Heavy migration traffic and bad weather are a dangerous combination: Bird collisions in New York City
Data files
Jan 09, 2024 version files 976.91 KB
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collisions_migration_weather_spring_fall_dataset.csv
973.08 KB
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README.md
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Abstract
Bird-building collisions account for 365-988 million bird fatalities every year in the United States alone. Understanding conditions that heighten collision risk is critical to developing effective strategies for reducing this source of anthropogenic bird mortality. Meteorological factors and regional migration traffic may influence collision rates but also may be difficult to disentangle from other effects. We used 5 years of bird collision counts in New York City to examine the influence of nocturnal weather conditions and bird migration traffic rates on collisions with buildings during spring and fall. We found that seasonally unfavorable winds and conditions that impede visibility are important factors that influence rates of bird-building collisions during both seasons. Specifically, northerly and westerly winds and low visibility in the spring, and southerly and westerly winds and low cloud ceiling height in the fall are associated with higher collision risks. Generally, these weather variables associated most strongly with increased collisions when nocturnal bird migration traffic was high, with the exception of low visibility in spring, which was predicted to triple collision rates compared to high visibility, independent of bird migration traffic. Although legislation to turn off unnecessary nocturnal lighting for the entirety of the migration seasons may be an ultimate goal, a proximate goal invaluable for reducing collisions will be predicting which nights will be of highest risk and using this information to determine when mitigation efforts could be most effective.
README: Heavy migration traffic and bad weather are a dangerous combination: bird collisions in New York City
The collisions_weather_migration_spring_fall_dataset.csv file contains all of the variables included in our final spring and fall generalized linear mixed effects models of the effects of weather and migration traffic on bird collisions with buildings in New York, NY, 2017-2021.
Note that the buildings that were monitored for collisions were known or expected to be high collision hazards and were specifically chosen to increase the likelihood of detecting collision events under a range of weather conditions. Thus, this dataset's sample is not necessarily representative of citywide collision rates. Also note that the KOKX radar station, where we obtained the data used for our migration traffic variable, is located just under 100 km from NYC. As such, this metric was not a direct calculation of the number of migrants in NYC and was treated as a regional measure of migration activity in the NYC area.
Description of the variable columns:
- date - the date from when the collision data was collected. Nocturnal weather and migration data are averaged measurements taken from dusk the night prior to dawn the morning of.
- year - the year.
- yday - the day of year. Also known as the Julian date.
- building - the letter code we assigned to the building surveyed. For the corresponding building addresses, please refer to Table S2 in the supplementary materials for the associated manuscript.
- Data source: NYC Audubon's Project Safe Flight.
- volunteer - the volunteer or pair of volunteers who conducted the survey.
- Data source: NYC Audubon's Project Safe Flight.
- count - collisions counts of individual birds per building per day.
- Data source: NYC Audubon's Project Safe Flight.
- uwind - east–west wind component (speed and direction) in ms-1 measured at 9 m above ground level. Positive values indicate winds coming from the west. Also known as zonal wind.
- Data source: LaGuardia Airport weather station.
- vwind - north–south wind component (speed and direction) in ms-1 measured at 9 m above ground level. Positive values indicate winds coming from the south. Also known as meridional wind.
- Data source: LaGuardia Airport weather station.
- ceiling_height - the height in meters above ground level of the lowest cloud or obscuring phenomena layer aloft with 5/8 or more summation total sky cover, which may be predominately opaque, or the vertical visibility into a surface-based obstruction.
- Data source: LaGuardia Airport weather station.
- visibility_distance - the horizontal distance in meters at which an object can be seen and identified.
- Data source: LaGuardia Airport weather station.
- visibility - a categorical variable where “low” indicates a visibility distance <10 km, “medium” indicates a visibility distance between 10 to 16 km, and “high” indicates a visibility distance >16 km.
- Created using the visibility distance data obtained from the LaGuardia Airport weather station.
- temperature - the temperature of the air in degrees Celsius (˚C) measured at 9 m above ground level.
- Data source: LaGuardia Airport weather station.
- amt - average migration traffic. The average number of individual birds passing by the radar per night measured as number of individuals per kilometer per hour.
- Data source: KOKX radar.
Day of year, zonal wind component, meridional wind component, cloud ceiling height, temperature, and average migration traffic variables were standardized to have a mean of 0 and a variance of 1 to aid model convergence. Column names for the standardized variables start with "scaled_".
Methods
This dataset includes five years of spring and fall data compiled from three sources: (1) bird collision data from NYC Audubon's Project Safe Flight, (2) bird migration traffic data processed from the KOKX radar station, and (3) historical weather data from LaGuardia Airport weather station.
The bird collision data from NYC Audubon's Project Safe Flight was collected at a total of 27 buildings in NYC across 11 spring/fall monitoring seasons. Volunteer collision monitors walked a route consisting of 1 to 6 buildings once per day and, for each building, recorded their monitoring start and end times and the number of birds they found.
Weather data are from the LaGuardia Airport weather station and provide local, proximate measurements of observed weather conditions at ground-level. Values included in this dataset are mean nocturnal (dusk-dawn) values of the following measurements: zonal (east-west) and meridional (north-south) wind components, cloud ceiling height, visibility distance, and air temperature. Due to a highly skewed distribution, we converted visibility distance into a categorical variable and considered visibility “low” when visibility distance was <10 km, “medium” when visibility distance was between 10 to 16 km, and “high” when visibility distance was >16 km.
Bird migration traffic data was obtained and processed from the KOKX radar station. The migration traffic values included in this dataset are calculated nightly averages of migration traffic rate (# individuals/km/hr). We defined medium migration traffic as average migration traffic (x̄ = 9.46 x 102 individuals/km/hr in spring and 1.69 x 103 individuals/km/hr in fall), low migration traffic as x̄ - 1 SD (4 individuals/km/hr in spring and 9 individuals/km/hr in fall), and high migration traffic as x̄ + 1 SD (1.86 x 103 individuals/km/hr in spring and 3.42 x 103 individuals/km/hr in fall).
For our study, we standardized cloud ceiling height, zonal wind component, meridional wind component, temperature, day of year, and average migration traffic variables to have a mean of 0 and a variance of 1 to aid model convergence. We did this using the scale() base R function, which uses the following equation: ((x – x̄)/SD), where x̄ is the mean and SD is the standard deviation.