Urban habitats are rapidly changing, making the conservation and management of species adapted to these environments challenging. Nest site selection is a pivotal point in the process of habitat selection and breeding for bird species. We measured 10 structural and spatial characteristics at 32 nest presence sites and 64 randomly selected nest absence sites of Laughing Doves (Spilopelia senegalensis) in an urban environment in Karaj, Iran. To model the nest site selection, we performed spline binary logistic regression. Two variables significantly influenced the nest site selection of Laughing Doves: nest height above ground, with an optimal range of ~286–347 cm, and nest concealment, favoring invisible places from the front and sides. Distance to opposite building, with an optimal range of ~16–34 m, was marginally significant. Additionally, we surveyed the feasibility of occupying artificial nestboxes (n = 17) by Laughing Doves between February and September 2019. The occupancy rate of the artificial nestboxes was ~35%. Overall, these results suggest that despite the relatively high structural heterogeneity of our urban environment, Laughing Doves exhibit distinct preferences for certain nest site characteristics, which may reflect a dependence on close proximity to humans for safety and access to food and water.

From 25 February to 3 April 2019, we searched both sides of the streets and alleys, alternating between going and returning on foot from morning to afternoon, ensuring each side was searched once. Moreover, from 29 February to 15 March 2019, we directly approached 82 local residents from our own neighborhood, familiar to us, asking them to report any Laughing Dove nests they observed in the study area. Additionally, we requested that they encourage others to do the same. As a result, we believe that even more individuals indirectly contributed to our study. Based on the assumption that the abandoned nests were built in favorable places by this bird, we also recorded and accounted for them as nest presence sites. The tools and devices used in sampling included a tape measure, a Global Positioning System (GPS) device from Garmin^® (USA), a sliding ladder, a compass, and a closed-circuit television (CCTV). Until 3 April 2019, we recorded 32 nest presence sites, 10 of which (31.2%) were found by local residents, and 64 randomly selected nest absence sites (see “Presence and Absence data.txt” and, inside the folder “GIS data,” “Presence_Points.shp” and “Absence_Points.shp”).

Ten structural and contextual variables were measured in this study. The vertical distance from the ground to the base of the nest (HEIGHT; cm) was measured using a measuring tape positioned directly below the nest. Similarly, the vertical distance from the ceiling to the base of the nest (CEILING; cm) was measured with a measuring tape, with one end placed at the base of the nest and the other at the ceiling. The horizontal distance from the edge of the nest to the edge of the ceiling (H_CEILING; cm) was also measured using a measuring tape held horizontally. The horizontal distances from the nest to the nearest tree with a diameter at breast height (DBH) greater than 10 cm (TREE_DIST; m) and to the nearest opposite building (BUILD_DIST; m) were both measured by counting steps to estimate the distances. The distances from the nest to the edge of the nearest green space (area > 2 km²; GREEN_DIST; m) and to the nearest counterpart nest (NEST_DIST; m) were both measured using a combination of GPS coordinates and mapping software (ArcMap). see “Presence_Points.shp,” “Absence_Points.shp,” and “Green_Spaces.shp”) inside the folder “GIS data.” The nest concealment (CONCEAL) was assessed visually by us. We imagined our eyes were ~4 m horizontally away from the nest, in the opposite and side directions of the base structure, because it was often not possible to physically reach those viewpoints, especially when they were at a high height or when placing our sliding ladder on the street was required. The nest concealment was then categorized as A (invisible from the front and sides), B (invisible from the front but visible from one side), or C (visible from the front but invisible from the sides). The base structure of the nest (B_STRUCT) was categorized as A (shop boards; a photo of a nest in a shop board is provided as “A_Nest_in_a_Shop_Board.png”), B (building frontispieces), or C (balconies) through visual inspection. Finally, the aspect of the base structure where the nest was located (B_ASPECT) was determined using a compass and categorized as A (North), B (East), C (South), or D (West). All data are provided in “Presence and Absence data.txt” and, inside the folder “GIS data,” “Presence_Points.shp” and “Absence_Points.shp.

Seventeen artificial nest boxes were erected from 15 to 22 April 2019, with seven placed near shops, two on the frontispieces of buildings, and eight on building balconies (see “Nest_Box_Presence_Points.shp” and “Nest_Box_Absence_Points.shp” inside the folder “GIS data”). Subsequently, all 10 structural and contextual variables were recorded for these nest boxes in a separate dataset (see “Nest box data.txt”).

Additionally, Our observations using CCTV on 14 May 2019 revealed a possible nesting behavior in Laughing Doves (the video is provided as "A possible nesting behavior.mov"). While constructing the nest in a nest box, the male dove placed his head in the location where the eggs will be laid. Given that male Laughing Doves are responsible for bringing nest materials, it is possible that this behavior allows the male to assess the nest condition to complete it with appropriate materials.

Another possibility is that the female Laughing Dove is gauging the nest condition to arrange the nest materials appropriately. It is also plausible that both the male and female are involved in assessing the nest condition through this behavior. Lastly, it is possible that this action is random and without any specific purpose. Further investigation is needed to determine the exact reason for this behavior.

Although we are aware that this possible nesting behavior is not directly related to the nest site selection of Laughing Doves, we prefer to attach this observation in the supplementary part of our manuscript. This is because the observation alone does not warrant a separate manuscript or even a short note.