Strategies of protected area use by Asian elephants in relation to motivational state and social affiliations

Animals’ space requirements may vary according to life-history and social considerations. We observed 516 wild adult Asian elephants from both sexes, over 9 years, to investigate how life-history traits and social behavior influence protected-area (PA) use at Udawalawe National Park, Sri Lanka. Male PA-use, quantified in terms of average between-sightings-interval (BSI), was significantly influenced by the interaction of age class and motivational state (i.e. reproduction vs. foraging). Musth lengthened with age, with a median of 24.5 days for ages 21–30, 32.5 days for ages 31–40, and 45 days for those \u3e 40. A minority (11%) used it exclusively during musth, while others used it exclusively for foraging (44%) or both (45%). Males using it in both states and older musth-only males were more likely to be seen across years. There were 16 social communities containing between 2–22 adult females. Females’ BSI was significantly influenced by social ties, but this relationship was weak, because members of social communities do not necessarily disperse together, resulting in high individual variation in space-use. Inter-annual variability in sightings among individuals of both sexes indicates that around ¾ of the population is likely non-residential across years, challenging the prevailing fortress-conservation paradigm of wildlife management

Decreasing reservoir water levels improve habitat quality for Asian elephants

Population health and habitat quality are intimately related and seasonal changes in habitat quality are likely to be reflected in the body condition of animals. We studied seasonal variation of body condition in free ranging Asian elephants (Elephas maximus) in Udawalawe National Park, Sri Lanka based on visual scoring of individually identified elephants. We assessed the body condition of 218 adult females and 329 adult males from January 2008 to November 2012 and examined its relation to monthly rainfall and water level of the Udawalawe reservoir. Contrary to expectations, body condition of elephants was higher in the dry season, when primary productivity decreases due to lack of rainfall. However, the body condition showed both a seasonal and inter-annual negative co-relation with reservoir water level. A possible explanation for improved body condition in the dry season is the greater availability of fresh grass due to the emergence of reservoir bed grasslands with the drawdown of water. Our results underscore the importance of water management of large irrigation reservoirs in elephant conservation in Sri Lanka

Assessing the extent and impacts of linear infrastructure on Sri Lanka’s natural and protected areas: Implications for future development planning

Linear infrastructure (LI) has varying effects on landscapes depending on different ecosystems' sensitivity and threat levels. Economically developing tropical countries are particularly at risk from LI. Therefore, understanding a country’s current LI network and planning future developments to avoid further fragmentation and disturbance is crucial. This study aimed to assess the extent of Sri Lanka’s LI network (i.e., roads, railroads, and powerlines), given that it is both a biodiversity hotspot and an economically developing country in the tropics. First, we calculated the average normalized difference vegetation index (NDVI) and normalized difference built-up index (NDBI) indices and examined their spatial autocorrelation per divisional secretariat division. Then a multivariate cluster analysis was used to determine clusters of natural and protected areas that may receive similar impacts from different LI and their combinations. Results indicated that roads are the most widespread LI type in Sri Lanka, followed by powerlines and railroads. Over 80% of Sri Lanka’s total land area falls within 1 km of either a national or a provincial/local road. Areas with high NDVI were primarily manmade habitats, with less than 20% contribution from protected areas. Over 50% of the total protected area of Sri Lanka is being impacted by all three types of LI. Powerlines were the most common LI type in protected areas in proportion to their total network lengths. To minimize environmental impact while achieving development goals, future LI development activities should use a landscape approach to identify development needs and strategies informed by these findings

Characterization of Daboia russelii and Naja naja venom neutralizing ability of an undocumented indigenous medication in Sri Lanka

Background: Indigenous medicinal practice in Sri Lanka talks about powerful compounds extracted from native plants for treating venomous snake bites which are hardly documented in literature but are used by the indigenous doctors for thousand years. Objective: We screened the neutralizing ability of a herbal preparation practiced in indigenous medicine of Sri Lanka, consisting of Sansevieria cylindrica, Jatropha podagrica and Citrus aurantiifolia, for its ability to neutralize venom toxins of Naja naja (Common Cobra) and Daboia russelii (Russell's viper). Materials and methods: The venom toxicity was evaluated using a 5-day old chicken embryo model observing the pathophysiology and the mortality for six hours, in the presence or absence of the herbal preparation. The known toxin families to exist in snake venom, such as Phospholipase A2, Snake venom Metalloprotease, were evaluated to understand the mechanism of venom neutralizing ability of the herbal preparation. Results: The LD50 of D. russelii venom, as measured using the 5-day old chicken embryo model, was 4.8 ± 0.865 ug (R2 = 84.8%, P = 0.079). The pre-incubation of venom with the herbal preparation increased the LD50 of D. russelii venom to 17.64 ± 1.35 μg (R2 = 81.0%, P = 0.100), showing a clear neutralizing action of D. russelii venom toxicity by the herbal medicine. Whereas the pre-incubation of venom with the 1× venom neutralizing dose of commercially available polyvalent anti-venom serum shifted the LD50 venom only up to 5.5 ± 1.35 μg (R2 = 98.8%, P = 0.069). In the presence of the herbal preparation, Phospholipase A2 activity of D. russelii venom was significantly reduced from 9.2 × 10−3 mM min−1 to 8.0 × 10−3 mM min−1 and that of N. naja from 2.92 × 10−2 mM min−1 to 0.188 × 10−2 mM min−1. Further, the pre-incubation of N. naja venom with the herbal preparation significantly reduced its Metalloprotease activity from 0.069 units min−1 to 0.019 units min−1. Conclusion: The herbal preparation shows a clear neutralizing action against the toxicities of D. russelii and N. naja venoms demonstrating the potential to be used as a plant based antidote for snake envenomation

Strategies of protected area use by Asian elephants in relation to motivational state and social affiliations

Animals’ space requirements may vary according to life-history and social considerations. We observed 516 wild adult Asian elephants from both sexes, over 9 years, to investigate how life-history traits and social behavior influence protected-area (PA) use at Udawalawe National Park, Sri Lanka. Male PA-use, quantified in terms of average between-sightings-interval (BSI), was significantly influenced by the interaction of age class and motivational state (i.e. reproduction vs. foraging). Musth lengthened with age, with a median of 24.5 days for ages 21–30, 32.5 days for ages 31–40, and 45 days for those \u3e 40. A minority (11%) used it exclusively during musth, while others used it exclusively for foraging (44%) or both (45%). Males using it in both states and older musth-only males were more likely to be seen across years. There were 16 social communities containing between 2–22 adult females. Females’ BSI was significantly influenced by social ties, but this relationship was weak, because members of social communities do not necessarily disperse together, resulting in high individual variation in space-use. Inter-annual variability in sightings among individuals of both sexes indicates that around ¾ of the population is likely non-residential across years, challenging the prevailing fortress-conservation paradigm of wildlife management

Births and rainfall periods.

<p>Top: Frequency of births by month for those accurate to within two months (N = 84). Bottom: Average monthly rainfall. Error bars indicate inter-annual variation (SE).</p

Uda Walawe National Park.

<p>The study was conducted along the road network in the middle portion of the park, represented by the hashed lines (<100 Km²). Images sources: NASA Earth Observatory (<a href="http://earthobservatory.nasa.gov" target="_blank">http://earthobservatory.nasa.gov</a>), the Department of Wildlife Conservation, Sri Lanka, and the Center for Conservation Research, Sri Lanka.</p

Estimated (a) ages at primiparity and (b) inter-birth intervals (IBI).

<p>Curves represent the cumulative probability that a female gives birth to her first calf at a particular age (a), or exhibits an IBI of a specified length (b). Histograms show counts of observed ages at primiparity and birth intervals respectively. Data are included as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082788#pone.0082788.s005" target="_blank">Tables S2</a> & <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082788#pone.0082788.s006" target="_blank">S3</a>.</p

Fecundity averaged over births observed from 2006–2012 for N = 280 females.

<p>The average ranges between 0.13–0.17 female offspring per individual per year. Data are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082788#pone.0082788.s007" target="_blank">Table S4</a>.</p

Sex of calves when births were observed within 2 months and sex was determined.

<p>Sex of calves when births were observed within 2 months and sex was determined.</p