Ornithol Sci 18: 3 – 16 (2019)

ORIGINAL ARTICLE An evaluation of ve agricultural habitat types for openland : abandoned farmland can have comparative values to undisturbed wetland

Munehiro KITAZAWA1,#, Yuichi YAMAURA2,3, Masayuki SENZAKI1,4, Kazuhiro KAWAMURA1, Masashi HANIOKA1 and Futoshi NAKAMURA1

1 Graduate School of Agriculture, Hokkaido University, Nishi 9, Kita 9, Kita-ku, Sapporo, Hokkaido 060–8589, Japan 2 Department of Forest Vegetation, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305–8687, Japan 3 Fenner School of Environment and Society, Australian National University, Canberra, ACT, 2601, Australia 4 Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies, 16–2, Onogawa, Tsukuba, Ibaraki 305–8506, Japan

ORNITHOLOGICAL Abstract Populations of birds inhabiting wetlands and grasslands are decreasing globally due to farmland expansion and subsequent agricultural intensification. In SCIENCE addition to conserving natural habitats, managing cultivated farmland and abandoned © The Ornithological Society farmland are likely to be important future conservation measures; however, their of Japan 2019 relative suitability as avian habitat remains understudied. In this study, we evaluated five habitat types (wetland, pasture, cropland, abandoned farmland, and solar power plant) for openland birds in an agricultural landscape in central Hokkaido, northern Japan. Abandoned farmlands had species richness and total bird abundance val- ues similar to those of wetlands. These values were generally higher in abandoned farmlands and wetlands than in croplands, pastures, and solar power plants. The per pair reproductive success of Stejneger’s Stonechat Saxicola stejnegeri and the amount of its prey (arthropods) did not differ among the five habitat types. Three species (Black-browed Reed Warbler Acrocephalus bistrigiceps, Common Reed Bunting Emberiza schoeniclus, and Japanese Bush Warbler Cettia diphone) arrived earlier in wetlands than in other habitat types. These results suggest that, although protecting the remaining wetlands is of prime importance for the conservation of openland birds in agricultural landscapes, valuing and managing abandoned farmlands would be a promising alternative.

Key words First arrival date, Food abundance, Hokkaido, Reproductive success, Stejneger’s Stonechat

Conserving bird species that inhabit wetlands or investment (Main et al. 1999; Holzkämper & Seppelt grasslands (hereafter referred to as openland birds) is 2007). Previous studies have shown that many open- now widely regarded as an urgent issue, mainly due to land bird species use various habitat types including the drastic replacement of their original habitats with cultivated land. For example, pastures and croplands farmland and subsequent agricultural intensification in European agricultural landscapes harbor diverse (Finlayson & Spiers 1999; Millennium Ecosystem openland bird species (Robinson et al. 2001; Batáry Assessment 2003; Ceballos et al. 2010). Although et al. 2010). In , rice paddies serve as important preserving and restoring original avian habitats is habitats for openland birds (Maeda 2001; Wood et al. clearly important for bird conservation, this approach 2010). Therefore, valuing and managing cultivated inevitably requires considerable social and financial habitats in agricultural landscapes may be an option alongside conservation of original habitats. (Received 11 November 2017; Accepted 18 May 2018) Globally, farmlands are being rapidly abandoned # Corresponding author, E-mail: [email protected] (Ramankutty & Foley 1999; Alcantara et al. 2013),

3 M. KITAZAWA et al. potentially reducing suitable habitat for many open- successful (Cooper et al. 2011) and mates were easily land birds (MacDonald et al. 2000; Sanderson et al. found (Lozano et al. 1996). Prey amount is another 2013). However, although many existing studies have important metric because it has substantial impacts emphasized the negative effects of farmland -aban on bird abundance and reproductive success (Newton donment (Queiroz et al. 2014), it is noted that some 1998). papers have reported the importance of abandoned farmlands as habitat for openland birds (Kamp et al. MATERIALS AND METHODS 2011; Katayama et al. 2015). For example, in east- ern Hokkaido, northern Japan, Hanioka et al. (2018) 1) Study area compared the habitat suitability of wetland and aban- We conducted the field survey on the Yufutsu Plain, doned farmland for birds. In abandoned farmland, located in central Hokkaido, northern Japan (42°38 ́N, many openland bird species had larger than 1/2 141°46 ́E). In the early 1900s, this region was cov- densities of wetlands. Globally, solar power plants ered with approximately 8,000 ha of wetlands (GSI are being increasingly constructed in agricultural 2000). From the 1950s to the 1970s, approximately landscapes. Little is known about the environmental 80% of these wetlands were converted into farmland, impacts of these developments (Turney & Fthenakis urban, and industrial areas (GSI 2000). Only a few 2011; Gibson et al. 2017). Habitat suitability for fragmented and isolated wetland patches remain (Fig. openland birds thus varies for each habitat type, and 1). Some croplands have been abandoned since 1969 recent land use changes in agricultural landscapes (Wild Bird Society of Japan 2006), and abandoned may also affect the diversity of openland birds; nev- farmlands now occupy approximately 700 ha of the ertheless, the relative suitability of various habitat Yufutsu Plain (Kitazawa Munehiro personal observa- types in agricultural landscapes remains unclear. tion). The area occupied by solar power plants in this Avian habitats in agricultural landscapes have been region has been increasing since the 2010s and is cur- evaluated according to bird species richness and bird rently estimated at approximately 390 ha (Kitazawa abundance (e.g., Bengtsson et al. 2005; Flohre et al. Munehiro personal observation). 2011). However, bird abundance does not always indicate reproductive success (van Horne 1983; 2) Habitats in the agricultural landscape Vickery et al. 1992), suggesting that habitat evalu- We surveyed openland birds in wetlands, aban- ation based solely on bird species richness or bird doned farmlands, pastures, croplands, and solar abundance may fail to identify habitats with high power plants within the study area. We defined a reproductive success (Purvis et al. 2000; Kristan wetland as an area characterized by the Common 2003). This is particularly important in agricultural Reed Phragmites australis and Bluejoint Reedgrass landscapes because human intervention can disrupt Calamagrostis langsdorffii, both of which are domi- the links between traditional habitat selection cues nant wet grass species in this area. Abandoned farm- and habitat quality (Schlaepfer et al. 2002; Bock & land was defined as land that had once been cropped Jones 2004). Thus it is desirable to examine habitat and was abandoned more than 10 years ago. Japanese suitability in agricultural landscapes not only based Silver Grass Miscanthus sinensis was the dominant on bird species richness and bird abundance, but also species in abandoned farmland. In some plots, Com- using other metrics such as reproductive success. mon Reed and Japanese Alder Alnus japonica growth The objective of this study was to evaluate five was patchy. In pastures, grass was mown from late habitat types (wetland, abandoned farmland, pasture, June to mid July. The main crops in the croplands cropland, and solar power plant) for openland birds in were leaf vegetables, corn, and soybeans. Common an agricultural landscape, in central Hokkaido, based Reed, Japanese Silver Grass, and Japanese Butterbur on bird species richness, bird abundance, reproduc- Petasites japonicus were the dominant species in the tive success, first arrival date, and prey amount. First field margins of pastures and croplands. The width arrival date, which is the date when the first indi- of the margins was 15.2±8.6 m (mean±SD). We vidual of a species is observed (Goodenough et al. defined solar power plants as land where solar panels 2014), is a reasonable metric of habitat suitability for were arranged in parallel rows at equal intervals. In migratory birds (Sergio & Newton 2003; Robertson the solar power plants that we surveyed, solar panels & Hutto 2006) because individuals arriving early can (1.6 m2 per panel) occupied 50–60% of the area, occupy territories where reproduction was previously and the remainder was covered by grass vegetation

4 Agricultural habitats for openland birds

Fig. 1. Spatial distribution of four habitat types (wetland, natural grassland, farmland, and forest) of part of the Yufutsu Plain in 1919 (a), 1953 (b), and 2006 (c). Classification and distribution of habitat types are based on 1:50,000–scale topographical maps provided by the Geographical Survey Institute of Japan (http://mapps.gsi.go.jp/maplibSearch.do#1). Farmland includes pasture, cropland, and rice paddy. Although abandoned farmland is not identified, but included in wetland or grassland, dynamics of habitat types and the appearance of abandoned farmland are shown. For example, in the enlarged map shown in black squares, wetlands were converted into farmland from 1919 to 1953, and then partly changed into natural grassland from 1953 to 2006, meaning that these farms were abandoned.

Fig. 2. Study area and distribution of the census plots. We established 25 census plots (open circles): wetlands (five plots), abandoned farmland (five plots), pasture (six plots), cropland (six plots), and solar power plants (three plots). One solar power plant plot is not shown, because the landowner requested anonymity. Census plots were spaced at least 500 m apart.

(Poaceae or Cyperaceae), which was cut from early habitat types (five in wetlands and abandoned farm- June to early July. lands, six in pastures and croplands, and three in solar power plants; Fig. 2). All census plots were 3) Establishment of census plots established randomly on the condition that plots We established 25 census plots in the five focal were spaced at least 500 m apart and within com-

5 M. KITAZAWA et al. partments (mean±SD: 59.9±68.4 ha) consisting of chat Saxicola stejnegeri and Chestnut-eared Bunting a single focal habitat type. Using this method, we Emberiza fucata, were easily detectable (Yamashina prevented double counting of individual birds (Ralph 1941), because they tended to sing or perch on top et al. 1993) and avoided recording birds that breed of shrubs. Therefore, we deemed bird detectability as in different habitat types near the census plots (i.e., stable regardless of time of day or habitat type. spill-over effect: Barlow et al. 2007). Each census plot was 300 m long×100 m wide (3 ha). The survey 5) Prey amount survey line ran through the center of each plot. We estab- Almost all openland birds on the Yufutsu Plain lished the plots using QGIS Desktop 2.16.3 (QGIS feed on arthropods during the breeding season Development Team 2016). (Yamashina 1941). Therefore, we surveyed the amount of arthropods (prey) present using sweep-net 4) Bird surveys sampling. Sampling was performed six times at each From May 15 to July 16, 2016, we slowly walked plot at intervals of 12 to 16 days from May 15 to the survey lines nine times and recorded individual August 3, 2016, and was completed between 0800 birds seen or heard, species, sex, and breeding behav- and 1600 under good weather conditions (sunshine, ior (e.g., singing, nest building, or carrying food to wind speed<4 m/s). We randomly established two nestlings) within the plots (i.e., territory mapping: 20 m long survey lines within each census plot. In Bibby et al. 2000). Survey times were from dawn croplands, we surveyed in field margins to ensure to 1000, and from 1700 to dusk, when activity and that we did not disturb farm work. We performed song output of birds was greatest (Bibby et al. 2000). one stroke per metre walked along each survey line. Avoiding rain, fog, or heavy wind (>4 m/s), we Arthropod samples were immediately conserved in walked each line at 7-day intervals during the sur- ethyl acetate. We later identified arthropods to order vey period. To avoid survey time bias, we visited (Aranea, Coleoptera, Diptera, , Odonata, each plot at different times. We drew the territories Orthoptera, Hemiptera, Hymenoptera, and Plecop- of birds that were recorded at least twice (Bibby et tera). Arthropods were dried in an oven for 24 h at al. 2000) during this period within the range of their 60°C and weighed with a precision balance to the known territory sizes (e.g., Nakamura et al. 1968; nearest 0.001 g. We calculated the summed values of Haneda & Okabe 1970; Cramp 1977–1994; Higuchi all arthropods separately for each plot from May 15 et al. 1997). We then obtained the number of ter- to August 3, by which time nearly all openland birds ritories and species within a census plot. We defined had arrived on the Yufutsu Plain. Hereafter, we used bird abundance as the number of territories. We also these summed values in our analyses. recorded the approximate locations of nests within a plot as frequently as possible. We recorded any fledg- 6) Comparisons among the five habitats lings found, and defined the number of fledglings as We compared bird species richness, bird abun- a metric of reproductive success. dance (i.e., number of territories) for each species To record the first arrival date of each species, and for all species (total bird abundance), and repro- we conducted a first arrival date survey 14 times ductive success per plot and per pair using general- from April 10 to May 28, 2016. We slowly walked ized linear mixed models (GLMMs) with Poisson the survey lines used for the territory mapping sur- error and log link functions. Plot identity (ID) was vey from dawn until dusk. When a bird species was treated as a random intercept. For bird abundance detected for the first time during this period, its date for each species, the models including habitat types was treated as the first arrival date. We required three where no individuals occurred did not converge; we days to visit all census plots and defined this as the thus excluded the data of these habitat types from the survey period (Appendix 1). When we did not finish analyses. We used generalized linear models (GLMs) surveys in all plots within three days, we extended with Gaussian error for first arrival date and prey the survey period to 4–8 days (adding 1–5 days). amount. For first arrival date, we only analyzed spe- Throughout the period of the first arrival date survey, cies for which we had confirmed breeding behavior vegetation was not very dense in each habitat type (e.g., singing, nest building, or carrying food to nest- (i.e., resultant detectability was sufficiently high; cf. lings) in more than one plot for a given habitat type. Yamaura et al. 2016). The focal migrants through- For this analysis, we used the median of the survey out the first arrival date survey, Stejneger’s - Stone period converted to Julian date. For example, the first

6 Agricultural habitats for openland birds arrival date recorded during 13–15 April was 104 species: Appendix 2). The four dominant species (April 14). As the final species did not arrive until were Black-browed Reed Warbler Acrocephalus bis- May 28 (e.g., Middendorff’s Grasshopper Warbler trigiceps (73 territories), Stejneger’s Stonechat (40 Locustella ochotensis), we also used the results of our territories), Chestnut-eared Bunting (37 territories), territory mapping survey between May 29 and June and Lanceolated Warbler Locustella lanceolata (32 18 as the results of the first arrival date (Appendix territories). The abundance of the remaining species 1). Consequently, we analyzed first arrival dates from was lower than 30 each. For most species, territories April 10 to June 18. We analyzed prey amounts by were confirmed by completion of the sixth territory comparing the dried prey amount (summed values) mapping survey, with the exception of the Black- among habitat types. Five habitat types were used as browed Reed Warbler (seventh survey), Chestnut- a single categorical explanatory variable, which was eared Bunting (eighth survey), and Japanese Bush coded using the cell means method (i.e., omitting Warbler Cettia diphone (eighth survey). the intercept: Kéry 2010). When the 95% confidence intervals did not overlap between two habitat catego- 1) Bird species richness and bird abundance ries, we interpreted the differences as significant. Bird species richness was higher in abandoned farmland than in pasture, cropland, or solar power 7) Comparison of effects of habitat types, prey plants (Fig. 3a). The differences among the other amount, and first arrival date pairs were not significant. Total bird abundance in Previous studies have shown that both habitat type wetlands and abandoned farmland was greater than and prey amount can limit the abundance and repro- in cropland, and also tended to be (non-significantly) ductive success of birds (Newton 1998). Moreover, greater than in pasture and solar power plants (Fig. first arrival date can be related to reproductive success 3b). Although habitat type was a significant predic- (Smith & Moore 2003; Cooper et al. 2011). There- tor of total bird abundance and bird species richness, fore, we compared the effects of habitat type and prey amount had no significant effect on either of prey amount on total bird abundance and bird spe- these metrics (Table 1). cies richness. We also compared the effects of habitat We compared the abundance of 12 openland bird type and prey amount/first arrival date on reproduc- species recorded in multiple habitat types (Appendix tive success per plot. For total bird abundance and 3). Lanceolated Warbler abundance was significantly bird species richness, we built a null model (with no higher in wetlands and abandoned farmland com- explanatory variables except for the intercept) and pared to pasture (Appendix 3h). Stejneger’s Stonechat two models using prey amount or habitat type as abundance in abandoned farmland and Black-browed the explanatory variable. For reproductive success Reed Warbler abundance in wetlands tended to be per plot, we built a null model and three models higher compared to cropland (Appendix 3a, c). The using prey amount, first arrival date, or habitat type abundance of Chestnut-eared Buntings in pastures as the explanatory variable. We again used Poisson tended to be higher than in wetlands (Appendix 3b). GLMMs (with plot ID as the random intercept) for Among the remaining eight species, habitat type had these analyses. We quantified the explanatory power no significant or distinct effect on their abundance of individual models using the proportion of devi- among the habitat types they occupied, although ance explained: ((null deviance) – (residual deviance five species did not occur in pastures or solar power of each model)) / (null deviance). Analyses were plants, and seven species did not occur in croplands performed using the lme4 package, version 1.1–12 (Appendix 3). Besides the 12 species above, four spe- (Bates et al. 2015), in the R software, version 3.3.1 cies occurred only in abandoned farmland (Appendix (R Development Core Team 2016). 3m-p), while the Brown cristatus was recorded only in pastures (Appendix 3q). RESULTS 2) Reproductive success During the bird surveys, we recorded 17 species Stejneger’s Stonechat was the only species for and 287 bird territories for which we confirmed which we could record the number of fledglings in breeding behavior (e.g., singing, nest building, or more than one habitat type. The reproductive success carrying food to nestlings). All of the species that of Stejneger’s Stonechat per plot and per pair did we recorded were openland species (i.e., no forest not differ between the five habitat types (Fig. 3c, d),

7 M. KITAZAWA et al.

Fig. 3. Bird species richness (a), total bird abundance (b), reproductive success (RS) of Stejneger’s Stonechats per plot (c) per pair (d), prey amount (e). Black circles indicate model-predicted values of each metric; open circles indicate measured values; bars indicate 95% CIs (confidence intervals). W: wetlands; A: abandoned farmlands; P: pastures; C: croplands; S: solar power plants.

Table 1. Outputs of models with different hypotheses. For the analysis with total bird abundance or bird species richness as the response variable, we compared models with habitat type or prey amount as the single explanatory variable. For the analysis with the reproductive success of Stejneger’s Stonechats per plot as the response variable, we compared models with habitat type, first arrival date, or prey amount as the single explanatory variable.

Models Coefficient SE P Intercept AIC Deviance explained Total bird abundance Habitat type model ― ― <0.001# ― 157.3 0.14 Prey amount model 0.30 0.38 0.44 1.97 173.5 0.004 Bird species richness Habitat type model ― ― 0.003# ― 111.4 0.14 Prey amount model –0.13 0.25 0.61 1.72 121.5 0.003 Reproductive success per plot Habitat type model ― ― 0.16# ― 111.9 0.06 First arrival date model –0.13 0.08 0.09 1.42 103.1 0.09 Prey amount model 1.00 0.66 0.12 –0.46 110.1 0.02

SE: Standard error; P: p-value; AIC: Akaike’s information criterion. ―: Results not shown because habitat type models have five different coefficients/standard error values/intercepts. #: Results of likelihood ratio test between the null and habitat type models because habitat type models have five different coef- ficients. although per-plot reproductive success in cropland reproductive success of this species, the model with was comparatively lower than in the other habitat first arrival date had the highest explanatory power types. When comparing the effects of habitat types, and the lowest AIC of the three models (Table 1). prey amount, and first arrival date on the per-plot

8 Agricultural habitats for openland birds

3) First arrival date and prey amount species (Fig. 4). The Black-browed Reed Warbler We analyzed 14 species for which we confirmed arrived earlier in wetlands than in abandoned farm- breeding behavior in more than one plot for a given land and cropland (Fig. 4c). The Common Reed Bun- habitat type (Appendix 2). We found differences in ting Emberiza schoeniclus arrived earlier in wetlands the first arrival dates among habitat types for three and solar power plants than in cropland (Fig. 4d).

Fig. 4. First arrival dates. Black circles indicate model-predicted values of first arrival dates; open circles indicate measured values; bars indicate 95% CIs. W: wetlands; A: abandoned farmland; P: pasture; C: cropland; S: solar power plants. Model-predicted values and their 95% CIs were not estimated for habitat types where the species occurred in only one plot.

9 M. KITAZAWA et al.

The Japanese Bush Warbler arrived earlier in wet- al. 2015). However, in this study, we found no clear lands than in abandoned farmland (Fig. 4i). impacts of pasture mowing on the productivity of During the prey amount survey, we recorded a total Stejneger’s Stonechat. We identified eight nests in of 19.3 g of arthropod biomass (Orthoptera: 0.56 g, pasture plots. Two of these were likely within mowed Hemiptera: 4.6 g, Coleoptera: 3.2 g, Lepidoptera: areas and the others were likely in field margins. 2.4 g, Diptera: 2.7 g, Hymenoptera: 3.4 g, Odonata: Therefore, the time lag between mowing and fledg- 0.1 g, and Aranea: 2.3 g) and found no differences in ing may explain this result. In census plots, pastures prey amount among habitat types (Fig. 3e). were mown from the end of June to the middle of July (Kitazawa Munehiro personal observation). All Stejneger’s Stonechats in the census plots fledged DISCUSSION between early June and early July, suggesting that 1) Bird species richness and bird abundance mowing time rarely overlapped with fledging time, Bird species richness was higher in abandoned although the detrimental impacts of mowing may be farmland than in pasture, cropland, or solar power clearer in other species or years (e.g., Santangeli et plants (Fig. 3a). This result can be explained by the al. 2018). high tree coverage and the presence of species, such as the Grey-capped Greenfinch Chloris sinica, and 3) Evaluation by first arrival date the Long-tailed Rosefinch Uragus sibiricus (Kiyosu To our knowledge, no study has examined whether 1952, Appendix 3n, o), nesting in trees (Suárez- first arrival date differs among species or habitat Seoane et al. 2002) in abandoned farmland. Addi- types in agricultural landscapes. We analyzed the tionally, total bird abundance tended to be higher in first arrival dates of 14 species and showed that only wetlands and abandoned farmland than in the other three species arrived earlier in wetlands than in other habitat types (Fig. 3b). These results can be explained habitat types. Because earlier arrival can represent by the large coverage of wetland vegetation (e.g., higher productivity (Smith & Moore 2003; Cooper et Common Reed or sedges) and the dominance of al. 2011), these results suggest that wetlands may be several bird species nesting specifically on this type superior habitats for these three species. The repro- of vegetation (e.g., Black-browed Reed Warbler or ductive success of Stejneger’s Stonechat per plot also Lanceolated Warbler; Kennerley & Pearson 2010) in tended to be higher in plots where it arrived earlier these two habitat types (Appendix 3c, h). From the (Table 1). The lack of difference in first arrival date perspectives of bird species richness and total bird among habitat types for the other 11 species may be abundance, our results suggest that both natural wet- attributable to our coarse survey interval (3–8 days). lands and abandoned farmland provide more suitable It may be possible to detect differences in the first habitats for openland birds than do the other habitat arrival dates of these species if daily censuses were types that we examined. conducted, as has been done in previous studies (e.g., Lozano et al. 1996; Cooper et al. 2011). 2) Evaluation by reproductive success Although we attempted to survey reproductive suc- 4) Evaluation by prey amount cess for all species, we were only able to obtain the Along with agricultural intensification, declines necessary data for Stejneger’s Stonechat due to the in the availability of prey such as invertebrates can difficulty of observing the breeding behavior of the limit avian abundance (Wilson et al. 1999) and repro- other species. The number of fledglings per plot and ductive success (Newton 1998) among birds living per pair did not differ significantly among the five in agricultural landscapes. However, in this study, habitat types (Fig. 3c, d), although per-plot reproduc- prey amount had no effect on bird species richness or tive success in cropland was relatively lower than total bird abundance (however, note that we surveyed that in other habitat types (Fig. 3c). This was because only field margins in croplands), and did not differ there were fewer breeding pairs of this species in among habitat types. Although we also compared the cropland (Appendix 3a). summed values of individual families among the five The reproductive success of grassland birds in pas- habitat types, in seven of eight families (with the tures suffers from management intensification (e.g., exception of the Diptera), the amount of prey did not earlier and more frequent mowing or increased appli- differ (results not shown). Thus, bird abundance in cation of fertilizers: Grüebler et al. 2008; Strebel et our study area is presumed to have been determined

10 Agricultural habitats for openland birds by other factors such as shelter, space, or the pres- Batáry P, Matthiesen T & Tscharntke T (2010) Land- ence of other species (Hildén 1965; Fuller 2012). scape-moderated importance of hedges in conserving farmland bird diversity of organic vs. conventional croplands and grasslands. Biol Conserv 143: 2020– CONCLUSION 2027. Overall, wetlands seemed to be the most impor- Bates D, Mächler M, Bolker B & Walker S (2015) Fit- tant habitats for openland birds in terms of the five ting linear mixed-effects models using lme4. J Stat metrics we assessed, which suggests that protecting Softw 67: 1–48. remnant wetlands is the highest priority for avian Bengtsson J, Ahnström J & Weibull A (2005) The effects conservation in agricultural landscapes. However, the of organic agriculture on biodiversity and abundance: a meta-analysis. J Appl Ecol 42: 261–269. area occupied by abandoned farmland is expanding Bibby CJ, Burgess ND, Hill DA & Mustoe S (2000) rapidly, both in Japan and globally. According to the Bird census techniques. 2nd ed. Academic Press, five metrics we used in our evaluation, in terms of London. avian species richness and total bird abundance, the Bock CE & Jones ZF (2004) Avian habitat evaluation: suitability of abandoned farmland was comparable to should counting birds count? Front Ecol Environ 2: that of wetlands. However, the low number of repli- 403–410. cates per habitat type in our study makes it difficult Ceballos G, Davidson A, List R, Pacheco J, Manzano- to generalize from our findings. Nevertheless, previ- Fischer P, Santos-Barrera G, et al. (2010) Rapid ous studies in eastern Hokkaido have also suggested decline of a grassland system and its ecological and that abandoned farmland can serve as suitable habi- conservation implications. PloS ONE 5: e8562. tat for openland bird species (Hanioka et al. 2018), Cooper NW, Murphy MT, Redmond LJ & Dolan AC which is consistent with our findings. Therefore, at (2011) Reproductive correlates of spring arrival date least in Hokkaido, valuing and managing this rapidly in the Eastern Kingbird Tyrannus tyrannus. J Ornithol expanding habitat type can also provide opportunities 152: 143–152. for the conservation of openland birds. Cramp S (ed) (1977–1994) Handbook of the birds of , the Middle East and North Africa: the birds of the Western Palearctic. Oxford Univ Press, Oxford. ACKNOWLEDGMENTS Finlayson CM & Spiers AG (eds) (1999) Global review We thank Tomatoh, Inc., anonymous solar power of wetland resources and priorities for wetland inven- plant companies, the Tomakomai Experimental Forest tory. Wetlands International Publication 53, Supervis- (TOEF), and the citizens of Atsuma and Mukawa for ing Scientist, Canberra. their cooperation with our field survey. Thoughtful Flohre A, Fischer C, Aavik T, Bengtsson J, Berendse F, comments by J. Kamp and an anonymous reviewer Bommarco R, et al. (2011) Agricultural intensifica- helped to improve the manuscript. Finally, we thank tion and biodiversity partitioning in European land- scapes comparing plants, carabids, and birds. Ecol the members of the Forest Ecosystem Management Appl 21: 1772–1781. Laboratory of Hokkaido University for their helpful Fuller RJ (2012) The bird and its habitat: an overview discussions. This study was supported by the Envi- of concepts. In: Fuller RJ (ed) Birds and habitat: ronmental Research and Technology Development relationships in changing landscapes. pp 3–36. Cam- Fund (4-1504 and 4-1805) of the Ministry of the bridge Univ Press, Cambridge. Environment of Japan. Gibson L, Wilman EN & Laurance WF (2017) How green is ‘green’ energy? Trends Ecol Evol 32: 922– REFERENCES 935. Goodenough AE, Fairhurst SM, Morrison JB, Cade Alcantara C, Kuemmerle T, Baumann M, Bragina EV, M, Morgan PJ & Wood MJ (2014) Quantifying the Griffiths P, Hostert P, et al. (2013) Mapping the extent robustness of first arrival dates as a measure of avian of abandoned farmland in Central and Eastern Europe migratory phenology. Ibis 157: 384–390. using MODIS time series satellite data. Environ Res Grüebler MU, Schuler H, Müller M, Spaar R, Horch Lett 8: 035035. P & Naef-Daenzer B (2008) Female biased mortal- Barlow J, Mestre LAM, Gardner TA & Peres CA (2007) ity caused by anthropogenic nest loss contributes to The value of primary, secondary and plantation forests population decline and adult sex ratio of a meadow for Amazonian birds. Biol Conserv 136: 212–231. bird. Biol Conserv 141: 3040–3049.

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Appendix 1. Survey periods and duration of first arrival date survey and territory mapping survey.

First arrival date survey Territory mapping survey Survey Note Survey periods Duration Duration periods 4/10–4/12 3 4/13–4/15 3 4/16–4/18 3 4/19–4/22 4 Extended by one day due to heavy rain 4/23–4/25 3 4/26–4/28 3 4/29–5/1 3 5/2–5/4 3 5/5–5/12 8 Extended by five days due to bad weather 5/13–5/15 3 5/16–5/18 3 5/15–5/21 7 Conducted both territory mapping survey and first arrival date survey* 5/19–5/21 3

5/22–5/24 3 Conducted both territory mapping survey and first arrival date survey* 5/22–5/28 7 5/25–5/28 4 and extended first arrival date survey period by one day due to rain Conducted territory mapping survey only; results were also used for 5/29–6/4 7 the analysis of first arrival date Conducted territory mapping survey only; results were also used for 6/5–6/11 7 the analysis of first arrival date Conducted territory mapping survey only; results were also used for 6/12–6/18 7 the analysis of first arrival date 6/19–6/25 7 Excluded from the analysis of first arrival date# 6/26–7/2 7 Excluded from the analysis of first arrival date# 7/3–7/9 7 Excluded from the analysis of first arrival date# 7/10–7/16 7 Excluded from the analysis of first arrival date#

*: Once we had conducted a territory mapping survey in a plot during this period, we did not survey the plot as part of the first arrival date survey. This is because we could obtain sufficient data to record first arrival date by the territory mapping survey. That is, in such a case, the results of the territory mapping survey were also treated as the results of the first arrival date survey. #: All openland birds considered to have arrived, hence we excluded this period. In total, the first arrival date survey was conducted 14 times, while the territory mapping survey was conducted nine times.

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Appendix 2. Species surveyed.

English names Scientific names First arrival date Stejneger’s Stonechat Saxicola stejnegeri Analyzed Chestnut-eared Bunting Emberiza fucata Analyzed Black-browed Reed Warbler Acrocephalus bistrigiceps Analyzed Common Reed Bunting Emberiza schoeniclus Analyzed Black-faced Bunting Emberiza spodocephala Analyzed Skylark Alauda arvensis Analyzed Middendorff’s Grasshopper Warbler Locustella ochotensis Analyzed Lanceolated Warbler Locustella lanceolata Analyzed Japanese Bush Warbler Cettia diphone Analyzed Siberian Rubythroat Luscinia calliope Analyzed Bull-headed Shrike Lanius bucephalus Analyzed Gray’s Grasshopper Warbler Locustella fasciolata Recorded Latham’s Snipe Gallinago hardwickii Analyzed Long-tailed Rosefinch Uragus sibiricus Analyzed Grey-capped Greenfinch Chloris sinica Analyzed Brown-cheeked Rail Rallus aquaticus Recorded Brown Shrike Lanius cristatus Recorded

For first arrival date, we only analyzed the species for which we confirmed breeding behavior in more than one plot for a given habitat type. Therefore, we did not analyze Gray’s Grasshopper Warbler, Brown-cheeked Rail, or Brown Shrike (indicated in ‘Recorded’).

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Appendix 3. Abundance of each species. Black circles indicate model-predicted values of the number of territories; open circles indicate measured values; bars indicate 95% CIs. W: wetlands; A: abandoned farmland; P: pasture; C: cropland; S: solar power plants. We could not show the model- predicted values and 95% CIs of some or all habitat types in (d)-(q). This is because the models including habitat types where no individuals occurred (e.g., wetlands in (f)) did not converge, hence we excluded the data of these habitat types from the analyses. However, the model for the abundance of Japanese Bush Warbler (i.e., (i)) did not converge. We could not obtain 95% CIs for the abundance of Brown-cheeked Rail or Brown Shrike since they only occurred in single plots (i.e., (p), (q)).

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