DOI: 10.5061/dryad.b2rbnzsmf
title: Concrete habitat: Impervious surface and avian fitness decline in two urban adapters

description: The conversion of natural habitats to impervious surfaces in cities
 affects biotic and abiotic attributes of urban ecosystems. Detailed
 information on the gradual influence of impervious surfaces on
 reproductive output, however, is lacking. Using five years of
 nestbox-breeding great tit and blue tit data collected across various
 habitat types within and outside a Central-Eastern European capital city,
 we quantified the impact of impervious surfaces on avian reproductive
 success. Impervious surfaces strongly and negatively covaried with the
 number of fledged young in both species: a 0 to 50% increase in impervious
 surface within 100 m of the nest was associated with 3.56 fewer fledged
 offspring in great tits (95% CI: -4.85, -2.27) and 2.91 fewer fledged
 offspring in blue tits (95% CI: -4.26, -1.56), thus halving the
 reproductive output of two widespread urban species. These results provide
 benchmark values of avian productivity for ecologists and urban policy
 makers, and for the management of urban areas.
description: Study area Data were collected from 500
 Schwegler woodcrete-nestboxes (type 1b, with a 32 mm-diameter entrance
 hole, suitable for great tits and blue tits) set in a 50m grid within
 eight study sites in and outside the city of Warsaw, Poland (Fig.1). Our
 set up comprehends study sites from highly urbanized locations close to
 the city center (e.g., an office area and two residential sites – blocks
 of flats typical of post-war Eastern European architecture, built in the
 late 40’s and 50’s of the 20th century) and from green urban spaces (an
 urban park and two urban woodlands). The study system is also composed of
 two study areas located outside the city: a suburban village and a natural
 forest. More details relative to each study site location are reported in
 earlier publications (Corsini <em>et al.</em> 2019,
 2020). <strong>Breeding
 data</strong> Great tit and blue tit breeding
 data were collected for five years (2017-2021). Each year, nestboxes were
 inspected weekly, starting from March until mid-July with the only
 exception of one urban woodland (the cemetery), which could not be visited
 regularly in 2020 due to pandemic-related access restrictions (Corsini
 <em>et al.</em> 2022). Overall, such visiting frequency
 allowed for estimating the date of the first egg laid and clutch size, as
 these species lay one egg daily. Hatching date was determined by checking
 the nestboxes one day before expected hatching or every other day after
 that, until hatching occurred. Parents were caught, aged (as first year
 breeders or older), measured, and ringed when nestlings were 10-13 days
 old. Fifteen days after hatching, alive nestlings were counted,
 individually weighed and ringed. Twenty-five days after hatching,
 nestboxes were checked to record fledging success. Only first broods
 initiated within 30 days after the first brood recorded for each species
 in a given year and site were included in the study (Van Balen
 1973). <strong>Quantifying
 urbanization</strong> Urbanization was measured
 as the percentage of Impervious Surface Area (ISA) in a 100m-radius from
 each nestbox. Namely, a 20-m pixels resolution ISA-raster file was
 downloaded from Copernicus Land Monitoring Services (https://land.copernicus.eu/sitemap), and averaged for each nestbox via buffer-analyses in qGIS v.3.10 (Team 2016) (see Szulkin <em>et al.</em> (2020)). The ISA layer contained all built-up areas which replaced original natural cover with impervious or any other artificial surface. The 100m-radius was selected based on the food foraging distance covered by blue tit parents while feeding the nestlings (Tremblay <em>et al.</em> 2004). <strong>Statistical analyses</strong> Statistical analyses were performed in R (v. 4.1.2). Because of species-specific differences in life-history, great tits and blue tits were analyzed separately. To test the association between number of fledged offspring and ISA, we fitted Generalized Linear Mixed Effects Models (GLMMs). Namely, we included all nests where at least one egg hatched. Because data were over dispersed, we used a quasi-Poisson error-structure. We included the continuous predictors <em>ISA</em>, <em>Lay date </em>(1<sup>st</sup> of April recorded as 1), and <em>Female Body Mass </em>(<em>as </em>heavier females produce larger clutches and start breeding earlier in the season (Perrins & McCleery 1989)). We also fitted <em>Year </em>(5 levels) as a fixed effect. When including <em>Site</em> (8 levels) as a random effect to control for inter-site variation in avian breeding, we found that the between sites variance was close to zero, and therefore removed it from the models. Interactions between <em>Year</em> and <em>ISA</em>, and between <em>Lay date</em> and <em>Female body mass</em> were tested and removed from the models if not significant. Further, as the influence of ISA on <em>Clutch size</em> may influence the variability in fledging success, we conducted supplementary analyses using the same structure as previously indicated, incorporating <em>Clutch size</em> as a continuous predictor in the models. Potential multicollinearity issues were verified using the <em>vif</em>-function (<em>car</em> package (Fox <em>et al.</em> 2012)), which always yielded values below 2. Plots were built in <em>ggplot2 </em>(Wickham 2011) after calculating predictions in <em>ggeffects </em>(Lüdecke <em>et al.</em> 2020). Unit decreases in fledged offspring were calculated using the function <em>avg_comparisons</em> in the package <em>marginaleffects </em>(Arel-Bundock, 2023)<em>.</em>
description: We used R v.4.1.2 to analyze the data, Inkscape to visualize the
 final plots, and qGIS v.3.34.2 to run the buffer analyses and generate the
 map.
description: # Concrete habitat: Impervious surface in nest vicinity is associated with
 avian fitness decline in two urban adapters We included data and codes
 used for the analyses presented in the manuscript entitled "Concrete
 habitat: Impervious surface in nest vicinity is associated with avian
 fitness decline in two urban adapters" by Michela Corsini and Marta
 Szulkin. ## Description of the Data and file structure Data are included
 for each species. The file **GT_fled** includes data for fledglings
 analyses in Great tits, **BT_fled** includes data for fledglings analyses
 in Blue tits. The text file GT_fled includes data on the total number of
 fledglings per breeding event. Nests were checked 25 days after hatching
 (hatching date was recorded as Day 1) to record ho many ringed birds died.
 The R-file entitled "**Fled_analyses_ISA_Corsini2024**" includes
 all codes for models (glms with quasi-Poisson distribution) and plots
 (built in ggplot2). ### Labels: Year: Includes the year of the study:
 2017, 2018, 2019, 2020 or 2021 Site: CMZ: Urban woodland Jewish cemetery,
 KPN: Kampinos national park, OLO: residential area Las Olszyna, MUR:
 residential area Muranow, POL: Urban park Pole Mokotowskie, UNI:
 University campus - office area, LOL: Urban woodland Las Olszyna. All
 sites were located in Warsaw or in its outskirts, Poland. BroodNr: Brood
 number, standardized by picking the first broods of the season. Only first
 broods initiated within 30 days after the first brood recorded for each
 species in a given year and site were included in the study (Van Balen
 1973). NestboxID: id of the nestbox. Species: GT= Great tit, BT=Blue tit.
 Lay date: Date of the first egg laid per breeding event. Julian date: 1st
 of April as 1 every year. CS: Clutch size. Total number of eggs per
 breeding event. NrHatchlings: Total number of hatched birds per breeding
 event. BroodSize15: Total number of nestlings that were alive in the nest
 15 days after hatching. Ring_fem: Ring id of the adult female. Mass_Fem:
 Body mass of adult female in grams. It was measured between 10 and 14 days
 after the first nestling of the brood hatched. ISA: Percentage of
 Impervious Surface Areas measured in a 100m radius around each nestbox. We
 used a 20m resolution raster map layer downloaded from the web site
 Copernicus Land Monitoring. Bufer analyses were run in qGIS. Fledglings:
 Total number of fledged nestlings per breeding event. Broods were checked
 25 days after hatching. hatch_ratio: Ratio of hatched birds over the
 number of eggs laid per breeding event. Fledg_ratio: Ratio of fledged
 birds over the number of hatched nestlings per breeding event. ISAlev: ISA
 level measured as low or high after taking the median value of ISA across
 all the set up. LayDate_sc: Scaled Lay date. Mass_Fem_sc: Scaled mass of
 adult female. CS_sc: Scaled clutch size ISA_sc: scaled ISA The text file
 entitled **Fledg_ISA_DataPreparation** contains all the steps to prepare
 the datasets described above for the analyses. Labels here reported are
 analogous to those indicated above.