Urban environmental predictors of group size in cliff swallows (Petrochelidon pyrrhonota): A test using community-science eBird data

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..., , , # 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...,