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Much remains to be learned about how anthropogenic structures affect migration in large mammals. We examined the potential influence of the international railroad in Mongolia on migration in Mongolian gazelles (Procapra gutturosa). We examined gazelle movements and the normalized difference vegetation index (NDVI) on both sides of the railroad. The tracked gazelles never crossed the railroad, despite movements that mainly followed the railroad in winter and higher NDVI values on the opposite side. It is likely that the railroad had a barrier effect on gazelle migration because it split the gazelles' habitat. Our results, although based on an extremely small sample, have utility in indicating approaches that might be useful for examining migration in ungulates.Resumen: Falta mucho por conocer sobre el efecto de estructuras antropogénicas sobre la migración de mamíferos mayores. Examinamos la potencial influencia del ferrocarril internacional en Mongolia sobre la migración de gacelas de Mongolia ( Procapra gutturosa). Examinamos los movimientos de las gacelas y eĺ ındice de vegetación de diferencia normalizada (IVDN) a ambos lados de la vía férrea. Las gacelas rastreadas nunca cruzaron la vía férrea, a pesar de que los movimientos mayormente seguían la vía en invierno y que los valores de IVDN eran mayores del lado contrario. Es probable que la vía férrea produjera un efecto de barrera sobre la migración de las gacelas porque dividió al hábitat de las gacelas. Nuestros resultados, aunque basados en una muestra extremadamente pequeña, sonútiles para señalar estrategias que pueden ser utilizadas provechosamente para examinar la migración de ungulados.

Conservation and management are urgently required for Mongolian gazelles Procapra gutturosa inhabiting the Mongolian steppe. We captured and satellitecollared two adult females in Dornogobi Province and two adult females in Omnogobi Province and examined whether their seasonal migration corresponded to shifts in the normalized difference vegetation index (NDVI) in their habitat. The mean NDVI values of their annual, summer and winter ranges were calculated based on data acquired by the moderate-resolution imaging spectrometer (MODIS) onboard the Terra satellite. Satellite tracking of gazelles proved their ability to move long distances and provided details of their migration routes. In Omnogobi, the NDVI of the summer range was higher than those of annual and winter ranges during summer, but from October to November the NDVI of the summer range was lower than annual or winter ranges. The shift in NDVI values between summer and winter ranges corresponded with seasonal migrations of gazelles. In contrast, NDVI values were higher in the winter ranges than in both the summer and annual ranges throughout the year in Dornogobi. The results showed that the NDVI is a good indicator of gazelle habitat, but the NDVI alone cannot the explain seasonal migration of gazelles. It is important to evaluate the effectiveness and limitations of the NDVI as an indicator of habitat quality.

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