DOI: 10.5061/dryad.xksn02vdg
title: Increased microclimatic variation in artificial nests does not create ecological traps for a secondary cavity breeder, the European roller

description: Artificial devices are increasingly used in conservation measures to
 mitigate the disappearance of natural habitats. However, few studies have
 demonstrated their benefits for the target species, and they may pose a
 risk of creating ecological traps. This occurs when lower individual
 fitness is found in artificial habitats that are more attractive than
 their natural equivalents. In this study, we tested the ecological trap
 hypothesis on a dense population of European rollers Coracias garrulus
 breeding in both natural cavities and nest-boxes. Our initial prediction
 was that the more stressful microclimatic conditions of nest-boxes would
 lead to reduced fitness of European rollers, thus creating an ecological
 trap. The results showed that nest-boxes were preferred over natural
 cavities. Despite significantly more extreme microclimatic conditions in
 nest-boxes, we found similar breeding parameters between artificial and
 natural nest types. Our results also suggest that European rollers
 selected the nest-boxes which best buffered the temperature, thus avoiding
 potential ecological traps. Overall our results led to the conclusion that
 nest-boxes do not create ecological traps for European rollers in this
 study area. However, other species may be more sensitive to microclimatic
 variations or less able to avoid the least favourable nest-boxes. These
 findings could help to inform the placement of nest-boxes in order to
 reduce extreme temperatures and variation in humidity rates. Future
 studies could compare nest types for other fitness parameters, such as
 juvenile body condition or survival. We also recommend the ecological trap
 hypothesis as a useful framework to evaluate the outcomes of artificial
 devices used for conservation.
description: See paper (open access)
description: Meaning of each column:
 ##########################
 alldata_microclimate_15days.csv 
 Name of the column Description Daily microclimate variables MaxTint Maximal temperature in the nest (°C) MinTint Minimal temperature in the nest (°C) MoyTint Mean temperature in the nest (°C) DiffTint Difference between maximal and minimal temperature in the nest (°C) Dtmoyabs Mean over a day of the absolute delta between interior and exterior temperature (°C) Dtmaxabs Absolute value of the daily maximum delta between interior and exterior temperature (°C) Maxhum Maximum humidity level in the nest (%RH) Minhum Minimum humidity level in the nest (%RH) Moyhum Mean humidity level in the nest (%RH) DiffHum Difference between maximal and minimal humidity level in the nest (%RH)   Name Name of the nest-box or cavity Type Nest type : either nest-box or cavity occupation Occupation of the nest by rollers during the breeding season : 1 for roller nests, 0 otherwise OccR Real occupation of the nest during monitoring (roller or starling) : 1 for occupied nests sensor measurements, 0 for empty nests during sensor measurements Developmental stage Number of days between the day of measurement and the first egg-laying date (0 for nests not occupied by rollers) First egg-laying date Day of the laying of the first egg (for roller nests only) (Julian calendar date) CH Cavity height (m) CBH Circumference of the tree at breast height (1.30m) (cm) (natural cavities only) CCH Circumference of the tree at cavity height (cm) (natural cavities only) Orientation Entrance orientation of the nest (degrees) Ori Simplified orientation of the nest (either N, E, S or W with N: 316°-45°; E: 46°-135°; S: 136°-225°; W: 226°-315°) EH Entrance height (cavity) (mm) (natural cavities only) EW Entrance width (cavity) (mm) (natural cavities only) CL Cavity length (cm) (vertical) : minimum distance from the bottom of entrance hole to the bottom of the chamber (natural cavities only) CD Cavity depth (cm) (horizontal) : minimum distance from the entrance hole to the back wall of the cavity (natural cavities only) Date Day of the measurement (Julian calendar date) ############################ reproduction_data_2016-2019.csv Name of the column Description Name Name of the nest-box or cavity Type Nest type : either nest-box or cavity year Year of monitoring of the nest eggs Size of the clutch (complete clutches only) chicks Number of hatched eggs in complete clutches fledglings Number of fledglings success 1 if at least 1 fledgling, 0 otherwise n_failed_eggs Number of eggs that did not produce a fledgling ############################################## average_microclimate_&_characteristics_NB_CAV.csv Name of the column Description Mean microclimate variables over 15 consecutive days MAXTint Maximal temperature in the nest (°C) MINTint Minimal temperature in the nest (°C) MOYTint Mean temperature in the nest (°C) DIFFTint Difference between maximal and minimal temperature in the nest (°C) DTMOYabs Mean over a day of the absolute delta between interior and exterior temperature (°C) DTMAXabs Absolute value of the daily maximum delta between interior and exterior temperature (°C) MAXHum Maximum humidity level in the nest (%RH) MINHum Minimum humidity level in the nest (%RH) MOYHum Mean humidity level in the nest (%RH) DIFFHum Difference between maximal and minimal humidity level in the nest (%RH)   Name Name of the nest-box or cavity Type Nest type : either nest-box or cavity occupation Occupation of the nest by rollers during the breeding season : 1 for roller nests, 0 otherwise OccR Real occupation of the nest during monitoring (roller or starling) : 1 for occupied nests sensor measurements, 0 for empty nests during sensor measurements CH Cavity height (m) CBH Circumference of the tree at breast height (1.30m) (cm) (natural cavities only) CCH Circumference of the tree at cavity height (cm) (natural cavities only) Orientation Entrance orientation of the nest (degrees) Ori Simplified orientation of the nest (either N, E, S or W with N: 316°-45°; E: 46°-135°; S: 136°-225°; W: 226°-315°) EH Entrance height (cavity) (mm) (natural cavities only) EW Entrance width (cavity) (mm) (natural cavities only) CL Cavity length (cm) (vertical) : minimum distance from the bottom of entrance hole to the bottom of the chamber (natural cavities only) CD Cavity depth (cm) (horizontal) : minimum distance from the entrance hole to the back wall of the cavity (natural cavities only)