The Impact of Raptor Presence at Dairy Barns on Nuisance Birds
Eric k. Mathiesen, [1] Department of Fisheries, Wildlife and Environmental Studies. State University of New York at Cobleskill, 106 Suffolk Cir. Cobleskill, NY 12043, USA
KATHERINE A. VAHSEN, [2] Department of Fisheries, Wildlife and Environmental Studies. State University of New York at Cobleskill, 106 Suffolk Cir. Cobleskill, NY 12043, USA
ABSTRACT: Rock pigeon (Columbia livia) and European starling (Sturnus vulgaris) are viewed generally as a nuisance species in many different environments such as city infrastructure and at farms. We intend to investigate if the presence of raptors affect abundance of nuisance birds at dairy facilities. This study is being conducted around Cobleskill in Schoharie County, New York at 4 different dairy barn facilities. To assess if the presence of raptors influences nuisance bird abundance at dairy facilities, we conducted pre and post surveys of pigeon and starling abundance at each facility. Three perches were placed at each barn facility to increase chances of perches being utilized by raptors. Raptor species using perches were only recorded at one of the study sites, Stanton farms. T-test for unequal variances was conducted separately for the pre and post tests and control site to determine if change in nuisance bird population is due to seasonal change and not presence of raptors at perches. The p-value for pre and post population t-test for the control farm was 0.02 (variance pre=4645.33, variance pro=876, n=3, d.f=2, t stat=3.94, and t-critical=3.18) indicating that the significant difference is due to seasonal change. This study supported that weather and seasonal change impacted the presence of nuisance birds at dairy facilities rather than raptor presence.
___________________________
KEYWORDS abundance, Columbia livia, dairy facilities, European starling, non-lethal, nuisance birds, populations, perches, raptors, rock pigeon, Sturnus vulgaris
Rock pigeons (Columbia livia) and European starling (Sturnus vulgaris) are viewed generally as a nuisance species in many different environments such as city infrastructure and at farms. Pigeons and starlings are a non-native species that originated from Eurasia and were introduced to North America. Pigeons were brought over during the 1600s while starlings were introduced in the 19th century (Cornell Lab of Ornithology). Since arriving in North America pigeons and starlings have rapidly grown and now populate most of the continent. They are viewed as a nuisance species due to the damage they cause to buildings and diseases transmitted from constant nesting and droppings (Wackernagel and Geigenfeind 2008). This poses a threat to human and animal health due to spread of pathogens from feces to surrounding people, livestock, or other species of birds (Carlson et al. 2011). European starlings in large flocks at winter roosting sites on dairy complexes also cause a significant financial loss. A single adult starling is capable of consuming 1 kg of feed a day, and in large flocks' of 1000 birds, they can consume up to $84 ($0.03/lb) a day in feed (Depenbush et al. 2011).
The presence of nuisance birds in dairy complexes poses a threat to humans and cows for disease transmission of up to 60 different diseases consisting of Salmonellosis, E. coli, Histoplasmosis and many more (Birds and their droppings can carry over 60 diseases 2014). In a study by Wells et al. (2001) 91 milk cows and 97 cull milk cows’ feces were tested for salmonella. The results showed that 5.4% of the fecal samples in milk cows were positive with salmonella and 18.1% of cull milk cows from nuisance birds. Wells et al.’s findings didn’t directly link salmonella to pigeons or starlings. Yet, nuisance birds are able to transmit diseases if they’re infected through their feces which can contaminate livestock feed and water. This poses a threat for livestock as well as humans working in the facility (Daniels et al. 2003, Kirk et al. 2002).
Pigeon are social; they live together in large flocks and can produce 6 to 11 young per nest. Even when numbers are removed from the initial flock immigrant pigeons tend to move in their place (Murton et al. 1972). Previous studies have found that if pigeons are provided an abundant and a constant food source, they will not utilize multiple feeding sites (Carlson et al. 2011). These factors combined makes regulating pigeon numbers very difficult for farmers especially with limited money.
Pigeon and starling nesting and breeding habits also directly cause a significant amount of building damage to the dairy complexes. In a study in 2008, Wackernagel and Geigenfeind introduced new designs to agricultural buildings to eradicate the presence of pigeons in the buildings. Pigeons have a total surface area of 6x6 inches so in designing these new dairy complexes openings wouldn’t allow the access of pigeons to get into the building. This exclusion is essential as the nesting and breeding in the buildings over time deteriorates the structural stability due to large amounts of feces. The methods used by Wackernagel and Geigenfeind (2008) were successful in lowering pigeon populations but many farmers do not have the resources to completely reconstruct their barns so we sought to explore a more inexpensive alternative.
Since structural changes to the dairy complexes in this study are not an option as the financial costs are extremely high, we looked at a non-lethal way to manage nuisance birds. Lethal practices have been widely used as control method for nuisance birds in barns and the problem continues to be present annually (USDA APHIS | Wildlife Service 2019). We introduced the use of non-lethal methods of managing nuisance bird populations by attracting aerial predators to manmade perches to lower nuisance bird abundance.
Having an elevated area such as trees or perches is an important factor needed for most raptor species. Elevated areas or perches are useful for hunting, resting, and feeding for most birds of prey (Reinert 1984). Perches can be useful for raptors when there is a lack of available perch sites in a given area. Installing perches in agricultural areas provides a mutual benefit for the raptor species and for farmers. Agricultural areas tend to have an abundance of prey species such as voles or smaller birds yet have a lack of suitable perch areas due to clear cutting for use of fields. This mutual relationship of pest control while providing a useful roost spot for raptors could be very beneficial and a cheaper alternative for nuisance control (Wong and Kross 2018). Due to these factors we are seeking to increase the presence of raptors and decrease the presence of nuisance species of birds at dairy facilities.
A variety of non-lethal methods have attempted to manage nuisance birds in agricultural settings, but few have been a long-term solution because of high availability of nesting, food, and immigration or emigration of birds. The attraction of natural predators such as raptors to perching sites in an agricultural setting needs to be tested for its efficiency (Wong and Kross 2018). Raptors or birds of prey are a vastly studied taxonomic group of birds but there haven’t been any studies linking raptor presence to management of nuisance species. There is a gap in the knowledge known about how to control these nuisance species and how the use of raptor perch installation can help to lower their populations. We intend to investigate if the presence of raptors affect abundance of nuisance birds at dairy facilities.
The null hypothesis (Ho) is that nuisance bird abundance will not differ before and after perches are installed while the alternate hypothesis (H1) is that nuisance bird abundance will differ after perches are installed. The independent variable for this research is perch presence while the dependent variable is the number of nuisance birds in area. In addition, there are multiple confounding variables that could affect the dependent and independent variable. Farm size, weather, immigration/emigration of birds, food availability/storage, food scheduling, and perching availability are all variables that could affect our research.
STUDY AREA
This study was conducted around Cobleskill in Schoharie County, New York at 4 different dairy barn facilities (Figure 1). These dairy farms are mostly agricultural fields yet there is a mixture of hardwoods and conifer forests near the barns. All 4 farms conduct similar farming methods and have been family farms passed through generations.
The 4 dairy barn complexes all shared similarities in they used a mixture of free stall and tie stall for the dairy cows and silage was stored in silage pits or bunkers covered with tarps. Another shared trait across all the study areas are the ease of access to nesting areas in the rafters at these dairy complexes. Barn doors and gaps in the roof don’t have a metal mesh, slowing access for birds into the barns. Tissiere farms (Figure 1A) is the smallest of the farms with 285 head of Holstein Friesian. The Tissiere farm consists of a largely open area with very little natural roosting availability near the barn complexes and having a total of 257.785 hectares of land. Stanton Farms (Figure 1B) has both Holstein Friesian and Jersey cattle with a total of 440 head. The Stanton farm consists of the most natural roosting availability and the farm consisted of a total of 158.232 hectares. The Phelan’s farm on West Fulton Rd (Figure 1C) has 325 head of cows dominated by Holstein Friesian cattle. The farm has a total of 169.159 hectares and is lacking natural roosting for raptors near the barn complexes. Cacciola Farms (Figure 1D) has a total of 380 head of cattle consisting of Holstein Friesian and Jersey cattle. The Cacciola Farm was the control farm and had a total of 182.1085 hectares and has a very small amount of roosting availability much like the other farms. Each of the 4 farms have used previous lethal control methods with the New York State Department of Environmental Conservation (NYS DEC). They used shooting and gas to lower populations of nuisance birds yet at the time of this study these other control methods weren’t being conducted.
METHODS
We conducted pre and post surveys of pigeon and starling populations at each facility. Pre-surveys were conducted 3 times prior to perch installment farm from 6th through the 13th March 2019. Surveys were conducted between 0900-1300 hours in the pre and post surveys. Population counts were conducted by walking around the property and inside the barns while recording how many pigeons and starling are observed. Additional confounding factors were recorded such as weather, temperature, wind speed, and cloud cover. This was recorded to help determine if nuisance population varied based upon raptor presence or due to other confounding variables or a combination of both. Once the perches were placed, 3 post-treatment surveys were conducted 3 weeks after perches were installed from 22nd through the 28th April 2019. Survey times varied and were conducted from 0930-1100 and 1230-1615. This allowed 3 weeks for raptors to become acclimated to the new structures.
A control farm at Cacciola farms was added to the project in early April that didn’t have any perch placement. This was added to give insight into season fluctuations in nuisance bird abundances in the absence of predator controls. Pre-surveys at the control farm were conducted from 4th through the 8th April 2019 both early morning 0830-1000 and one midafternoon at 1300. Post-surveys were conducted in the same dates as the other 3 farms.
Three perches were placed at each barn facility to attract raptors. Also, to give raptors the ability to perch, 3 perching locations at each farm were installed. Perches were constructed of 0.05 by 0.10-meter piece of wood that stands 3.048 meters tall. At the top of the 3.048-meter perch is a 0.61-meter cross section allowing the raptors to perch and watch for prey. The perches were anchored into the ground using 1.82-meter garden posts. Posts were driven 0.91-meter into the ground and then bolted to the perch. Perch placement was chosen working with farmers to ensure no conflict with their daily duties and in locations to enhance the usability for raptors such as higher elevated areas (Preston 1980). Perches were placed near feeding areas and access points to barn within 50 meters. To ensure that the raptors were present to the area perches were monitored by trail cameras. The cameras were mounted to a 0.30 by 0.20-meter piece of plywood angled at 30 degrees to point the camera directly toward the perching top.
RESULTS
There was a 91.31% decrease in nuisance bird population from pre to post survey in our experimental sites (Figure 2). Pigeon and starling population means were also compared. Average pigeon population decreased 74.51% and average starling population decreased 93.08% from pre to post survey in our sites.
The only study site where raptors were captured on trail cameras using installed perches was Stanton property. Perched raptor species consisted of great horned owl (Bubo virginianus), barred owl (Strix varia), and American kestrel (Strix varia). A red-tailed hawk was captured in the background of the perch yet not on it. Each species had multiple visits to the perches over the course of the study.
A descriptive statistical analysis showed pre-survey nuisance bird populations at study sites had a mean of 416.77, median of 341, kurtosis of -1.01, and skewness of 0.73. Post-survey nuisance bird population had a mean of 36.22, median of 28, kurtosis of -1.97, and skewness of 0.36. A q-q plot showed the data was normally distributed so a t-test for unequal variances was conducted to compare the pre-population to post-population of nuisance birds at experimental sites. We found that pre- and post-populations differed significantly (variance pre=79613.44, variance post=245.94, n=9, d.f=8, t stat=4.03, p=0.003, and t-critical=2.3) which rejects H0. We also evaluated changes in the number of nuisance birds at the control site to assess seasonal change and not presence of raptors at perches. The p-value for pre and post population t-test for the control farm was 0.02 (variance pre=4645.33, variance pro=876, n=3, d.f=2, t stat=3.94, and t-critical=3.18) indicating that the significant difference is due to seasonal change.
A correlation coefficient r was measured between temperatures (x) and nuisance bird population (y) to calculate relationship between the two variables. Nuisance bird populations declined from March to April (r = -0.264) (Figure 3). As temperature (C°) increased nuisance bird populations decreased.
DISCUSSION
The p-value for pre and post population t-test of study sites was 0.003 < 0.05 which rejects the null and supports the alternate hypothesis that perches have an influence on nuisance bird population. Yet, our control site also had a value of 0.02 < 0.05. Since the control site without perches also had a p value < 0.05 it doesn’t allow us to accept the alternate since there was also a significant change in population without perches being present. Even though our original hypothesis cannot be supported they’re other factors collected that influence nuisance bird abundance on dairy barn facilities.
This study supports that weather and seasonal change impacted the presence of nuisance birds at dairy facilities. The seasons transitioning from winter to spring and having temperatures increase over time may have caused nuisance birds to leave their wintering roosts in for spring migration (Cabe 1999). The starling pre-survey average population during the winter to spring post-survey dropped at a significant 93.08% possibly because of high dispersal rates of juvenile starlings moving great distances in search of breeding (Cabe 1999). Pigeons showed a 74.51% decrease showing a change but not nearly as drastic as the change in starlings (Figure 3). Pigeons are a more local population that stays resident to dairy complexes (Carlson et al. 2011).
We found that the 3 weeks that perches were observed by trail cameras wasn’t enough time for raptors to acclimate to the perches and begin using them at most sites. Manmade perch effectiveness is dependent on the types of raptors you are targeting (Reinert 1984). At Stanton farms we did have raptor species use the perches but had none at Phelan’s and Tissiere’s. The 3 raptor species (great horned owl, barred owl, and american kestrel) all observed in multiple photos using the perches at Stanton farms. We suggested that the use of these manmade perches at Stanton’s was due to the prevalent natural perching forest in the vicinity of the barns. Phelan’s and Tissiere’s farms in open fields had little to no natural perching near the barns and it may be that the acclimation of these perches at these farms may take longer.
When conducting this project there were sources of error when collecting data. Initially, performing pre-survey instalment surveys there was a method error when recording population. When birds were flying in flocks, populations were underestimated, and we couldn’t determine a correction factor. This is due to there being a large decrease in population for post survey population and little to no large flocks to take pictures of to create a correction factor. Heisterberg et al. in 1984, found European starlings once at a winter roost didn’t leave till spring migration, so the use of 3 or more surveys in the future could give a good representation of each dairy complex's population. Population recording techniques should be improved for future studies using more people and pictures for more accurate numbers. Another error when performing counts of population is the possibility of counting the same bird multiple times. This is from birds being flushed from barn facilities and joined the outside barn population or just maneuvering around the property. A factor that had a recorded effect on data collection was the study being conducted in transition from winter to spring season. This change in season caused emigration of starlings and didn’t allow for proper assessment of raptor presence effects on nuisance birds. Future studies should be conducted over one season, such as beginning of winter in January, instead of in transition between two to avoid immigration and emigration of birds as much as possible.
ACKNOWLEDGMENTS
I would like to thank the State University of New York at Cobleskill for providing the project with 6 trail cameras to observe the perches and Dr. A. Quinn for her suggestions and guidance throughout the project. Thank you to Assistant Technician E. B. Struening that assisted with equipment, acquiring perch materials, and the building of the perches. In addition, I would like to thank the farmers; E. Stanton, R. Tissiere, M. Phelan, and K. Cacciola for allowing access to their properties to conduct this project. Lastly, I would like to thank GCobb for aiding in perch installment.
LITERATURE CITED
Birds and their droppings can carry over 60 diseases. 2014. <https://www.medicalnewstoday.com/releases/61646.php>. Accessed 2 May 2019.
Cabe, P. R. 1999. Dispersal and Population Structure in the European Starling. The Condor 101:451–454.
Carlson, J. C., L. Clark, M. F. Antolin, and M. D. Salman. 2011. Rock pigeon use of livestock facilities in northern Colorado: implications for improving farm bio-security. Human-Wildlife Interactions 5:112–122.
Daniels, M. J., M. R. Hutchings, and A. Greig. 2003. The risk of disease transmission to livestock posed by contamination of farm stored feed by wildlife excreta. Epidemiology & Infection 130: 561-568.
Depenbusch Brandon E., Drouillard James S., and Lee Charles D. 2011. Feed depredation by European starlings in a Kansas feedlot. Human-Wildlife Interactions 5:58.
Heisterberg, J. F., C. E. Knittle, O. E. Bray, D. F. Mott, and J. F. Besser. 1984. Movements of Radio-Instrumented Blackbirds and European Starlings among Winter Roosts. The Journal of Wildlife Management 48:203.
Kirk, J. H., E. Atwill, C. Holmberg, M. Arana, C. Collar, D. Ghiriardelli, G. Higginbotham, G. Markagaard, D. Mullinax, and A. Wubishet. 2002. Prevalence of and risk for salmonella in water offered to weaned dairy calves in California, USA. Preventine Veterinary Medicine 54: 169-178.
Murton, R. K., C. F. B. Coombs, and R. J. P. Thearle. 1972. Ecological studies of the feral pigeon Columbia livia var. I. population, breeding biology and methods on control. Journal of Applied Ecology 9:835-874.
Preston, C. R. 1980. Differential perch site selection by color morphs of the red-tailed hawk (Buteo jamaicensis). The Auk. 97:782-789.
Reinert, S. E. 1984. Use of introduced perches by raptors: experimental results and management implications. Raptor Research. 18:25-29.
The Cornell Lab of Ornithology. 2019. European starling. https://www.allaboutbirds.org/guide/European_Starling/overview, Accessed 9 March 2019.
United States Department of Agriculture Animal Plant and Health Inspection Service [USDA APHIS]. 2019. Wildlife Services. <https://www.aphis.usda.gov/aphis/ourfocus/wildlifedamage/SA_Program_Overview>. Accessed 21 Apr 2019.
Wackernagel, H. A., and I. Geigenfeind. 2008. Protecting buildings against feral pigeons. European Journal of Wildlife Research 54:715-721.
Wells, S. J., P. J. Fedorka-Cray, D. A. Dargatz, K. Ferris, and A. Green. 2001. Fecal shedding of salmonella spp. By dairy cows on farm and at cull cow markets. Journal of Food Protection 64: 3-11.
Wong, E. L., and S. M. Kross. 2018. Effects of perch location on wintering raptor use of artificial perches in California vineyard. Journal of Raptor Research 52:250-256.
Eric k. Mathiesen, [1] Department of Fisheries, Wildlife and Environmental Studies. State University of New York at Cobleskill, 106 Suffolk Cir. Cobleskill, NY 12043, USA
KATHERINE A. VAHSEN, [2] Department of Fisheries, Wildlife and Environmental Studies. State University of New York at Cobleskill, 106 Suffolk Cir. Cobleskill, NY 12043, USA
ABSTRACT: Rock pigeon (Columbia livia) and European starling (Sturnus vulgaris) are viewed generally as a nuisance species in many different environments such as city infrastructure and at farms. We intend to investigate if the presence of raptors affect abundance of nuisance birds at dairy facilities. This study is being conducted around Cobleskill in Schoharie County, New York at 4 different dairy barn facilities. To assess if the presence of raptors influences nuisance bird abundance at dairy facilities, we conducted pre and post surveys of pigeon and starling abundance at each facility. Three perches were placed at each barn facility to increase chances of perches being utilized by raptors. Raptor species using perches were only recorded at one of the study sites, Stanton farms. T-test for unequal variances was conducted separately for the pre and post tests and control site to determine if change in nuisance bird population is due to seasonal change and not presence of raptors at perches. The p-value for pre and post population t-test for the control farm was 0.02 (variance pre=4645.33, variance pro=876, n=3, d.f=2, t stat=3.94, and t-critical=3.18) indicating that the significant difference is due to seasonal change. This study supported that weather and seasonal change impacted the presence of nuisance birds at dairy facilities rather than raptor presence.
___________________________
KEYWORDS abundance, Columbia livia, dairy facilities, European starling, non-lethal, nuisance birds, populations, perches, raptors, rock pigeon, Sturnus vulgaris
Rock pigeons (Columbia livia) and European starling (Sturnus vulgaris) are viewed generally as a nuisance species in many different environments such as city infrastructure and at farms. Pigeons and starlings are a non-native species that originated from Eurasia and were introduced to North America. Pigeons were brought over during the 1600s while starlings were introduced in the 19th century (Cornell Lab of Ornithology). Since arriving in North America pigeons and starlings have rapidly grown and now populate most of the continent. They are viewed as a nuisance species due to the damage they cause to buildings and diseases transmitted from constant nesting and droppings (Wackernagel and Geigenfeind 2008). This poses a threat to human and animal health due to spread of pathogens from feces to surrounding people, livestock, or other species of birds (Carlson et al. 2011). European starlings in large flocks at winter roosting sites on dairy complexes also cause a significant financial loss. A single adult starling is capable of consuming 1 kg of feed a day, and in large flocks' of 1000 birds, they can consume up to $84 ($0.03/lb) a day in feed (Depenbush et al. 2011).
The presence of nuisance birds in dairy complexes poses a threat to humans and cows for disease transmission of up to 60 different diseases consisting of Salmonellosis, E. coli, Histoplasmosis and many more (Birds and their droppings can carry over 60 diseases 2014). In a study by Wells et al. (2001) 91 milk cows and 97 cull milk cows’ feces were tested for salmonella. The results showed that 5.4% of the fecal samples in milk cows were positive with salmonella and 18.1% of cull milk cows from nuisance birds. Wells et al.’s findings didn’t directly link salmonella to pigeons or starlings. Yet, nuisance birds are able to transmit diseases if they’re infected through their feces which can contaminate livestock feed and water. This poses a threat for livestock as well as humans working in the facility (Daniels et al. 2003, Kirk et al. 2002).
Pigeon are social; they live together in large flocks and can produce 6 to 11 young per nest. Even when numbers are removed from the initial flock immigrant pigeons tend to move in their place (Murton et al. 1972). Previous studies have found that if pigeons are provided an abundant and a constant food source, they will not utilize multiple feeding sites (Carlson et al. 2011). These factors combined makes regulating pigeon numbers very difficult for farmers especially with limited money.
Pigeon and starling nesting and breeding habits also directly cause a significant amount of building damage to the dairy complexes. In a study in 2008, Wackernagel and Geigenfeind introduced new designs to agricultural buildings to eradicate the presence of pigeons in the buildings. Pigeons have a total surface area of 6x6 inches so in designing these new dairy complexes openings wouldn’t allow the access of pigeons to get into the building. This exclusion is essential as the nesting and breeding in the buildings over time deteriorates the structural stability due to large amounts of feces. The methods used by Wackernagel and Geigenfeind (2008) were successful in lowering pigeon populations but many farmers do not have the resources to completely reconstruct their barns so we sought to explore a more inexpensive alternative.
Since structural changes to the dairy complexes in this study are not an option as the financial costs are extremely high, we looked at a non-lethal way to manage nuisance birds. Lethal practices have been widely used as control method for nuisance birds in barns and the problem continues to be present annually (USDA APHIS | Wildlife Service 2019). We introduced the use of non-lethal methods of managing nuisance bird populations by attracting aerial predators to manmade perches to lower nuisance bird abundance.
Having an elevated area such as trees or perches is an important factor needed for most raptor species. Elevated areas or perches are useful for hunting, resting, and feeding for most birds of prey (Reinert 1984). Perches can be useful for raptors when there is a lack of available perch sites in a given area. Installing perches in agricultural areas provides a mutual benefit for the raptor species and for farmers. Agricultural areas tend to have an abundance of prey species such as voles or smaller birds yet have a lack of suitable perch areas due to clear cutting for use of fields. This mutual relationship of pest control while providing a useful roost spot for raptors could be very beneficial and a cheaper alternative for nuisance control (Wong and Kross 2018). Due to these factors we are seeking to increase the presence of raptors and decrease the presence of nuisance species of birds at dairy facilities.
A variety of non-lethal methods have attempted to manage nuisance birds in agricultural settings, but few have been a long-term solution because of high availability of nesting, food, and immigration or emigration of birds. The attraction of natural predators such as raptors to perching sites in an agricultural setting needs to be tested for its efficiency (Wong and Kross 2018). Raptors or birds of prey are a vastly studied taxonomic group of birds but there haven’t been any studies linking raptor presence to management of nuisance species. There is a gap in the knowledge known about how to control these nuisance species and how the use of raptor perch installation can help to lower their populations. We intend to investigate if the presence of raptors affect abundance of nuisance birds at dairy facilities.
The null hypothesis (Ho) is that nuisance bird abundance will not differ before and after perches are installed while the alternate hypothesis (H1) is that nuisance bird abundance will differ after perches are installed. The independent variable for this research is perch presence while the dependent variable is the number of nuisance birds in area. In addition, there are multiple confounding variables that could affect the dependent and independent variable. Farm size, weather, immigration/emigration of birds, food availability/storage, food scheduling, and perching availability are all variables that could affect our research.
STUDY AREA
This study was conducted around Cobleskill in Schoharie County, New York at 4 different dairy barn facilities (Figure 1). These dairy farms are mostly agricultural fields yet there is a mixture of hardwoods and conifer forests near the barns. All 4 farms conduct similar farming methods and have been family farms passed through generations.
The 4 dairy barn complexes all shared similarities in they used a mixture of free stall and tie stall for the dairy cows and silage was stored in silage pits or bunkers covered with tarps. Another shared trait across all the study areas are the ease of access to nesting areas in the rafters at these dairy complexes. Barn doors and gaps in the roof don’t have a metal mesh, slowing access for birds into the barns. Tissiere farms (Figure 1A) is the smallest of the farms with 285 head of Holstein Friesian. The Tissiere farm consists of a largely open area with very little natural roosting availability near the barn complexes and having a total of 257.785 hectares of land. Stanton Farms (Figure 1B) has both Holstein Friesian and Jersey cattle with a total of 440 head. The Stanton farm consists of the most natural roosting availability and the farm consisted of a total of 158.232 hectares. The Phelan’s farm on West Fulton Rd (Figure 1C) has 325 head of cows dominated by Holstein Friesian cattle. The farm has a total of 169.159 hectares and is lacking natural roosting for raptors near the barn complexes. Cacciola Farms (Figure 1D) has a total of 380 head of cattle consisting of Holstein Friesian and Jersey cattle. The Cacciola Farm was the control farm and had a total of 182.1085 hectares and has a very small amount of roosting availability much like the other farms. Each of the 4 farms have used previous lethal control methods with the New York State Department of Environmental Conservation (NYS DEC). They used shooting and gas to lower populations of nuisance birds yet at the time of this study these other control methods weren’t being conducted.
METHODS
We conducted pre and post surveys of pigeon and starling populations at each facility. Pre-surveys were conducted 3 times prior to perch installment farm from 6th through the 13th March 2019. Surveys were conducted between 0900-1300 hours in the pre and post surveys. Population counts were conducted by walking around the property and inside the barns while recording how many pigeons and starling are observed. Additional confounding factors were recorded such as weather, temperature, wind speed, and cloud cover. This was recorded to help determine if nuisance population varied based upon raptor presence or due to other confounding variables or a combination of both. Once the perches were placed, 3 post-treatment surveys were conducted 3 weeks after perches were installed from 22nd through the 28th April 2019. Survey times varied and were conducted from 0930-1100 and 1230-1615. This allowed 3 weeks for raptors to become acclimated to the new structures.
A control farm at Cacciola farms was added to the project in early April that didn’t have any perch placement. This was added to give insight into season fluctuations in nuisance bird abundances in the absence of predator controls. Pre-surveys at the control farm were conducted from 4th through the 8th April 2019 both early morning 0830-1000 and one midafternoon at 1300. Post-surveys were conducted in the same dates as the other 3 farms.
Three perches were placed at each barn facility to attract raptors. Also, to give raptors the ability to perch, 3 perching locations at each farm were installed. Perches were constructed of 0.05 by 0.10-meter piece of wood that stands 3.048 meters tall. At the top of the 3.048-meter perch is a 0.61-meter cross section allowing the raptors to perch and watch for prey. The perches were anchored into the ground using 1.82-meter garden posts. Posts were driven 0.91-meter into the ground and then bolted to the perch. Perch placement was chosen working with farmers to ensure no conflict with their daily duties and in locations to enhance the usability for raptors such as higher elevated areas (Preston 1980). Perches were placed near feeding areas and access points to barn within 50 meters. To ensure that the raptors were present to the area perches were monitored by trail cameras. The cameras were mounted to a 0.30 by 0.20-meter piece of plywood angled at 30 degrees to point the camera directly toward the perching top.
RESULTS
There was a 91.31% decrease in nuisance bird population from pre to post survey in our experimental sites (Figure 2). Pigeon and starling population means were also compared. Average pigeon population decreased 74.51% and average starling population decreased 93.08% from pre to post survey in our sites.
The only study site where raptors were captured on trail cameras using installed perches was Stanton property. Perched raptor species consisted of great horned owl (Bubo virginianus), barred owl (Strix varia), and American kestrel (Strix varia). A red-tailed hawk was captured in the background of the perch yet not on it. Each species had multiple visits to the perches over the course of the study.
A descriptive statistical analysis showed pre-survey nuisance bird populations at study sites had a mean of 416.77, median of 341, kurtosis of -1.01, and skewness of 0.73. Post-survey nuisance bird population had a mean of 36.22, median of 28, kurtosis of -1.97, and skewness of 0.36. A q-q plot showed the data was normally distributed so a t-test for unequal variances was conducted to compare the pre-population to post-population of nuisance birds at experimental sites. We found that pre- and post-populations differed significantly (variance pre=79613.44, variance post=245.94, n=9, d.f=8, t stat=4.03, p=0.003, and t-critical=2.3) which rejects H0. We also evaluated changes in the number of nuisance birds at the control site to assess seasonal change and not presence of raptors at perches. The p-value for pre and post population t-test for the control farm was 0.02 (variance pre=4645.33, variance pro=876, n=3, d.f=2, t stat=3.94, and t-critical=3.18) indicating that the significant difference is due to seasonal change.
A correlation coefficient r was measured between temperatures (x) and nuisance bird population (y) to calculate relationship between the two variables. Nuisance bird populations declined from March to April (r = -0.264) (Figure 3). As temperature (C°) increased nuisance bird populations decreased.
DISCUSSION
The p-value for pre and post population t-test of study sites was 0.003 < 0.05 which rejects the null and supports the alternate hypothesis that perches have an influence on nuisance bird population. Yet, our control site also had a value of 0.02 < 0.05. Since the control site without perches also had a p value < 0.05 it doesn’t allow us to accept the alternate since there was also a significant change in population without perches being present. Even though our original hypothesis cannot be supported they’re other factors collected that influence nuisance bird abundance on dairy barn facilities.
This study supports that weather and seasonal change impacted the presence of nuisance birds at dairy facilities. The seasons transitioning from winter to spring and having temperatures increase over time may have caused nuisance birds to leave their wintering roosts in for spring migration (Cabe 1999). The starling pre-survey average population during the winter to spring post-survey dropped at a significant 93.08% possibly because of high dispersal rates of juvenile starlings moving great distances in search of breeding (Cabe 1999). Pigeons showed a 74.51% decrease showing a change but not nearly as drastic as the change in starlings (Figure 3). Pigeons are a more local population that stays resident to dairy complexes (Carlson et al. 2011).
We found that the 3 weeks that perches were observed by trail cameras wasn’t enough time for raptors to acclimate to the perches and begin using them at most sites. Manmade perch effectiveness is dependent on the types of raptors you are targeting (Reinert 1984). At Stanton farms we did have raptor species use the perches but had none at Phelan’s and Tissiere’s. The 3 raptor species (great horned owl, barred owl, and american kestrel) all observed in multiple photos using the perches at Stanton farms. We suggested that the use of these manmade perches at Stanton’s was due to the prevalent natural perching forest in the vicinity of the barns. Phelan’s and Tissiere’s farms in open fields had little to no natural perching near the barns and it may be that the acclimation of these perches at these farms may take longer.
When conducting this project there were sources of error when collecting data. Initially, performing pre-survey instalment surveys there was a method error when recording population. When birds were flying in flocks, populations were underestimated, and we couldn’t determine a correction factor. This is due to there being a large decrease in population for post survey population and little to no large flocks to take pictures of to create a correction factor. Heisterberg et al. in 1984, found European starlings once at a winter roost didn’t leave till spring migration, so the use of 3 or more surveys in the future could give a good representation of each dairy complex's population. Population recording techniques should be improved for future studies using more people and pictures for more accurate numbers. Another error when performing counts of population is the possibility of counting the same bird multiple times. This is from birds being flushed from barn facilities and joined the outside barn population or just maneuvering around the property. A factor that had a recorded effect on data collection was the study being conducted in transition from winter to spring season. This change in season caused emigration of starlings and didn’t allow for proper assessment of raptor presence effects on nuisance birds. Future studies should be conducted over one season, such as beginning of winter in January, instead of in transition between two to avoid immigration and emigration of birds as much as possible.
ACKNOWLEDGMENTS
I would like to thank the State University of New York at Cobleskill for providing the project with 6 trail cameras to observe the perches and Dr. A. Quinn for her suggestions and guidance throughout the project. Thank you to Assistant Technician E. B. Struening that assisted with equipment, acquiring perch materials, and the building of the perches. In addition, I would like to thank the farmers; E. Stanton, R. Tissiere, M. Phelan, and K. Cacciola for allowing access to their properties to conduct this project. Lastly, I would like to thank GCobb for aiding in perch installment.
LITERATURE CITED
Birds and their droppings can carry over 60 diseases. 2014. <https://www.medicalnewstoday.com/releases/61646.php>. Accessed 2 May 2019.
Cabe, P. R. 1999. Dispersal and Population Structure in the European Starling. The Condor 101:451–454.
Carlson, J. C., L. Clark, M. F. Antolin, and M. D. Salman. 2011. Rock pigeon use of livestock facilities in northern Colorado: implications for improving farm bio-security. Human-Wildlife Interactions 5:112–122.
Daniels, M. J., M. R. Hutchings, and A. Greig. 2003. The risk of disease transmission to livestock posed by contamination of farm stored feed by wildlife excreta. Epidemiology & Infection 130: 561-568.
Depenbusch Brandon E., Drouillard James S., and Lee Charles D. 2011. Feed depredation by European starlings in a Kansas feedlot. Human-Wildlife Interactions 5:58.
Heisterberg, J. F., C. E. Knittle, O. E. Bray, D. F. Mott, and J. F. Besser. 1984. Movements of Radio-Instrumented Blackbirds and European Starlings among Winter Roosts. The Journal of Wildlife Management 48:203.
Kirk, J. H., E. Atwill, C. Holmberg, M. Arana, C. Collar, D. Ghiriardelli, G. Higginbotham, G. Markagaard, D. Mullinax, and A. Wubishet. 2002. Prevalence of and risk for salmonella in water offered to weaned dairy calves in California, USA. Preventine Veterinary Medicine 54: 169-178.
Murton, R. K., C. F. B. Coombs, and R. J. P. Thearle. 1972. Ecological studies of the feral pigeon Columbia livia var. I. population, breeding biology and methods on control. Journal of Applied Ecology 9:835-874.
Preston, C. R. 1980. Differential perch site selection by color morphs of the red-tailed hawk (Buteo jamaicensis). The Auk. 97:782-789.
Reinert, S. E. 1984. Use of introduced perches by raptors: experimental results and management implications. Raptor Research. 18:25-29.
The Cornell Lab of Ornithology. 2019. European starling. https://www.allaboutbirds.org/guide/European_Starling/overview, Accessed 9 March 2019.
United States Department of Agriculture Animal Plant and Health Inspection Service [USDA APHIS]. 2019. Wildlife Services. <https://www.aphis.usda.gov/aphis/ourfocus/wildlifedamage/SA_Program_Overview>. Accessed 21 Apr 2019.
Wackernagel, H. A., and I. Geigenfeind. 2008. Protecting buildings against feral pigeons. European Journal of Wildlife Research 54:715-721.
Wells, S. J., P. J. Fedorka-Cray, D. A. Dargatz, K. Ferris, and A. Green. 2001. Fecal shedding of salmonella spp. By dairy cows on farm and at cull cow markets. Journal of Food Protection 64: 3-11.
Wong, E. L., and S. M. Kross. 2018. Effects of perch location on wintering raptor use of artificial perches in California vineyard. Journal of Raptor Research 52:250-256.
Figure Captions
Figure 1 A. Phelan farm. Located in Warnerville, NY 12187 driving south along W Fulton Road. B. Stanton farm. Located in Cobleskill, NY 12043 by cross section of Phillip Schuyler Rd, Lake Rd, and Lamont District Rd. C. Tissiere farm. Located in Cobleskill, NY 12043 driving West along NY-10 through Hyndsville then West on Clove Rd. D. Cacciola farm. Located in Cobleskill, NY 12043 on Grovenors Corners Rd.
Figure 2. Average of nuisance bird population (pigeons and starlings) from pre and post surveys of perch installment sites including calculated standard error. Pre-surveys were conducted from 6th through the 13th March 2019. Post-surveys were conducted from 22nd through the 28th April 2019.
Figure 3. Data collected over time for pre and post surveys of temperature (C°) when conducting nuisance bird population (pigeons and starlings) surveys for all study sites including the control. Data collected from March 6th through April 28th 2019.
Figure 1 A. Phelan farm. Located in Warnerville, NY 12187 driving south along W Fulton Road. B. Stanton farm. Located in Cobleskill, NY 12043 by cross section of Phillip Schuyler Rd, Lake Rd, and Lamont District Rd. C. Tissiere farm. Located in Cobleskill, NY 12043 driving West along NY-10 through Hyndsville then West on Clove Rd. D. Cacciola farm. Located in Cobleskill, NY 12043 on Grovenors Corners Rd.
Figure 2. Average of nuisance bird population (pigeons and starlings) from pre and post surveys of perch installment sites including calculated standard error. Pre-surveys were conducted from 6th through the 13th March 2019. Post-surveys were conducted from 22nd through the 28th April 2019.
Figure 3. Data collected over time for pre and post surveys of temperature (C°) when conducting nuisance bird population (pigeons and starlings) surveys for all study sites including the control. Data collected from March 6th through April 28th 2019.
Figure 1
3 May 2019
Eric Mathiesen Loomacres Airport Wildlife Biologist
Katherine Vahsen
State University of New York at Cobleskill
106 Suffolk Circle
Cobleskill, NY 12043
(845) 663-3827
[email protected]
RH: Mathiesen and Vahsen • Impact of Raptors on Nuisance Birds
Eric k. Mathiesen, [1] Department of Fisheries, Wildlife and Environmental Studies. State University of New York at Cobleskill, 106 Suffolk Cir. Cobleskill, NY 12043, USA
KATHERINE A. VAHSEN, [2] Department of Fisheries, Wildlife and Environmental Studies. State University of New York at Cobleskill, 106 Suffolk Cir. Cobleskill, NY 12043, USA
Eric Mathiesen Loomacres Airport Wildlife Biologist
Katherine Vahsen
State University of New York at Cobleskill
106 Suffolk Circle
Cobleskill, NY 12043
(845) 663-3827
[email protected]
RH: Mathiesen and Vahsen • Impact of Raptors on Nuisance Birds
Eric k. Mathiesen, [1] Department of Fisheries, Wildlife and Environmental Studies. State University of New York at Cobleskill, 106 Suffolk Cir. Cobleskill, NY 12043, USA
KATHERINE A. VAHSEN, [2] Department of Fisheries, Wildlife and Environmental Studies. State University of New York at Cobleskill, 106 Suffolk Cir. Cobleskill, NY 12043, USA