Partial altitudinal migration of the Near Threatened satyr tragopan Tragopan satyra in the Bhutan Himalayas: implications for conservation in mountainous environments N AWANG N ORBU,UGYEN,MARTIN C. WIKELSKI and D AVID S. WILCOVE Abstract Relative to long-distance migrants, altitudinal mi- To view supplementary material for this article, please visit grants have been understudied, perhaps because of a percep- http://dx.doi.org/./S tion that their migrations are less complex and therefore easier to protect. Nonetheless, altitudinal migrants may be at risk as they are subject to ongoing anthropogenic pressure from land use and climate change. We used global position- Introduction ing system/accelerometer telemetry to track the partial alti- tudinal migration of the satyr tragopan Tragopan satyra in elative to long-distance migrants, altitudinal migrants central Bhutan. The birds displayed a surprising diversity of Rhave been understudied, perhaps because of a percep- migratory strategies: some individuals did not migrate, tion that their migrations are less complex and easier to pro- others crossed multiple mountains to their winter ranges, tect. In montane regions many species migrate altitudinally others descended particular mountains, and others as- up and down mountain slopes (Stiles, ; Powell & Bjork, cended higher up into the mountains in winter. In all ; Burgess & Mlingwa, ; Chaves-Champos et al., cases migration between summer breeding and winter ; Faaborg et al., ). Although attempts have been non-breeding grounds was accomplished largely by walk- made (Laymon, ; Cade & Hoffman, ; Powell & ing, not by flying. Females migrated in a south-easterly dir- Bjork, ; Chaves-Champos et al., ; Hess et al., ection whereas males migrated in random directions. ), few studies have illustrated patterns of altitudinal mi- During winter, migrants occupied south-east facing slopes gration using telemetry (but see Norbu et al., ). whereas residents remained on south-west facing slopes. Montane regions, which cover an estimated .% of land Migratory and resident tragopans utilized a range of forest surface area (Kapos et al., ), are being exposed to cli- types, with migratory individuals preferring cool broad- mate change (Nogués-Bravo et al., ) and loss of forest leaved forests during winter. These complex patterns of mi- cover (Blyth et al., ; Pandit et al., ), both of gration suggest that conservation measures should extend which will put mountain species and their migrations at across multiple mountains, protect the full range of forest risk (Inouye et al., ). types and encompass multiple landscape configurations to In general, animal migrations are undergoing decline protect aspect diversity. Given the diversity of migratory (Wilcove & Wikelski, ; Harris et al., ) as a result strategies employed by this single species it seems clear of habitat loss and climate change (Both et al., ; that more research on altitudinal migrants is needed to Møller et al., ). These declines are of concern because understand what must be done to ensure their future in migration is important in maintaining ecological processes an era of widespread land-use and climate change. and shaping ecosystems (Holland et al., ; Wilcove & Wikelski, ; Bowlin et al., ). However, the conserva- Keywords Altitudinal migration, Bhutan, conservation, tion of migratory species remains a daunting task, given the mountains, partial migration, protected areas, satyr trago- complexity of the phenomenon and the geographical scale pan, Thrumshingla National Park at which it occurs (Moore et al., ; Wilcove, ; Faaborg et al., ). NAWANG NORBU* (Corresponding author) and UGYEN Ugyen Wangchuck In comparison to long-distance migrants, the conserva- Institute for Conservation and Environment, Lamai Gompa Dzong, Bumtang, tion of altitudinal migrants may be perceived to be relatively Bhutan. E-mail [email protected] easier given their occurrence over a smaller geographical MARTIN C. WIKELSKI Max Planck Institute for Ornithology, Radolfzell, Germany area. This may not necessarily be the case, however. For ex- DAVID S. WILCOVE Woodrow Wilson School for Public and International Affairs ample, telemetry studies (Powell & Bjork, , , ) and Department of Ecology and Evolutionary Biology, Princeton University, USA have shown that habitat types required by two altitudinally migrating species, the resplendent quetzal Pharomachrus *Also at: The International Max Planck Research School for Organismal Biology, University of Konstanz, Germany mocinno and three-wattled bellbird Procnias tricarunculata, ’ Received January . Revision requested February . were not included within Costa Rica s protected area system. Accepted June . First published online March . To ensure the protection of altitudinal migrants, the Oryx, 2017, 51(1), 166–173 © 2016 Fauna & Flora International doi:10.1017/S0030605315000757 Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.229, on 30 Sep 2021 at 07:38:31, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605315000757 Satyr tragopan in the Bhutan Himalayas 167 FIG. 1 Location of the study area in Thrumshingla National Park, Bhutan. incorporation of all habitat types within reserve systems has are believed to be extant in the wild (BirdLife International, been recommended as a principle of effective reserve design b). The tragopan has been shown to be a partial altitud- (Powell & Bjork, , , ). inal migrant (Norbu et al., ). Here, we assess the adequacy Establishment of protected areas (Terborgh et al., ; of a protected area in Bhutan to provide protection for an alti- Brooks et al., ; Cantú-Salazar et al., ) and biological tudinal migrant, by examining the migration mode, patterns corridors (Roever et al., ) has become one of the key and habitat requirements of the tragopan. strategies to protect biodiversity. However, the adequacy and effectiveness of protected areas and corridors have Study area been questioned (Hobbs, ; Beier & Noss, ; Ervin, ), particularly regarding the conservation of migratory We studied the tragopan in Thrumshingla National Park, a species (Moore et al., ; Thirgood et al., ; Martin km protected area in central Bhutan (Fig. ), at ,– et al., ); for example, wildlife movement data have , m elevation. Mean daily temperature is −–°C. The been used in only a few instances to influence corridor de- area has four distinct seasons, with most rainfall occurring sign (Zeller et al., ). during May–August as part of the Asian monsoons. The With protected areas, the network of protected areas study area is mostly covered by conifer forests dominated in the Himalayas covers an estimated , km (Chettri by Bhutan fir Abies densa, with rhododendron understorey et al., ). Despite this extensive coverage we are not at higher elevations (. , m) transitioning to mixed aware of any telemetry-based study of altitudinal migrants conifer forests (,–, m) comprising Sikkim spruce to assess the effectiveness of protected areas in the Picea spinulosa, Himalayan hemlock Tsuga dumosa and Himalayas. Given that the Himalayas are undergoing habi- Sikkim larch Larix griffithii. Below , m conifer forests tat loss (Pandit et al., ) and climate change (Shrestha give way to conifer–broadleaved mixed forests and to cool et al., ), and noting that many of the birds in the broadleaved forests of oak Quercus glauca and Quercus la- Himalayas are altitudinal migrants (Inskipp et al., ; mellosa. There are also a few patches of open grazing areas Grimmet et al., ; BirdLife International, ), data that are used by nomadic cattle herders. are needed to test the adequacy of conservation landscapes in protecting altitudinally migrating species. We used global positioning system (GPS)/accelerometer Methods telemetry to track the seasonal migration of the satyr trago- Trapping We trapped tragopans during June–October in pan Tragopan satyra, a pheasant endemic to the central and , and using neck noose traps laid along ridges eastern Himalayas of Bhutan, India and Nepal. The species known to be used by tragopans, which we barricaded with (hereafter referred to as the tragopan) is categorized as Near bamboo and shrubs. We flushed tragopans towards traps Threatened on the IUCN Red List (BirdLife International, during early mornings and evenings. In , when the a) and listed on Appendix III of CITES (). Only an birds were trapped for the first time, all captured individuals estimated , individuals (c. ,–, mature adults) were released immediately after GPS tags were attached, to Oryx, 2017, 51(1), 166–173 © 2016 Fauna & Flora International doi:10.1017/S0030605315000757 Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.229, on 30 Sep 2021 at 07:38:31, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605315000757 168 N. Norbu et al. reduce the risk of any handling-related fatalities. Tragopans period (December–February) we extracted the aspect (in captured in and were weighed (to the nearest g) degrees) of the given location from a digital elevation and their tarsus length (mm) and beak size (mm) were model at a spatial resolution of x m . For each measured. All trapping was approved by the Ministry of individual, using the Rayleigh statistic at a significance Agriculture and Forests in Bhutan. level of ., we assessed whether the aspect data were distributed uniformly or whether the individual showed a preference