Increased microclimatic variation in artificial nests does not create ecological traps for a secondary cavity breeder

Abstract

14Artificial devices are increasingly used in conservation measures to mitigate the 15 disappearance of natural habitats. However, few studies have demonstrated their benefits for 16 the target species, and they may pose a risk of creating ecological traps. This occurs when 17 lower individual fitness is found in artificial habitats that are more attractive than their natural 18 equivalents. In this study, we tested the ecological trap hypothesis on a dense population of 19 European rollers Coracias garrulus breeding in both natural cavities and nest-boxes. Our 20 initial hypothesis was that the more stressful microclimatic conditions of nest-boxes would 21 lead to reduced fitness of rollers, thus creating an ecological trap. The results showed that 22 nest-boxes were preferred over natural cavities. Despite significantly more extreme 23 microclimatic conditions in nest-boxes, we found similar breeding parameters between 24 artificial and natural nest types. Our results also suggest that rollers selected the nest-boxes 25 which best buffered the temperature, thus avoiding potential ecological traps. Overall our 26 results lead to the conclusion that nest-boxes do not create ecological traps for rollers in this 27 study site. However, other species may be more sensitive to microclimatic variations or less 28 able to avoid the least favourable nest-boxes. These findings could help to inform the 29 placement of nest-boxes in order to reduce extreme temperatures and variation in humidity 30 rates. Future studies could compare nest types for other fitness parameters, such as juvenile 31 body condition or survival. We also recommend the ecological trap hypothesis as a useful 32 framework to evaluate the outcomes of artificial devices used for conservation. 33 3 Keywords 34 European roller; Coracias garrulus; nest box; natural cavities; preference; buffering capacity; 35 temperature; humidity 36 4

Climate and behaviour influence thermal suitability of artificial hollows for a critically endangered mammal

“…Nest boxes are used globally to increase the availability of den and nest sites for hollow-dependent species (Newton, 1994). However, questions have been raised about the suitability of the microclimatic conditions they provide (Isaac et al 2008;Rowland et al 2017), and studies from different systems have yielded mixed conclusions regarding their thermal suitability (Goldingay, 2020;Schwartz et al 2020). Previous studies have focussed largely on the microclimate of unoccupied artificial dens (Goldingay, 2015;Rowland et al 2017;Griffiths et al 2018, although see Goldingay & Thomas, 2021), but this fails to account for the potentially confounding effect of individual heat production (Kearney et al 2011;Maziarz, 2019).…”

“…2017), and studies from different systems have yielded mixed conclusions regarding their thermal suitability (Goldingay, 2020; Schwartz et al . 2020). Previous studies have focussed largely on the microclimate of unoccupied artificial dens (Goldingay, 2015; Rowland et al .…”