Searching a Site for a Civil Airport Based on Bird Ecological Conservation: an Expert-Based Selection (Dalian, China)

Global Ecology and Conservation 20 (2019) e00729

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Original Research Article Searching a site for a civil airport based on bird ecological conservation: An expert-based selection (Dalian, China)

* Bing Zhao a, Nuo Wang b, , Qiang Fu b, Hua-Kun Yan c, d, Nuan Wu b a College of Economic and Management, Civil Aviation University of China, Jinbei Road 2898#, Tianjin, 300300, China b Department of Transportation Engineering, Dalian Maritime University, 217 Room Jidian Building, Linghai Road 1#, Dalian, 116026, China c Sino-US Global Logistics Institute, Antai College of Economics & Management, Shanghai Jiaotong University, Shanghai, 200030, China d Fujian Provincial Communication Transportation Group Co Ltd., Fuzhou, 350014, China article info abstract

Article history: The construction and operation of a civil airport will inevitably destroy the biodiversity Received 13 June 2019 and ecosystem components. Especially when located on bird migration routes, the Received in revised form 22 July 2019 emergence of a civil airport will have a large impact on birds, resulting in immeasurable Accepted 23 July 2019 ecological loss. Therefore, it is necessary to carry out an evaluation of the ecological impact on birds at the airport site selection stage for the sustainable development of humans and Keywords: the nature. Geographically, Dalian, China, is an important site in the bird migration routes Airport in northeast Asia, and the National Conservation Area of Snake Island and Laotieshan Site selection Bird Mountain located in the south of Dalian has been included in the Man and Biosphere Ecology Programme (MBP) network as a biosphere reserve. Therefore, the expansion plan of a new Expert-based civil airport in this region is a major challenge to the bird ecology. Here, using the detailed AHP investigation data about migratory birds in Dalian, we evaluate the impact of different site schemes on the bird ecology by an expert-based approach and choose the more favourable one for bird ecological environments. The innovative attempt to a civil airport site selection based on the bird ecological conservation presented in this paper is of great signiﬁ- cance for improving airport site planning and exploring the sustainable development of airports and the bird ecology around the world. © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction

The development of the world air transport industry has brought great convenience to human transportation. However, at the same time, this free expansion of the airspace has continuously encroached on the original living space of birds. If a civil airport is built in the range of a bird migration route, the anthropogenic disturbances such as the frequent aircraft take-off and landing, the airport noise and the light will cause bird strikes, habitat fragmentation, species population decline and rare bird extinction. Moreover, it may result in the drastic and irreversible reduction of environmental system complexity and resil- ience (Salafsky et al., 2008; Battisti et al., 2016a). In the long run, it will be a foreseeable ecological disaster that should been given high attention.

* Corresponding author. E-mail addresses: [email protected] (B. Zhao), [email protected] (N. Wang), [email protected] (Q. Fu), [email protected] (H.-K. Yan), [email protected] (N. Wu). https://doi.org/10.1016/j.gecco.2019.e00729 2351-9894/© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/). 2 B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729

Practice has shown that airport operations have a serious impact on the bird ecology. Taking bird strikes as an example, according to the Bird Attack Information System (IBIS) (ICAO, International Civil Aviation Organization, 2018), 97,751 reports were received from 91 states about strikes occurring in 105 states and territories from 2008 to 2015, with an average annual number of 12,219 strikes, twice the average annual number between 2001 and 2007. This indicates that the ecological impact of the civil aviation industry on birds has become increasingly serious in recent years. In China, bird strike events have also increased significantly. According to the Chinese Bird Strike Aircraft Accident Analysis Report (CAAC, Civil Aviation Administration of China, 2017), 21,599 bird strike reports were received in China, with an average annual growth rate of 34.5% from 2007 to 2016. From the perspective of seasonal patterns, bird strikes occur mostly in autumn, indicating that bird strikes are significantly related to the migratory patterns of birds. It can be speculated that if a civil airport is built in the range of a bird migration route, it will have a serious impact on the bird ecology. There are some studies about the bird strike management, mainly from three aspects, namely the influencing factors of bird strikes, the species-specific bird strike risk index assessment, and the bird strike risk evaluation. (Table 1). There are some studies about the impact of other artificial buildings on the bird ecology, mainly on the impact of wind farm facilities on birds, such as the causes and the mitigation strategies of bird collisions at wind farms (Marques et al., 2014; Wang et al., 2015; Dierschke et al., 2016), the site selection of wind farms based on the bird ecological conservation (Al Zohbi et al., 2015), the impact of wind farms on birds from collisions, disturbances, and habitat alteration (Laranjeiro et al., 2018), the assessment of the ecological vulnerability and the risk index of birds based on wind farm construction (Garthe and Hüppop, 2004; Furness et al., 2013; Thaxter et al., 2017; Kelsey et al., 2018) and the law of bird population change under the influence of wind farms (Pearce-Higgins et al., 2012; Erickson et al., 2015; New et al., 2015; Bastos et al., 2016; Busch and Garthe, 2016; Beston et al., 2016; Battisti et al., 2016b; Martín et al., 2018; May et al., 2018; Warwick-Evans et al., 2018; Goodale and Milman, 2019). These results can be used as a reference for studying the impact of airports on the bird ecology. In the studies above, the relationship between airports and birds is mainly assessed from the perspective of ensuring flight safety. In the process of the airport site selection decision-making, although some scholars have begun to pay attention to study the impact on rare animals (Yan et al., 2018), a comprehensive evaluation of the ecological impact from the perspective of protecting birds has not yet been performed. The lack of this research angle is a great deficiency considering the rapid development of air transportation and the increasing decrease in rare bird populations. Therefore, it is an important task to make a prospective assessment of the impact of different airport site schemes on the bird ecology and to minimize the damage to the natural environment based on a bird ecology perspective. Taking the site selection of Dalian Civil Airport in China as an example, based on the extensive literature review and the detailed field research, we establish an evaluation model to study the ecological impact of the existing Dalian Zhoushuizi Airport and the planned relocation of Jinzhou Bay Airport on birds by the analytical hierarchy process (AHP) method. The important concept, based on the ecological impact on birds, and the analysis method can provide a reference for other airport site selection processes, especially for airports in bird migration routes.

2. Materials and methods

2.1. Study area

The study was conducted in Dalian, Liaoning Province, China. According to our ﬁeld investigation, it showed an increasing trend of the bird strike events year by year in Dalian, from 6 in 2006 to 92 in 2013, increasing by 15 times in 8 years. The rate of bird strikes/10,000 movements rose to 8.36 in 2013, which was far above the world average level. These results all proved that

Table 1 Overview of bird strike research, from 2010 onward.

Research content Authors Study regions/data Influencing factors of bird strikes Wang and Herricks (2012) SeattleeTacoma International Airport Coccon et al. (2015) Venice Marco Polo International airport, Treviso Antonio Canova International airport Conkling et al. (2018) B. Bryan Farm in Clay County, Mississippi, USA Fernandez-Juricic et al. Seven major U.S. (2018) Pfeiffer et al. (2018a) 98 civil airports in the United States Pfeiffer et al. (2018b) The United States Navy wildlife strike database and Air Force dataset Species-specific bird strike risk index Soldatini et al. (2010) Venice Marco Polo International Airport, Italy assessment DeVault et al. (2011) United States Holbech et al. (2015) Kotoka International Airport in Accra, Ghana Hauptfleisch and Avenant Namibia's two major airports, Hosea Kutako International and Eros (2016) Bird strike risk evaluation Ning and Chen (2014) Beijing Capital International Airport, Beihai Fucheng Airport Fu et al. (2016) Dalian Zhoushuizi Airport and Jinzhou Bay Airport Lopez-Lago et al. (2017) Simulated data Chen et al. (2018) Beihai airport B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729 3 the conflict between aircrafts and birds was more serious in Dalian than that in other cities. Consistent with the seasonal patterns of bird strikes in China, the season with the largest number of bird strikes in Dalian is autumn. Bird strikes that occurred in autumn account for more than 60% in a year. This is consistent with the migratory period of birds in Dalian. Currently, there is one civil airport in Dalian, namely, Dalian Zhoushuizi International Airport. In 2018, the passenger throughput has reached 18.76 million, which has exceeded the airport's capacity. As a result, the airport needs to be expanded or relocated to a new site as soon as possible. After a series of comparisons, two schemes were identified by the Dalian authority. One is the in-place expansion, and the other is to relocate to a new site in Jinzhou Bay, which is five kilometres away from the coast. Unfortunately, the city of Dalian in China is located on an important migration route for wild birds in northeast Asia. According to field observations, bird migration routes through Dalian can be divided into the eastern route, the middle route and the western route. The National Conservation Area of Snake Island and Laotieshan Mountain is located in the south of Dalian at the intersection of the three migration routes. According to the statistics, nearly 10 million migratory birds stopped, foraged, and replenished their physical strength in this reserve each year (Fu et al., 2016). Because of its significance to bird migration, the Snake Island and Laotieshan Mountain was included in the Man and Biosphere Programme (MBP) network as a world biosphere reserve by UNESCO (United Nations Educational, Scientific and Cultural Organization) in May 2013 (Fig. 1). As shown in Fig. 1, the in-place expansion scheme, namely, Dalian Zhoushuizi Airport, is located exactly on the bird middle migration route in Dalian, and the relocation scheme, namely, Jinzhou Bay Airport, is located between the middle and western migration routes.

2.2. Study procedure

In order to assess the ecological impact of the above two airport site schemes on birds, the criteria are selected after the extensive literature review and the expert consultation ﬁrstly. Then the impacts of different site schemes on the bird ecology are evaluated by AHP. Finally, the results are compared, and the more favourable scheme for bird ecological environments is chosen. The study procedure is listed as follows (Fig. 2):

(1) Selection of the criteria and scoring the factors; (2) Determination of the weights; (3) Calculation of the ecological impact of Zhoushuizi Airport and Jinzhou Bay Airport on different bird species around the two sites, respectively; and (4) Calculation of the overall ecological impact of Zhoushuizi Airport and Jinzhou Bay Airport on all bird species.

2.3. Data collection

The research data in this paper are from the bird investigation conducted around Zhoushuizi Airport and Jinzhou Bay airport from 2009 to 2011, as shown in Table 2 and Table 3.

2.4. Selection of the criteria

The criteria are selected based on the extensive literature investigation and the expert consultation. Nine experts who have relevant expertise and deep understanding of airport's ecological impact on birds were consulted. Among them, three experts are the professionals in airspace management, three experts are the researchers in the airport ﬂight safety management, and the rest ones are the researchers in the bird ecology. In the criteria selection, the factors that differ between the alternatives are considered, such as the airport landscape features, the airport location and runway direction, the distance between the airport and bird habitat, and the characteristics of bird species. The factors which cannot enable us to distinguish between the two schemes, such as the aircraft take-off and landing frequency, the aircraft types, the season, the weather, are not included in the set of criteria (van der Kleij et al., 2003). Table 4 provides the deﬁnitions of each criteria. According to the impact degree, scores were assigned on a scale of 1e5 for all factors by experts, where 5 is a strong anticipated negative impact. The factors assessed and calculations used to combine factor scores are outlined below.

2.4.1. Airport-speciﬁc factors

2.4.1.1. Airport landscape features. Airport landscape features may have detrimental effects on aviation safety as well as conservation efforts for birds (Conkling et al., 2018). If there are waters, open spaces, crops, and diverse landscape features near the airport, the probability of bird strikes at the airport will increase (Pfeiffer et al., 2018a). 4 B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729

Fig. 1. Bird migration routes in Dalian and the National Conservation Area of Snake Island and Laotieshan Mountain (①Snake Island; ②Laotieshan Mountain; ③Jiutoushan Mountain; ④Tiger Tail).

Fig. 2. The study procedure. B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729 5

Table 2 Investigation on migratory birds around Zhoushuizi Airport.

No. Spices Flight altitude Flight speed Density (per/ Habitat Threat and conservation status (m) (m/s) km2) type IUCN red list of threatened National List of Key Protected Wild species Animals in China 1 Eurasian Skylark 265 13.1 95 1 0 0 2 Common Quail 121 13.2 16 6 0 0 3 Barn Swallow 119 15.8 52 6 0 0 4 Pintail Snipe 418 17.8 4 1,4 0 0 5 Oriental Skylark 96 12.7 10 1 0 0 6 Grey Wagtail 295 13 19 1,3 0 0 7 Yellow Wagtail 200 13.8 20 1,3,4 0 0 8 Brown Shrike 138 19 25 1,2,3 0 0 9 Eurasian Hobby 3350 18.7 2 1 0 1 10 Northern Goshawk 3844 15.6 0.3 1 0 1 11 White-cheeked 242 17.7 3 6 0 0 Starling 12 White-Wagtail 179 15.1 12 1,3,4 0 0 13 Lesser Kestrel 2627 16.1 0.2 1 0 1 14 Grey-backed Thrush 193 11.7 3 1,2,3 0 0 15 Chinese Grey Shrike 88 17.6 6 1,2,3 0 0 16 Collared Scops Owl 2499 19.5 0.6 1,5 0 1 17 Yellow-Browed 66 13.7 12 6 0 0 Warbler 18 Short-eared Owl 3492 19.6 0.6 1,5 0 1 19 Eurasian Scops Owl 3325 19.4 0.8 1,5 0 1 20 Common Hoopoe 228 18.4 4 1,3 0 0 21 Meadow Bunting 107 12.9 7 6 0 0 22 Tawny Pipit 280 14.7 6 1,2,3 0 0 23 Long-eared Owl 3250 19.9 0.6 1,5 0 1 24 Red-footed Falcon 3212 16.7 0.3 6 1 1 25 Amur Falcon 3265 15.7 0.1 1 0 1 26 Chestnut-flanked 121 12.6 5 6 0 0 White-eye 27 Brambling Fringilla 264 14.9 4 1,3 0 0 28 Yellow-throated 139 11.4 3 1,3 0 0 Bunting 29 Little Owl 3986 14.4 0.1 1 0 0 30 Besra 2936 15.8 0.1 1,3,4 0 1 31 Dusky Thrush 172 13.1 0.8 1,2,3 0 0 32 Dark-sided Flycatcher 284 12.9 0.6 1,3 0 0 33 Yellow-breasted 275 11.7 2 1,3 0 0 Bunting 34 Yellow-browed 63 12.1 2 1,2,3 0 0 Bunting 35 Yellow-billed 59 15.5 0.8 6 0 0 Grosbeak 36 Chestnut-eared 226 13.5 2 1,3 0 0 Bunting 37 Black-faced Bunting 163 12.4 1 6 0 0 38 Siberian Rubythroat 44 10.2 2 1,2,3 0 0 39 Bluethroat 291 11.7 2 1,2,3 0 0 40 Scaly Thrush 44 12.4 0.4 1,2,3 0 0 41 Orange-flanked Bush 123 16.7 2 1,2,3 0 0 Robin 42 Asian Brown 35 12.6 0.6 1,3 0 0 Flycatcher 43 Light-vented Bulbul 231 14.4 7 3,5 0 0 44 Siberian Accentor 66 12 0.5 1,2,3 0 0 45 Eurasian Wryneck 81 13.8 0.8 1,3 0 0 46 New Zealand Pipit 295 13.7 0.8 1,3 0 0 47 Bohemian Waxwing 296 16.6 0.3 1,3 0 0 48 Dusky Warbler 19 14.6 2 6 0 0 49 Reed Warbler 181 12.6 0.5 1,3 0 0 50 Red-rumped Swallow 201 13.5 1 1,3 0 0 51 Black-naped Oriole 109 13.4 0.6 1,3 0 0 52 Pallan's Rosefinch 245 12.3 0.4 1,3 0 0 53 Water Pipit 224 13.2 0.2 3 0 0 54 Olive-backed Pipit 213 13.2 1 2,3 0 0

Habitat type: 1. Grassland; 2. Residential area; 3. Wood; 4. Wetland; 5. Shrub; 6. All environments. IUCN red list of threatened species: 0. Least concern; 1. Near threatened. National List of Key Protected Wild Animals in China: 0. Unprotected species; 1. Second class national protected animals. 6 B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729

Table 3 Investigation of migratory birds around Jinzhou Bay Airport.

No. Spices Flight altitude Flight speed Density (per/ Habitat Threat and conservation status (m) (m/s) km2) type IUCN red list of threatened National List of Key Protected Wild species Animals in China 1 Pintail Snipe 418 17.8 5 1,4 0 0 2 Greylag Goose 1122 17.6 0.2 4 0 0 3 Bar-tailed godwit 464 20.4 1 1,4 0 0 4 Beard Vulture 1000 20 0.1 1 1 2 5 Dunlin 328 17.7 0.8 1, 4 0 0 6 Grey Heron 494 19.4 0.2 4 0 0 7 Little Egret 375 19.1 0.2 4 0 0 8 White-tailed Sea 468 19.9 0.1 3, 4 0 2 Eagle 9 Whooper Swan 1306 14.1 0.1 4 0 1 10 Eurasian Woodcock 474 17.1 0.6 1, 4 0 0 11 Green Sandpiper 311 18.3 0.6 1, 4 0 0 12 Mew Gull 598 18.4 0.8 4 0 0 13 Swinhoe's Snipe 448 18 0.6 1, 4 0 0 14 Mallard 1203 14.6 0.2 4 0 0 15 Slaty-backed Gull 642 14.4 0.6 4 0 0 16 Common Cuckoo 132 16.4 1.5 3 0 0 17 Common Pochard 733 13.4 0.1 4 0 0 18 Common Merganser 1142 13.2 0.1 4 0 0 19 Cattle Egret 415 19.3 0.2 4 0 0 20 Northern Lapwing 430 20.2 0.6 1 0 0 21 Northern Pintail 894 13.7 0.2 4 0 0 22 Mandarin Duck 992 15.7 0.1 4 0 0 23 Grey-headed 465 19.1 0.7 1, 5, 6 0 0 Lapwing 24 Dollarbird 99 17.8 2 1, 2, 4 0 0 25 Chinese Egret 435 19.5 0.1 4 2 1 26 Common Black- 850 17.6 0.6 4 0 0 headed Gull 27 Baer's Pochard 1440 13.9 0.2 4 0 0 28 Fork-tailed Swift 70 19.1 0.6 6 0 0 29 Band-bellied Crake 314 13.1 0.4 1 0 0 30 Eurasian Hobby 80 18.4 0.1 1 0 0 31 Baillon's Crake 494 10.4 0.2 1 0 0 32 Common Teal 1159 14.1 0.2 4 0 0 33 Little Grebe 641 14.3 0.1 4 0 0 34 Great Crested Grebe 1011 14.2 0.1 4 0 0 35 Horned Grebe 927 13.7 0.1 4 2 1 36 Oriental Honey- 80 18.1 0.1 3, 5 0 1 buzzard

Habitat type: 1. GrHabitat type: 1. Grassland; 2. Residential area; 3. Wood; 4. Wetland; 5. Shrub; 6. All environments. IUCN red list of threatened species: 0. Least concern; 1. Near threatened; 2. Vulnerable. National List of Key Protected Wild Animals in China: 0. Unprotected species; 1. Second class national protected animals; 2. First class national protected animals.

Table 4 Deﬁnition of criteria.

Criteria Sub-criteria Definition References Airport- Airport landscape Degree of suitability for bird habitat in and Coccon et al. (2015); Conkling et al. (2018); Pfeiffer et al. (2018a) specific features around the airport factors Airport location and Relationship between airport location, and bird Fu et al. (2016); Lopez-Lago et al. (2017); Chen et al. (2018) runway direction migration route Distance between the Impact degree of airport on bird habitat Coccon et al. (2015) airport and bird habitat Bird- Flight altitude Flight altitude around the airport Holbech et al. (2015); Coccon et al. (2015); Pfeiffer et al. (2018b); specific Fernandez-Juricic et al. (2018) factors Flight manoeuvrability Potential to avoid collision with airplanes Garthe and Hüppop (2004); Furness et al. (2013); Fernandez- Juricic et al. (2018); Density around the Mean bird encounter rate around the airport Soldatini et al. (2010); DeVault et al. (2011); Wang and Herricks airport (2012); Holbech et al. (2015); Hauptfleisch and Avenant (2016) Habitat specialization Dependent degree on specific habitat features Garthe and Hüppop (2004); Furness et al. (2013) Threat and National List of Key Protected Wild Animals in Garthe and Hüppop (2004); Furness et al. (2013) conservation status China and the IUCN red list of threatened species B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729 7

The above mentioned nine experts were invited to score the landscape features factor, and the Delphi method was used to synthesize experts’ opinions. Possible results were evaluated in rounds until a rate of agreement of more than 70% was reached. Expert commentaries were used in each round to improve the scores (Schaap et al., 2017).

2.4.1.2. Airport location and runway direction. If an airport is located in the range of the migration route of birds, a large number of birds will appear around the airport during the migratory season. Furthermore, if the runway direction of the airport is perpendicular to the bird migration route, the possibility of bird strikes will increase signiﬁcantly, and the light and the noise of airports will also have an impact on a large number of migratory birds (Karp and Guevara, 2011; Russ et al., 2015; Sierro et al., 2017; Winger et al., 2019). Similarly, the Delphi method was used to score the factors of the two airport sites based on the relationship between the airport location and the bird migration route.

2.4.1.3. Distance between airport and bird habitat. The construction and operation of the airport will inevitably destroy the bird living space and habitat to some extent, forcing birds to leave their original habitat and compressing their living space. Habitat loss and declines in environmental quality are widely recognized as pivotal threats to wildlife populations (Maslo et al., 2018; Pratt et al., 2019). Therefore, if the airport is close to the bird habitat, it will have a great impact on the bird ecology. This factor was scored according to the distance between the two airport sites and the National Conservation Area of Snake Island and Laotieshan Mountain. After experts discussed, a score of 1 was given if the distance was >80 km, 2 was 61e80 km, 3 was 41e60 km, 4 was 21e40 km, and 5 was 0e20 km.

2.4.2. Bird-speciﬁc factors

2.4.2.1. Flight altitude. This factor is widely considered to be one of overwhelming importance in determining the risk of bird strikes. Therefore, with the consent of the experts, the factor was scored according to the following height classes: 1, >2500 m; 2, 1001e2500 m; 3, 501e1000 m; 4, 101e500 m; 5, 0e100 m.

2.4.2.2. Flight manoeuvrability. Based on the latest research findings, species with greater aerial manoeuvrability have higher frequency of collisions with aircraft. Species that tended to fly at higher speeds might have had extra time to engage in evasive manoeuvres (Fernandez-Juricic et al., 2018), so they are involved in fewer collisions. Due to the limitation of the species traits data, we adopt the experts' suggestion of using bird flying speed around the airport area to score the factor. A score of 1 was given if the bird's speed >20 m/s; 2, 17e20 m/s; 3, 15e17 m/s; 4, 13e15 m/s; 5, 13 m/s.

2.4.2.3. Density around the airport. This factor has a correlation with the occurrence of bird strike events, especially in the migratory season. We scored it according to the mean bird encounter rate obtained by direct observation around the two airport sites. A score of 1 was given for 1 individuals/km2; 2 was given for 1e5 individuals/km2; 3 was given for 5e10 individuals/km2; 4 was given for 10e20 individuals/km2; and 5 was given for >20 individuals/km2.

2.4.2.4. Habitat specialization. Different species of birds have different requirements for habitat environments. Some water birds, such as waders, have many habitat condition requirements such as water depth, water level, vegetation, and food availability (Wang et al., 2018). Once the construction and the operation of the airport has an impact on the habitat of these species, it will pose a direct threat to their survival. This score classifies species into categories from 1 (very flexible in habitat selection and can survive in all environments) to 5 (highly dependent on specific habitat features and can only survive in one type of habitat).

2.4.2.5. Threat and conservation status. Based on the National List of Key Protected Wild Animals in China and the IUCN (In- ternational Union for Conservation of Nature) red list of threatened species, scores were given as follows: 1 (unprotected species), 2 (second class national protected animals in China and least concern species in the red list), 3 (second class national protected animals in China and near threatened species in the red list), 4 (second class national protected animals and vulnerable species in the red list), and 5 (ﬁrst class national protected animals in China).

2.5. MCDM using an AHP approach

The impact evaluation of airport site selection on birds is a complex multi-criterion decision making (MCDM) problem, which includes several inﬂuencing factors. The AHP method proposed by Saaty (1990), which has been widely used in airport site selection decision can be used for the evaluation. van der Kleij et al. (2003) presented a methodology combining AHP and Monte Carlo approaches for a possible airport island location in the North Sea. Solnes and þorgeirsson (2005) evaluated the environmental impact of four different sites for a domestic airport in Reykjavik by AHP. Sennaroglu and Celebi (2018) identiﬁed the best location of a military airport by AHP integrated PROMETHEE and VIKOR methods. 8 B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729

Three important steps need to be conducted consecutively to apply AHP. Initially, the goal and the hierarchy of criteria and sub-criteria which will ultimately influence the goal must be defined (Ali et al., 2018). Thus, in this study the goal and the criteria are shown in Fig. 3. The next step is to determine the weights of the criteria. The above nine experts were asked to conduct pairwise comparisons of the main criterion and the sub-criteria, and to allot them scores on a fundamental 9-value scale as defined by Saaty (1990). A positive reciprocal matrix of comparisons should be constructed as follows. 2 3 / 6 C11 C12 C1n 7 6 7 6 C21 C22 / C2n 7 C ¼ 6 7 (1) 4 ««««5 Cn1 Cn2 / Cnn

ﬁ ① > ② ¼ ; where Cij demonstrates the relative importance of the criteria Ci over Cj, which satis es the characteristics: Cij 0; Cij 1 ¼ ③ ¼ = ; ; ¼ ; ; / i j; and Cij 1 Cji i j 1 2 n. To check the consistency of the comparisons, the deviation of the matrix is tested by the random consistency ratio CR, and

CI CR ¼ (2) RI

l n CI ¼ max (3) n 1 where CI is the consistency index, RI is the random index, lmax is the maximum eigenvalue and n is the matrix size in a pairwise comparison. When CR < 0.1, it can be considered that the consistency of the judgement matrix is acceptable. However, a CR above 0.1 indicates a major inconsistency in the judgement of the experts, which requires reassessment. The comparison matrix given by the nine experts are tested separately until all the matrix are consistent. Then the weight of each factor can be calculated based on the maximum eigenvalue and corresponding eigenvector of the judgement matrix. We take the average value of the weights given by the nine experts as the ﬁnal weight (Table 5). The ﬁnal step is the comprehensive evaluation. The formula for evaluating the ecological impact of an airport on a certain species of bird is shown as follows.

X8 ¼ , V Pi Wi (4) i¼1 where Pi is the evaluation score for each factor, and Wi is the weight of each factor. For the convenience of analysis, we divided the impact degree of airport site selection on bird into the ﬁve levels: extreme impact (V 3), strong impact (2.5 V < 3), moderate impact (2 V < 2.5), low impact (1 V < 2) and no impact (V < 1). If there are m species of birds around the airport, the overall ecological impact evaluation of airport on birds is shown as follows.

Fig. 3. Categorization of criteria and their overlaying to achieve the study objective. B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729 9

Table 5 Weight of factors.

Criteria Weight Sub-criteria Final weight Airport factor 0.5 Airport landscape features 0.14 Airport location and runway direction 0.29 Distance between airport and bird habitat 0.07 Bird factor 0.5 Flight altitude 0.22 Flight manoeuvrability 0.04 Density around the airport 0.12 Habitat specialization 0.05 Threat and conservation status 0.07

Xm ¼ U Vj (5) j¼1

Based on the evaluation results, the airport site scheme can be selected from the perspective of the bird ecological conservation.

3. Results

3.1. The ecological impact of Zhoushuizi Airport on birds

According to the calculation, Zhoushuizi Airport had an extreme impact on 43 species of birds, accounting for 80% of the 54 species around the airport. The rest of the birds were strongly affected by the airport. The overall ecological impact evaluation of Zhoushuizi Airport on birds was 177.81 (Table 6).

3.2. The ecological impact of Jinzhou Bay Airport on birds

It was calculated that among the 36 species of birds around the airport, Jinzhou Bay Airport had a strong impact on 22 species of birds, accounting for 61%. The rest of the birds were moderately affected, and no bird was extremely affected by the

Table 6 Ecological impact evaluation of Zhoushuizi Airport on different bird species.

Impact Degree Species Evaluation Value Impact Degree Species Evaluation Value Extreme impact Oriental Skylark 3.94 Extreme impact Water Pipit 3.32 Eurasian Skylark 3.79 Yellow-billed Grosbeak 3.32 Yellow-Browed Warbler 3.72 Dark-sided Flycatcher 3.32 Yellow Wagtail 3.70 Reed Warbler 3.32 Common Quail 3.63 Pallan's Rosefinch 3.32 Grey Wagtail 3.63 Pintail Snipe 3.31 Brown Shrike 3.62 Common Hoopoe 3.31 Yellow-browed Bunting 3.61 Orange-flanked Bush Robin 3.31 Siberian Rubythroat 3.61 Black-faced Bunting 3.30 Chinese Grey Shrike 3.61 New Zealand Pipit 3.28 Barn Swallow 3.57 Black-naped Oriole 3.28 White-Wagtail 3.54 Grey-backed Thrush 3.27 Asian Brown Flycatcher 3.54 Bohemian Waxwing 3.24 Light-vented Bulbul 3.51 Dusky Thrush 3.23 Eurasian Wryneck 3.50 White-cheeked Starling 3.18 Scaly Thrush 3.50 Strong impact Collared Scops Owl 2.83 Siberian Accentor 3.50 Eurasian Hobby 2.77 Dusky Warbler 3.48 Northern Goshawk 2.70 Yellow-throated Bunting 3.44 Lesser Kestrel 2.70 Yellow-breasted Bunting 3.44 Amur Falcon 2.70 Tawny Pipit 3.43 Little Owl 2.66 Meadow Bunting 3.42 Short-eared Owl 2.61 Chestnut-flanked White-eye 3.42 Eurasian Scopes Owl 2.61 Brambling Fringilla 3.40 Long-eared Owl 2.61 Chestnut-eared Bunting 3.40 Besra 2.61 Red-rumped Swallow 3.40 Red-footed Falcon 2.59 Olive-backed Pipit 3.40 Overall ecological impact evaluation 177.81 Bluethroat 3.39 10 B. Zhao et al. / Global Ecology and Conservation 20 (2019) e00729

Table 7 Ecological impact evaluation of Jinzhou Bay Airport on different bird species.

Impact Degree Species Evaluation Value Impact Degree Species Evaluation Value Strong impact White-tailed Sea Eagle 2.90 Strong impact Eurasian Woodcock 2.55 Oriental Honey-buzzard 2.90 Green Sandpiper 2.55 Dollarbird 2.85 Grey-headed Lapwing 2.51 Chinese Egret 2.83 Moderate impact Mandarin Duck 2.49 Eurasian Hobby 2.82 Slaty-backed Gull 2.46 Pintail Snipe 2.79 Common Pochard 2.46 Common Cuckoo 2.76 Common Merganser 2.46 Baillon's Crake 2.72 Northern Pintail 2.46 Horned Grebe 2.69 Little Grebe 2.46 Band-bellied Crake 2.68 Mew Gull 2.38 Beard Vulture 2.68 Common Black-headed Gull 2.38 Fork-tailed Swift 2.64 Whooper Swan 2.31 Bar-tailed godwit 2.63 Baer's Pochard 2.24 Grey Heron 2.60 Common Teal 2.24 Little Egret 2.60 Great Crested Grebe 2.24 Swinhoe's Snipe 2.60 Mallard 2.19 Cattle Egret 2.60 Greylag Goose 2.16 Northern Lapwing 2.56 Overall ecological impact evaluation 91.92 Dunlin 2.55

airport. The overall ecological impact evaluation of Jinzhou Bay Airport on birds was 91.92 (Table 7), which was 48.3% lower than the impact evaluation of Zhoushuizi Airport. It showed that this option can signiﬁcantly reduce the ecological impact on birds. Therefore, under the premise that other factors of airport location are acceptable, the planned relocation airport should be the preferred option.

4. Discussion

Based on the rapid growth of air traffic and its increasingly serious impact on the bird ecology, it is necessary and urgent to improve modern civilization's consciousness of sustainable development between humans and the nature and to carry out the airport site selection from the perspective of the bird ecological conservation. Based on the detailed investigation data, we evaluated the impacts of different airport site schemes on different species of birds scientifically in this paper. Ideas of the analysis can be used as a reference for other similar construction projects. This paper applies an expert-based approach to evaluate the ecological impact of a civil airport site selection on birds. The selection of the criteria is based on the analysis of the impact of Dalian airport on the bird ecology. Some of these criteria could be addressed by investigation data, and some could only be assessed by subjective considerations based on the expert experience. In the future, when using this method, we can further enrich the various data, such as strengthening the monitoring and tracking of birds, observing data with advanced technology, and inviting more experienced experts on the airport management and the bird ecology to conduct the evaluation. In addition, we should strengthen in-depth research on the types, numbers and activities of birds in the proposed airport site, increase the monographic study of the impacts on birds, adjust airport planning appropriately to minimize the impact of airport construction on birds and realize the sustainable development of human and the natural ecology. In conclusion, the expert-based approach proposed in this paper can objectively evaluate the degree of ecological impact of the airport location on different bird species, and can help people make scientific decisions about the airport site selection from the perspective of the bird ecological conservation. The analysis in this paper provide some insight for improving airport site selection in various countries, especially for the airport sites selection in the migratory region of birds, which has an important value and far-reaching significance.

Acknowledgements

Sincerely thanks to the reviewers for their useful comments on this paper. This research was supported by the Funda- mental Research Funds for the Central Universities, Civil Aviation University of China (Project No. 3122017051) and the Social Science and Humanity on Young Fund of the Ministry of Education of China (Project No. 17YJC630193).

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