Benefits of Conserving Wildlife Corridors

A wildlife corridor has been defined as a linear landscape element which serves as a linkage between historically connected habitat/natural areas, and is meant to facilitate movement between these natural areas (McEuen, 1993).

From a landscape ecology viewpoint, a corridor has been defined as a linear habitat that is embedded in a dissimilar matrix which connects two or more larger blocks of habitat and which is proposed for conservation on the grounds that it will enhance or maintain the viability of specific wildlife populations in the habitat blocks (Beier and Noss, 1998).

At large spatial scales, providing connec­tivity between large patches of core wildlife habitat requires corridors—land managed for its function as routes for wildlife movement and dispersal (Saunders and Hobbs, 1991).

The connectivity between wildlife habitats by means of corridors in fact implies a system of corridors and the core areas of habitat which they serve to link.

At a conceptual level, various models of core areas, movement corridors and buffer zones have been proposed by several researchers as frameworks for long-term survival and conservation of wildlife (Noss 1992; Noss and Harris 1996).

McEuen (1993) has summarized the following conservation benefits of corridors:

1. Enhanced immigration, which will support genetic flow, increase genetic diversity and enhance overall meta-population survival in connected patches.

2. Provide opportunity to avoid predation.

3. Accommodation of range shifts due to climate change.

4. Provision of a fire escape function.

5. Maintenance of ecological process connectivity.

The utility of wildlife corridors has been debated in ecological literature with contesting claims arguing that there is little evidence to suggest that corridors in fact deliver the benefits attributed to them (Simberloff and Abele, 1976). Simberloff et al. (1992) have argued that there is insufficient data on corridor use by animals to come to a conclusion on their benefits.

Corridors, they argue, may set into motion undesirable outcomes like high rates of poaching and trapping in corridor belts, increased exposure of wildlife to domestic animals causing disease, entry routes for weeds and exotic species and corridors acting as genetic sinks.

It is worthwhile to point out here that while there is a significant body of research on the negative impacts of habitat fragmentation on forested landscape, scientific knowledge examining the thresholds of habitat connec­tivity is quite inadequate.

In the past, for example, the concept of Population Viability Analysis (PVA) has been used to estimate Minimum Viable Popula­tions (MVP) as well as the amount of habitat needed to support them (Shaffer 1978, 1981, 1987; Gilpin and Soule, 1986). However little work has been has been done to estimate minimum thresholds of connectivity that would be required for protection of these species.

The scientific debate over the usefulness and necessity of species corridors is a reflection of this problem (Simberloff and Abele 1976, Simberloff et al., 1992). Despite of a lack of estab­lished scientific body of knowledge on the functions of corridors, a large number of corridor projects have been implemented in the US in 1980s. All these projects were heavily criticized by some of the researchers (Simberloff and Cox 1987, Simberloff et al., 1992). The general objection of the critics was against the glaring lack of evidence supporting the use and importance of corridors and extreme expenses involved.

However, many studies during the last few years have indicated that wildlife corridors have become a critical component in effective wildlife management and conservation strategy. Results from Parks Canada’s (2006) effort to manage elk populations suggest that wildlife corridors have facilitated the connectivity between wolves (major predators) and elks restoring natural ecological processes and help reduce man animal conflict.

In one of the most exhaustive studies done on corridors so far, researchers at the University of Florida have concluded that birds transfer more seeds in their droppings between habitats connected by corridors than between those that are uncon­nected (UFL, 2005). The study concludes that corridors not only help animal dispersal, they also help plant propagation.

In another study of dispersing cougars, Beier (1995) observed use of three corridors by dispersers by radio-tagging juvenile cougars. The Coal Canyon corridor was interspersed by an 8-lane freeway with only one underpass, two golf courts and one horse stable. The habitat of the area was degraded. The Penchang corridor showed analogous conditions. The third corridor was near Arroyo Tabuco and had nearly undisturbed vegetation. Studies revealed that in the Coal Canyon corridor area, two out of three dispersers could successfully traverse the area while one was killed in an accident.

Heavy use of culverts and underpasses was observed. The second corridor—the Penchang corridor—was rarely used by cougars. However all three cougars made a successful traverse through the Arroyo corridor, Beier found that lower quality habitat was not a problem for the dispersing cougar juveniles. The results of this study made Bier observe—”Any connection is always better than no connection in habitat patches”.

John Singh et al. (1989) examined four corridors to study elephant movement between Rajaji and Corbett National Parks of India. They observed that three corridors—Binjrao, Malin river, and Kotdwar-Amsod corridors—were rarely used by elephants. The fourth corridor—the Chilla-Motichur corridor—was however frequently used, particularly during summers.

The study found that the main reason why elephants avoided the three corridors was the rugged terrain. However, it was found that while elephants did not use these corridors, they were being used by other animals such as tigers and ungulates. The Chilla-Motichur corridor used by the elephants was found to be vulnerable to human disturbance, grazing, weed proliferation and lack of regeneration of natural species.

Hilty (2004) attempted to examine the use of riparian corridors and vineyards by native mammalian predators. Overall 21 corridors were identified which were classified into three categories—denuded, narrow, or wide-based on their width. Unbaited and remotely triggered cameras were used to determine the presence of predators.

The investigators found that mammalian predator detection rate was 11 folds higher in riparian corridors than in vineyards. More native predator species were found in wide corridors than in narrow or denuded corridors. The study concluded that wide and well vegetated corridors—which are vital for native predators—were highly desirable for maintaining connectivity.