Space fit for a king: spatial ecology of king cobras (Ophiophagus hannah) in Sakaerat Biosphere Reserve, Northeastern Thailand

Marshall, Benjamin Michael; Strine, Colin Thomas; Jones, Max Dolton; Artchawakom, Taksin; Silva, Inês; Suwanwaree, Pongthep; Goode, Matt

doi:10.1163/15685381-18000008

Cited by 23 publications

(38 citation statements)

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“…The transitional zone also contains 159 villages and a four-lane highway that 74 connects Nakhon Ratchasima to Bangkok. Further descriptions of the study site can be found in Silva 75 et al (2018) and Marshall et al (2018Marshall et al ( , 2019. 76…”

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“…The capture and implantation methods, alongside King Cobra measurements, have been previously 77 described in Marshall et al (2018Marshall et al ( , 2019. We tracked individuals four times a day, with approximately 78 four hours between tracks from 2014-03-22 to 2018-07-28 (06:30, 11:00, 16:00, 20:00; the distribution 79 of time lags between tracking is available in Supplementary Figure 1).…”

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No room to roam: King Cobras reduce movement in agriculture

Marshall

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13Studying animal movement provides insights into how animals react to land-use changes, specifically 14 how animals can change their behaviour in agricultural areas. Recent reviews show a tendency for 15 species to reduce movements in response to increased human landscape modification, but the study of 16 movement has not been extensively explored in reptiles. We examined movements of a large reptilian 17 predator, the King Cobra (Ophiophagus hannah), in Northeast Thailand. We used a consistent regime 18 of radio-telemetry tracking to document movements across protected forest and adjacent agricultural 19 areas. We then adapted GPS-targeting analytic methods to examine the movement using metrics of site 20 reuse and dynamic Brownian Bridge Movement Model derived motion variance. Examination of 21 motion variance demonstrated that King Cobra movements increased in forested areas and tended to 22 decrease in agricultural areas. Our Integrated Step-Selection Functions indicated that when moving in 23 agricultural areas King Cobras restricted their movements, thereby remaining within vegetated semi-24 natural areas, often located along the banks of irrigation canals. Site reuse metrics of residency time and 25 number of revisits remained unaffected by distance to landscape features. Neither motion variance nor 26 reuse metrics were consistently affected by the presence of threatening landscape features (e.g. roads, 27 human settlements); suggesting that King Cobras will remain in close proximity to threats, provided 28 habitat patches are available. Although King Cobras displayed heterogeneity in their response to 29 agricultural landscapes, the overall trend suggested a reduction in movements when faced with 30 fragmented habitat patches embedded in an otherwise inhospitable land-use matrix. Reductions in 31 movements are consistent with findings for mammals and forest specialist species. 32

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No room to roam: King Cobras reduce movement in agriculture

Marshall

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Silva

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“…Aquatic environments and the vegetation that typically grows on the edges of ponds and irrigation canals could also serve as suitable refuge in an area highly modified by human settlements, roads, and agricultural practices. Furthermore, irrigation canals could also serve as movement corridors for Burmese pythons as seen with King Cobras that often travel along irrigational canals while in the agricultural land within our study site (Marshall 2020b;Marshall et al, 2019). The use of connected systems of aquatic agriculture in their native range (this study site, rice paddies and irrigation canals, Thailand) may help explain their success in their invasive range (natural everglade wetlands, Florida, USA) that is similarly characterized by interconnected wetlands.…”

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Restricted constrictors: Space use and habitat selection of native Burmese pythons in Northeast Thailand

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Animal movement and resource use are tightly linked. Investigating these links to understand how animals utilize space and select habitats is especially relevant in areas that have been affected by habitat fragmentation and agricultural conversion. We set out to explore the space use and habitat selection of Burmese pythons (Python bivittatus) in a patchy land use matrix dominated by agricultural crops and human settlements. We used radio telemetry to record daily locations of seven Burmese pythons over the course of our study period of approximately 22 months. We created dynamic Brownian Bridge Movement Models (dBBMMs) for all individuals, using occurrence distributions to estimate extent of movements and motion variance to reveal temporal patterns. Then we used integrated step selection functions to determine whether individual movements were associated with particular landscape features (aquatic agriculture, forest, roads, settlements, terrestrial agriculture, water), and whether there were consistent associations at the population level. Our dBBMM estimates suggested that Burmese pythons made use of small areas (98.97 ± 35.42 ha), with low mean individual motion variance characterized by infrequent moves and long periods at a single location. At both the individual and population level, Burmese pythons in the agricultural matrix were associated with aquatic environments. Only one individual showed a strong avoidance for human settlements which is troublesome from a human-wildlife conflict angle, especially as Burmese pythons have been observed entering human settlements and consuming livestock in our study site. Our study is one of the first to contribute to the knowledge of Burmese python ecology in their native range as the majority of studies have focused on invasive populations.

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“…Movement is often conceptualized then presented as a home range, defined as the area animals move through during “normal” activities, including resource acquisition and reproduction [ 3 , 4 ]. While the utility of the home range concept has been questioned in recent years [ 5 , 6 ], its estimation continues to have a wide range of applications, such as identifying behavioural adaptations to predictable environmental features [ 7 ] or inferring habitat use [ 8 – 11 ]. It is clear that different biological questions have different appropriate estimators [ 12 ], but reptile spatial ecology studies evaluate not only long-term area requirements, but also movement behaviour and space-use regardless of the assumptions and applicability of each estimation method.…”

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Reptiles on the wrong track? Moving beyond traditional estimators with dynamic Brownian Bridge Movement Models

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Background Animal movement expressed through home ranges or space-use can offer insights into spatial and habitat requirements. However, different classes of estimation methods are currently instinctively applied to answer home range, space-use or movement-based research questions regardless of their widely varying outputs, directly impacting conclusions. Recent technological advances in animal tracking (GPS and satellite tags), have enabled new methods to quantify animal space-use and movement pathways, but so far have primarily targeted mammal and avian species. Methods Most reptile spatial ecology studies only make use of two older home range estimation methods: Minimum Convex Polygons (MCP) and Kernel Density Estimators (KDE), particularly with the Least Squares Cross Validation (LSCV) and reference (href) bandwidth selection algorithms. These methods are frequently applied to answer space-use and movement-based questions. Reptile movement patterns are unique (e.g., low movement frequency, long stop-over periods), prompting investigation into whether newer movement-based methods –such as dynamic Brownian Bridge Movement Models (dBBMMs)– apply to Very High Frequency (VHF) radio-telemetry tracking data. We simulated movement data for three archetypical reptile species: a highly mobile active hunter, an ambush predator with long-distance moves and long-term sheltering periods, and an ambush predator with short-distance moves and short-term sheltering periods. We compared traditionally used estimators, MCP and KDE, with dBBMMs, across eight feasible VHF field sampling regimes for reptiles, varying from one data point every four daylight hours, to once per month. Results Although originally designed for GPS tracking studies, dBBMMs outperformed MCPs and KDE href across all tracking regimes in accurately revealing movement pathways, with only KDE LSCV performing comparably at some higher frequency sampling regimes. However, the LSCV algorithm failed to converge with these high-frequency regimes due to high site fidelity, and was unstable across sampling regimes, making its use problematic for species exhibiting long-term sheltering behaviours. We found that dBBMMs minimized the effect of individual variation, maintained low error rates balanced between omission (false negative) and commission (false positive), and performed comparatively well even under low frequency sampling regimes (e.g., once a month). Conclusions We recommend dBBMMs as a valuable alternative to MCP and KDE methods for reptile VHF telemetry data, for research questions associated with space-use and movement behaviours within the study period: they work under contemporary tracking protocols and provide more stable estimates. We demonstrate for the first time that dBBMMs can be applied confidently to low-resolution tracking data, while improving comparisons across regimes, individuals, and species.

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Space fit for a king: spatial ecology of king cobras (Ophiophagus hannah) in Sakaerat Biosphere Reserve, Northeastern Thailand

Cited by 23 publications

References 65 publications

No room to roam: King Cobras reduce movement in agriculture

No room to roam: King Cobras reduce movement in agriculture

Restricted constrictors: Space use and habitat selection of native Burmese pythons in Northeast Thailand

Reptiles on the wrong track? Moving beyond traditional estimators with dynamic Brownian Bridge Movement Models

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