Figure 1: Bird count data for Southwest Florida International Airport after the employment of a single Border Collie on Feb. 11, 1999
Southwest Florida International Airport
Border Collie Effectiveness as a Method Of Wildlife Control
Date: December 1999
Prepared for: Lee County Port Authority 16000 Chamberlin Parkway., Suite 8671
Fort Myers, FL 33913
Prepared by: Kevin L. Erwin Consulting Ecologist, Inc. 2077 Bayside Parkway
Fort Myers, FL 33901
TABLE OF CONTENTS
Executive Summary
Introduction
Overview
Wildlife Observations
Wildlife
Behavior and Habitat Use of Wildlife
Wildlife Comparisons
Wildlife Responses to Border Collie
Recommended Areas to Utilize the Border Collie
Recommendations to Improve Wildlife Program
Conclusion
References
In the early 1980's, the Southwest Florida International Airport (RSW) operations staff started recording aircraft/wildlife strike data. The most notable strike occurred in March 1995 when a passenger plane struck two large wading birds and caused damage to the aircraft. Due to resulting aircraft damage, the Federal Aviation Administration (FAA) encouraged RSW to conduct an ecological study in accordance with FAA Regulations (FAR) 139.337. As a result, the Lee County Port Authority (LCPA) contracted an 11 month ecological study with the United States Department of Agriculture (USDA) from June 1997 to May 1998. Approximately 133 wildlife species were recorded within and just outside of the air operations area (AOA). The study indicated that mostly birds utilized the aircraft movement area. In coordination with the Florida Fish and Wildlife Conservation Commission (FWC), the LCPA contracted with Kevin L. Erwin Consulting Ecologist (KLECE) in 1998 to work with the LCPA to develop a Wildlife Habitat Management Plan. The FWC requested this plan as a requirement of Permit No. WX98037. This plan was to help minimize future sandhill crane and other listed wildlife species mortalities at RSW. The wildlife Habitat Management Plan was approved by the FWC on January 25, 1999. The plan provided recommendations to modify habitats within the AOA and the potential use of a border collie to harass wildlife. After considerable research, the LCPA found that border collies respond well to whistle and verbal commands therefore making the dog safe to use within the aircraft movement area. Border collie's natural instincts are to herd animals and have been bred to avoid attack. These traits are excellent for the AOA in that listed bird species could be harassed out of the AOA without causing harm to the species. A border collie was purchased and its initial training and use within the AOA by operations was February 11, 1999.
KLECE conducted wildlife monitoring within the AOA from February 1999 through September 15, 1999. Additional alligator monitoring was conducted for three nights in August to obtain a better population estimate of alligators within the AOA. Wildlife monitoring was initially conducted to track wildlife reactions to harassment from the border collie. After observing that the border collie had a positive effect on causing ground foraging species to flush away from the border collie, it was decided to intensify the frequency of monitoring events from June to September 15, 1999. Monitoring and data analysis was conducted so that general scientific comparisons could be made between the June through September 15 USDA 1997 and KLECE 1999 datasets. The USDA 1997 study was conducted before the use of the border collie and habitat modification, while the KLECE 1999 dataset was collected after border collie use and some habitat modifications. Due to the large number of wildlife species observed in 1997 and 1999, wildlife categories were used to analyze and compare the datasets. Only the most abundant or common species of each category was analyzed and discussed. This helped focus on wildlife problem areas and determining the reasons for reductions of wildlife within the AOA as a result of the border collie, other harassment techniques, or habitat modifications.
The 10 main wildlife categories recorded in 1999 within the AOA from the most abundant to the least abundant included the following: waterfowl, wading birds-shore birds, crows-blackbirds, amphibians-reptiles, raptors-vultures, swallows, doves-pigeons, other birds, starlings, and mammals. A total of 92.1% of the wildlife observed was included in the first three categories.
Wildlife data was compared between these 10 wildlife categories for the USDA 1997 and the KLECE 1999 studies. In 1999, there was an overall reduction in abundance of the 10 most common species of wading birds, waterfowls, and blackbirds as compared to 1997. Wading birds and shore birds are very responsive to the border collie and their reduced abundance within the AOA is most likely due to the border collie. Overall, 1999 wading birds and shorebirds abundance was less than half that observed in 1997.
Behavior and habitat use of wildlife within the AOA was also observed in 1999. The most important observation in 1999 was that no nesting or roosting of Florida sandhill cranes or other wading birds was observed within the AOA. In 1998, two pairs of sandhill cranes were observed both roosting and nesting within the AOA. Operation agents using the border collie prevented sandhill cranes and other wading birds from roosting and nesting within the AOA.
The border collie is very effective in harassing ground foraging wildlife such as wading birds, shorebirds, and blackbirds. It is also effective for waterfowl in small deepwater habitats that are narrow where the waterfowl can see the approaching dog. The border collie is not effective for species that spend most of their time flying or perching such as vultures, raptors, and swallows. It is also not effective for waterfowl located in large deepwater habitats. Nocturnal alligator monitoring results estimates that there were between 36 and 40 alligators located within the AOA. Therefore, the border collie is not allowed to work in deepwater habitats. Before the use of the border collie there were large aggregates (10-100 individuals) of wading birds and waterfowl. After the border collie, aggregate size decreased significantly. The only exception being for common moorhens and cattle egrets. Most wading birds, shore birds, waterfowl, and blackbirds that were approachable by the border collie were very responsive and flushed immediately. Several species of listed birds such as the Florida sandhill crane and tricolored heron would have to be flushed two to three times before they were flushed out of the AOA. Only a few individuals of tricolored herons and anhingas illustrated ambivalent behavior to the border collie. Overall, the dog handlers using the border collie successfully reduced the abundance of wading birds utilizing the AOA. Most of the wading birds and shore birds are so responsive to the border collie that these species flush when the vehicle transporting the border collie approaches within 200 to 300 feet of the birds. Aircraft/wildlife strikes have greatly decreased since the use of the border collie and the incorporation of habitat modifications such as cattail control and shrub removal. Wildlife flights over the runway and taxiway still exist; however, their frequency has decreased due to the overall reduction of wildlife within the AOA.
It is recommended that the border collie be used more than twice a day. It should be used at different times of the day and especially during heavier wildlife utilization of the AOA. A detailed log should be kept each time the dog is used to record wildlife location, abundance, and behavioral responses to the border collie. Florida sandhill cranes and other listed wading birds should be harassed from key locations within the AOA to prevent their abundance, nesting, roosting, and foraging. These recommendations would require a handler whose major responsibility would be to harass wildlife with the use of the border collie. Habitat modifications should continue according to the short-term and long-term recommendations of the Habitat Management Plan. Wildlife monitoring should continue in order to determine wildlife problems within the AOA and to adjust border collie use, other harassment techniques, and habitat modifications based on wildlife data and observations.
In February 1999, a new type of wildlife harassment program was initiated at the RSW. A trained border collie was added to the operations staff. RSW is the first commercial airport to test the use of a border collie as another alternative of harassment. Monitoring wildlife use of RSW after the implementation of the border collie and comparing the results to the USDA 1997 Ecological Study (USDA 1998) will provide insight as to the effectiveness of the border collie. Use of the border collie to reduce wildlife within the AOA is part of a pilot program to determine if this innovative approach to harassing wildlife is effective or not. The scientific information collected through this pilot program will be shared with other airports throughout the country. A standard methodology for wildlife surveys was developed (Appendix 1) and used to monitor wildlife inside the AOA from February 11, 1999 to September 15, 1999 by KLECE. This will allow the KLECE 1999 study to be compared to future studies. The KLECE survey was intensified from June through September 15th so that a general comparison could be made between the 1997 USDA study (before introduction of the border collie) and the 1999 KLECE study (after introduction of the border collie). A nocturnal alligator census was also conducted within the AOA in August 1999. The purpose of the alligator survey was to establish a better estimate of the number and size of alligators within the airfield wetlands. The alligator census will be used by operations to continue the removal of alligators as they could pose a hazard to aircraft on the runway.
In the early 1980's, RSW operations staff started recording aircraft/wildlife strike data. The most notable strike occurred in March 1995 when a passenger plane struck two great blue herons during take off. The plane was forced to make a precautionary landing at the Tampa International Airport because of damage to the aircraft. Due to the damage to the aircraft, the FAA encouraged RSW to conduct an ecological study in accordance with FAA Regulation (FAR) 139.337. As a result, the LCPA contracted an 11 month ecological study with USDA from June 1997 to May 1998. Wildlife surveys were conducted at least three days per week. Approximately 133 wildlife species were recorded inside and outside of the AOA. The study indicated that the AOA was utilized mostly by birds. In coordination with the Florida Fish and Wildlife Conservation Commission (FWC), formerly the Florida Game and Fresh Water Fish Commission (FGFWFC), and the LCPA, a Wildlife Habitat Management Plan (KLECE 1998) was developed for RSW. This plan was a requirement of Permit No. WX98037 in which Special Condition No. 2 states that a Habitat Management Plan is to be submitted which will minimize the likelihood of future sandhill crane mortalities at RSW. The FWC also provided correspondence to the LCPA that indicated the proposed sandhill crane relocation plan submitted to the FWC for approval on March 25, 1998 may receive a permit only with habitat modification. The objective of the LCPA is to prevent sandhill cranes and other problem wildlife from utilizing the AOA. The Wildlife Habitat Management Plan provided 12 short term and long term recommendations to modify habitats within the AOA to reduce listed and nonlisted wildlife to be implemented over a 20 year period. Some of the recommendations have already be completed.
Part of this plan also discussed the potential use of a border collie to harass wildlife within the AOA. After much research, the RSW learned that border collies can be directed by whistle or verbal commands. Therefore, the dogs can be precisely directed at the handler's commands and would be safe to use within the AOA. The border collie can silently stalk the target instead of rushing and barking. Border collies have an instinct to herd animals but have been bred to avoid attack. This trait was important so as not to harm wildlife especially listed species. Because of the border collie's qualities and potential to successfully harass wildlife out of the AOA, the RSW purchased a border collie. Training and use of the border collie was initiated within the AOA on February 11, 1999.
Recently, KLECE conducted wildlife monitoring within the AOA (February 1999 through September 1999). This monitoring was initially conducted to track wildlife reactions to harassment from the border collie, which was introduced to the RSW on February 11th. From June 10, 1999 to September 15, 1999 the frequency of wildlife surveys was increased within the AOA so that a general comparison of wildlife utilization before the border collie (USDA) and after (KLECE) could be made. The comparisons of these two studies is part of a pilot program to share scientific analysis information with other airports to illustrate if wildlife utilization is reduced or not by use of the border collie.
During the USDA and KLECE wildlife studies, the AOA was utilized not only by sandhill cranes, but also by a variety of wildlife. Florida sandhill crane use of the AOA is of concern because aircraft/wildlife strikes could cause significant damage to aircraft and possibly injury to passengers. However, other wildlife such as alligators, wading birds, waterfowl, boat-tailed grackles, hawks, eagles, vultures and swallows could also cause problems either by their size, frequent crossing of the runway, or size of flights over the runway. The 1999 survey demonstrated that most of the wildlife use is associated with the east-west drainage swale south of the runway, the wet prairie northwest of the runway, the wet detention stormwater ponds at both ends of the runway, the drainage canal finger extensions south of the runway, and the freshwater marsh near the southeast end of the runway. Comparisons of the two wildlife surveys demonstrates that there has been a significant reduction in wildlife utilization at the RSW. The most significant reductions were with wading birds-shore birds (including sandhill cranes), raptors-vultures, and crows-blackbirds categories, however, average numbers of most categories decreased following introduction of the border collie, and habitat management activities within the AOA.
Wildlife reductions observed between 1997 and 1999 can be attributed to several reasons. However, from observations of these surveys it is apparent that the border collie introduced to the RSW to harass wildlife is having a significant positive effect in reducing wildlife utilization.
The effort to reduce wildlife utilization within RSW is a tiered operation. Habitat modifications are being conducted to reduce favorable habitat such as dense vegetation, roosting trees, and expanses of shallow open water. Traditional harassment activities such as pyrotechnics continue to be used, and the border collie is being used to harass wildlife that utilizes open grassy areas as well as shallow water habitats. The border collie has been very successful in harassing large wading birds, shore birds, and boat-tailed grackles feeding on the ground in grassy and shallow water habitats. Several efforts are being used jointly to discourage wildlife uses in areas that are being used for the aircraft operations area. Recent observations show that the use of the border collie is a valuable addition to the tools available to help reduce wildlife utilization at the AOA.
The initiation of a standardized wildlife monitoring methodology and program is being used to supplement existing wildlife data. This methodology will be used for future wildlife monitoring at RSW and for comparisons of wildlife use at other airports. It will also be used to identify wildlife problems and to develop solutions to reduce wildlife within the AOA.
Wildlife monitoring was conducted according to a standardized wildlife monitoring methodology (Appendix 1) from February through September 15, 1999. Wildlife monitoring was conducted following a fixed route within the AOA. Wildlife observations were taken at 47 observation stations staked and numbered in the field. Each of the 54 monitoring events averaged three hours to complete. All observed wildlife data for each monitoring event was recorded on a wildlife grid map and wildlife data form on the back of the map. Daily total numbers (abundance) for wading birds and shore birds decreased from February to September 1999 except for sharp increases from April 21 to April 28 (Appendix 2-A and 3).
The great egret, snowy egret, cattle egret, white ibis, roseate spoonbill, and wood stork are the wading bird species responsible for the sharp peak in late April (Appendix 3). The slight increase in blackbirds is due to the boat-tailed grackle's increased use of the AOA. A large number of boat-tailed grackles were observed in the AOA between August 11 and August 25 (Appendix 2-A and 3). This increase of boat-tailed grackles was due to their feeding on large numbers of breeding frogs and toads attracted to the increased inundation of grass fields and wetlands. Additionally, there was a single large flock of over 300 boat-tailed grackles that influenced the August average. The slight increase in wading birds and waterfowl in September was due to a large number of cattle egrets following the mowing machine, a flock of white ibis that landed in the AOA and immediately flew off, and the beginning of fall migration of blue-winged teal and mottled ducks.
There were 10 main wildlife categories recorded within the AOA from February to September 15, 1999 (Appendix 2-B). This included waterfowl, wading birds-shore birds, crows-blackbirds, amphibians-reptiles, raptors-vultures, swallows, doves-pigeons, other birds, starlings, and mammals (Appendix 2-B and 3). The species grouped within each of these categories is illustrated in Appendix 3. The waterfowl and wading birds-shore birds were the most abundant categories observed during 1999 (Appendix 2-B). The next most abundant was the crows-blackbirds category (Appendix 2-B). These three most abundant categories included 46.4%, 28.8% and 16.2%, respectively, of the total number of wildlife observed. A total of 92.1% of the wildlife observed was included in these three categories (Appendix 2-B). This included 20 species of wading birds and shore birds, and 11 species of waterfowl (Appendix 3). Most of these observations were recorded in grids E5 through E8 throughout the east-west drainage swale south of the runway.
Most abundant species for waterfowl were American anhingas, American coots, blue-winged teal, common moorhens, mottled ducks, and ring-necked ducks. Most waterfowl such as American coots, blue-winged teal, and ring-necked ducks influenced observation counts due to spring and fall migration periods. American anhingas, common moorhens, and mottled ducks were more easily observed in 1999 due to removal of large areas of cattails within the east-west drainage swale south of the runway. The most abundant species, by total number, of the wading birds-shore birds category were cattle egrets, glossy ibis, great blue herons, great egrets, little blue herons, roseate spoonbills, snowy egrets, tricolored herons, and white ibis. Florida sandhill crane observations were low throughout the monitoring events due mostly to harassment by the border collie. The crows-blackbirds category accounted for 16.2% of the total wildlife observed; most of these observations were for the boat-tailed grackle. Although this percentage is low, there are periods when boat-tailed grackles were in high numbers (August 1999-Appendix 2-A). One flight of boat-tailed grackles was observed in August that exceeded greater than 300 individuals flying 50± feet above the runway (Appendix 2-A and 4-B). The amphibians-reptiles category accounted for 4.8% of the total wildlife observed. A total of 10 species were observed in this category including American alligators, aquatic turtles, frogs, and toads. Abundant species of this category included the Florida cricket frog, eastern narrow-mouth toad, and pig frog. These species provide an important food base for wading birds, shore birds and blackbirds, as well as reptiles such as snakes and alligators. The raptors-vultures category included eight species. The most abundant species of this category were the bald eagle, red-shouldered hawk, turkey vulture, and black vulture. Most of the flights over the runway included the turkey vulture and back vulture. These birds are mostly attracted to the AOA due to road kills and mowing machine kills. Vultures have been observed foraging on dead frogs, toads, snakes, turtles, birds, rats, rabbits, raccoons, and opossums. However, the number of vultures observed is generally low (Appendix 2-B and 3). Wildlife categories such as swallows, doves-pigeons, starlings, other birds, and mammals were less than 1% each of the total wildlife observed.
The 10 most common species observed within the AOA in 1999 from the most abundant to the least abundant were the American coot, boat-tailed grackle, common moorhen, cattle egret, blue-winged teal, great egret, white ibis, American anhinga, red-winged blackbird, and tricolored heron (Appendix 2-C). The American coot was observed in high monthly totals in February and March and in low numbers from April through September 15. The reduced abundance of American coots after March is due mostly to spring migration. The boat-tailed grackle was observed in low monthly total numbers except for August, which is attributed to their attraction to the high numbers of breeding frogs as a result of an increased hydroperiod in grass fields and wetlands within the AOA and a single large flock that flew across the AOA. Total monthly numbers for common moorhens increased drastically in July, August, and September due to the rearing of young which included two to six young per breeding pair. Cattle egret abundance increased in July, August, and September. Cattle egrets are strongly attracted to the mowing of grass fields within the AOA. They were also observed foraging on the high number of tadpoles and frogs associated with the inundated grass fields. Blue-winged teal's monthly totals were only high in March and September due to yearly migrations. Blue-winged teals were absent from the AOA from April until September. The great egret, white ibis, American anhinga, red-winged blackbird, and tricolored heron were observed in relatively low monthly totals.
Three alligator surveys were conducted within the AOA. A spotlight was used to explore all wetlands that were visible from the perimeter road. A total of three to four trips around the AOA were utilized to complete each night survey. Surveys were conducted from approximately six hours from 7:30 p.m. to 2:00 a.m. on two evenings and 3:00 a.m. to 8:30 a.m. for the other evening. The surveys were conducted on the 11th (p.m.), 12th (a.m.), 24th (p.m.), and 25th (a.m.) of August, 1999.
A total of 74 alligators were observed for the three night surveys. The number of alligators observed for the three nights were 26, 30 and 18 respectively. The arithmetic mean for the three nights is 24.7 alligators observed per night with a standard deviation of 6.1 alligators. The alligators observed were predominately in the three to four foot range. The greatest number of alligators were observed in grids E8S (29 alligators), E6S (17 alligators), and E7S (11 alligators) (Appendix 5-A and 5-B). Most of the alligators observed in these three grids were located in the large wetlands and canal system south of the runway.
All wetlands were easily observed except for the very large wetland located south of the runway in grids E6S and F6. Due to the wetlands large size and large amount of vegetation cover, observations were difficult. Based on observation data of the wetland system associated with this large wetland, it is estimated that five additional alligators may presently inhabit this area. Not all alligators would have been seen on a given night's survey due to chance. Therefore, it is estimated that 36 to 40 alligators are presently located within the AOA with most of them being three to four feet long. Two alligators were observed to be five to seven feet long. The maximum number of alligators observed during daytime wildlife surveys conducted during this same time periods was four alligators. Alligator counts during the day ranged from zero to four alligators.
Behavior and Habitat Use of Wildlife
Behavior of wildlife that were observed during wildlife monitoring events included foraging, flying, resting, perching, and nesting. Wading birds, shore birds, waterfowl, and blackbirds utilized the majority of their time foraging. Very little time was utilized by these bird groups for resting and roosting except for common moorhens and anhingas. Common moorhens and anhingas are annual residents of the wetlands within the AOA. Therefore, they forage, rest, roost, and nest within the AOA. Boat-tailed grackles were observed mostly foraging within the AOA while red-winged blackbirds were observed foraging and nesting. Nesting by red-winged blackbirds was limited to small patches of cattails and willows. Florida sandhill cranes utilizing the AOA were observed mostly foraging within inundated grass fields. No roosting or nesting and limited resting by sandhill cranes were observed inside the AOA. Cattle egrets heavily utilized the grass fields within the AOA especially following the mowing machine.
Black-necked stilts and killdeer were observed mostly foraging within the AOA. Limited nesting was observed by black-necked stilts. Meadowlarks and mourning doves were also observed mostly foraging. Foraging behavior for these species were observed mostly in grass fields and along the edges of wetlands. No nesting by these species were observed.
Wildlife utilization of the AOA observed in 1999 included mostly the wetland habitats associated with the large east-west drainage swale south of the runway. These habitats were utilized by wading birds, shore birds, waterfowl, blackbirds, and swallows. The most abundant species observed utilizing the east-west drainage swale included the tricolored heron, little blue heron, great egret, anhingas, common moorhen, American coot, and red-winged blackbird. Exceptions to these observed trends were the infrequent use by white ibis, glossy ibis, boat-tailed grackles, and blue-winged teal. On several monitoring events, these species were observed in greater abundance ranging from 20-30 individuals and greater than 300 individuals for the boat-tailed grackle.
Wading birds, shore birds, blackbirds, doves, small rodents and amphibians also utilized the large grass fields and fallow crop field. Florida sandhill cranes, cattle egrets, boat-tailed grackles, and amphibians were the dominant species observed utilizing these habitats. The stormwater retention ponds were utilized infrequently and in low abundance by waterfowl and wading birds. Waterfowl observed utilizing the stormwater ponds included common moorhens, anhingas, and mottled ducks. Wading birds included great egrets, great blue herons, little blue herons, and tricolored herons. Only one or two of a particular species was observed during an observation event.
The large wet prairie in the northwest corner of the AOA was also lightly utilized. Most species observed included little blue herons, great egrets, snowy egrets, Florida sandhill cranes, and mottled ducks. Only one or two of a particular species was observed during an observation event.
Turkey vultures, black vultures, red-shouldered hawks, and barn swallows behavior included mostly flying over the AOA. Turkey vultures and black vultures foraged within the AOA on road kills and mowing machine kills. This included foraging mostly on snakes, turtles, frogs, toads, rats, and rabbits. Red-shouldered hawks were observed foraging on frogs and rats. Perching by red-shouldered hawks was observed on pine trees within the AOA but was limited in late August and early September due to pine trees being removed from within the AOA. Limited flights were observed by bald eagles and common nighthawks.
Wildlife monitoring was conducted in 1997 by the USDA and in 1999 by KLECE. There are several differences in wildlife monitoring between the two years. The USDA 1997 ecological study did not follow a written standardized monitoring methodology, whereas the KLECE 1999 wildlife monitoring study did. Monitoring events in 1997 took 45 minutes while in 1999 each monitoring event averaged 3 hours. The 1997 study did not include fixed monitoring stations. All wildlife observed inside and immediately outside the AOA were recorded in 1997. This included some perching birds, such as logger head shrikes and mockingbirds, that are observed in the terminal and that infrequently fly within the AOA. In 1999, only the most frequently observed birds and those observed only in the AOA were recorded. A standardized grid map and data form was not used to record wildlife data in 1997, while in 1999, a standardized grid map and data form was filled out for each monitoring event. Amphibian and reptile data was not emphasized in 1997 while it was in 1999. Herpetofauna was emphasized in 1999 because amphibians provide a strong food base for wading birds and shore birds. Alligators were of concern also because a large alligator could pose a threat to incoming or outgoing aircraft. Wildlife data collected in 1997 was prior to habitat modification and use of the border collie to discourage wildlife utilization of the AOA. Wildlife data collected in 1999 was after habitat modification and use of the border collie.
The KLECE 1999 wildlife data was conducted after initiating the use of the border collie on February 15, 1999. To make comparisons of wildlife utilization before and after the introduction of the border collie, KLECE wildlife surveys were intensified (increased in number of samples) for June through September 15th. The USDA data from June to September 15, 1997 was provided by the LCPA to document utilization prior to the introduction of the border collie. Several USDA daily surveys were eliminated from the comparison due to species that indicated surveys were done primarily outside the AOA or for those days that had incomplete or otherwise suspect data.
Comparisons were made between the USDA 1997 and KLECE 1999 wildlife data for June through September 15th of each year. These comparisons are for the major wildlife categories: wading birds-shore-birds, waterfowl, raptors-vultures, crows-blackbirds, and amphibians-reptiles. Monthly averages (per observation) were compared within these groups. Dominant wildlife species and species richness (number of species observed) is also compared. Overall the USDA 1997 wildlife monitoring observed 69 species and the KLECE 1999 observations recorded 57 species (Table 1).
Greater numbers of wading birds and shore birds were observed in 1997 as compared to 1999 (Figure 1). The average observation per sample for 1997 during all four months was greater than double the averages for 1999. There were greater differences in June, July and August than in September. The dominant species for both data sets were cattle egrets, great egrets, white ibis and tricolored herons. White ibis were more dominant in 1997 as compared to 1999. Other important species included the sandhill crane, snowy egret, and little blue heron. Cattle egrets dominated all other wading birds because of their strong attraction to the mowing of the large areas of grass fields within the AOA. The use of the border collie in combination with other harassment techniques has significantly reduced wading bird numbers within the AOA. Species richness was also reduced in 1999 as compared to 1997 for this wildlife category. In 1997, species richness ranged from 15 to 21 species with an average of 17 species. The 1999 species richness ranged from 10 to 15 species with an average of 12 species.
Figure 1: Bird count data for Southwest Florida International Airport after
the employment of a single Border Collie on Feb. 11, 1999
Larger numbers of waterfowl were observed in 1999 as compared to 1997 (Figure 2). An extensive cattail removal program was conducted after 1997 within the large east- west drainage swale. With the removal of cattail, observations of wildlife was made much easier for waterfowl, wading birds and shore birds, therefore, waterfowl total numbers are expected to be higher and more accurate. Therefore, comparison figures (Figure 2) for waterfowl should consider the influence of cattail removal after 1997. Monthly average numbers were higher for waterfowl for July, August, and September. In June, waterfowl total numbers were slightly higher in 1997 than 1999. The largest difference was for the month of September. During this month in 1999, a large number of common moorhen breeding pairs were observed with a large number of young ranging from two to six young. Fall migration of blue-winged teal also elevated average total numbers for waterfowl in 1999. The most dominant waterfowl species observed for both data sets was the common moorhen and the American anhinga. American anhingas were much lower in numbers as compared to common moorhens. The dominant species in September of 1999 were the common moorhen and the blue-winged teal.
Average total numbers for raptors and vultures was greater than two and one-half times higher in 1997 as compared to 1999 (Figure 3). In June and August, 1997, average total numbers were six times higher than 1999 data and in July 1997, data was five times higher than 1999 data. This trend was reversed in September where 1999 average total numbers for raptors and vultures were slightly higher than 1997 data. This trend change was due to a sharp increase in the number of black vultures observed in early September 1999. The dominant species for both years included turkey vultures, black vultures, and red-shouldered hawks. The black vulture and the turkey vulture were more abundant in 1997 as compared to 1999 (Appendix 3). Red-shouldered hawks were more abundant in 1997 than 1999 and red-shouldered hawks observed in 1999 were more abundant than vultures. Another difference between data sets is that many observations of burrowing owls were made in 1997 and none were made in 1999. Species richness for the raptors-vultures category ranged from five to 10 species for 1997 with an average of 6.8 species. Species richness for 1999 ranged from two to four species with an average of three species. Vultures are highly attracted to mowing kills, aircraft/wildlife strikes, and road kills within the AOA. While conducting vegetation and wildlife studies for a wildlife habitat management plan in the summer of 1998 (KLECE 1998), many more vultures were observed feeding on kills within the AOA in 1998 as compared to 1999. These observations suggest that fewer kills were available to vultures in 1999 as compared to 1998. Wildlife reductions within the AOA may have helped reduce the number of animal kills. This has been the result of the border collie reducing the number of wading birds-shore birds and boat-tailed grackles within the AOA. Habitat modification such as cattail control has reduced boat-tailed grackles, red-winged blackbirds, other small birds, and rodents, therefore, reducing the number of raptors.
A greater average for total numbers of blackbirds were observed in 1997 as compared to 1999. June and July illustrated the greatest difference with 1997 data being eight and 40 times higher than 1999 data (Figure 4). August and September 1997 differences were smaller being only one and one third times higher for August and nearly three times higher for September. The most dominant species for both years were the boat-tailed grackles, red-winged blackbirds and eastern meadowlark. Boat-tailed grackles were the most dominant in all cases. Their numbers were greatly reduced in 1999. The greatest influence in reducing boat-tailed grackles and red-winged blackbirds is most likely due to the large cattail control program throughout the AOA, especially within the east-west drainage swale. The border collie has also reduced boat-tailed grackles by harassing them out of the large grass fields and wetland edges. However, boat-tailed grackles continue to be attracted to the AOA to cattail pockets, shrubby vegetation and large shallow breeding habitats for frogs and toads. There was an insignificant difference in species richness between 1997 and 1999 wildlife observations. Species richness ranged from three to five species for 1997 and three to four species for 1999.
Average total numbers for the amphibians-reptiles category was four times higher in 1999 as compared to 1997 (Figure 5). These averages were nine to 12 times higher for July and August due to heavy summer rains resulting in large breeding areas for eastern narrow-mouth toads, Florida cricket frogs, oak toads, and tree frogs. Amphibians are heavily preyed upon by wading birds, shore birds, blackbirds, and reptiles. Species richness ranged from two to five species for 1997 and three to seven species for 1999. Most species observed in 1997 were alligators and aquatic turtles while alligators, frogs, toads, and turtles were observed in 1999. These differences are because herpetofauna was emphasized more in 1999 as compared to 1997.
The 10 most common bird species for 1997 and 1999 were also compared for the months of June through September 15th (Figure 6). Monthly total number averages for 1999 were significantly lower as compared to 1997 (Figure 6). The only exception is that common moorhens total number averages were higher in 1999 than in 1997. Common moorhens and other waterfowl were easier to observe in 1999 than in 1997 because the majority of the thick and tall cattail had been removed prior to 1999 wildlife observations. The extensive areas of cattail located within the east-west drainage swale in 1997 prevented accurate waterfowl counts (i.e., common moorhen and other waterfowl estimates would be low). The most abundant species in 1997 were grackles, cattle egrets, common moorhens and barn swallows (Figure 6). The most abundant species in 1999 were boat-tailed grackles, common moorhens and cattle egrets. Boat-tailed grackles, cattle egrets, and red-winged blackbirds were much less abundant in 1999 than in 1997.
Percentage distribution for 10 wildlife categories were determined for total number of wildlife observed between June and September 15 of 1997 and 1999 (Figure 7). The wading birds-shore-birds category was reduced from 36.3% of the wildlife observed in 1997 to 30.8% in 1999. This reduction is believed to be the result of the use of the border collie for harassment purposes used in conjunction with pyrotechnics. Cattle egrets continue to be a problem due to their attraction to the mowing of the grass fields in the AOA. Cattle egrets are easily flushed by the border collie unless they are following the mowing machine. The cattle egrets are opportunistic feeders and are unwilling to leave an area of abundant prey as is provided by mowing activities. Waterfowl total numbers increased from 10.5% in 1997 to 32.6% in 1999. This increase is due to the extensive cattail control of wetlands within the AOA, especially of the east-wet drainage swale. Waterfowl and other wildlife observations were more easily made and more accurate in 1999 due to the removal of large stands of cattails. Waterfowl were observed to be concentrated in this large wetland system in both 1997 and 1999. Due to better visibility, a large number of breeding pairs of common moorhens with two to six young were observed in 1999. Blue-winged teal fall migration was also observed in early September 1999. Therefore, the waterfowl percentage increase between 1997 and 1999 may be misleading. The crows-blackbirds category total number percentage was reduced from 36.1% in 1997 to 24.8% in 1999 (Figure 7). This reduction is the result of reducing the number of boat-tailed grackles and red-winged blackbirds within the AOA. This has been accomplished by the cattail control program, especially within the east-west drainage swale. The border collie has also helped displace boat-tailed grackles from low grass fields and open edges of wetlands. Boat-tailed grackles feed predominately on the ground and since the border collie resembles a natural predator, the boat-tailed grackles immediately flush when approached by the border collie.
The raptors-vultures category was reduced from 3.9% in 1997 to 2.0% in 1999 (Figure 7). This is most likely a result of fewer aircraft wildlife strikes (due to lower numbers of wildlife within the AOA) and less raptors (due to less prey within the AOA). The cattail control program has reduced the overall abundance of blackbirds, small birds, and rodents therefore reducing the number of raptors. The border collie has reduced the abundance of wading birds and shore birds and to a smaller extent, blackbirds. This has resulted in reducing the number of vultures and raptors observed in 1999. A higher percentage of amphibians and reptiles were observed in 1999 as compared to 1997 (Figure 7). The reason for this difference is not actual abundance differences between years. In 1999 amphibians and reptiles were emphasized for two reasons. Large alligators could cause a problem to aircraft on the runway and amphibian observations were needed because they attract wading birds, shore birds, and blackbirds. Only 0.7% of amphibians and reptiles were observed in 1997 as compared to 7.5% in 1999. This included large numbers of pig frogs, Florida cricket frogs, eastern narrow-mouth toads, tree frogs and oak toads in 1999. These species were attracted to the wetlands and inundated grass fields within the AOA for breeding during the July and August heavy summer rains. Mammals and starlings were less than one percent each of the wildlife total for 1999 while mammals, other birds, starlings, doves, and swallows ranged from 0% to 1.1%. In 1997 percentages for other birds, doves, and swallows were 3.1%, 3.3% and 5.4%, respectively. Dominant species of other birds included the common nighthawk, loggerhead shrike, and northern mockingbird. The mourning dove was observed more frequently in 1997 as compared to 1999. The barn swallow was observed in moderately high numbers in August and September of 1997. The most important categories according to the dominant percentage distributions include wading birds-shore birds, waterfowl, crows-blackbirds and raptors-vultures. The amphibian-reptile category is important because they provide a strong prey base for wading birds, shore birds, and blackbirds.
Aircraft strikes with wildlife were higher in 1997 and 1998 than in 1999 (Table 2 and Figure 8). During 1997, there were 37 unconfirmed wildlife strikes and 10 confirmed strikes (Table 2 and Figure 8). The confirmed strikes in 1997 included two bald eagles and a hawk. The remaining confirmed strikes included five small birds, one grackle, and one dove. Of the 37 unconfirmed wildlife strikes, the larger birds included one sandhill crane, six egrets, and three vultures. The remaining wildlife strikes included smaller birds from the wildlife categories of crows-blackbirds, other birds, wading birds-shore birds, waterfowl, doves-pigeons and swallows. Wildlife abundance and wildlife utilization was more extensive in 1997 and 1998 before the use of the border collie and habitat modification within the AOA. During 1998, there were 30 unconfirmed wildlife strikes and 16 confirmed strikes (Table 2 and Figure 8). The 30 unconfirmed strikes in 1998 included shore birds, waterfowl, raptors-vultures, swallows, blackbirds, other birds, amphibians-reptiles, and mammals (Table 2 and Figure 8). Eleven of the 16 confirmed wildlife strikes included larger birds such as two sandhill cranes, four vultures, one hawk, two wading birds and two ducks (Table 2). The remaining five birds were swallows. The larger bird strikes included hawks, vultures, and waterfowl.
Figure 2: Comparison of bird strike data for RSW before and after the utilization
of the Border Collie.
In 1999, there were no confirmed wildlife strikes from January until September 15th (Table 2 and Figure 8). There were only eight unconfirmed strikes which included two wading birds, three blackbirds and three unknown species. There was a significant drop in wildlife use of the AOA after the initial use of the border collie in mid February of 1999 (Appendix 2-A and 2-C). The extensive cattail control program and shrub and tree removal throughout the wetlands within the AOA, especially of the east-west drainage swale south of the runway also played a part in reducing wildlife within the AOA.
Significant flight patterns over the runway and taxiway included large to medium sized birds or large flocks of small to medium sized birds. These significant flight patterns were summarized for the 1999 wildlife observations and illustrated in Appendix 4-A and 4-B. Appendix 4-A illustrates the highest frequency of fights for Florida sandhill cranes within the AOA. The flight patterns are a result of the sandhill cranes being harassed by the border collie. Although sandhill crane harassment flights are over the taxiway and runway, they happen only after coordination between the operation agents (dog handlers) and the airfield control tower. Extreme caution was taken to prevent flushing sandhill cranes and other wildlife into the path of any moving aircraft. In some harassment encounters, the sandhill cranes flew directly out of the AOA or in other encounters, they would have to be harassed from two or three different landing areas before they left the AOA. The former encounter type would take a few minutes to successfully harass the sandhill cranes out of the AOA, while the latter encounter would take one to one and one half hours to achieve the same goal. The AOA grids most heavily utilized for flights over the runway and taxiway were grids E5, E6 and E7 (Appendix 4-A).
Dominant bird flight patterns included wading birds, blackbirds, vultures and waterfowl (Appendix 4-B). Large flocks of 20-50 individuals per species of glossy ibis, great egrets, and white ibis had flight patterns across grids E9 and E10. These flights were to and from a hydric farm field located south of the AOA in grid F8. Many small flights of mottled ducks, cattle egrets, and anhingas were observed crossing the runway and taxiway throughout the AOA. Turkey vultures and black vultures circling flights were observed in grids E4, E5, E6, E7, E8, and E9. Boat-tailed grackles were observed on just a few occasions in April and August to fly across the runway in large flocks (50-300 individuals) in grids E6, E7 and E8. Most of the flight patterns for wading birds and waterfowl were over and throughout the east-west drainage swale. This included the glossy ibis, great egret, white ibis, snowy egret, blue-winged teal, tricolored heron, and ring-necked duck. This included 20-50 individuals for February, March and September and only a few individuals per species for April through August.
Wildlife Responses to Border Collie
Operation agents within the AOA handle the border collie. The border collie is used within the AOA twice a day to harass wildlife out of the AOA. Operation agents are in constant communications with the airfield tower so that the border collie does not flush birds into the path of an aircraft incoming or outgoing from the runway. The border collie is transported in an enclosed pet carrier inside a vehicle and released by the operations agent when needed to harass wildlife. The dog stays by the operations agent and responds to and from wildlife by a set of whistle and voice commands. Wildlife that forage on the ground or in shallow water such as wading birds, shore birds, and some waterfowl are very responsive to the approaches of the border collie. This is most likely due to the border collie resembling a natural predator. Wildlife that spend most of their time flying, such as vultures, raptors, and swallows are less responsive to the border collie. This would also include waterfowl in deep water habitats and alligators in both deep water and shallow water habitats.
Use of the border collie with operation agent dog handlers was observed through most of the wildlife monitoring from February 1999 through September 15, 1999. The border collie was utilized throughout the wildlife monitoring except for April 4 through April 20 for alligator avoidance training, April 21 through May 3 for unrelated stitches, and June 18 through June 28 for injured paws. The border collie was used in open vegetation and shallow water habitats to harass wading birds, shore birds, and waterfowl away from the runway and ultimately out of the AOA. The dog was taught to avoid deep water and heavily vegetated habitats to prevent injury to the dog from alligators. Important observations of the border collie are as follows:
Recommended Areas to Utilize the Border Collie
The border collie can be used to harass wading birds and waterfowl within 50 to 100 feet of the narrow deep water habitats in grids E4, E5, E7, E8, and E9. Most wading birds and waterfowl flush when the border collie or vehicle transporting the border collie approaches within 100 to 300 feet of the targeted birds. Most wading birds and waterfowl were observed south of the runway and this is where the border collie can be the most effective. However, sandhill cranes also utilize grass fields north of the taxiway and the border collie should also be utilized in these areas especially when frequented by sandhill cranes.
Recommendations to Improve Wildlife Program
The border collie should be used as frequently as possible each day. The times of day the border collie is used should vary to include all parts of the day dependent upon wildlife abundance and utilization of the AOA. This should include early morning and late evening use especially for wading birds such as the Florida sandhill crane. A detailed log should also be kept on wildlife responses to the border collie. These recommendations most likely would include adding an additional staff person dedicated to handling the border collie. Presently wildlife that is responsive to the border collie, such as wading birds, shore birds, and some waterfowl are most abundant along the east-west drainage swale. Florida sandhill cranes and other wading birds also utilize the low grass field immediately north of the taxiway. Border collie use should be emphasized in the grass fields and very shallow wetland habitats in these areas to harass wildlife. Other harassment techniques, such as firing shell crackers and blank rounds of ammunition to scare birds, should continue to be used in combination with the border collie.
Habitat modification should continue, including cattail control and shrub removal in all wetlands, especially within the east-west drainage swale. Aquatic vegetation should be kept low as far into the wetlands as possible. This recommendation will help make alligators more visible to operations staff and to the border collie. Alligators should continue to be removed from the east-west drainage swale as well as other wetland habitats within the AOA. The removal of the cattails and shrub areas will help reduce boat-tailed grackles, red-winged blackbirds, American anhingas, wading birds, and small rodents.
Road kills should be picked up each day to reduce foraging by vultures within the AOA. Vultures feed on dead animals within the AOA including frogs, toads, snakes, rats, rabbits, raccoons, and opossums.
An airboat would be very effective in flushing wading birds, shore birds, blackbirds, and waterfowl out of the east-west drainage swale and out of the AOA. The airboat could be used where the border collie and pyrotechnics are not effective (e.g., very large wetland areas associated with the east-west drainage swale). The airboat could also be used to locate large alligators and spot treat cattail areas within the east-west drainage swale.
Some Wax-myrtle/Willow/Hydric (FLUCFCS Code 7491) habitat has been removed from the east-west drainage swale. The remainder of this habitat needs to be removed. Cattail areas should also continue to be targeted for removal. These two steps will help reduce wildlife utilization of boat-tailed grackles, red-winged blackbirds, anhingas, wading birds, and small rodents. Aquatic vegetation should be kept low as far into the wetlands as possible. This step will help make alligators more visible to the border collie and operation border collie handlers. Alligators should continue to be removed from the east-west drainage swale as well as other wetland habitats within the AOA.
Wildlife monitoring should continue to determine relative abundance of wildlife and effectiveness of wildlife management techniques. Wildlife use of the AOA will also shift as habitat modifications are made. Wildlife observations are critical in determining trends in wildlife species abundance, species richness, and habitat use within the AOA. Depending on wildlife observations wildlife harassment techniques, including use of the border collie and habitat modification, will most likely have to be adjusted to reduce wildlife within the AOA.
Comparison of wildlife monitoring data was made between the USDA 1997 and the KLECE 1999 studies. The average wildlife observations per survey were compared on a monthly basis for June 10th through September 15th for each year. Wildlife data was compared between 10 wildlife categories. This included wading birds-shore birds, waterfowl, raptors-vultures, swallows, doves-pigeons, other birds, mammals, and starlings. The USDA 1997 data was conducted prior to the use of the border collie as a technique to harass major wildlife species out of the AOA. This was also prior to habitat modification such as the cattail control program for the east-west drainage swale south of the runway and other wetlands within the AOA.
In 1999 there was a reduction in the wildlife categories of wading birds-shore birds and waterfowl after initiating the use of the border collie with operations' handlers on February 11, 1999. Wading bird totals declined significantly from February to April with a sharp increase in late April. This sharp increase correlates positively with the time period the border collie was absent due to alligator training and an unrelated injury. Wading birds-shore birds are very responsive to harassment by the border collie. Overall, 1999 wading birds-shore birds abundance was less than half that observed in 1997. Waterfowl reductions and increases in 1999 were more related to spring and fall migration than any other factor. However, the border collie was observed displacing waterfowl throughout the east-west drainage swale as well as flushing them out of the AOA. Observed waterfowl abundance was higher in 1999 as compared to 1997, however, this is due to wildlife observations being easier in 1999. An extensive cattail removal program within the east-west drainage swale provided better visual observation as compared to 1997. Waterfowl increase included higher visibility of large numbers of common moorhen breeding pairs with two to six young each.
The reduction of cattails and shrubs within the AOA has also significantly reduced the abundance of boat-tailed grackles, red-winged blackbirds, other smaller birds, and small rodents within the AOA in 1999 as compared to 1997. As a result, this has also reduced the number of raptors for the same time period comparisons. There was a sharp increase in boat-tailed grackles in August due to a single observed large flock of over 300 boat-tailed grackles. Boat-tailed grackles use of the AOA also increased in August due to their predation of the large number of frogs and toads breeding in shallow inundated grass fields and wetlands as a result of heavy summer rains.
Aircraft/wildlife strikes have greatly decreased since the use of the border collie to harass wildlife and the incorporation of habitat modification such as wetland cattail control and shrub removal. Wildlife flights over the runway and taxiway still exist, however, their frequency has decreased due to the overall reduction of wildlife within the AOA. Alligator census data has also determined that alligator abundance is greatly reduced especially by the number of alligators greater than five feet long. The border collie had no direct influence in the reduction of alligators within the AOA.
Initial observations of the border collie as an alternative to reduce wildlife within the AOA has been a success in reducing wading birds and shore birds and to some extent, blackbirds. This alternative has worked well with other harassment techniques, such as pyrotechnics, and habitat modification including wetland cattail control and shrub removal. It is recommended that the border collie and habitat modification programs continue.
The border collie should be used as frequently as possible each day. The times of day the border collie is used should vary to include all parts of the day dependent upon wildlife abundance and utilization of the AOA. This could include early morning and late evening use especially for wading birds such as the Florida sandhill crane. A detailed log should be kept on wildlife responses to the border collie. These recommendations would likely include adding an additional staff person dedicated to handling the border collie. Some birds are more resistant to harassment and will take a large amount of time to discourage their use of the AOA. Wildlife also utilize the AOA at different times of the day and wildlife patrols with the dog need to be conducted at different times throughout the day. This would include dawn and dusk surveys. It will take a full time person to properly utilize the dog to discourage use of the AOA by wildlife. Presently wildlife that is responsive to the border collie, such as wading birds, shore birds, and some waterfowl are most abundant along the east-west drainage swale. Florida sandhill cranes and other wading birds also utilize the low grass field immediately north of the taxiway. Use of the border collie should be emphasized in the grass fields and very shallow wetland habitats to harass wildlife. Other harassment techniques, such as firing shell crackers and blank rounds of ammunition to scare birds, should continue to be used in combination with the border collie.
Habitat modification should continue, including cattail control and shrub removal in all wetlands, especially within the east-west drainage swale. Aquatic vegetation should be kept low as far into the wetlands as possible. This recommendation will help make alligators more visible to operations staff and to the border collie. Alligators should continue to be removed from the east-west drainage swale as well as other wetland habitats within the AOA. The removal of the cattails and shrub areas will help reduce boat-tailed grackles, red-winged blackbirds, American anhingas, wading birds, and small rodents. The large inundated grass fields should be filled and culverted so these areas will not provide habitat for breeding frogs and toads.
Road kills should be picked up each day to reduce foraging by vultures within the AOA. Vultures feed on dead animals within the AOA including frogs, toads, snakes, rats, rabbits, raccoons, and opossums.
An airboat would be very effective in flushing wading birds, shore birds, blackbirds, and waterfowl out of the east-west drainage swale and out of the AOA. The airboat could be used where the border collie and pyrotechnics are not effective (e.g., very large wetland areas associated with the east-west drainage swale). The airboat could also be used to locate large alligators and to spot treat cattail areas within the east-west drainage swale.
Florida Department of Transportation. 1985. Florida Land Use, Cover Forms Classification System. Procedure No. 550-010-001-a.
KLECE. 1998. Wildlife Habitat Management Plan for Southwest Florida International Airport. Kevin L. Erwin Consulting Ecologist, Inc. Fort Myers, Florida.
Logan, T.H. 1997. Official Lists of Endangered and Potentially Endangered Fauna and Flora in Florida, Division of Wildlife, Nongame Wildlife Section, Florida Fish and Wildlife Conservation Commission, Tallahassee, Florida.
McCormick, J. 1998. Border Collie Rescue, Inc. Alternative Method of Bird and Wildlife Control for RSW. Lee County Port Authority. Office of Planning.
Stys, B. 1997. Ecology of the Florida Sandhill Crane. Nongame Wildlife Technical Report No. 15. Office of Environmental Services, Florida Fish and Wildlife Conservation Commission. Tallahassee, Florida.
USDA. 1998. An Ecological Study of Southwest Florida International Airport to Alleviate Wildlife Hazards to Aircraft Operations. United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services. Gainesville, Florida.
USDA. 1998. Wildlife Assessment for Southwest Florida International Airport Fort Myers, Florida. United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services. Gainesville, Florida.
Preliminary Data Reports
Border Collie Effect on Bird Populations (I)
Border Collie Effect on Bird Populations (II)
Comparison of March 1999 Bird Populations to March 1998 Populations (with and without the dog) (I)
Comparison of March 1999 Bird Populations to March 1998 Populations (with and without the dog) (II)
