeding activities presented us with a number
of confounding factors including unequal sample sizes and differences in the
number of days each feed type was available. More samples of TMR were exposed
to wildlife than other feed samples because of its propensity to mold if not consumed
within 24 hours. This reduced the time during which the samples could have
been visited compared to the other feed types. While not ideal, we felt that collecting
a greater number of samples of TMR per week would sufficiently compensate
for the difference.
Analyses
JMP® 8.0.2 statistical software was used for all analyses (α = 0.05). We compared
wildlife visitation among units for live-trapping and camera-detection methods by
means of likelihood ratio chi-square tests with unit (the independent variable) and
visitation (0 = no visitation recorded and 1 = visitation recorded) assigned categorical
roles. In JMP®, the negative log-likelihood of the response probabilities is
used to compute the likelihood ratio (Sall et al. 2005). We used Fisher’s exact test
to perform post-hoc pair-wise comparisons of number of visitations between units
(Sall et al. 2005). To determine changes in visitation patterns for each mammal species,
we also used likelihood ratio chi-square tests with month as the independent
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variable and whether or not visitations were recorded for each day of the month as
the response variable (Sall et al. 2005).
We standardized fecal-contamination and consumption data by dividing the
number of contaminated samples or weight of feed removed from samples by
days of sample availability. Distributions of both the fecal-contamination data and
feed-removal data were skewed as the majority of samples either did not contain
feces or did not have feed removed from them. We used Mann-Whitney U tests
for nonparametric distributions to make relevant comparisons among explanatory
variables (Sall et al. 2005). Numbers of standardized fecal-contaminated samples
were compared among feed types, with livestock unit as an additional explanatory
variable, among the months of the study. Standardized weights of feed removed
were also compared among the explanatory variables feed type, livestock units, and
months of the study. We also calculated percentages of samples containing feces by
month and for the study period and percentage of feed lost by weight by month and
for the study period after combining all samples of each type from the units.
Results
Wildlife observations
We documented 9 species of wildlife by direct observation, motion-detecting
camera, and live trapping (Table 1). Images of one or more individual mammals
were recorded among the cameras on 64 days (21.2% of recording days). The
number of visitations documented by camera varied by unit (likelihood ratio chisquared
test: G = 95.13, df = 2, G2 < 0.0001; Table 1) with more wildlife visits
at the beef unit compared to both the dairy and equine units (Fisher’s exact test:
df = 1, for the probability of camera documentation at the beef unit greater than
the dairy unit P < 0.0001, and probability of camera documentation at the beef unit
greater than the equine unit P < 0.0001); more visits were documented by camera
at the dairy unit than the equine unit (Fisher’s exact test: df = 1, P = 0.018). Eleven
Table 1. Visitations by mammalian wildlife species to feeding and/or feed-storage areas within 3
livestock-management teaching units on a college campus in Georgia. Visitations (presence or absence
per day) were documented by visual observation (V; June 2011–April 2012), remote camera
(C; June 2011–April 2012), or live-trapping (T; July–August 2011). Zero values indicated no species
were detected by any of the methods used, and + indicates individuals were detected but not counted.
Livestock unit
Wildlife species Equine Dairy Beef
Procyon lotor (Raccoon) 4 (T), 1 (C) 1 (T) 0
Didelphis virginiana (Virginia Opossum) 1 (T) 0 1 (C)
Marmota monax (Groundhog) 0 0 58 (C)
Mus musculus (House Mouse) 0 1 (T) 4 (T)
Odocoileus virginianus (White-tailed Deer) 0 8 (C) 0
Passer domesticus (House Sparrow) + (V) + (V) + (V)
Sturnus vulgarus (European Starling) 0 + (V) + (V)
Columba livia (Rock Dove) 0 + (V) 0
Hiurndo rustica (Barn Swallow) + (V) 0 0
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mammals were trapped during 10 of 23 days (43.5% of trapping days) during July
and August 2011 (mean =11.5 days per month). No animals were trapped on the
same day that animal images were recorded on camera. There was no significant
difference in the number of days that mammals were trapped among the livestock
units (likelihood ratio chi-squared test: G = 1.61, df = 2, G2 = 0.44; Table 1). Although
we trapped Mus musculus L. (House Mouse) or other small rodents, we also
noted their presence by fecal evidence in the feed samples we examined. Other
wild mammals visiting the units included White-tailed Deer (Fig. 2A), Marmota
monax L. (Groundhog; Fig. 2B), Raccoons, and Virginia Opossums. After House
Mice, Groundhogs were the most frequent visitors, followed by White-tailed Deer,
Raccoons, and Virginia Opossums (Table 1). Most of the medium-sized mammals
tended to be secretive and thus we only captured or documented them by photography
at night and in barns or buildings that were mostly enclosed and had limited
human activity. Mammals visited the units primarily after sunset, but birds were
seen most often during daylight hours. Birds were present at all units throughout
the study. We observed them frequently in the open-air barns of the dairy, but also
in the equine unit and inside the enclosed feed-storage barn. We visually observed
Passer domesticus L. (House Sparrow) and European Starlings feeding alongside
dairy cows inside the dairy barn each time we collected feed samples. House Sparrows
and Hirundo rustica L. (Barn Swallow) also nested in the equine and dairy
barns in proximity to stored hay, and Columba livia Gmelin (Rock Dove) roosted
in the beef feed- and hay-storage barn.
Documented visitation by camera of mammals occurred during summer and fall
months but not during mid-to-late winter months. The number of documented visits
per month by Groundhogs (likelihood ratio chi-squared test: G = 113.67, df = 10,
G2 < 0.0001), but not White-tailed Deer (likelihood ratio chi-squared test: G =
15.10, df = 10, G2 = 0.1284), differed significantly (Fig. 3); Raccoons and Virginia
Opossums were only documented by camera once, and because trapping was limited,
comparisons to demonstrate seasonal patterns were not possible.
Figure 2. Wildlife remotely documented consuming feed within livestock units located on
a college campus in Georgia: (A) White-tailed deer photographed within the dairy unit,
September 2011 at 03:37. (B) Groundhogs photographed on corn gluten pellets in a beef
feed-storage building, June 2011 at 19:49.
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Feed contamination
We examined a combined total of 827 feed and hay samples for wildlife fecal
contamination (Table 2). Most (83.2%) of the samples were not contaminated with
feces. In total (combined across all locations and feed types), we recovered bird
feces more frequently (10.04% of contaminated feed) than feces from small rodents
(1.8%) and other unidentified non-rodent mammals (0.5%). Insects, including beetles,
small flies, ants, and spiders, were also recovered from some (4.5%) samples.
Figure 3. Number of visits per month by Groundhogs and White-tailed Deer at livestock
units on a college campus in Georgia, June 2011–April 2012, as documented by remote
camera.
Table 2. Percentages of total livestock feed samples contaminated by wildlife feces or insects grouped
by taxon, livestock unit, and feed type, and mean number of samples contaminated per day with standard
error (SE). Feed samples consisted of total mixed ration (TMR), hay, or corn gluten pellets. Trays
containing samples were positioned on or adjacent to feed stored or distributed within livestock units
of a college campus in Georgia, June 2011–April 2012.
Dairy unit Equine unit Beef unit
Wildlife contaminator TMR Hay (hay only) Pellets Hay
None 80.3% 78.6% 94.5% 75.8% 89.5%
Bird 14.6% 8.6% 1.4% 3.2% 5.3%
Small rodent 0.4% 0.3% 2.7% 8.1% 2.6%
Other mammal 0.0% 0.0% 0.7% 16.0% 2.6%
Insect 0.47% 10.0% 0.7% 11.3% 0.0%
Total samples (n =827) 472 70 147 62 76
Mean samples contaminated/day 0.144 0.025 0.008 0.032 0.08
(SE) ( 0.016) (0.008) (0.003) (0.009) (0.006)
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Birds were the most-frequent contaminators by percentage of contaminated samples
of both TMR (97.0%) and stored hay (41.1%). However, more contaminated
samples of corn gluten pellets from the beef feed-storage barn contained feces from
mammals (80.0%) than birds (20.0%). Few samples of stored hay from the equine
barn contained feces of any kind, and no samples from the dairy barn contained
feces from non-rodent mammals. There were significant differences in the types
of feed contaminated (Mann-Whitney U test: U = 7.84, df = 2, P = 0.0198), with
more samples of TMR contaminated than pellets or hay (Table 2); livestock unit
as a factor did not contribute to the model (Fig. 4A). More samples of TMR were
contaminated in November and December than any other month (Mann-Whitney U
test: U = 56.75, df = 10, P < 0.001). Contamination of hay, the only feed type used
in all units, varied by month (Mann-Whitney U test: U = 21.22, df = 10, P < 0.019;
Fig. 4A), but did not vary among units (Mann-Whitney U test: U =5.276, df = 2,
P = 0.071). Contamination of corn gluten pellets, which were used only in the beef
unit, also varied by month (Mann-Whitney U test: U = 19.03, df = 10, P = 0.039;
Fig. 4A).
Feed consumption/loss
We compared weights of 721 feed samples before and after exposure to potential
consumption by wildlife (Table 3). Consumption or loss of grain-based feed
was significantly greater than hay (Mann-Whitney U test: U = 436.53, df = 2, P less than
0.001); livestock unit was not an appropriate factor because only hay samples were
examined from the equine unit. Approximately 22 kg (35.3% of the total sample
weight) of corn gluten pellets were removed or consumed from trays located in the
beef feed-storage barn and a total of 15.68 kg (21.6%) of TMR (dry matter) was
lost or consumed from dairy-barn samples. Consumption or loss of hay did vary
among the units (Mann-Whitney U test: U =11.28, df = 2, P = 0.0036), with more
loss occurring at the beef (24.0% of total sample weight) and dairy (19.5%) units
than the equine unit (10.6%). The amount of hay lost from sample trays by consumption
or removal was less than 1 kg per unit over the course of the study, but
when combined, represented a loss of 15.1% of the total sample weight.
There was a loss of feedstuffs of all types each month during the study (Fig.
4B). Seasonally, loss of TMR was greatest from June through September of 2011
compared to other months (Mann-Whitney U test: U = 128.94, df = 10, P < 0.0001).
Table 3. Summary statistics of feed consumed or removed by wildlife (g/day) by feed type at livestock
units on a college campus in Georgia (June 2011–April 2012).
Livestock Unit
Dairy Equine Beef
Mean Mean Mean
Feed type n (g/day) SE n (g/day) SE n (g/day) SE
Hay 37 1.49 0.29 113 0.76 0.14 70 2.36 0.46
Corn gluten pellets - - - - - - 53 74.12 8.98
Total mixed ration 448 93.03 4.46 - - - - - -
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Figure 4. (A) Percentages of livestock-feed samples containing wildlife feces grouped by
month and feed type. (B) Percentages of feed removed from sample trays by wildlife visiting
livestock units grouped by month and feed type. Samples were exposed to potential wildlife
visitation for a period of 12 hours (total mixed ration (TMR) or 7 days (hay and corn gluten
pellets) during the study period June 2011–April 2012 within mixed livestock units on a
college campus in Georgia.
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Similarly, more corn gluten pellets were lost from June through August 2011, but
also in November 2011 and March and April 2012, than in other months (Mann-
Whitney U test: U = 32.16, df = 10, P = 0.0004). Monthly variation in loss of hay
was significant at the beef unit (Mann-Whitney U test U = 30.82, df = 10, P =
0.0006), with losses greater in June, July, and August 2011, but not at the dairy
(Mann-Whitney U test: U = 10.51, df = 10, P = 0.39) or the equine unit (Mann-
Whitney U test: U = 17.03, df = 10, P = 0.073).
Discussion
A variety of wildlife species visited the feeding and feed-storage areas of the
livestock units, and many were the same as those reported in other studies (Anderson
et al. 2007, Berentsen et al. 2013, Carlson et al. 2011, Corn et al. 2005, Daniels
et al. 2003, Kirk et al. 2002, Philips et al. 2012, VerCauteren et al. 2008). The patterns
of wildlife visitation and fecal contamination of feeds observed in this study
and others are most likely reflective of their ecological phenology. For example,
studies conducted in the United Kingdom found that farm-building visitations by
Meles meles L. (Eurasian Badger) were more likely to occur during the spring
and summer and mainly during periods of low rainfall when their earthworm prey
were less available (Garnett et al. 2002, Tolhurst et al. 2009). The Groundhogs
we observed were the dominant mammal within the beef feed- and hay-storage
areas. While these animals were active mostly at night, they were occasionally
seen during the day depending on time of year and weather conditions. We rarely
observed them during the winter months, which coincided with the minimal loss of
corn gluten pellets we documented from December 2011 through February 2012.
Groundhogs typically enter hibernation as early as November and may not emerge
until March (Davis 1967, Grizzell 1955). Their tendency to hibernate and only occasionally
emerge from their burrows during these months (Davis 1967) is a reasonable
explanation for their absence. During the month of April, we recorded no
Groundhog presence, and it was possible some of them had emerged from hibernation
to breed in March and left the immediate area to find mates farther away (Davis
1967). White-tailed Deer have been previously documented visiting cattle-feeding
areas (Berentsen et al. 2013, Philips et al. 2012). White-tailed Deer visitations at
these operations have been observed to increase during January and peak in June
coinciding with the fawning season and lactation (Berentsen et al. 2013). We documented
visits by 1 or more White-tailed does within the dairy barn in June, July,
and also a single visit in September, but not in other months. As the visits occurred
during fawning season, we hypothesize the increased energy demands attributed to
lactation prompted the visitations. We found no reports of them entering a partially
enclosed structure to feed, as was the case on our site, which is atypical of their
normal behavior. Similar to other findings (Daniels et al. 2003), we found birds
and small rodents to be frequent fecal contaminators of grain-based feeds. Because
mammals other than rodents tend to defecate away from food sources, we found
very little evidence of fecal contamination by them. Visitation by Raccoons was not
unexpected because they can often be found in the vicinity of artificial food sources
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(Prange et al. 2004). Although we trapped Raccoons in the equine-housing areas
and found a latrine in an adjacent barn, we were surprised none were documented
in the hay-storage shed given its proximity to the trapping location. It is possible
that the lack of secluded areas in the hay-storage area, abundance of hiding places
in adjacent barns, and the simple lack of appeal of grass hay compared to other
foodstuffs discouraged them to venture there.
The necessity of not interfering with normal feeding operations restricted the
number of feed sample trays we could employ. We were limited to using only 2
sample trays per sampling area within each unit and were restricted in where we
could place the trays to avoid consumption by livestock or interference by and
disturbance of unit workers. Both of these factors may have reduced the likelihood
of wildlife contact with the samples. Our finding of fecal contamination
in 16.8% of samples may seem minor but, given the total amount of feed or hay
to which birds and rodents had access, we conclude that much of the stored feed
at the units becomes contaminated by 1 or more wildlife species, and hence, a
potential for disease transmission exists. In their study examining fecal contamination
of stored livestock feeds, Daniels et al. (2003) found in Scotland that a
single cow could potentially ingest well over 1000 rodent and/or bird feces during
the winter and, based on infectious-disease modeling, ingestion of contaminated
feed would increase risk of infection by diseases known to be carried by wildlife
and prevalent in that country. Cows housed in the dairy unit of this study consume
approximately 13 kg of TMR daily (I. Peeler, Berry College, Mount Berry, GA,
pers. comm.). Based on our estimate that 14.4% of TMR samples were contaminated
with bird or rodent feces, 1.83 kg of their daily ration could be contaminated.
As we had no disease-prevalence data for the wildlife species visiting the
units, calculation of infection risk was not possible.
The amount of feed consumed or removed by wildlife, which we reported as
percentage lost, is likely much greater than the loss our sample trays represented
because the amount of feed placed in the trays, the basis of the analyses, was only a
minimal proportion of the total feed exposed to wildlife. Groundhogs, by virtue of
their size and the regularity of their visits, appeared to consume more feed, namely
corn gluten pellets, than any of the other wildlife species we documented. The easy
accessibility of the pellets, along with the relative seclusion of the storage barn and
ability of the animals to feed undisturbed, probably contributed to the amount of
sample lost. Groundhogs frequently inhabit burrows under farm buildings, as was
the case at the beef feed-storage barn, and so, like other species of rodents, would
focus much of their feeding in these areas.
The results of our study suggested that visitation by a variety of wildlife species
occurs commonly within the livestock units and results in consumption and fecal
contamination of feedstuffs. This situation is cause for concern, mainly because of
a potential for disease transmission from wildlife to livestock and the unit workers
through fecal contamination of feedstuffs and unit areas. The design of the facilities
and manner in which livestock were fed and feedstuffs stored appeared to influence
visitation patterns, but other factors, such as human activity and weather, may
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2015 Vol. 14, No. 2
have also contributed. A mark-and-release study would increase our understanding
of visitation patterns and help estimate disease prevalence and transmission
risks. While it is not possible to completely prevent wildlife from entering feeding
or storage areas, we recommend instituting protection by storing feed in sealed
containers or secure, non-accessible enclosures, covering potential entry ways, or
using deterrent devices, such as electrical fencing, to reduce consumption loss and
risk of contamination.
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