Insights from distribution dynamics inform strategies to conserve a dhole Cuon alpinus metapopulation in India

Abstract

Most large carnivore populations currently occur in heterogeneous landscapes, with source populations embedded in a matrix of human-dominated habitats. Understanding changes in distribution of endangered carnivores is critical for prioritizing and implementing conservation strategies. We examined distribution and dynamics of a dhole Cuon alpinus metapopulation, first in 2007 and subsequently in 2015, based on indirect sign surveys across 37, 000sq. km of India's Western Ghats. Predicted dhole occupancy declined from 0.62 (95% CI: 0.58-0.66) in 2007 to 0.54 (95% CI: 0.50-0.58) in 2015. Occupancy was associated with abundance of primary prey species and anthropogenic disturbance. Local extinction appeared to be influenced by forest cover loss, and offset by protected reserves; colonization was influenced by occupancy in neighbouring sites. Perturbation analysis indicated that occupancy was more sensitive to local extinction within reserves and to colonization in sites abutting reserves. The Western Ghats could serve as a stronghold for the endangered dhole, provided future colonizations are facilitated through habitat consolidation beyond reserve boundaries, and local extinctions are prevented by increasing protection efforts within select reserves. We advocate for wildlife managers to adopt a landscape-based approach and periodic monitoring to ensure persistence of the dhole metapopulation in Western Ghats, and in other critical conservation regions across the species' geographic range.

Figure 1

Study area in the Western Ghats of Karnataka, India. The map shows forest cover and protected wildlife reserves, with superimposition of 197 grid-cells measuring 188sq. km each. Protected reserves: (1) Bhimgad, (2) Kali, (3) Sharavati, (4) Mookambika, (5) Someshwara, (6) Kudremukh, (7) Shettihalli, (8) Bhadra, (9) Pushpagiri, (10) Talakaveri, (11) Brahmagiri, (12) Nagarahole, (13) Bandipur, (14) Biligiri Rangaswamy Temple, (15) Cauvery-MM Hills, (16) Bannerghatta. Inset: location of Karnataka State in India.

Figure 2

Patterns of dhole distribution in the Western Ghats of Karnataka, India. (a) Estimates of site-specific occupancy probabilities in 2007 where the average occupancy is 62% and (b) estimated occupancy probabilities in 2015 where the average occupancy in the landscape is 54%.

Figure 3

Patterns of dhole occupancy dynamics in the Western Ghats of Karnataka, India. (a) colonizations and (b) local extinctions of dholes in Karnataka’s Western Ghats, between 2007 and 2015. Site-specific values are based on model-averaged estimates of the dynamic parameters.

Figure 4

Correlates of occupancy dynamics. Top panel: Relationship between number of occupied sites (neighborhood effect) on colonization probability for dholes based on model M1 (x-axis range: 0.81–7.89); dotted lines are 95% confidence intervals. Bottom panel: Difference in average local extinction probabilities for dholes between sites with and without reserves, based on model M2 (left). Relationship between estimated probabilities of local extinctions with change in forest cover during the eight-year period, based on model M1 (right). Change in forest cover calculated as log-ratios of forest habitat proportion between 2007 and 2015 (x-axis range: −1.23–2.44); dotted lines are 95% confidence intervals and vertical line represents ‘no change’ in forest cover.

Figure 5

Sensitivity of equilibrium occupancy to colonization and local extinction. Top panel: Site-wise sensitivities of equilibrium occupancy (ψ^*) to colonizations and local extinctions in Karnataka’s Western Ghats, from model where colonization γ and extinction ε were functions of reserve area. The darker shades represent sites where equilibrium occupancy is most sensitive to changes in colonizations and local extinctions. Bottom panel: ψ^*, S_γ and S_ε expressed as functions of reserve area– values on primary y-axis correspond to ψ^* and S_γ, values on secondary y-axis correspond to S_ε.

Figure 6

Prioritizing management actions for dhole conservation. Sites identified for prioritizing management interventions based on the top 25% quartile estimates of sensitivity: 49 sites to be targeted for habitat consolidation (high sensitivity to colonization) and 49 sites for sustaining or increasing protection efforts (high sensitivity to local extinction).