Animals do not move through landscapes randomly. Several species locate their resources by memorizing resources’ locations, recognizing places of fear, and sometimes repeating familiar travel routes. But what happens when they travel through places of fear?
Our recent study investigated whether human hunting influences the navigation of two very different endangered mammals: African elephants (Loxodonta africana) living around Victoria Falls, Zimbabwe, and yellow-breasted capuchin monkeys (Sapajus xanthosternos) living in the Atlantic Forest of Bahia, Brazil.
A landscape shaped by fear
Animals perceive risk differently across their environments. This perception of spatial variation is the landscape of fear. An animal may consider some parts of its range relatively safe while perceiving others as dangerous because of the risk of predation.
We asked whether this perception of risk could influence the use of habitual routes, which are familiar paths that animals repeatedly follow between locations.
Habitual routes require less cognitive effort than cognitive maps, which require triangulating information to build new routes through an environment. So, when animals follow a habitual route, they could dedicate more attention to monitoring their surroundings for hunters, predators, or other threats.
Two species, two continents
We studied ten male African elephants around Victoria Falls and one group of yellow-breasted capuchin monkeys in the Una Biological Reserve in Brazil.
The two landscapes are very different. Elephants move across a mosaic that includes protected areas, hunting areas, woodland, agricultural fields, grasslands, bushlands, water, and urban environments. The capuchins live within the Atlantic Forest, containing mature, secondary forests, and Cabruca, an agroforestry system of cacao.
Elephants changed their routes depending on both hunting and habitat
The elephant travel pattern showed that the influence of hunting was not the same everywhere. Instead, it depended on the type of habitat through which the elephants were moving.
Within hunting areas, elephants showed increased habitual-route use in woodlands, agricultural areas, urban areas, bushlands, and grasslands. This interaction is important because hunting alone did not cause elephants to use more habitual routes, but the effect of hunting changed according to the landscape.
One possible explanation is that habitual routes might be remembered by the elephants as safe routes through risky environments. Woodland patches between agricultural fields, for example, may function as travel corridors. In more open habitats such as bushland and grassland, using habitual routes may also help elephants to use safe routes where they are more exposed.
Capuchins used habitual routes more often near risky locations
Capuchin travel patterns showed a clear relationship with perceived risk.
The monkeys increased their use of habitual routes as they moved closer to locations associated with human hunting, terrestrial predators, and places where the group traveled silently.
Silent movement that represents cryptic behavior is an interesting finding because the monkeys were not only using habitual routes near risky locations; they were also more likely to travel quietly in some of these areas. Together, increasing the number of habitual routes and reducing communication could allow the monkeys to move through places with a high perception of predation risk, while remaining attentive to risks.
The strongest effect was associated with human hunting. The capuchins increased the number of habitual routes near locations where evidence of hunting had been recorded.
Habitual routes may help animals manage risk
Taken together, the elephant and capuchin results suggest that the landscape of fear can alter an animal's response to fear.
Both species altered their habitual route use according to their perception of predation risk within different parts of their environments. One possibility is that habitual routes allow animals to restrict their movement to locations they remember as relatively safe while simultaneously paying attention to signs of risk.
This does not mean that habitual routes are always created specifically to avoid risks. Landscape structure, food availability, roads, agricultural fields, and other environmental characteristics also influence where animals use these routes. Nevertheless, the association between hunting-related risk and habitual route use in two very different species indicates that perceived risk may be an important component of animals’ use of a habitual-route strategy.
Why does this matter for conservation?
Behavioral flexibility can help animals survive in human modified landscapes, but travel adaptation may come with costs. When species become restricted to habitual routes, the lack of flexibility to travel could have ecological consequences. Both elephants and capuchins contribute to the ecology of the landscape, including seed dispersal. With human pressure, they might be restricted to patches of natural forests, which can affect where seeds are dispersed and how ecological connections are maintained across landscapes.
Understanding conservation therefore requires more than identifying how much habitat remains. We also need to understand how animals perceive and move through that habitat.
Our study suggests that hunting can influence navigation of wild animals, such as the variation in the number of times they travel over the same route. Combined, behavioral responses occurring in human-dominated landscapes may be essential for designing conservation strategies that not only preserve habitat but also provide opportunities for species to explore larger areas while moving safely through them.