In Executive Order 13112 "Invasive Species", an alien species is defined as one "that is not nati... more In Executive Order 13112 "Invasive Species", an alien species is defined as one "that is not native" to a particular ecosystem. In North America today, there are nearly 100 alien bird species with self-sustaining populations. These include numerous game birds (primarily gallinaceous birds) and escaped pet birds (primarily psittacine species). Others, such as house sparrows (Passer domesticus), European starlings (Sturnus vulgaris), and mute swan (Cygnus olor), were originally introduced for aesthetic reasons or to control agricultural insect pests. The establishment of alien bird populations through purposeful or accidental introductions has resulted in numerous problems including crop damage, transmission of disease, adverse impacts to native species, and aircraft safety concerns. The estimated cost associated with alien bird species in North America approaches $2 billion annually. Although many alien bird species apparently cause minimal or no harm, others are considered persistent and destructive pest species. The challenge for wildlife managers often is one of public opinion and education rather than identifying effective management and control strategies. For many bird damage situations, techniques currently exist for addressing the specific problem, and ongoing research is providing new tools. Many times, however, the will of the public overrides the scientific and economic need to manage aggressively to reduce detrimental alien bird populations. Specific examples of this dilemma for wildlife managers are provided by case studies featuring monk parakeets (Myiopsitta monachus), and mute swan.
Animals communicate with potential mates using species-specific signals, and pheromones are power... more Animals communicate with potential mates using species-specific signals, and pheromones are powerful sexual signals that modify conspecific behavior to facilitate mate location. Among the vertebrates, snakes are especially adept in mate searching via chemical trailing, which is particularly relevant given that many snake species are invasive outside their native ranges. Chemical signals used in mate choice are, thus, potentially valuable tools for management of invasive snake species. The Burmese python (Python bivittatus) is an invasive snake in the Florida Everglades where it is negatively impacting native fauna. In this study, we sought to: (i) determine if males can follow conspecific chemical trails in a Y-maze; and (ii) describe the mate searching behaviors exhibited by males while trailing. All males consistently followed a single female scent trail in the maze, but when only a male scent trail was present they did not discriminate between the male and blank arms. Rate of tongue-flicking, a proxy for chemosensory sampling, was also marginally higher when males were following female versus male scent trails. However, when both female and male scent trails were simultaneously present in the Y-maze, males did not show a preference for the female arm, although the tongue-flick rate was higher in the female-only trial compared to female versus male. Analyses of multiple male behaviors individually and using an ethogram revealed that behaviors were more frequent and complex in the female-only trials compared to male-only trials. Additional behavioral trials are needed to determine if an effective pheromonal approach to Burmese python management is possible.
Throughout its North American range, the turkey vulture (Cathartes aura) appears to be thriving. ... more Throughout its North American range, the turkey vulture (Cathartes aura) appears to be thriving. Turkey vulture populations wintering at Key West Naval Air Station (KWNAS), Florida are no exception to this trend. As vulture numbers continue to increase, so do potential conflicts with human activities. Abundant feeding opportunities and ample roost sites create ideal circumstances for wintering vultures. The increasing TUVU winter population is of particular concern because of the potential interaction with aircraft using the landing facility at KWNAS. Prior to developing vulture management recommendations at KWNAS, we needed to learn more about TUVU activity and movement patterns. Here we present results from 2013-2014 on trapping and marking efforts, with emphasis on vulture movement data acquired using GSM transmitters.
In the United States, black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) pose s... more In the United States, black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) pose significant birdstrike risks to aircraft. Understanding flight behaviors of vultures in and around military and civilian airfields is necessary to alleviate these risks. Using satellite telemetry data collected from 11 black vultures and 7 turkey vultures equipped with Global Positioning System backpack harness technology, we collected data on location and altitude near the Marine Corps Air Station (MCAS) in Beaufort, South Carolina from September 2006 to September 2008. We used military aircraft flight landing patterns to visualize a new concept, a flight altitude cone of depression (FACOD), which models a three-dimensional flight pattern over the airfield. We then identified areas in and around MCAS where vulture flight paths penetrated the FACOD and locations of vultures were proximate to flight approach routes that posed potential risk to aircraft for a birdstrike. Combining altitude of in-flight locations of vultures or other species with three-dimensional flight patterns of aircraft provides a novel method for managers of military and domestic airfields to assess birdstrike risk and to focus corrective actions.
Growing vulture populations represent increasing hazards to civil and military aircraft. To asses... more Growing vulture populations represent increasing hazards to civil and military aircraft. To assess vulture flight behavior and activity patterns at the Marine Corps Air Station in Beaufort, South Carolina, we equipped 11 black vultures (Coragyps atratus) and 11 turkey vultures (Cathartes aura) with solarpowered Global Positioning System (GPS) satellite transmitters during a 2-year study (1 Oct 2006-30 Sep 2008). Turkey vultures had larger seasonal home ranges than did black vultures, and 2 turkey vultures made round-trips to Florida. Black vultures consistently spent less time in flight (8.4%) than did turkey vultures (18.9%), and black vultures flew at higher altitudes than did turkey vultures in all seasons except summer when altitudinal distributions (above ground level) did not differ. Although we recorded maximum altitudes of 1,578 m for black vultures and 1,378 for turkey vultures, most flights were low altitude. A matrix of vulture flight altitude versus time of day revealed that >60% of vulture flight activity occurred from 4 hr to 9 hr after sunrise at altitudes below 200 m. Continuation of aggressive harassment coupled with flexible training schedules to avoid times and altitudes of high vulture activity will decrease hazards to aircraft posed by these birds.
Depredations to livestock by black vultures are a concern for many producers, and there is an inc... more Depredations to livestock by black vultures are a concern for many producers, and there is an increasing need for effective means to alleviate conflicts between livestock and vultures. One approach to this problem is to identify the roost site that is the source of the offending birds and then disperse that roost. We evaluated this approach in southwestern Virginia, where sheep and cattle operations in the New River Valley have historically experienced depredations by black vultures. During February 2004, we trapped and tagged 200 vultures and equipped 20 of them with radio transmitters. We established data-logger receiving stations at the main roost site in Radford, VA and at 4 nearby livestock operations. We monitored vulture use of the roost and the livestock sites for 2 weeks and then we dispersed the Radford roost using vulture effigies and hand-held lasers. We continued to monitor vulture activity at the livestock study sites for 8 weeks. Our findings showed that although the roost in Radford was dispersed, vulture use of the livestock operations after roost dispersal did not differ from pre-dispersal activity. Vultures in the area apparently shifted to alternate roost sites with no noticeable disruption to their foraging activities. For roost management to be effective against livestock depredations, dispersal activity must include the ancillary roosts as well as the main roost. Furthermore, prompt removal and proper disposal of livestock carcasses should greatly reduce the attractiveness of cattle and sheep operations for foraging black vultures.
One component of brown tree snake (Boiga irregularis) management on Guam is the use of a toxic ba... more One component of brown tree snake (Boiga irregularis) management on Guam is the use of a toxic bait that consists of acetaminophen tablets inserted into a dead neonatal mouse (DNM), which in turn is placed within a cylindrical polyvinyl chloride (PVC) bait station suspended above ground. Whereas this technique is effective in killing snakes, possible hazards to nontarget species, especially the Mariana crow (Corvus kubaryi), are of concern. We used the fish crow (C. ossifragus) as a surrogate for the Mariana crow to evaluate (1) oral toxicity of acetaminophen, (2) behavior of crows exposed to DNM containing acetaminophen tablets, and (3) ability of crows to remove DNM from cylindrical bait stations. In the oral toxicity test, all five crows that were each force-fed two 40-mg acetaminophen tablets survived and at least two birds regurgitated the tablets. Five additional crows received a double dose (four 40-mg tablets); each regurgitated all of its tablets, but one bird died. Crows g...
In Executive Order 13112 "Invasive Species", an alien species is defined as one "that is not nati... more In Executive Order 13112 "Invasive Species", an alien species is defined as one "that is not native" to a particular ecosystem. In North America today, there are nearly 100 alien bird species with self-sustaining populations. These include numerous game birds (primarily gallinaceous birds) and escaped pet birds (primarily psittacine species). Others, such as house sparrows (Passer domesticus), European starlings (Sturnus vulgaris), and mute swan (Cygnus olor), were originally introduced for aesthetic reasons or to control agricultural insect pests. The establishment of alien bird populations through purposeful or accidental introductions has resulted in numerous problems including crop damage, transmission of disease, adverse impacts to native species, and aircraft safety concerns. The estimated cost associated with alien bird species in North America approaches $2 billion annually. Although many alien bird species apparently cause minimal or no harm, others are considered persistent and destructive pest species. The challenge for wildlife managers often is one of public opinion and education rather than identifying effective management and control strategies. For many bird damage situations, techniques currently exist for addressing the specific problem, and ongoing research is providing new tools. Many times, however, the will of the public overrides the scientific and economic need to manage aggressively to reduce detrimental alien bird populations. Specific examples of this dilemma for wildlife managers are provided by case studies featuring monk parakeets (Myiopsitta monachus), and mute swan.
Animals communicate with potential mates using species-specific signals, and pheromones are power... more Animals communicate with potential mates using species-specific signals, and pheromones are powerful sexual signals that modify conspecific behavior to facilitate mate location. Among the vertebrates, snakes are especially adept in mate searching via chemical trailing, which is particularly relevant given that many snake species are invasive outside their native ranges. Chemical signals used in mate choice are, thus, potentially valuable tools for management of invasive snake species. The Burmese python (Python bivittatus) is an invasive snake in the Florida Everglades where it is negatively impacting native fauna. In this study, we sought to: (i) determine if males can follow conspecific chemical trails in a Y-maze; and (ii) describe the mate searching behaviors exhibited by males while trailing. All males consistently followed a single female scent trail in the maze, but when only a male scent trail was present they did not discriminate between the male and blank arms. Rate of tongue-flicking, a proxy for chemosensory sampling, was also marginally higher when males were following female versus male scent trails. However, when both female and male scent trails were simultaneously present in the Y-maze, males did not show a preference for the female arm, although the tongue-flick rate was higher in the female-only trial compared to female versus male. Analyses of multiple male behaviors individually and using an ethogram revealed that behaviors were more frequent and complex in the female-only trials compared to male-only trials. Additional behavioral trials are needed to determine if an effective pheromonal approach to Burmese python management is possible.
Throughout its North American range, the turkey vulture (Cathartes aura) appears to be thriving. ... more Throughout its North American range, the turkey vulture (Cathartes aura) appears to be thriving. Turkey vulture populations wintering at Key West Naval Air Station (KWNAS), Florida are no exception to this trend. As vulture numbers continue to increase, so do potential conflicts with human activities. Abundant feeding opportunities and ample roost sites create ideal circumstances for wintering vultures. The increasing TUVU winter population is of particular concern because of the potential interaction with aircraft using the landing facility at KWNAS. Prior to developing vulture management recommendations at KWNAS, we needed to learn more about TUVU activity and movement patterns. Here we present results from 2013-2014 on trapping and marking efforts, with emphasis on vulture movement data acquired using GSM transmitters.
In the United States, black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) pose s... more In the United States, black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) pose significant birdstrike risks to aircraft. Understanding flight behaviors of vultures in and around military and civilian airfields is necessary to alleviate these risks. Using satellite telemetry data collected from 11 black vultures and 7 turkey vultures equipped with Global Positioning System backpack harness technology, we collected data on location and altitude near the Marine Corps Air Station (MCAS) in Beaufort, South Carolina from September 2006 to September 2008. We used military aircraft flight landing patterns to visualize a new concept, a flight altitude cone of depression (FACOD), which models a three-dimensional flight pattern over the airfield. We then identified areas in and around MCAS where vulture flight paths penetrated the FACOD and locations of vultures were proximate to flight approach routes that posed potential risk to aircraft for a birdstrike. Combining altitude of in-flight locations of vultures or other species with three-dimensional flight patterns of aircraft provides a novel method for managers of military and domestic airfields to assess birdstrike risk and to focus corrective actions.
Growing vulture populations represent increasing hazards to civil and military aircraft. To asses... more Growing vulture populations represent increasing hazards to civil and military aircraft. To assess vulture flight behavior and activity patterns at the Marine Corps Air Station in Beaufort, South Carolina, we equipped 11 black vultures (Coragyps atratus) and 11 turkey vultures (Cathartes aura) with solarpowered Global Positioning System (GPS) satellite transmitters during a 2-year study (1 Oct 2006-30 Sep 2008). Turkey vultures had larger seasonal home ranges than did black vultures, and 2 turkey vultures made round-trips to Florida. Black vultures consistently spent less time in flight (8.4%) than did turkey vultures (18.9%), and black vultures flew at higher altitudes than did turkey vultures in all seasons except summer when altitudinal distributions (above ground level) did not differ. Although we recorded maximum altitudes of 1,578 m for black vultures and 1,378 for turkey vultures, most flights were low altitude. A matrix of vulture flight altitude versus time of day revealed that >60% of vulture flight activity occurred from 4 hr to 9 hr after sunrise at altitudes below 200 m. Continuation of aggressive harassment coupled with flexible training schedules to avoid times and altitudes of high vulture activity will decrease hazards to aircraft posed by these birds.
Depredations to livestock by black vultures are a concern for many producers, and there is an inc... more Depredations to livestock by black vultures are a concern for many producers, and there is an increasing need for effective means to alleviate conflicts between livestock and vultures. One approach to this problem is to identify the roost site that is the source of the offending birds and then disperse that roost. We evaluated this approach in southwestern Virginia, where sheep and cattle operations in the New River Valley have historically experienced depredations by black vultures. During February 2004, we trapped and tagged 200 vultures and equipped 20 of them with radio transmitters. We established data-logger receiving stations at the main roost site in Radford, VA and at 4 nearby livestock operations. We monitored vulture use of the roost and the livestock sites for 2 weeks and then we dispersed the Radford roost using vulture effigies and hand-held lasers. We continued to monitor vulture activity at the livestock study sites for 8 weeks. Our findings showed that although the roost in Radford was dispersed, vulture use of the livestock operations after roost dispersal did not differ from pre-dispersal activity. Vultures in the area apparently shifted to alternate roost sites with no noticeable disruption to their foraging activities. For roost management to be effective against livestock depredations, dispersal activity must include the ancillary roosts as well as the main roost. Furthermore, prompt removal and proper disposal of livestock carcasses should greatly reduce the attractiveness of cattle and sheep operations for foraging black vultures.
One component of brown tree snake (Boiga irregularis) management on Guam is the use of a toxic ba... more One component of brown tree snake (Boiga irregularis) management on Guam is the use of a toxic bait that consists of acetaminophen tablets inserted into a dead neonatal mouse (DNM), which in turn is placed within a cylindrical polyvinyl chloride (PVC) bait station suspended above ground. Whereas this technique is effective in killing snakes, possible hazards to nontarget species, especially the Mariana crow (Corvus kubaryi), are of concern. We used the fish crow (C. ossifragus) as a surrogate for the Mariana crow to evaluate (1) oral toxicity of acetaminophen, (2) behavior of crows exposed to DNM containing acetaminophen tablets, and (3) ability of crows to remove DNM from cylindrical bait stations. In the oral toxicity test, all five crows that were each force-fed two 40-mg acetaminophen tablets survived and at least two birds regurgitated the tablets. Five additional crows received a double dose (four 40-mg tablets); each regurgitated all of its tablets, but one bird died. Crows g...
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