DOI: 10.5061/dryad.c866t1gfd
title: Data from: Urban environmental predictors of group size in cliff swallows (Petrochelidon pyrrhonota): A test using community-science eBird data

description: Studies on the impacts of urbanization on birds have explored a wide
 variety of behaviors (e.g. foraging, breeding, migratory), but there is
 little research on the impacts of cities on avian coloniality. Various
 urban-environmental factors may impact colonial birds, including the
 predominance of impervious surfaces in cities, as well as the urban heat
 island effect and shifts in habitat and resource availability (e.g. food,
 water). Here we used five years of community-science data available in
 eBird to investigate urban impacts on group size in cliff swallow
 (Petrochelidon pyrrhonota), an abundant colonial bird species that now
 breeds readily under bridges and other built structures over or near water
 in Phoenix, Arizona, USA. We hypothesized that, based on the unique
 breeding habits of these neotropical migratory birds in this desert
 environment, swallows in Phoenix would form larger groups in areas with
 more food and water sources and with more built structures. In fact, we
 found that proximity to water sources and cropland, but not impervious
 surface density, was positively and significantly related to group size.
 These results suggest that, in this desert ecosystem, an abundance of
 often-human-provided food/water resources permits cliff swallows to form
 larger social groups during breeding. Although many studies show harmful
 impacts of cities on local wildlife, our findings highlight how urban
 and/or agricultural ‘oases’ may relieve some native species from natural
 resource stressors and permit them to thrive and increase in group size in
 human-impacted environments.
description: # Urban environmental predictors of group size in cliff swallows
 (Petrochelidon pyrrhonota): A test using community-science eBird data
 [https://doi.org/10.5061/dryad.c866t1gfd](https://doi.org/10.5061/dryad.c866t1gfd) ## Description of the data and file structure RuedaMcGraw2025.xlsx  Bird data were gathered from eBird. Environmental data were gathered from a variety of sources (see manuscript). **Column abbreviations** * \#birds observed = number of swallows sighted during an observation - Site name = name of the observation site (as listed by the observer(s)) * LATITUDE = latitude of an observation site - LONGITUDE = longitude of the observation site * DATE = date of the observation - Observation protocol = means by which observation data were collected (stationary or traveling) * Duration (mins) = duration of an observation, in minutes - Effort (distance) = distance traveled during an observation, in kilometers * \#observers = number of observers that participated in an observation - Mean Monthly Temp (C) = mean temperature, in Celsius, at an observation site given the observation date * DistPriSecRd = distance from observation site to primary or secondary road, in meters - DistCanal = distance to canal, in meters * DistMajRiv = distance to major river, in meters - DistLLake&River = distance to large lake and river, in meters * MonthlyMeanPrecip = mean precipitation, in millimeters - DistDevOpenSp = distance to nearest developed open space, in meters * DistLowDev = distance to nearest low developed area, in meters - DistMedDev = distance to nearest medium developed area, in meters * DistHighDev = distance to nearest high developed area, in meters - DistBarrenLand = distance to nearest barren land, in meters * DistForest = distance to nearest forest, in meters - DistGrass = distance to nearest grassland, in meters * DistPasture = distance to nearest pasture, in meters - DistCrops = distance to nearest cropland, in meters - DistWoodyWetla = distance to nearest woody wetland, in meters * DistEHWetl = distance to nearest emergent herbaceous wetland, in meters - PopulationDensity = human population density of the census tract in which the observation site resided * %Minority = percent of the human population that was racial minority, within the census tract in which the observation site resided - FocalDevOpenSpace = percentage of the area surrounding an observation site (1 km radius) that was covered by developed open space * FocalLowDev = percentage of the area surrounding an observation site (1 km radius) that was covered by low developed space - FocalMedDev = percentage of the area surrounding an observation site (1 km radius) that was covered by medium developed space * FocalHighDev = percentage of the area surrounding an observation site (1 km radius) that was covered by high developed space - FocalBarren = percentage of the area surrounding an observation site (1 km radius) that was covered by barren land * FocalGrass = percentage of the area surrounding an observation site (1 km radius) that was covered by grassland - FocalForest = percentage of the area surrounding an observation site (1 km radius) that was covered by forest * FocalPasture = percentage of the area surrounding an observation site (1 km radius) that was covered by pasture - FocalCrop = percentage of the area surrounding an observation site (1 km radius) that was covered by cropland * FocalWoodyWetla = percentage of the area surrounding an observation site (1 km radius) that was covered by woody wetland - FocalEHWetla = percentage of the area surrounding an observation site (1 km radius) that was covered by emergent herbaceous wetland * %ImpSurf = percent of impervious surface at an observation site - FocalImpSurf = percentage of the area surrounding an observation site (1 km radius) that was covered by impervious surface