From climbing snow-covered hills to crossing roaring rivers to returning home – the GPS data of a tagged gazelle female reads like an adventurous travelogue. Over a period of five years, the animal covered half the distance around the world in the Mongolian steppe, as the researchers report.
Animals living in regions with rapidly and unpredictably changing environmental conditions have evolved a range of adaptations to respond. Some species complete nomadic migrations, during which they can cover enormous distances. In contrast to migratory birds, for example, the movements of these animal nomads do not follow any regular patterns and they usually do not return to specific places of origin such as breeding grounds or calving grounds.
Gazelle journey recorded over five years
One of the nomadic animal species is the Mongolian gazelle (Procapra gutturo). She lives in the steppes of Mongolia, which are characterized by cold continental climate and volatile resources. So far, however, it was unclear how far these gazelles migrate over longer periods of time, because the current battery-powered GPS trackers last a few years at most. But this has now changed thanks to a GPS collar equipped with solar cells: “We were able to record the extraordinary five-year journey of a single Mongolian gazelle of the genus Procapra gutturosa,” report Nandintsetseg Dejid from the Biodiversity and Climate Research Center in Frankfurt and her colleagues.
In October 2014, they fitted 15 Mongolian gazelles with the new GPS collars. In one of these gazelles, the GPS tracker remained active for a particularly long time: it reported the position of the animal every hour for almost five years. Since gazelles live for a maximum of 9.5 years and the GPS tracker was put on in adulthood, the scientists were able to use it to follow the animal for most of its life.
Adventures across snowy landscapes and rivers
The tracking data revealed that the gazelle completed a journey of more than 18,000 kilometers, traversing eastern Mongolia from north to south, which is about half the Earth’s equatorial circumference, the research team reports. “Their journey was exceptional not only because of the sheer length, but also because the Gazelle often ventured hundreds of kilometers into new and unfamiliar regions,” explain Dejid and her team.
On a long journey north she crossed two large frozen rivers until she reached snow-free territory near the Russian border. Some time later she went back south via a different route, where she had difficulties crossing the now water-bearing rivers. Several times during its migration, the gazelle also reached the border fence of China before it finally became quite sedentary last year and the GPS device finally reported its death in August 2019. The animal’s collar was found in the yurt of a shepherd, who reported that the gazelle had apparently died from a maggot infestation on its hip.
Long hikes as a survival strategy
The data collected on their life journey now provide for the first time a comprehensive picture of the migrations of such a nomadic animal. They confirm that, unlike seasonal migratory species, gazelles not only move between fixed foraging or rearing areas, but also show a migration pattern that is guided more by environmental conditions. “Their irregular movements become clearest when you compare the areas where they stayed every year during the winter and calving season,” the researchers explain. She rarely went to the same place to hibernate and carry her offspring, but rather to different places, some of which were 440 kilometers apart.
However, there are apparently some patterns in the nomadic migration of gazelles: During the vegetation period, they usually seek out areas with good feeding grounds and try to avoid areas with deep snow during the winter, as Dejid and her team explain. Since they also returned twice to the same wintering area and three times to the same sanctuary, the researchers suspect that gazelles may remember favorable areas and revisit them on purpose.
According to the scientists, the gazelle’s multi-year journey highlights the importance of being able to migrate through permeable landscapes for nomadic ungulates. This allows the animals to find food resources and escape local weather extremes. “This in turn shows that there should be no insurmountable barriers separating the northern and southern regions of the eastern steppe,” says Müller: “Further long-term studies are necessary to better understand the navigation mechanisms, group communication and refuges of these animals and to offer them such reliable protection”
Source: Senckenberg Research Institute and Natural History Museums; Specialist article: Ecology, doi: 10.1002/ecy.3660