FIRST INSIGHTS INTO THE MIGRATION PATTERN OF AN UPLAND GOOSE (CHLOEPHAGA PICTA) BASED ON SATELLITE TRACKING

– Detailed knowledge of the migratory strategies is important to understand the ecology and evolution of migration and the conservation of migratory birds The Argentinean federal government declared sheldgeese (Chloephaga spp.) pests in 1930, claiming that they reduce crop yield. Currently sheldgeese have suffered severe reductions in their populations and are the focus of serious conservation concern. From September to April they breed in southern Patagonia (Argentina and Chile) while from May to September they winter mainly in the southern Pampas (central east Argentina). The precise knowledge of their migratory routes is essential to ensure protection of necessary resources and sites needed on their annual journeys. Here, by using a satellite transmitter for the first time we unravel the

migration route of an Upland Goose (Chloephaga picta), a species endemic to southern South America with an unknown migration strategy.We received data for 121 days (from September 2014 to January 2015).During this time, the bird migrated 1485 km from the wintering grounds in Buenos Aires Province to the breeding area in Santa Cruz province, Patagonia.Part of the migration route was over the sea.The largest displacement was 817 km in 19 hours, representing a minimum mean speed of 43 km h -1 .

INTRODUCTION
The capability to track individual migration routes opens extraordinary opportunities to reveal not only migratory routes and connectivity (Trierweiler et al. 2014), but also hazards encountered during migration and environmental conditions in the wintering and breeding grounds (Stanley et al. 2012, Trierweiler et al. 2014).Detailed knowledge of the migratory strategies is important to understand the ecology and evolution of migration (Alerstam 2011), the effects of climate change on populations (Crick 2004) and the conservation of migratory species (Dolman & Sutherland 1994, Webster et al. 2012).Despite some longterm banding efforts, our understanding of the migration strategies for the majority of bird species is still rather limited because it is expensive and time-consuming to follow the annual movements of individuals using sophisticated methodology, such as satellite tracking (Seegar et al. 1996, Gillespie 2001, Bograd et al. 2010).In America, migratory routes are best known for many Nearctic migrants (Pan New World Migration system, sensu Joseph 1997), such as shorebirds and terns, while there have been no specific studies for Patagonian migrants (South American Cool-Temperate migration system, sensu Joseph 1997).Indeed, the basic natural history of bird migration in most of the Southern Hemisphere is poorly understood, largely because of the lack of infrastructure, fewer ornithologists and birders, and deficits in bird-banding, making tracking any organism across a large scale more difficult (Jahn et al. 2009).Bird migration in South America is the third-largest bird migration system in the world and exhibits different types (Chesser 1994, Jahn et al. 2004).
Waterfowl are aquatic birds that include, e.g., ducks, geese, and swans.Many of them have historically been an important human food source, and continue to be hunted as game, or raised as poultry for meat and eggs (Boere et al. 2007).In South America, the three species of sheldgeese (Ruddy-headed Goose Chloephaga rubidiceps, Ashy-headed Goose C. poliocephala, and Upland Goose C. picta), have a similar migratory pattern since they breed in southern Patagonia (Argentina and Chile) from September to April, while from May to August-September they winter mainly in the southern Pampas (central east Argentina) (Blanco et al. 2003, Schulenberg 2010).The Argentinean federal government declared these species pests in 1930, claiming that they reduce crop yield (Blanco et al. 2003, Chebez 2008, Pedrana et al. 2014).Hunting of this species has been encouraged across their entire range and allowed without restrictions in terms of number of birds killed (Martin et al. 1986, Blanco & De la Balze 2006).However, in 2008 all species were listed as endangered by the Argentine government, and hunting was banned although illegal hunting continues (Blanco et al. 2003, López-Lanús et al. 2008).Conservation efforts are needed to prevent local extinction or even extirpation of sheldgeese.The human-sheldgeese conflict in agricultural landscapes and the national endangered status of these species make it necessary to gather essential knowledge about their migratory patterns and to identify important areas for their conservation throughout their migration routes.
Precise knowledge of the migratory routes is essential to ensure that the sheldgeese have suitable habitat available along their annual journeys.Currently, both ornithologists and managers can obtain information about migratory routes using miniaturized tracking devices that can be attached to the birds, and provide highly detailed information on migration routes and habitat use (e.g., Robinson et al. 2009).Here, we use a satellite transmitter to unravel the migration route of an Upland Goose for the first time.

MATERIAL AND METHODS
Study area.The study was conducted in the southern Pampas of Argentina, which range between 36.46°-41.04°Sand 63.39°-58.62°W,with extent surface of 106,000 km 2 .The climate is sub-humid to humid-mesothermal, with a mean annual temperature of 10 to 20°C and a mean annual rainfall between 400 and 1600 mm (Soriano et al. 1991).The area is characterized by low to moderate undulations dissected by lakes and marshes, and large areas of crops and pastures.In the past, pristine vegetation was dominated by grassland steppes of several species of Stipa spp.and Piptochaetium spp.(Soriano et al. 1991).Nowadays, many portions of the original grasslands in the Pampas have been replaced by pastures and croplands, with a particular expansion of soybean in the last few decades (Baldi & Paruelo 2008).
Field work.On 3 September 2014, one male Upland Goose (hereafter Angus), Argos ID: 40467) was captured at the Estancia Alta Gra-ciana (38°37'12"S, 60°04'48"W), Buenos Aires province, at the end of the wintering period using foot-noose carpets.Because the species shows a strong sexual plumage dimorphism (males: white, females: reddish-brown) (Narosky & Izurieta 2010) we could identify the captured individual as a male.The individual was weighed (body mass 3.3 kg), banded with a numbered metal band, and equipped with a satellite transmitter (Model K3H 179, 63 g; Kiwisat Argos Transmitters, Sirtrack, New Zealand).The device was attached to the birds' back using a Teflon harness (Fijn et al. 2012, Humphrey & Avery 2014).The whole package weighed 76 g and did not exceed 3% of the individual's body mass, thus minimizing the effects of carrying an additional weight during movements (Kenward 2001).The procedure used in this study was assessed and approved by the Buenos Aires Provincial Agency for Sustainable Development (OPDS).
Data analysis.Duty cycles were programmed in phases to save battery life while still collecting sufficient data: 1) During the migration period (March-May and mid August-October), we obtained positions every day between 10:00-16:00 h local time (GMT-3); and 2) during the breeding period (November-February), positions were obtained every three days between 10:00-16:00 h local time.Geographical locations were provided by the Argos service, with location accuracy (Class designation) calculated using the Kalman filtering method (Service Argos 2015).Only location classes 3 (accuracy ≤ 150 m) and 2 (accuracy ≤ 350 m) were used for further analysis (Pfeiffer & Meyburg 2009, Service Argos 2015), while positional fixes associated with less accurate location classes were removed.Positional data were then incorporated into a Geographical Information System (IDRISI Taiga, Eastman 2009).

RESULTS AND DISCUSSION
We received satellite-tracking data for 121 days from 4 September 2014 to 1 January 2015.During this time, the bird migrated a minimum distance of 1485 km from the wintering grounds in Buenos Aires province to the breeding area in Santa Cruz province, Patagonia (Fig. 1).This distance was calculated as the minimum distance travelled and is based on the assumption that the bird travelled in a straight line between two consecutive positions.Initially, Angus stayed for two days in an area dominated by crops near the village of Claromecó, Buenos Aires province, where it used an area of 5 km 2 during the day (Table 1, Fig. 1a).Afterwards, the bird headed southwest and migrated a minimum distance of 72 km to a region near the city of Oriente, Buenos Aires province, where it remained for 9 days using an area of 655 km 2 also dominated by crops and pastures (Table 1, Fig. 1b).From Oriente it travelled 120 km south, where it stopped for the second time near Hilario Ascasubi city (Villarino partido) (Table 1; Fig. 1a, b).During this migration from Oriente to Villarino, high-class positions were obtained over the sea, about 20 km from the nearest shore.This is the first finding that sheldgeese migrate over the sea and not only over mainland (Lucero 1992, Rumboll et al. 2005).
From Villarino, Angus migrated approximately 180 km south to reach an area near the city of Viedma (Fig. 1a, b).There, it stayed for another 3 days, moving around in an area covering ca. 5 km 2 .From Viedma, Angus eventually travelled around 800 km to reach Santa Cruz province, the first stop in the potential breeding grounds, the 'Central Plateau', Southern Patagonia (Table 1, Fig. 1b), where it stayed again for 3 days before travelling a further 230 km to reach its final destination, Lago Argentino.In this area, further positions were recorded for 101 days covering an area of approximately 16,000 km 2 (Table 1, Fig. 1b), indicating final arrival at the breeding grounds.Angus stayed in the last three stopover sites for less than 2 days ('Villarino', 'Viedma', 'Central Plateau'), probably representing the time needed to restore energy reserves between stops.The whole migration from the wintering ground to the breeding ground was performed in two weeks.
The breeding ground selected by Angus was located in Santa Cruz province, which is one of the most remote and least populated areas in the world.Relatively low-impact land use, such as extensive livestocking, has been the dominant human activity in the region after colonization by Europeans c. 200 years ago.The area is characterized by hills and plains dissected by small streams and rivers flowing from the Andes.Vegetation is highly uniform and dominated by a mixed steppe of grass and shrubs, which rarely exceed 0.5 m in height (Movía et al. 1987) (Fig. 2).Associated with streams, river valleys, and endorheic depressions are ponds, lagoons, and temporarily flooded wet meadows, locally called mallines, with hydrophytic vegetation communities.The association of sheldgeese with wetlands, lakes, and streams reported in other studies (Summers & Grieve 1982, Martin et al. 1986, Pedrana et al. 2011) may reflect a dependence on relatively productive sites and freshwater.These habitats seem to be of special value for this species in the semiarid Patagonian steppe because they may provide an abundant food supply and perhaps also a higher quality substrate to build nests (Martin et al. 1986, Summers & McAdam 1993).The area adjacent to villages like El Calafate and El Chaltén, near Angus' breeding ground (Fig. 2), is the most important tourist destination in southern Patagonia and has good access by roads (Fig. 2).Although the hunting of sheldgeese is prohibited in Argentina, there are still some hunting lodges in the Patagonian region that continue to sponsor and advertise their hunting (JP pers.observ.).
From Angus's geographical positions, it was also possible to calculate the minimum speed travelled between stopover sites using an estimate of the shortest distance between these areas.The speed varied from 4 to 11 km h -1 , except in the longest migration from Viedma (the last stopover site) to the Central Plateau (the potential breeding ground) where it reached values of 43 km h -1 (Table 1).The Satellite Tracking and Analysis Tool (STAT) provided the speed within stopover areas, and the mean speed of Angus varied between 2 and 46 km h -1 within stopover areas (Coyne & Godley 2005).The Argos service also reported the altitude calculated for each position.The mean altitude varied among the wintering and breeding sites, being lower than 100 m a.s.l. on the wintering ground (Claromecó, Oriente, Villarino, and Viedma) and between 1000-1500 m a.s.l. on the breed-ing ground (Central Plateau and Lago Argentino).
Based on data from banded sheldgeese two possible migration routes have been postulated (Lucero 1992, Rumboll et al. 2005): one over eastern Patagonia along the Atlantic coast and the second along western Patagonia over land.Lucero (1992) considered that the different migratory routes might be related to the breeding location.In our study, Angus's breeding site is situated in southern Santa Cruz province (Fig. 2), and the bird apparently took the eastern Patagonian route, partly across the Atlantic Ocean.
Our study represents the first satellitetracking study on sheldgeese migration, linking the wintering sites in Buenos Aires province with the breeding areas in Patagonia.Additional studies should be performed to understand the different migration routes and strategies, and to identify hazards that these species might encounter during migration and TABLE 1. Migration route of a male Upland Goose (Chloephaga picta) tracked between Buenos Aires and Santa Cruz provinces, Argentina (cf.Fig. 1).Minimum travel distance is the distance the bird traveled in a straight line between two positions; area used is the minimum area that enclosed all high class positions registered in a site, and speed between stops the minimum travel speed during migration.

Site name
Nearest  graphics (www.seaturtle.org).The editor and the reviewers provided highly valuable comments that have been essential for improving the text, tables, and figures.

FIG. 1 .
FIG. 1. Migration route of one male Upland Goose (Chloephaga picta) satellite-tracked from wintering ground to breeding ground: a) Movements registered in the wintering grounds, Buenos Aires province, Argentina; and b) Movement from wintering grounds to breeding grounds (Santa Cruz province, Argentine).Green stars are high class positions, black triangles low class positions (see Materials and Methods) and the red line is an estimate of the shortest distance between stops.