Fruit, Minerals, and Forest Elephant Trails: Do All Roads Lead to Rome?

Abstract

Tropical forests are among the most heterogeneous environments on earth, and food resources for many animals are patchy both in time and space. In Africa's equatorial forest, permanent trails created and maintained by forest elephants are conspicuous features. Trails may be several meters wide and continue for tens of kilometers. Speculation on which resources determine the distribution of trails has identified fruit, browse, and mineral deposits as candidates. In this study, the relationships between these habitat variables and elephant trails were investigated. The size of individual trails and the density of the trail system increased dramatically with proximity to mineral deposits. Fruit tree basal area decreased with perpendicular distance from trails, while that of non-fruit trees did not. Fruit tree abundance and basal area were significantly higher on trail intersections than random sites and increased with intersection size. No relationship was found between monocotyledon browse abundance and elephant trail system characteristics. Clumped resources, which are at least partially reliable, provide a high nutritional payback, and are not rapidly depleted and can thus be visited repeatedly, appear to influence permanent trail formation by forest elephants. Permanent trails may allow naive individuals or those with imperfect knowledge to locate and acquire important resources.

Forest Landscape Structure, Degradation and Condition: Some Commentary and Fundamental Principles

“…One of the most important of those interactions in forest landscapes is the interaction between the natural dendritic network of streams and the artificial rectilinear network of roads or other transportation systems (Trombulak & Frissell 2000). Trails of large mammals represent another important network type that reflects a variety of landscape-scale factors, including topography (Forman 1995;Ganskopp et al 2000) and resource availability (Blake & Inkamba-Nkulu 2004).…”

Plant ecology meets animal cognition: impacts of animal memory on seed dispersal

“…The latter would be more likely to find new food sources and increase the probability that seeds would be transported and deposited in new areas, but leading to unpredictable seed shadows (Boyer and López-Corona 2009) with wider spatial spread. Frugivores that tend to repeatedly visit the same areas and follow the same paths would create seed shadows with less spread than the one originated by random movement, creating areas where the density of seeds might be high (Boyer and López-Corona 2009;Blake and Inkamba-Nkulu 2004). A number of recent studies have focussed on frugivores' spatial memory capabilities and travel patterns (Di Fiore and Suarez 2007;Normand et al 2009;Noser and Byrne 2010;Janmaat and Chancellor 2010).…”

“…This also resulted in predictable seed deposition with areas of high seed density along the paths connecting food sources used by tamarins. Elephants appear to form permanent trails connecting areas with high densities of fruit trees (Blake and Inkamba-Nkulu 2004), which may help guide naïve animals to food sources, but could also influence seed dispersal patterns (Blake et al 2009). Therefore, knowing about animals' spatial memory skills and understanding how these might influence their movements through the environment could help predict the structure of future plant communities.…”

“…elephants (Blake et al 2009;Polansky et al 2015;Foley et al 2008) or from heterospecifics (Saracco et al 2004) to help them identify and navigate to resources or may follow trails left by conspecifics (e.g. Blake and Inkamba-Nkulu 2004). Differences between individuals in quality and quantity of memory might arise due to species-specific cognitive capabilities, previous experience or individual longevity.…”

Etat actuel de la sécondarisation de la forêt en périphérie nord de la Réserve de biosphère du <i>Dja</i> (Sud-est Cameroun) : influences des facteurs anthropiques passés et des éléphants

“…Comme celles de Plumtre (1993), nos données montrent que la perturbation des éléphants dépend du type de forêt. Les milieux déjà perturbés et ouverts sont préférentiellement visités par les éléphants (Vanleeuwe et Gautier, 1998 ;Blake et Inkamba-Nkulu, 2004 ;Paul et al, 2004). Dans le Dja, l'intense activité des éléphants dans les jeunes forêts secondaires est à l'origine d'un faciès particulier de la forêt que nous avons qualifié de "forêt secondaire jeune clairsemée".…”