Topography shapes the internal organisation of tiger home ranges in the plateau-gorge landscapes of central India
While topographic correction minimally altered the total estimated area of tiger home ranges in central India's plateau-gorge landscapes, terrain features critically shaped the internal organization of space use by concentrating core activities in rugged refuges and low-drainage landforms, particularly for females and during specific seasons.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
To understand how animals move through the world, scientists often draw a map around the places an animal visits most often. This map, called a home range, helps researchers figure out how much space a creature needs to find food, raise young, and avoid danger. For decades, these maps were drawn on flat surfaces, like a piece of paper or a standard computer screen. This approach assumes the ground is level, ignoring the hills, valleys, and cliffs that make up the real world. While this works well for animals living on flat plains, it can miss the mark for creatures living in rugged terrain. In steep landscapes, the actual ground an animal walks on is much longer and more complex than the flat distance shown on a map. Scientists have long wondered if this difference matters: does the shape of the land change how much space an animal actually uses, or does it simply change where the animal chooses to spend its time within that space?
In the central Indian landscape of the Panna Tiger Reserve, a team of researchers set out to answer this question for tigers. This reserve is not a high, jagged mountain range, but a complex mix of flat plateaus, deep gorges, and steep rocky slopes. The scientists wanted to know if the roughness of this terrain made the tigers' territories larger than they appeared on a flat map, and more importantly, whether the land's shape dictated where the tigers concentrated their daily activities. By tracking tigers with GPS collars and comparing flat maps with three-dimensional models of the ground, the researchers discovered that while the land did not make the tigers' total territory significantly bigger, it powerfully shaped where the tigers chose to live and hunt inside that territory.
The study focused on twelve tigers, nine females and three males, that had been fitted with GPS collars over a long period. The researchers collected thousands of location points, recording exactly where each tiger was at every hour. They then used a digital model of the earth's surface to calculate the true area of the ground the tigers walked on, accounting for every slope and dip. When they compared this three-dimensional area to the traditional flat, two-dimensional area, the difference was surprisingly small. The actual ground surface was only about half a percent larger than the flat map suggested. This finding suggests that for tigers in this specific type of landscape, the vertical ups and downs of the ground do not significantly expand the total size of their home ranges. The flat maps were accurate enough to show the overall size of the territory.
However, the story changed completely when the researchers looked inside those territories. They divided each tiger's home range into two parts: a large outer area where the tiger roamed occasionally, and a smaller inner core where the tiger spent most of its time. They then examined the types of landforms found in these two zones. They found that the outer areas were dominated by open, flat plateaus. But the inner cores were different. The tigers, especially the females, spent a disproportionate amount of time in rugged, broken terrain. These were the steep slopes, the edges of the plateaus, and the deep gorges and ravines. The flat, open plateaus, which made up the bulk of the total territory, were actually under-represented in the areas where the tigers spent their most intensive time.
The researchers used a statistical method to measure how much more likely a tiger was to be found in a specific type of land compared to what was available around it. They found that rugged terrain, which offers hiding spots and secure resting places, was heavily favored in the core areas. This preference was strongest during the hot summer months and the monsoon season. Female tigers showed the strongest pattern, consistently choosing these rugged, sheltered spots over the open plateaus. Male tigers also preferred rugged terrain for their core areas, but they maintained a stronger connection to the open plateaus, likely because they need to travel longer distances to patrol their large territories and find mates. The open plateaus served as highways for movement, while the rugged gorges and slopes served as the living rooms and nurseries where the tigers rested and hid.
This distinction is crucial for understanding how tigers use their environment. The land did not force the tigers to roam over a larger area, but it did force them to organize their lives in a specific way. The flat maps told the scientists how big the territory was, but only by looking at the three-dimensional shape of the land could they see where the tigers actually lived. The study suggests that for conservation efforts, simply measuring the size of a tiger's territory is not enough. Protecting the flat plateaus is important for movement, but preserving the rugged gorges and steep slopes is essential for the tigers' daily survival, offering them the shade, water access, and security they need to raise their young. In this landscape, the value of the habitat is not just in how much space it covers, but in the complex, broken terrain that provides the best places for a tiger to call home.
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