DOI: 10.5061/dryad.z08kprrgj
title: Data from: Combined effects of cold snaps and agriculture on the growth rates of Tree Swallows (<em>Tachycineta bicolor</em>)

description: The decline of avian aerial insectivores has been greater than any other
 foraging guild and both climate change and agricultural intensification
 are leading hypotheses explaining this decline. Spring cold snaps are
 predicted to increase in frequency due to climate change, and factors
 associated with agricultural intensification (e.g., toxicological agents,
 simplification of agricultural landscapes, and reductions of insect prey)
 potentially exacerbate the negative effects of cold snaps on aerial
 insectivore nestling growth and body condition. We evaluated this
 hypothesis using repeated measures of Tree Swallow (Tachycineta bicolor
 (Vieillot, 1808)) nestling body mass and 9th primary length across an
 expansive gradient of agricultural intensification. Growth rate,
 asymptotic body mass, and near-fledging 9th primary length were lower for
 nestlings in landscapes consisting of more agro-intensive monocultures.
 This 14-year dataset of body measures occurring at 2, 6, 12, and 16 days
 of age showed that the negative impact of cold snaps on the growth of
 these two traits was stronger for nestlings reared in more agro-intensive
 landscapes. Our findings provide further evidence that two of the primary
 hypothesized drivers for the decline of many aerial insectivores may
 interact and aggravate their decline by reducing fledging survival.
description: # Data from: Combined effects of cold snaps and agriculture on the growth
 rates of Tree Swallows (*Tachycineta bicolor*)
 [https://doi.org/10.5061/dryad.z08kprrgj](https://doi.org/10.5061/dryad.z08kprrgj) ## Description of the data and file structure Data sets used in the determination of how agricultural cover and the appearance of cold snap (days where the maximum observed temperature fell below 18.2 °C) interact to impact the growth rates of Tree Swallows breeding within southern Quebec, Canada. The following are the definitions of the columns found in data sets. The data set names describe the contents of each data set. The text fine and coarse in the data set name refers to the fine and coarse temporal scale used in the formal analysis, respectively. ### Files and variables • Brood.id = Unique brood identification • Nestling.id = Unique nestling identification • Year = Breeding season (Year between 2006 and 2019) • Farm = Unique farm identification • NestBox = Unique nest box identification • Time = Time in the day the measure occurred • Hatch.day = Estimated hatching day of the brood (January 1 = day 1) • Age = Age of the brood/nestling (days after hatching) • Mass = Body mass (g) of the nestling • Wing = Wing length (mm) of nestling • brood.days = Summation of the daily brood size (full explanation found in manuscript body and supplemental sections) • Female.age = Morphological age of the female (i.e., second year (SY) vs. after-second year (ASY)) • rain.6.day.check = Mean daily accumulation of rain over the six days prior to the measure (ml). • snap.6.day.check = Number of cold snaps occurring over the previous six days. • Comp.1 = The sites score (i.e., first principal component value) assigned to the brood • Comp.2 = The sites score (i.e., second principal component value) assigned to the brood • Water = Percent cover of water within 3km from the nest box.