East to West Migration of Steppe Eagle Aquila Nipalensis and Other Raptors in Nepal Abundance, Timing and Age Class Determination
EAST TO WEST MIGRATION OF STEPPE EAGLE AQUILA NIPALENSIS AND OTHER RAPTORS IN NEPAL ABUNDANCE, TIMING AND AGE CLASS DETERMINATION
Prepared by: TULSI SUBEDI Executive Member Nepalese Ornithological Union P.O. Box: 21016 Kathmandu, Nepal www.birdsofnepal.org Email: [email protected] [email protected]
Project Duration: 15 Sept 2012 to 8 Dec 2014
Submitted to: National Birds of Prey Trust, UK
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
ABSTRACT This study on east to west migration of Steppe Eagle and other raptors was conducted in central west Nepal in Thoolakharka watch site (28018.188' N, 083049.788', El 2050 m) between 15 September through early December in 2012, 2013 and 2014. Goal of the study was to identify total migrating raptor species as well as their number and determine Steppe Eagles age class migration phenology. In total 81 days of migration study was conducted in 2012 and 85 days in 2013 and 2014. We have counted approximately 10,000 to 14,000 individuals of raptors leaving the Tibetan plateau and northern Asia that heading to south in unknown wintering ground (may be Middle-East or even Africa) following the Himalayan Range of Nepal and India. In total we have counted 37 species of migrating raptors with highest number of Steppe Eagles in all years studied. Among the migrating raptor species observed 12 species were Eagles, five species of Vultures, six species of Falcons, three species of Buteos, three species of Accipiters, four species of Harriers, two species of Kites, Osprey (Pandion haliaetus) and Oriental Honey-buzzard (Pernis ptilorhyncus).Steppe Eagle migration was started from 3rd October and continued till last date of observation. We have counted highest of 308 Steppe Eagles within single hour between 14h00 to 15h00 on 21 Nov 2013 and highest daily count 1102 eagles on 20 November 2013. Migration of Steppe Eagle has observed between 0800 H to 1700 H with a peak number in the afternoon hours (12h00 to 16h00) with highest numbers between 14h00 to 15h00. In Thoolakharka watch site >60% Steppe Eagles passing overhead were aged; among them we identified and counted 20% Juveniles, 37% Sub-adults and 43% adults. Overall, the best time to see the most species in one day is in early November – but different species peak at different times during the autumn migration. For example, Amur Falcon (Falco amurensis) and Lesser Kestrel (Falco naumanni) migration peaked from approx. 20 October through 5 November, Oriental Honey-buzzard peaked from 25 to 31 October, and Himalayan Vulture (Gyps himalayensis) peaked from 10 to 30 November. On the other hand, the largest movement of Steppe Eagles occurred in early to mid-November in 2012 while third week of November to late November in 2013.
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
BACKGROUND
Raptors are secretive, wide-ranging, highly mobile avian predators whose populations can be both logistically difficult and financially prohibitive to survey and monitor (Fuller and Mosher 1987). One potentially cost-effective method for monitoring regional populations of raptors is sampling their numbers during migration at watch-sites along traditional migratory corridors. Counts of migrating raptors at established watch-sites have been used to study raptor migration ecology since the late nineteenth century. Recently, counts of visible raptor migration at watch- sites (hereafter referred to as migration counts) have helped determine the conservation status of migratory populations of raptors (Carson 1962, Hickey 1969, Kerlinger 1989). In addition to their value in monitoring regional populations of raptors, migration counts have led to the identification of principal migration routes, the phenology of raptor migration, as well as to valuable information on raptor flight dynamics and other aspects of raptor behaviour (Smith 1980, Kerlinger 1989).
Indeed, because they are cost-effective and relatively easy to implement, migration counts constitute one of the most commonly used methods in raptor migration science (Kerlinger 1989). Conducted over time, migration counts have been used to determine daily and seasonal timing of migration, species diversity, and the volume of migration as a function of weather (Kerlinger 1989). In addition, direct visual observations associated with migration counts at watch-sites have yielded valuable information on the behaviour of migrating raptors, including the importance of different flight patterns, such as soaring or flapping, flocking behaviour, inter- species interactions, and roosting behaviour (Kerlinger 1989).
Although the use of such counts to indicate population trends is not without its problems, and while statistical methodologies continue to be modified (Fuller and Titus 1990, Titus et al. 1990), preliminary evaluations of the usefulness of migration counts at watch-sites for determining population trends are encouraging (Bednarz and Kerlinger 1989). Properly collected and analysed, such data can provide important information regarding population fluctuations in these species.
Diurnal raptors (Order Falconiformes), constitute a diverse group of approximately 338 species of highly mobile land predators, specializing in different kinds of prey, and occurring in a range of habitats across six continents (Ferguson-Lee and Christie 2001). Approximately 130 species,
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
or about 40 percent of all raptors, engage in periodic seasonal movements biologists call migration (Kerlinger 1989, Bildstein 2006). Although several species (22) are complete migrants (i.e., species in which 90 percent or more of the individuals move on a seasonal basis), most migrating raptors (107) are partial migrants (i.e., species in which less than 90 percent of all individuals move on a seasonal basis, while others remain sedentary). The remaining species of migrants engage in seasonal movements of a more irruptive and local nature. (Kerlinger 1989 and Bildstein 2006)
Raptors exist at the tops of many food chain, their populations are especially sensitive to alterations in ecosystem structure and energy flow. Raptors currently face a variety of human threats, including the widespread use of pesticides; the loss of natural habitat, and consequent declines in prey abundance; direct persecution, including shooting, trapping, and poisoning; and the wild-bird trade (Meyburg and Chancellor 1989, 1994; Newton and Chancellor 1985; Bildstein 2006). Although much has been done in recent decades to enhance the conservation of raptors, significant challenges remain (Bildstein 2006).
The falconiforms are geographically widespread, occurring in every continent except Antarctica, as well as in mid-oceanic islands, such as Hawaii. Two species, the Osprey and Peregrine Falcon (Falco peregrinus), are genuinely cosmopolitan, as are several genera (e.g., Accipiter, Buteo, Falco). Falconiforms occur in all habitats except the most arid deserts and the highest-latitude tundra. The group has a wide altitudinal range, occurring from below sea level to the summits of the Himalayas e.g., Himalayan Vulture Gyps himalayensis and Andes e.g., Andean Condor Vultur gryphus (del Hoyo et al. 1995).
The feeding habits of the falconiforms are as varied as their distributions. Diurnal raptors feed on insects, carrion, and a range of vertebrates from amphibians and reptiles, to birds, small rodents, and meso-mammals (including primates). Many species, particularly migratory ones, are known to shift their diets according to changes in local prey densities, geographic foraging range, and other (Collopy and Bildstein 1987). Migrating raptors are good ecological indicators to predict the environmental changes. Almost half a century ago, declines in annual migration counts of several species of raptors at traditional watch-sites in eastern North America were used to confirm the widespread infiltration of DDT into the aquatic ecosystems of that continent (Carson 1962, Hickey 1969). Population shifts, however, typically represent complicated and frequently indirect relationships between birds and environmental change (Temple and Wiens 1989). Long- Page | 3
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
term studies of changes in the behaviour and physiology of migrants offer considerable potential for the use of migrating raptors as indicators of environmental change.
OBJECTIVES
The primary objectives of this research project were (a) to determine the extent, timing and age class migration phenology of the Steppe Eagle (Aquila nipalensis), as this species moves from its summer range in the eastern grasslands of China to as yet unknown wintering areas in western Asia (Meyburg et al. 2003). The number of Steppe Eagles migrating past the watch site here in Nepal is extraordinary: it is the highest total for any eagle species on the Indian subcontinent as well as the Far East.
In addition, (b) to collect data on flock size and age structure of resident vultures in the region, as well as identify and count migratory vultures as they pass the watch site. Since the late 1990s, four vulture species have declined by over 97% on the Indian subcontinent, making these birds some of the most endangered animals in the world (Oaks et al. 2004, Pain et al 2008, Prakash et al. 2007). Our previous research has shown many of these species are regularly seen at our watch site, so we are in an ideal position to evaluate the current status of at least seven (of the nine) vulture species that occur in Nepal.
Finally, (c) study anthropogenic threats to migrants including hunting, trapping and raptor trade that occur in the area. We wanted to understand the degree to which humans directly affect raptors as they pass through the region. In other parts of the world where raptors pass in large number, several species, including eagles and falcons, are illegally trapped and then sold to falconers in other countries. We wanted to determine the degree to which trapping and hunting of raptors occurs in this part of Nepal so conservation strategies can be developed to insure the safe passage of migrants through the region.
RESEARCH HYPOTHESES
Following were the research hypothesis of this study
(a) What is the total number of migratory Steppe Eagles that pass through the region each year? How does this number vary from year-to-year depending upon weather conditions and other
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
factors? When does the migration begin, peak and end? Do significantly more adult Steppe Eagle precede first-year and other sub-adult eagles? What are the weather conditions correlated with days of the largest number of migrants?
(b) What other raptor species, and in what number, also utilize this migration corridor? How common are raptor species with special conservation status such as Amur Falcon (Falco amurensis), Lesser Kestrel (Falco naumanni) and Saker Falcon (Falco cherrug)?
(c) For the Himalayan Vulture, what is the average flock size, and how does this vary through the weather? What is the maximum flock size and age composition (first-year vs. immature vs. adult) of members of the flock? What is the status, timing and age of migrant vultures in the area, particularly the Cinereous Vulture?
(d) What human related factors affect migrating raptors through the region?
MATERIALS AND METHODS
Study area:
Thoolakharka (Khare) is a mountaintop watch site, geographically located at 28.303210 N and 083.829640 E, at the elevation of 2050 m in the foothills of Himalayan Mountains of central Nepal, south of Annapurna Himalaya range (Map 1). This area is a major corridor for migrating raptors, including endangered, vulnerable and near threatened species (Zalles and Bildstein 2000, DeCandido et al. 2001, Gurung et al. 2004). It is situated on the trekking trail that connects the towns of Kande to the South and Annapurna Base Camp (ABC) to the North, approximately 35 km northwest of the city of Pokhara. Thoolakharka watch site has a 360° view of the surrounding countryside. There are several small valleys around the watch site, including the Mardi river valley to the North east, Hyangja valley to the east, Pokhara valley to the east-east south, Marsikhola valley to the southeast and Modi river valley to the West. Agricultural land is dominated in the lowlands of the valleys while oak-rhododendron forest occurs at higher elevations (Inskipp and Inskipp 1991, Zalles and Bildstein 2000). Approximately 40 km North; east to west extended chain of the Annapurna Himalayan Mountain is situated (with highest elevation 8091 m. asl) including 13 additional peaks over 7000 m.
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Map 1. ▲Thoolakharka (Nepal) – location of current migration study at 2,050 m; the town of Dhampus is directly east across a valley at approx. 1,800 m. (1) Ghasa in the Kaligandaki valley, (2) Kathmandu Valley, (3) Ilam District, Nepal (4) Bardia National Park, Nepal (5) Jhatingri and Dharamsala, Himachal Pradesh, India, (6) Chihkiang Hongjiang], China, (7) Eastern Tibet, (8) Kalamaili, Xinjiang Province, China.
Legends
Breeding range (summer) of Aquila n. nipalensis.
Breeding range (summer) of Aquila n. orientalis
Winter range of Aquila n. nipalensis.
? Presumed ‘zone of overlap’ or ‘intergrade zone’
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Methodology:
a. Migration counting; Spotting, identification and count of raptors:
The period for field research on the autumn migration of Steppe Eagles and other raptors was started from 15th of September and continued till 4 Dec (80 days) in 2012 and 8 Dec (85 days) in 2013 and 2014. Each day counting of the birds was carried out from dawn to dusk (7 am to 5 pm).
For all three years (2012-2014) counting of the migrants was done from two watch site (Paudur Hill and Thoolakharka). In the beginning of the season (15 Sept through approximately 15 Oct) counting was carried out only from the Paudur Hill watch site (1760 m asl) because the Thoolakharka watch site (2050 m asl) to the north was seen obscured with clouds due to the lingering effect of monsoon. After 15 October counting was conducted from Thoolakharka watch site because this watch site was mainly clear for this time of the year. However if the moist air is blown from the south, which collides with the cold environment, apparently helps on cloud formation and makes difficulties on migration counting. Both the locations are mountain top watch sites which provide 3600 view of surrounding countryside. Direct count of all raptorss passing through the migratory corridor were spotted, identified and counted through the methodologically scanning of the sky using optical equipment (ZenED310x43, Swarovski 15x56 binoculars and Vortex RazerHD 20-60x 85 angled spotting scope). Pictures of the migrants were also taken with Canon 7D camera with 400 mm/f5.6 canon lens and Canon 5D mark III with 800 mm/f5.6 canon lens. Protocols were followed those set forth by the Hawk Migration Association of North America (HMANA), as well as those published in similar raptor migration studies. Birds were identified through the study of available field marks and on the basis of using a combination of cues such as flight pattern, wing-to-tail ratio, head-to-body ratio, wing shape, etc. Once a migrant is identified to species, it was then (whenever possible), be assigned an age class (first plumage, second to fourth plumage and full adult, etc. particularly for Steppe Eagle and Himalayan Vultures). Other data recorded on an hourly basis were weather conditions including wind speed and direction, barometric pressure, temperature and cloud cover (particularly over the nearby Himalayan Mountains). Other important data collected were the size and composition of Himalayan Vulture flocks and important behaviour of the migrants. All count and additional data were recorded hourly on data sheets specially designed for this project (Annex I and II). Also the methodology was followed from the studies of Fuller and Mosher Page | 7
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
1987, Kerlinger and Gauthreaux 1985, Klem et al. 1985, Bildstein 2006, Besten 2004, Spaar and Bruderer 1996, Forsman 2005 and Shelley and Benz 1985.
b. Human Threats to Migrating Raptors:
Questionnaires survey and informal interview was conducted to study the threats to raptors. Survey was conducted through the random selection of respondents around the migration corridor and wintering areas in Pokhara valley. Questions were focused to determine if raptors are being shot, hunted or trapped for sale in local or international markets. In addition, market survey was conducted in the area to determine if (and what) raptor species are being sold. Also local raptor rescue and rehabilitation centre was visited and interviewed to find out the threats to raptors.
c. Data analysis:
Collected data were analysed using t-test (two-sample assuming unequal variances) and ANOVA using Microsoft excel 2013. Also the median date (the date at which 50% of the individuals counted) for the migrants was calculated.
RESULTS This project was a part of Raptor Migration Project in Nepal for which preliminary study was conducted in Nov 2011 and study is continuously conducted in each autumn migration season (Sept to Dec) from 2012. In this period we are able to set baseline data for the population trend of several raptor species (more than 35 species) that were observed during the migration; as well as few resident raptors. We have also collected data on demographic structure of the Steppe Eagle which is the most numerously seen raptor (somewhere between 6,000 to 10,000 individuals) in our study site. The demographic data will be helpful to predict/analyse status of this eagle species whose population is believed to be declining. Objective wise major achievement and output is summarise below.
a. Total raptor species and their number:
During our three years of study we have observed and identified total of 37 species of raptors during the migration. If we go through yearly basis, total of 30 species in 2012, 35 species in 2013 and 32 species in 2014 were observed. Except single species (Indian Spotted Eagle), all other species were recorded in 2013 observation. Similarly in 2013 we also able to photograph Shikra Accipiter badius in our watch site and which is added on migration list in 2014 that made Page | 8
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
us 37 migratory species of raptors in Thoolakharka. In 2012 we have counted Black Kite Milvus migrans govinda and Black-eared Kite Milbus migrans lineatus together, however these two subspecies were splited and given the status of separate species. Therefore from 2013 study we have recorded those as a different species. Among the species we observed during our observation; Eagles (12 species), Falcons (6 species), Accipiter (3 species), Buteo (3 species), Kites (2 species), Vultures (5 species), Harriers (4 species), Osprey and Oriental Honey-buzzard. Detail about the number and species recorded each year is presented below in table 1.
Highest Total Count Total Count Total Count SN Species Daily Count (2012) (2013) (2014)
1 Oriental Honey-buzzard 60 381 642 561 2 Himalayan Buzzard 12 180 102 66 3 Long-legged Buzzard 3 4 11 3 4 Upland Buzzard 2 4 8 7 Unidentified Buteo 1 3 3 2 5 Northern Sparrowhawk 7 107 110 103 6 Northern Goshawk 4 3 10 15 7 Shikra 2 ------13 Unidentified Accipiter 1 9 1 3 8 Steppe Eagle 1,102 6,597 8,684 6,166 9 Booted Eagle 15 155 109 118 10 Short-toed Eagle 1 2 2 0 11 Crested Serpent-eagle 4 26 5 6 12 Pallas's Fish Eagle 1 2 1 2 13 White-tailed Eagle 1 0 2 0 14 Imperial Eagle 2 0 1 3 15 Indian Spotted Eagle 1 3 0 0 16 Greater Spotted Eagle 1 3 2 0 17 Bonelli's Eagle 8 13 30 23 18 Mountain Hawk-eagle 4 1 6 9 19 Golden Eagle 1 7 4 3 Unidentified Eagle 1 8 2 1 20 Black Kite 40 324 356 287 21 Black-Eared Kite 25 153 110 22 Osprey 2 3 5 2 23 Hen Harrier 4 19 9 19 24 Western Marsh Harrier 1 0 1 1 25 Pallid Harrier 2 1 2 2 26 Pied Harrier 1 0 1 0 Unidentified Harrier 1 3 0 4 27 Peregrine Falcon ssp. calidis 3 29 18 16 28 Saker Falcon 3 5 1 1
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
29 Northern Hobby 33 80 211 100 30 Amur Falcon 24 78 90 20 31 Lesser Kestrel 29 66 69 22 32 Common Kestrel 29 83 318 197 Unidentified Falcon 2 21 14 17 33 Egyptian Vulture 6 24 40 19 34 White-rumped Vulture 17 0 127 138 35 Himalayan Vulture 221 1,270 2,215 1,415 36 Cinereous Vulture 11 73 57 47 37 Griffon Vulture 14 85 44 25 Unidentified Vulture 1 3 1 0 Unidentified Raptor 3 79 18 19 Total 1,238 9,754 13,485 9,565 Table 1: Raptor species identified and number counted at Thoolakharka raptor migration watch site (Nepal), 15 September through 4 December 2012 and 15 September through 8 December 2013 and 2014 including highest daily count and unidentified raptors. The total comes from daily observations made of migrants heading east to west by Tulsi Subedi, Sandesh Gurung and others.
b. Timing and migration phenology of Steppe Eagle and other raptors:
During autumn migration study (15 Sept through 8th Dec) in 2014 Steppe Eagles were the common migrant in Thoolakharka raptor migration watch site and counted 6,166 which is the lowest number recorded in our study since 2012 (6,795 in 2012 and 8,684 in 2013). In 2014 first date of the Steppe Eagle arrival in Thoolakharka was 3 October which was 2 days earlier than in 2012 and 4 days earlier than in 2013 study, in all years of study Steppe Eagle migration was continued till the last date of observation (8th Dec). Thus we believe Steppe Eagle has the longest migration period among all the raptor species seen in this watch site. The highest single day Steppe Eagle count was on 7 November 2014 – 614 individuals passed by the watch site, while the peak date was 3 Nov in 2012 (572 birds) and 20 Nov 2013 (1102 birds).
During the peak day of Steppe Eagle migration in 2014 we recorded 2 to 6 km/hr of wind from NW to E with 50 to 100% cloud cover, while in 2012 we observed 4 to 9 km/hr of South to South-East wind with no cloud which pushed the birds towards north very close to the Himalayas approximately 20 km from us, while in 2013 we observed 2 to 5 km/hr of wind from North-East with 20 to 100 % of cloud cover. Therefore it is very difficult to conclude the local weather condition associated with peak migration of Steppe Eagle from the three years of study and we assume the peak migration could be associated with the overall regional weather condition of the Central-South Asian Flyway. Figure 1 below shows the migration pattern of
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Steppe Eagle observed in our study.
1200
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0 16-Sep 23-Sep 30-Sep 7-Oct 14-Oct 21-Oct 28-Oct 4-Nov 11-Nov 18-Nov 25-Nov 2-Dec 2012 Autumn 2013 Autumn 2014 Autumn
Figure 01. Migration pattern of Steppe Eagles (2012 to 2014) autumn in Thoolakharka Raptor Migration Watch Site Nepal.
In our studies from 2012 Steppe Eagles passed us from the reasonable distance so that we could age most of the individual eagles and approximately 67% (4128) in 2014, 57% (4967) in 2013 and 60% (3956) in 2012 were aged. In our study migration of juvenile Steppe Eagle was found greatly outnumbered by adults and sub-adult birds. Figure 02, 03 and 04 below shows the age composition and migration timing of different age group.
1st plumage (Juvenile) 2nd-4th plumage (sub-adult) >5th plumage (Adult) 180 160 140 120 100 80 60 40 20 0 3-Oct 10-Oct 17-Oct 24-Oct 31-Oct 7-Nov 14-Nov 21-Nov 28-Nov 5-Dec
Figure 02. Age composition of Steppe Eagles on daily basis crossing the raptor migration watch site at Thoolakharka, Nepal 2014 (n=4128) autumn
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
1st plumage (Juvenile) 2nd-4th plumage (sub-adult) ≥5th plumage (Adult) 500
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5-Oct 7-Oct 9-Oct
2-Dec 4-Dec 6-Dec 8-Dec
2-Nov 4-Nov 6-Nov 8-Nov
11-Oct 13-Oct 15-Oct 17-Oct 19-Oct 21-Oct 23-Oct 25-Oct 27-Oct 29-Oct 31-Oct
12-Nov 14-Nov 16-Nov 18-Nov 20-Nov 22-Nov 24-Nov 26-Nov 28-Nov 30-Nov 10-Nov
Figure 03. Age composition of Steppe Eagles on daily basis crossing the raptor migration watch site at Thoolakharka, Nepal 2013 (n=4967) autumn
1st plumage (Juvenile) 2nd-4th plumage (Sub-adult) ≥5th plumage (Adult) 200 180 160 140 120 100 80 60 40 20 0 5-Oct 12-Oct 19-Oct 26-Oct 2-Nov 9-Nov 16-Nov 23-Nov 30-Nov
Figure 04. Age composition of Steppe Eagles on daily basis crossing the raptor migration watch site at Thoolakharka, Nepal 2012 (n=3956) autumn.
During our study the ratio of 1st plumage (juvenile) birds was seen higher during the beginning of migration for 2012 and 2013, while 2nd to 4th plumage (sub-adults) birds was seen in higher proportion on 2014 migration season. According to our observation median date for juvenile birds was 15 November, sub-adult was 18 November and for ≥ plumage (adults) was 19
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
November. T-test was done to find out is there significant different on the timing of migration of different age class. For this test our assumption was; there is no significant difference between migration timing (date) of different age group of Steppe Eagle during autumn migration so we set the null hypothesis (H0) as there is no significant difference on the time (date) and age of migrating Steppe Eagles in autumn migration. T-test was conducted between different age categories; for juvenile and adults migration date; t-test rejects the null hypothesis (t= 3.55, df = 83, p=0.0006) which indicates there is statistical significant difference on the migration date of juvenile and adult Steppe Eagle. For sub-adult and adult migration date; t-test can’t rejects null hypothesis (t=0.72, df = 119, p=0.47) which indicates there is no statistical significant difference on the migration date of sub-adults and adults Steppe Eagles. Similarly for juvenile and sub- adult; t-test rejects null hypothesis (t=3.64, df = 98, p=0.0004) which indicates there is statistical significant difference on the migration date of juvenile and sub-adult Steppe Eagle. From the above statistical test it is concluded that juvenile birds proceed their migration earlier than adults and sub-adult Steppe Eagle while sub-adults and adults may proceed the migration during the same time of the year.
We also assume there is similar pattern (date) of Steppe Eagle migration for year to year. For this ANOVA test was conducted and null hypothesis (H0) was set up as there is similar date of migration of Steppe Eagle for year to year (2012, 2013 and 2014) during autumn migration. ANOVA test can’t rejects null hypothesis (F = 0.96, df = 196, p = 0.38) and statistically proven there is no yearly significance difference on migration date of Steppe Eagle between 2012 to 2014.
In all three years of study higher number of Steppe Eagles were seen in the afternoon hours, and 14h00-15h00 time frame was the peak time/hour to see migration through the season 2012 and 2013 however in 2014 peak time for the Steppe Eagle passage was seen between 10h00-11h00 which was followed by 14h00-15h00. In average only 32.55% of Steppe Eagles passed before noon (between 07h00 – 12h00) and 67.45% were passed after noon (between 12h00 to 17h00). This likely has to do with the way clouds build over the nearby Annapurna Range, so that the eagles shift their migration to the south, particularly if there is a light to moderate wind from the northeast. In 2014 southerly moist air was hitting Thoolakharka raptor migration watch site and just over the watch site that meet the cold air from the north and cloud formed. This cloud often obscured the views to the south valleys. We assume there might be a continuous movement of
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
the eagles over the south valley, we couldn’t see those. Detail about the daily migration timing of the Steppe Eagle is given in the figure 05.
2,500 2012 Autumn 2013 Autumn 2014 Autumn
2,000
1,500
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0 7:00-8:00 8:00-9:00 9:00-10:00 10:00-11:00 11:00-12:00 12:00-13:00 13:00-14:00 14:00-15:00 15:00-16:00 16:00-17:00
Figure 05. The number of Steppe Eagles on migration counted per hour at Thoolakharka, Nepal (autumn 2012 to 2014).
c. Status and timing of migrant vulture:
Of the nine vulture species found on the Indian sub-continent including Nepal, eight species have been observed at Thoolakharka watch site. Out of these species five species were migratory: White-rumped Vulture (Gyps bengalensis), Egyptian Vulture (Neophron percnopterus), Cinereous Vulture (Aegypius monachus), Griffon Vulture (Gyps fulvus) and Himalayan Vulture (Gyps himalayensis). Three other species: Bearded Vulture (Gypaetus barbatus), Red-headed Vulture (Sarcogyps calvus) and Slender-billed Vulture (G. tenuirostris) were strictly resident in the region. In this study, the most common vulture species seen (> 85% of all migrating vultures) was the Himalayan Vulture with 1270 individuals in 2012, 2,215 individuals in 2013 and 1,415 in 2014. Figure 06 shows their migration through the season with the latter half of November through early December being the peak period. However, flocks of resident vultures were seen throughout the study. To test statistical significance for the number of Himalayan Vulture migration on different date, null hypothesis (H0) was Himalayan Vulture had similar migration date in every year of the study. ANOVA test can’t rejects the null hypothesis (F = 2.58, df = 205, p = 0.07) and which statistically proven there is no yearly significance difference on migration date of Himalayan Vulture between 2012 to 2014. Page | 14
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
According to Figure 07, most of the vultures (of all species) we saw on migration were observed from 10am through 3pm (10h00 – 15h00). Compared to the pattern of Steppe Eagle migration, greater percentage of vultures passed earlier in the day. However for both eagles and vultures, 14h00 – 15h00 time frame was the peak hour of migration in 2012 and 2013 and it was 10h00 – 11h00 in 2014.
2012 Autumn migration 2013 Autumn migration 2014 Autumn migration 300
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0 16-Sep 23-Sep 30-Sep 7-Oct 14-Oct 21-Oct 28-Oct 4-Nov 11-Nov 18-Nov 25-Nov 2-Dec
Figure 06. The number of migrating Himalayan Vultures counted per day in autumn 2012 to 2014 at the Thoolakharka Migration Watch site in Nepal.
Total number of migrant vulture 2012 Total number of migrant vulture 2013 Total number of migrant vulture 2014 600
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0 7-8 am 8-9 am 9-10 am 10-11 am 11-12 12-1 pm 1-2 pm 2-3 pm 3-4 pm 4-5 pm noon
Figure 07. The total number of all migrating vultures counted per hour during autumn 2012, 2013 and 2014.
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
d. Resident vulture flock size:
In Thoolakharka three species of vulture seen Red-headed, Slender-billed and Bearded Vultue were strictly residentially and seen throughout the season, while White-rumped, Himalayan and Egyptian Vulture were partial migrants. Among all the species vast majority of the vulture seen were Himalayan Vulture (juveniles and sub-adults). Highest flocks of the vultures seen were between 10h00 to 14h00 in all years (Fig 08). In 2014 total of 47 resident vulture flocks were seen while the number of flocks were 178 in 2012 and 135 in 2013.
Resident vultura flock 2012 Resident vultura flock 2013 Resident vultura flock 2014 45
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5
0 7-8am 8-9am 9-10am 10-11am 11-12noon 12-1pm 1-2pm 2-3pm 3-4pm 4-5pm
Fig 08. Total resident vulture flocks counted per hour in Thoolakharka watch site. The blue tile indicated the flocks in 2012, red tiles indicated the flocks in 2013 and finally green tiles indicates the flocks in 2014 autumn.
e. Status of Falcons:
Late September through late October is the best time to see falcon diversity at Thoolakharka watch site. Altogether six falcon species were seen on migration including the globally endangered Saker Falcon Falco cherrug, however this species was very rare in Thoolakharka watch site and highest of five individual counted in 2012, while single bird was spotted in subsequent years. The latter half of the October is the best time to see small flocks of Amur Falcon Falco amurensis – the highest number of this species counted was 17 October 2013 (24 birds). According to recent information, the majority of Amur Falcons migrating through Nepal use a different flyway through the eastern half of the country: along the Arun River valley. If we compare three fall migration seasons, 2013 was better year for the falcon migration at
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Thoolakharka and subsequently the number went down in 2014. At Thoolakharka, Lesser Kestrels Falco naumanni also migrate in small flocks. Other falcons observed on migration were Northern Hobby Falco subbuteo, Peregrine Falcon Falco peregrinus ssp. calidus and Common Kestrel Falco tinnunculus. In 2013 we counted a total of 721 falcons which is almost twice as many as 2012 count (362), while again this number is going down as 373 in 2014 count. Fig 9 below shows the comparative number of each falcon species observed and counted at Thoolakharka between 2012 and 2014.
2012 2013 2014
350
300
250
200
150
100
50
0 Lesser Kestrel Common Kestrel Northern Hobby Amur Falcon Peregrine Falcon Saker Falcon
Fig 09. Status of six species of falcon migration in Thoolakharka 2012 – 2014 Autumn
f. Migration of Oriental Honey-buzzard (OHB):
OHB was another common migrating raptor species in Thoolakharka and few hundreds of those were observed and counted in our study. Mid-September through October was the good time to see OHB migration and median date was 26 Oct in 2012 and 18 October in 2013 and 2014. For the timing (date) of migration of Oriental Honey Buzzard (OHB) on different years (2012 to
2014) null hypothesis (H0) was set as OHB perform same migration time (date) in different years studied at Thoolakharka. F-test for the OHB migration between 2012 to 2014 cannot rejects the null hypothesis (F= 2.15, df = 148, P= 0.12) and statistically proved there is no difference on migration date on OHB between 2012 to 2014 autumn migration in Thoolakharka. Our studies also shows morning hours (before noon) is the best time for OHB migration in Thoolakharka, Fig 10 shows the hourly migration pattern of OHB between 2012 to 2014.
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
160
140
120
100
80
60
40
20
0 7-8am 8-9am 9-10am 10-11am 11-12noon 12-1pm 1-2pm 2-3pm 3-4pm 4-5pm
OHB 2012 OHB 2013 OHB 2014
Fig 10. Total OHB Migration hourly migration in Thoolakharka raptor watch site in 2012 to 2014 autumn
g. Threats to Raptors: In the study strong evidence was found that peoples hunt raptors for various purpose. Information from this study shows mainly peoples collects raptor chicks and eggs. Peoples mainly eat the eggs because they believe eggs are highly nutritious and chicks grown in the home to export to different cities and countries. For the trafficking of raptors some middle mans were found involved however the exact trading route is unknown however some cities like Kathmandu and Dharan are highly vulnerable and developing as a raptor trading hub.
During the home rearing; raptors were mainly feed with unnatural foods like vegetables and rice. This study also found the information that traditionally and culturally peoples collect the raptors to use different raptor parts such as feathers, bones, beaks, claws etc. for different purposes. Also we found some peoples willing to keep the dead and preserved (taxidermy) raptor in their home for decorative purpose and they believe if they do so the evil spirit never come to them. Spiritual people also found to use feathers of vultures, eagles, hawks and owls frequently in black magic. Mostly they use the vulture feathers on their hats. Vultures are masters of the sky and there is a belief if they use vulture feathers, they carry the evil spirit away from the man. Some peoples believe blood of Kestrels is useful to cure the Epileptic Convulsion. This study shows some peoples think raptors frequently attack the small pet animals like pigeons, chickens etc. and therefore people persecute raptors hitting with sticks (specially vulture), use of poisoned bait, targeted by catapult, stones and nest site destructions. In the local raptor rescue centre more than
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
70 injured raptors were found rescued and the cause of injuries were similar as mentioned above. The species of the injured raptors rescued in the centre were Steppe Eagle, Himalayan Vulture, Mountain Hawk-eagle, Crested Serpent Eagle, Egyptian Vulture, White-tailed Eagle and Black Kite.
DISCUSSION AND CONCLUSIONS In Thoolakharka watch site total of 37 raptor species were observed, identified and counted during the autumn migration between 2012 and 2014. Among them Steppe Eagles were most numerous migrants in this study and comprised approximately 65% of the total migrant raptors. The highest daily count of the Steppe Eagle was 572 in 3 Nov 2012, 1102 in 20 Nov 2013, and 614 in 7 Nov 2014. When we compare our study with the study of Robert Fleming Jr. and others from the Jomsom trek south of Annapurna range in 1970s where they counted 305 Steppe Eagles on 2 November 1976 at Dhampus ridge (Fleming 1983). Overall, Fleming also estimated 45,000 individual eagles migration from the 24 October through 30 of November which is much higher than our observation. There could be several explanations for the differences in present observation. Fleming’s estimation was based on the peak time observation of the eagle migration or the population of the Steppe Eagle is declining as study conduct in Israel (Zduniak et al 2010). Other possible explanations could be the changing weather condition made some of the birds to shift their route or we didn’t see many birds due to the cloud or they pass very far from us and we couldn’t see all of them. But in 1984, from 6 October through 4 November, Bijlsma (1991) made observations, and found Steppe Eagle migration peaked in late October at Khare, with a daily high count of 817 on 27 October. Similarly in 1985, from 20 October through 7 November, deRoder (1989), counted 7,852 Steppe Eagles in migration (58.2 eagles/hr). A maximum of 1,397 were counted on 1 November. In 1999 DeCandido observed 821 Steppe Eagles and eight other raptor species in migration in their nine days of observation between late October and early November (DeCandido et al. 2001). Subsequently in 2003, Surya Gurung and his family recorded 6,503 migrating Steppe Eagles from 24 October through 5 December, with a highest count of 571 on 23 November (Gurung et al. 2004). Above observation of steppe eagle migration are more or less similar with our observation however peak date of migration seems different year to year. The weather has significance influences on the migration timing of raptors which might have shown this result. deRoder believed that juvenile Steppe Eagles migrate in
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
greater number later in the season compared to other age classes unlikely present study shows the juvenile birds proceed their migration approximately 04 days earlier than the adults and 3 days earlier than the sub-adults . He also noted up to 17 additional raptor species on migration including a few Imperial Eagle Aquila heliaca and Greater Spotted Eagles Aquila clanga, as well as Lesser Kestrel Falco naumanni and Amur Falcon Falco amurensis – both falcon species peaking in number between 20-30 October which is similar as present study however we discovered more species ever recorded using this migration route.
The best weather conditions for migration at Thoolakharka occur when (a) clouds obscure the Annapurna Mountain range, approx. 25 km to our north; and (b) when winds are from the northeast at approx. 10 km/hr. When dense clouds fill the mountain foothills, migrants – particularly Steppe Eagles – shift their flight south to lower elevation. At such times eagles and other raptor migrants pass directly over Thoolakharka watch site. This allowed to age Steppe Eagles and >60% of the migrating Steppe Eagles that passed above and below us. Typically, weather early in the migration period (from mid-September through approx. 20 October) is dominated by the lingering effects of the summer monsoon that comes to this area from the southeast. At this time, the nearby Annapurna Mountains are often shrouded in clouds, and rain occurred. Beginning in late October and continuing through approx. 20 November, high pressure building in from the north dominates our weather. Generally clear conditions prevail and some migration shifts back to our north, away from our watch site and into the foothills of the mountains. Rain is rare during this time, and weather becomes increasingly cool (25C during the day up to approx. 20 November, and 5-10C at night; then after 20 November, it is closer to 20C by day, and down to 3-5C at night). For the 25 November through 8 December time frame, the weather becomes unsettled again – and clouds and fog increase.
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
ACKNOWLEDGEMENT Three years of raptor migration study between 2012 and 2014 was possible due to the joint effort of many people and organizations. I thank Sharad Singh, Director of Himalayan Nature for his support to develop and conduct field studies. I thank my senior colleagues and friends Dr. Hem Sagar Baral, senior ornithologist of Nepal, Dr. Keith Bildstein, Director of Hawk Mountain Sanctuary USA, Dr. Robert DeCandido from USA and Deborah Allen from Canada for their encouragement, support and advice. Carol and Tim Inskipp, as well as Martti Siponen and Late Henk Smit, AunTiah Lim, Mohammed Syafiq Sivakumaran provided books and literature which are very useful for identifying migrants which were not familiar with. Thanks also to the Brooklyn Bird Club of NYC, USA for sending me books as well. Dr. Jeffery Lincer keeps providing ideas and suggestions for how to maximize our research time in the field. Brian Williams, Director of the Red Panda Network (2012), and the Malaysian Nature Society (2013) transported essential research equipment to Nepal. Idea Wild supplied scientific equipment, including a weather meter, DSLR camera and we appreciate their support. Ooi Beng Yean from Malaysia has donated Spotting Scope for the study in 2014 and similarly Hawk Mountain Sanctuary of the USA donated a spotting scope (2012) for use in this study. National Birds of Prey Trust, UK (2013), The Nagao Natural Environment Foundation, Japan (2012) and The Rufford Foundation, UK (2014) provided financial support to conduct this study, as well as equipment that were necessary for daily observation – and it would be impossible to do this research without their help. I thank to many friends from Thailand, Malaysia, Singapore, South Africa, USA, Netherlands, Finland, Canada who has supported this project and visited the site in different years – space doesn’t permits for their name… my apologize and thanks. I also thank to Surya Gurung, Bijay Gurung, Krishna Mani Baral, Hemanta Dhakal for their support at the site. I also thank to Sandesh Gurung for his continuous field support, without whom it would be very difficult for this long field observation. Finally, I thank Hari KC and his wife Mina, owner of Australian Camp Guest House, Nirmal and Man Prasad Gurung, owners of the Sunrise Restaurant for allowing us to use their chairs, and for wonderful meals, neat accommodation and cups of tea/coffee.
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LITERATURE CITED Bednarz, J. C., and P. Kerlinger. 1989. Monitoring hawk populations by counting migrants. Pages 328-342 in Proceeding of the Northeast Raptor Management Symposium and Workshop. National Wildlife Federation, Washington D. C., USA. Besten, J.W.D. 2004. Migration of Steppe Eagles Aquila nipalensis and other raptors along the Himalayas past Dharamsala, India, in autumn 2001 and spring 2002. Forktail 20: 9– 13 Bildstein, K. L. 2006. Migrating raptors of the world: their ecology and conservation. Cornell University Press, Ithaca, USA. Bijlsma, R.G. 1991. Migration of raptors and Demoiselle cranes over central Nepal. Birds of prey bulletin 4:73-80 Carson, R. 1962. Silent spring. Houghton Mifflin Company, Boston, USA. Collopy, M. W., and K. L. Bildstein. 1987. Foraging behavior of Northern Harriers wintering in southeastern salt and freshwater marshes. Auk 104:11-16. DeCandido, R., D. Allen and K.L. Bildstein. 2001. The migration of steppe eagles Aquila nipalensis and other raptors in central Nepal, autumn 1999. Journal of raptor research. 35(1):35-39. del Hoyo, J., A. Elliott, and J. Sargatal. 1995. Handbook of the birds of the world. Vol 2. Lynx Edicions, Barcelona, Spain. DeRoder, F.E. 1989. The migration of raptors south of Annapurna, Nepal, autumn 1985. Forktail 4:9-17 Ferguson-Lees, J., and D. A. Christie. 2001. Raptors of the world. Christopher Helm, London, England. Fleming, R. L. Jr. 1983. An east-west Aquila eagle migration in the Himalayas. Journal of Bombay Natural history Society, 80:58-62 Forsman, D. 2005. Steppe Eagles plumages. Alula 1:2-9 Fuller, M. R., and K. Titus. 1990. Sources of migrant hawk counts for monitoring raptor populations. Pages 41-46 in Survey designs and statistical methods for the estimation of avian population trends, ed. by J. R. Sauer, J. R and S. Droege. U.S. Fish and Wildlife Service, Biol. Rep. 90(1), Washington D. C., USA. Fuller, M. R., and J. Mosher. 1987. Raptor survey techniques. Pages 37-65 in Raptor management techniques manual, ed. by B. A. Giron Pendleton, B. A. Millsap, K. W. Cline, and D. M. Bird. National Wildlife Federation, Washington D. C., USA. Gurung, S.B., Gurung, S., Gurung, S. and McCarty, K. 2004. Autumn 2003 Raptor Migration in Central Nepal. International Hawkwatcher No.9: 12-15
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Hickey, J. J. 1969. Peregrine Falcon populations: their biology and decline. University of Wisconsin Press, Madison, USA. Inskipp, C. and T. Inskipp. 1991. A guide to the birds of Nepal. Smithsonian Institution press, Washington, USA Kerlinger, P. 1989. Flight strategies of migrating hawks. University of Chicago Press, Chicago, USA. Kerlinger, P. and S.A. Gauthreaux. 1985. Flight behaviour of raptor during spring migration in Texas studied with radar and visual observation. Journal of field ornithology. 56:394-402 Klem, D.,Jr.,B.S. Hillegass and D.A. Peters. 1985. Raptors killing raptors. Wilson bulletin. 97:230-231. Meyburg, B. -U. and R. D. Chancellor. 1989. Raptors in the modern world. World Working Group on Birds of Prey and Owls, Berlin, Germany. Meyburg, B. -U. and R. D. Chancellor. 1994. Raptor conservation today. World Working Group on Birds of Prey and Owls, Berlin, Germany. Newton, I., and R. D. Chandler. 1985. Conservation studies on raptors. ICBP Technical Publication No. 5. International Council for Bird protection, Cambridge, England. Oaks, J.L., Gilbert, M., Virani, M., Watson, R.T., Meteyer, C.U., Rideout, B., Shivaprasad, H.L., Ahmed, S., Chaudhry, M.J.I., Arshad, M., Mahmood, S., Ali, A. and Khan, A.A. 2004. Diclofenac residues as the cause of vulture population declines in Pakistan. Nature 427: 630–633. Pain, D.J., Bowden, C.G.R., Cunningham, A.A., Cuthbert, R., Das, D., Gilbert, M., Jakati, R.D., Jhala, Y., Khan, A.A., Naidoo, V., Oaks, J.L., Parry-Jones, J., Prakash, V., Rahmani, A., Ranade, S.P., Baral, H.S., Senacha, K.R., Sarvanan, S., Watson, R.T., Virani, M.Z., Wolter, K. and Green, R.E. 2008. The race to prevent the extinction of South Asian vultures. Bird Conservation International 18:S30–S48. Birdlife International 2008 doi: 10.1017/S0959270908000324 Prakash, V., Green, R.E., Pain, D.J., Ranade, S.P., Saravanan, S., Prakash, N., Venkitachalam, R., Cuthbert, R., Rahmani, A.R. and Cunningham, A.A. 2007. Recent changes in populations of resident Gyps vultures in India. Journal of the Bombay Natural History Society 104:129-135 Shelley, E. and S. Benz. 1985. Observations of the aerial hunting, food carrying, and crop size of migrant raptors. Pages 299-301 in I. Newton and R.D. Chancellor [EDS.]. Conservation studies on raptors. ICBP Technical Publication 5. International Council for Bird Preservation, Cambridge, United Kingdom. Smith, N. G. 1980. Hawk and vulture migration in the Neotropics. Pages 51-65 in Migrant
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birds in the Neotropics: ecology, behavior and conservation, ed. by A. Keast and E.S. Morton. Smithsonian Institution Press, Washington D.C., USA. Spaar, R. and Bruderer, B. 1996. Soaring migration of Steppe Eagles Aquila nipalensis in southern Israel: flight behaviour under various wind and thermal conditions. Journal of Avian Biology 27: 289-301. Temple, S. A., and J. A. Wiens. 1989. Bird populations and environmental changes: can birds be bio-indicators? American Birds 43:260-270. Titus, K., M. R. Fuller, and D. Jacobs. 1990. Detecting trends in hawk migration count data. Pages 105-113 in Survey designs and statistical methods for the estimation of avian population trends, ed. by J. R. Sauer and S. Droege. U.S. Fish and Wildlife Service, Biol. Rep. 90(1), Washington D.C., USA. Zalles J.I. and Bildstein, K.L., eds. 2000. Raptor watch: A global directory of raptor migration sites. Cambridge, UK: Birdlife International and Kempton, PA, USA: Hawk Mountain Sanctuary (Birdlife conservation Series No. 9) Zduniak, P., Yosef, R., Sparks, T.H., Smit, H. and Tryjanowski, P. 2010. Rapid advances in the timing of the spring passage migration through Israel of the Steppe Eagle Aquila nipalensis. Climate Research Vol. 42: 217–222, doi: 10.3354/cr00900
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MIGRATING AND LOCAL RAPTORS ON CAMERA
Photo: Steppe Eagle (Juvenile- 1st plumage)
Photo: Steppe Eagle (4th plumage)
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Steppe Eagle (sub-adult) attacked by large-billed crow
Photo: Steppe Eagle (adult) from above Page | 26
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Bonelli’s Eagle (Juvenile)
Photo: Golden Eagle (Sub-adult) Page | 27
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Mountain Hawk-eagle
Photo: Booted Eagle (dark morph)
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Himalayan Buzzard
Photo: Common Kestrel (female)
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Amur Falcon
Photo: Peregrine Falcon (ssp peregrinator) Page | 30
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Northern Goshawk (Juvenile)
Photo: Besra
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Black-eared Kite (Juvenile) Page | 32
East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Oriental Honey-buzzard (Juvenile)
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Osprey
Photo: Himalayan Vulture (Juvenile) from above
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Himalayan Vulture (Adult) from below
Photo: White-rumped Vulture (Adult)
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Cinereous Vulture
Photo: Red-headed Vulture (Sub-adult)
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East to West Migration of Steppe Eagle Aquila nipalensis and other Raptors in Nepal: Abundance, Timing and Age Class Determination
Photo: Bearded Vulture and Large-billed Crow
Photo: Bearded Vulture
Photo: Egyptian-Vulture (Adult)
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