Monitoring Impacts of U.S.-Mexico Border Barrier and Lighting on Migratory Birds
Portable Doppler radar
A portable Doppler radar, such as the one shown here, will provide information about bird stopover, traffic rates, and responses to border barrier infrastructure. (Credit: Bryan Piazza, The Nature Conservancy)
Researchers will use a multi-scale approach to determine how barrier construction and lighting may impact migratory birds in the Lower Rio Grande Valley.
The Science Issue and Relevance: Since 1970, 2.9 billion birds have been lost across the continental U.S. and Canada. The likely primary driver behind bird declines is loss of habitat, which is critical for breeding as well as migration. Human-altered landscapes tend to fragment existing habitats into small, disjointed patches, which can reduce abundance, species richness, and nesting success of birds. Moreover, human development is typically associated with artificial light at night (ALAN), which can disrupt the natural cycles of birds as well as impact migratory behaviors. The infrastructure associated with the barrier established along the U.S.-Mexico border within the Lower Rio Grande Valley (LRGV) is a human development project that has altered habitats by 1) causing fragmentation, 2) creating a physical barrier, 3) producing ALAN, and 4) introducing vehicular traffic. While most flying animals, including migratory birds, are likely able to negotiate the physical barrier, they and other animals can be affected by impacts from fragmentation, ALAN, and vehicular traffic. Management partners within the LRGV need to understand how migratory birds are responding to the presence of the border barrier and its associated infrastructure so they can develop effective mitigation strategies for current and future barrier construction.
Methodology for Addressing the Issue: Our objective is to determine how barrier construction and lighting may impact migratory birds in the LRGV. We will use a multi-scale approach that addresses how such animals have responded to the border barrier within the LRGV by integrating multiple remote sensing techniques. At the largest scale, data from three weather surveillance radars that provide information at the regional scale from approximately 1995 to present will be used to conduct a before-after-control-impact study design (BACI). For a landscape scale approach, we will use portable Doppler radar to strategically sample the airspace of the U.S.-Mexico border with and without a barrier and/or lights. At the finest spatial scale, we will establish a network of automated telemetry and audio recording stations that will be placed in areas with and without a barrier and/or lights. All three remote sensing approaches will be conducted during spring and autumn, when birds typically migrate. The automated recording stations will also collect data during the breeding and non-breeding seasons. Additional funding or collaborations for fieldwork within the LRGV could further leverage use of the automated recording stations (i.e., deployment of transmitters, point count surveys). Moreover, some of our remote sensing equipment may be capable of investigating how other animals, such as bats or arthropods, are responding to border infrastructure.
Future Steps: We will produce seasonal maps of observed mean bird stopover (locations where birds pause between migratory flights to rest and/or forage) around each weather surveillance radar and portable Doppler radar. We will also perform statistical analyses to determine how covariates such as distance from border barrier, barrier type, and distance from bright ALAN, are associated with seasonal bird densities. Using Doppler radar data, we will statistically analyze traffic rates of migrating birds for areas with and without a barrier and/or lights. The automated recording stations will provide species-specific information as well as audio and telemetry data to perform analyses of areas with and without a barrier and/or lights. This information will allow us to identify patterns and relationships in the data that can be used to inform management and mitigation related to border barrier systems. Actions that may reduce current negative impacts or minimize impacts of future barrier construction could also be identified.
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Researchers will use a multi-scale approach to determine how barrier construction and lighting may impact migratory birds in the Lower Rio Grande Valley.
The Science Issue and Relevance: Since 1970, 2.9 billion birds have been lost across the continental U.S. and Canada. The likely primary driver behind bird declines is loss of habitat, which is critical for breeding as well as migration. Human-altered landscapes tend to fragment existing habitats into small, disjointed patches, which can reduce abundance, species richness, and nesting success of birds. Moreover, human development is typically associated with artificial light at night (ALAN), which can disrupt the natural cycles of birds as well as impact migratory behaviors. The infrastructure associated with the barrier established along the U.S.-Mexico border within the Lower Rio Grande Valley (LRGV) is a human development project that has altered habitats by 1) causing fragmentation, 2) creating a physical barrier, 3) producing ALAN, and 4) introducing vehicular traffic. While most flying animals, including migratory birds, are likely able to negotiate the physical barrier, they and other animals can be affected by impacts from fragmentation, ALAN, and vehicular traffic. Management partners within the LRGV need to understand how migratory birds are responding to the presence of the border barrier and its associated infrastructure so they can develop effective mitigation strategies for current and future barrier construction.
Methodology for Addressing the Issue: Our objective is to determine how barrier construction and lighting may impact migratory birds in the LRGV. We will use a multi-scale approach that addresses how such animals have responded to the border barrier within the LRGV by integrating multiple remote sensing techniques. At the largest scale, data from three weather surveillance radars that provide information at the regional scale from approximately 1995 to present will be used to conduct a before-after-control-impact study design (BACI). For a landscape scale approach, we will use portable Doppler radar to strategically sample the airspace of the U.S.-Mexico border with and without a barrier and/or lights. At the finest spatial scale, we will establish a network of automated telemetry and audio recording stations that will be placed in areas with and without a barrier and/or lights. All three remote sensing approaches will be conducted during spring and autumn, when birds typically migrate. The automated recording stations will also collect data during the breeding and non-breeding seasons. Additional funding or collaborations for fieldwork within the LRGV could further leverage use of the automated recording stations (i.e., deployment of transmitters, point count surveys). Moreover, some of our remote sensing equipment may be capable of investigating how other animals, such as bats or arthropods, are responding to border infrastructure.
Future Steps: We will produce seasonal maps of observed mean bird stopover (locations where birds pause between migratory flights to rest and/or forage) around each weather surveillance radar and portable Doppler radar. We will also perform statistical analyses to determine how covariates such as distance from border barrier, barrier type, and distance from bright ALAN, are associated with seasonal bird densities. Using Doppler radar data, we will statistically analyze traffic rates of migrating birds for areas with and without a barrier and/or lights. The automated recording stations will provide species-specific information as well as audio and telemetry data to perform analyses of areas with and without a barrier and/or lights. This information will allow us to identify patterns and relationships in the data that can be used to inform management and mitigation related to border barrier systems. Actions that may reduce current negative impacts or minimize impacts of future barrier construction could also be identified.