DOI: 10.5061/dryad.rfj6q57gh
title: Does social information affect the settlement decisions of resident birds in their second breeding attempt? A case study of the Japanese tit (Parus minor)

description: Individuals may gather information about environmental conditions when
 deciding where to breed in order to maximize their lifetime fitness. Many
 studies have shown that birds can rely on social information to select
 their nest site. The location of active nests and the reproductive success
 of conspecifics and heterospecifics can provide accurate predictions
 about the quality of the breeding habitat. Some short-lived
 species can facultatively reproduce two and/or more times within
 a breeding season. However, few studies have focused
 on how multiple-brooding individuals select nest
 sites for their second breeding attempts. In this study,
 we use long-term data to test whether the Japanese tit (Parus
 minor) can use social information from conspecifics and/or heterospecifics
 to select a nest site for the second breeding attempt. Our results showed
 that the nest boxes occupied by tits on their second breeding attempt
 tended to be surrounded by more breeding conspecific nests, first-breeding
 successful conspecific nests, and fewer first-breeding failed conspecific
 nests than the nest boxes that remained unoccupied (the control group).
 However, the numbers of breeding heterospecific nests, successful
 heterospecific nests, and failed heterospecific nests did not differ
 between the nest boxes occupied by tits on their second breeding attempt
 and the unoccupied nest boxes. Furthermore, the tits with local successful
 breeding experience tended to choose areas with more first-breeding
 successful conspecific nests than those without successful breeding
 experience. Thus, we suggest that conspecifics’ but not heterospecifics’
 social information within the same breeding season is the major factor
 influencing the nest site selection of Japanese tits during second
 breeding attempts.
description: The
 fieldwork was conducted from March-July over successive
 years from 2014 to 2021 in an
 approximately 134.5 ha mixed
 deciduous forest at Zuojia Nature Reserve (44°1′–45°0′N, 126°0′–126°8′E)
 in Jilin Province, northeastern China. The study area consisted of 9
 discrete deciduous forest patches, with nearly
 homogeneous forest characteristics. The dominant tree species
 were <em>Quercus
 mongolica</em>,
 <em>Tilia
 mandshurica</em>,
 <em>Betula
 davurica</em>,
 <em>Phellodendron
 amurense</em>, and
 <em>Sophora japonica.</em> Since 2004, many artificial nest boxes have been
 provided for secondary cavity-nesting birds in this area. The Japanese
 tit, Eurasian nuthatch,
 Daurian redstart, and yellow-rumped flycatcher readily accept artificial
 nest boxes for breeding, allowing detailed breeding data and the identity
 of breeders to be collected on a large number of nests.
 Approximately 400 artificial nest boxes were provided per
 year in our study area. The nest boxes
 were distributed among patches and separated by 30–50 m, with 40 to 50 boxes equally distributed per patch. The density of nest boxes was 0.24 boxes/ha.
 All nest boxes were the same size (inner dimensions: 12 cm
 ×<em> </em>12 cm × 25 cm, entrance diameter approximately 4.5
 cm) and had removable roofs. The
 artificial nest boxes were hung on trees
 approximately 2.5–3 m above
 the ground. The tree species on which the nest boxes were hung and the
 orientation of the box holes were randomly
 determined. We removed
 old nest materials from the artificial nest boxes before the initiation of
 the breeding season and routinely monitored all nest boxes from late March
 until mid-July. We monitored nests at least once a week (and
 more frequently near expected hatch/fledge dates) until the nest fledged
 or failed. Failed nests were classified as predated (empty nest cup with
 all contents removed before estimated fledge date; potential predators
 included snakes or chipmunks) or abandoned (dead nestlings or cold eggs on
 two or more consecutive visits). The breeding attempts and reproductive
 data (e.g., the date the first egg was laid, clutch size, hatching date,
 brood size, and the number of fledglings) of all four bird species
 (Japanese tits, yellow-rumped flycatchers, Eurasian nuthatches, and
 Daurian redstarts) were recorded as part of routine monitoring (Yu et al.
 2017). We surveyed these forest patches and found few natural holes, with
 almost all breeding Japanese tits occupying the nest boxes. During the
 breeding season, an average of 39.8% of nest boxes were occupied
 (egg-laid) by birds (Japanese tits 26.3%, yellow-rumped flycatchers 8.4%,
 Eurasian nuthatches 2.8%, and Daurian redstarts 2.2%, unpublished data).
 Among the species which occupy nest boxes for breeding, Japanese tits are
 the most defensive in our study area and rarely find their nests usurped
 by other species. We determined the
 coordinates of occupied nest boxes using handheld GPS units with an
 accuracy of &lt; 10 m. All nest boxes occupied by
 birds that had initiated egg-laying were considered and included in the
 data collection. Almost all adult Japanese tits
 breeding in nest boxes in the study area
 were captured inside boxes during the mid-to-late chick-rearing period.
 The second breeding attempt
 was defined as an individual initiating a second clutch following a
 successful first clutch (at least one fledging leaving the nest) in the
 same breeding season (Fan et al. 2021). We defined the pairs recaptured from the first
 breeding attempt as second-breeding pairs (i.e., pairs with
 successful breeding experience). In addition, we defined
 pairs that initiated breeding after the first brood of chicks had fledged
 in the study area (i.e., those with no information on the first clutch) as
 late-breeding pairs (i.e., pairs without local successful breeding experience). The
 phenology variables were encoded as the number of days that elapsed since
 the first of April (with day 1 = 1 April). The mean date that Japanese
 tits laid their first egg was
 24.14 ± 0.38 (n=576 nests) in the first broods and 63.85 ± 0.95 (n=60
 nests) in the second broods. The mean dates that Eurasian nuthatches, Daurian redstarts, and
 yellow-rumped flycatchers laid their first egg were 22.05 ±
 0.69 (n=74 nests), 37.61 ± 2.75 (n=49 nests), and 53.45 ± 0.54 (n=240
 nests), respectively. The clutch sizes of Japanese tits’ first and second
 broods were 11.20 ± 0.07 (range: 6–16, n=530 nests) and 8.05 ± 0.19
 (range: 6–12, n=60 nests), respectively. The clutch sizes of Eurasian
 nuthatches, Daurian redstarts, and yellow-ridged flycatchers were 6.90 ± 0.16 (range: 6–8, n=65
 nests), 6.50 ± 0.14 (range: 5–10, n=46 nests) and 5.73 ± 0.06 (range: 4–8,
 n=230 nests), respectively. The reproductive success rates of the first
 breeding Japanese tits, Eurasian nuthatches, Daurian redstarts, and
 yellow-ridged flycatchers were approximately 81.25% (n=576
 nests), 87.84% (n=74 nests), 87.86% (n=49 nests), 79.58% (n=240 nests),
 respectively. Data
 preparation From 2014
 to 2021, a total of 63 pairs initiated second breeding attempts (i.e.,
 were recaptured from the first breeding attempt) with the same
 mate (Table
 1). Among the 63 second breeding pairs, 3 pairs had been
 recaptured in previous years. We excluded those 3 pairs to avoid
 duplication in subsequent analysis. In
 addition, 161
 late-breeding pairs were
 monitored in the eight years of the study (2014–2021; Table 1).
 We focused on available social information (i.e., the numbers of
 conspecifics and heterospecifics) around the nest sites that Japanese tits
 selected for their second breeding attempt. We measured the Euclidean distance between the
 GPS points of nest sites during 2014–2021. The distance between the first
 and second nest
 sites of the 60 pairs of
 Japanese tits recaptured
 within the same breeding season was &lt; 200 m (range: 20.1–182.9 m; mean ± standard error [SE] = 78.50 ± 6.77 m). Here, we
 labelled the second-breeding nests and late-breeding nests of Japanese
 tits as the focal nest and then assessed the social information within a
 200 m radius around this focal nest at the time of the first egg-laying
 date of
 second
 breeding Japanese
 tits. We counted 1) the
 number of breeding conspecific nests, 2) the number of breeding
 heterospecific nests, 3) the number of first breeding successful
 conspecific nests (successfully fledged at least one young), 4) the number
 of successful heterospecific nests, 5) the number of first breeding failed
 conspecific nests (no chicks have successfully fledged), and 6) the number
 of failed heterospecific nests. In
 addition, for each pair of
 second-breeding and late-breeding Japanese tits, we randomly selected one
 unoccupied nest box (unoccupied by any birds) in the same forest patch within the corresponding
 year as the control nest box. These nest boxes had not been occupied by
 any birds in the current year, but approximately 90% of them had been
 occupied in other years. We also utilized the control nest boxes as focal
 nests and used the first egg date of this corresponding tit pair as the
 node time to assess the control nest’s social information. Data on the
 available social information around the control nest boxes were collected
 using the methods described above. We used
 conditional logistic regression to compare social information around the
 second breeding nests with paired selected control (i.e., unoccupied)
 nests (“control nest” = 0, “occupied nest” = 1), where the nest was the
 grouping variable (Thomas and Taylor 2006). The explanatory variables used in the models were
 1) the number of breeding conspecific nests, 2) the number of breeding
 heterospecific nests, 3) the number of first breeding successful
 conspecific nests, 4) the number of successful heterospecific nests, 5)
 the number of first breeding failed conspecific nests, and 6) the number
 of failed heterospecific nests. We used
 conditional logistic regression to compare social information around the
 late-breeding nests with paired selected control (i.e., unoccupied) nests
 (“control nest” = 0, “late-breeding nest” = 1), where the nest was the
 grouping variable. The
 explanatory variables used in the models were 1) the number of breeding
 conspecific nests, 2) the number of breeding heterospecific nests, 3) the
 number of first breeding successful conspecific nests, 4) the number of
 successful heterospecific nests, 5) the number of first breeding failed
 conspecific nests, and 6) the number of failed heterospecific
 nests. We used a generalized linear
 mixed-effects model (GLMM) with a logit link and binomial error
 distribution to compare social information around second-breeding pairs
 and late-breeding pairs. The response variable was whether the artificial
 nest boxes were occupied by second-breeding pairs or late-breeding pairs
 (“late-brooding pairs” = 0, “second-breeding pairs” = 1). The explanatory
 variables were 1) the number of breeding conspecific nests, 2) the number
 of breeding heterospecific nests, 3) the number of first
 breeding successful conspecific nests, 4) the number of successful
 heterospecific nests, 5) the number of first breeding failed conspecific
 nests, and 6) the number of failed heterospecific nests. Since the data
 were collected over a span of several years, from 2014 to 2021, “year” was
 added as a random variable to avoid pseudoreplication.
description: The significance level was set at α= 0.05. All analyses were
 undertaken using the statistical software R 4.1.1 (R Core Team). We
 calculated all P values using Wald chi-square tests with the
 <em>ANOVA</em> function in the car package (Fox and Weisberg
 2019). Conditional logistic regression models were implemented using the
 <em>clogit</em> function found within the survival package
 (Therneau 2015). The GLMMs were implemented using the package “lme4’’
 (Bates et al. 2015).