DOI: 10.5061/dryad.wdbrv15p4
title: Dataset for: Assessing pesticides exposure effects on the reproductive performance of a declining aerial insectivore

description: In the context of increasing global environmental changes, it has become
 progressively important to understand the effects of human activity on
 wildlife populations. Declines in several avian populations have been
 observed since the 1970s, especially with respect to many farmland and
 grassland birds, which also include some aerial insectivores. Changes in
 farming practices referred to as agricultural intensification coincide
 with these major avian declines. Among those practices, increased
 pesticide use is hypothesized to be a key driver of avian population
 declines as it can lead to both toxicological and trophic effects. While
 numerous laboratory studies report that birds experience acute and chronic
 effects upon consuming pesticide treated food, little is known about the
 effects of the exposure to multiple pesticides on wildlife in natural
 settings. We monitored the breeding activities of tree swallows
 (Tachycineta bicolor) on 40 farms distributed over a gradient of
 agricultural intensification in southern Québec, Canada, to evaluate the
 presence of pesticides in their diet and quantify the exposure effects of
 those compounds on their reproductive performance between 2013 and 2018.
 We first assessed the presence of 54 active agents (or derivatives) found
 in pesticides in 2,081 food boluses (insects) delivered to nestlings by
 parents and documented their spatial distribution within our study area.
 Second, we assessed the effect of pesticide exposure through food (number
 of active agents detected and number of contaminated boluses on a given
 farm for a given year, while controlling for sampling effort) on clutch
 size as well as hatching and fledging successes and nestling’s mass upon
 fledging. Pesticides were ubiquitous in our study system and nearly half
 (46%) of food boluses were contaminated by at least one active agent. Yet
 we found no relationship between our proxies of food contamination by
 pesticides and tree swallow reproductive performance. More studies are
 needed to better understand the putative role of pesticides in the decline
 of farmland birds and aerial insectivores as potential sublethal effects
 of pesticides can carry over later life stages and impact fitness.
description: <strong>Variables description for
 DB_females</strong><br> yearfarm: concatenante of
 year and farm number yearidnestbox: concatenate of farm
 and nestbox id idnestbox: concatenante of farm and
 nestbox number neggs: number of eggs laid
 nhatchlings: number of nestlings that hatched
 nfledglings: number of nestlings that fledged
 ndead: number of nestlings that died before fledging
 dlaying: julian day of first egg laid dincub:
 julian date of incubation start dhachingmin: minimum
 julian date of hatching dhatchingmax: maximum julian
 date of hatching dflegingmin: minimum julian date day
 of fledging dfledgingmax: maximum julian date of
 fledging idfemale: unique female id
 mass: female mass (g) age_morpho: female
 morphological age d12: julian date with clutch aged 12
 days year: year farm: farm
 id nonintensive: % of non-intensive culture within
 500-m of the nest box intensive: % of intensive culture
 within 500-m of the nest box water: % of water
 cover within 500-m of the nest box npestdiff.54: number
 of different pesticides detected for a specific farm-year
 nboul2tot: total number of boluses collected for a specific
 farm-year nboulcont.54: number of contaminated boluses
 for a specific farm-year nnonfledging: number of
 nestlings that didn't fledged (includes dead and disapeared
 nestlings) hatchingsuccess: number of hatchlings
 divided by number of eggs laid fledgingsuccess: number
 of fledglings divided by number of hatchlings
   <strong>Variables description
 for DB_nestlings</strong> idclutch:
 concatenate of nest box id, year and clutch number
 yearfarmnich: concatenante of year, farm and nest box
 id idfemale: unique female id
 idnestling: unique nestling id
 nestling_massd16: nestling's mass at 16 days old
 (g) fledged: 0 if nestling did not flegde, 1 if it
 fledged age_morpho: female morphological age
 female_mass: female mass (g) nonintensive: %
 of non-intensive culture within 500-m of the nest box
 nboul2tot: total number of boluses collected for a specific
 farm-year nboulcont.54: number of contaminated boluses
 for a specific farm-year year: year
 dlaying: julian day of first egg laid
 idnestbox: concatenante of farm and nestbox number