DOI: 10.5061/dryad.41ns1rnmw
title: Heavy migration traffic and bad weather are a dangerous combination: Bird collisions in New York City

description: 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.
description: 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 &lt;10 km, “medium” when visibility distance
 was between 10 to 16 km, and “high” when visibility distance was
 &gt;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. 
description: # 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 &lt;10 km, “medium” indicates a
 visibility distance between 10 to 16 km, and “high” indicates a visibility
 distance &gt;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_".