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Space Fit for a King

Our new paper detailing the movements and home ranges of king cobras is available now at: https://doi.org/10.1163/15685381-18000008

 

Marshall, B. M., Strine, C. T., Jones, M. D., Artchawakom, T., Silva, I., Suwanwaree, P., & Goode, M. (2018). Space fit for a king: spatial ecology of king cobras (Ophiophagus hannah) in Sakaerat Biosphere Reserve, Northeastern Thailand. Amphibia-Reptilia

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Here is a little about the king cobras we tracked.

To start is our first tracked king was JM002 (juvenile male, second captured king). He was the first king large enough to safely be tracked (the first captured king was a tiny neonate). Not a huge snake he had an SVL of 1893 mm. JM002 spend his entire tracked period in the forests of the reserve. He was tracked for 223 days until his demise by the hands of an unknown predator.

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The second tracked king, AM004, was the first of only two females tracked. She, like JM002, spend her days deep in forested areas making use of deep streambeds. Unfortunately she was only tracked for little over a month. She was killed by a predator, suspected to be a hog badger, judging by the bite marks on the recovered radio transmitter.

Our third tracked king was a monster; AM005, nicknamed Big John, was a huge 3714 mm SVL and was well over 4 m total length. His range was far more extensive than JM002 or AM004. While he did make ample use of forested areas, he would frequently venture into agricultural areas and settlements. His story is an extremely sad one; this giant met his end after consuming a plastic bag. The details of Big John's death were previously described here in Strine et al. (2015).

Our longest tracked king was AM006. A good sized male, with an SVL of 2742 mm, AM006 had the largest home range of any of the tracked kings. He ranged over an area greater than 1000 ha. The longer tracking time of AM006 enabled us to begin to see seasonal changes in home range size and placement. Outside of the breeding season AM006 stayed largely in the forest. But during the breeding season he moved considerably more (~341m per day up from ~200m per day) and ventured into agricultural areas and settlements. Such is the increase in movements during the breeding season that AM006 range during just the few breeding months is double his range for the rest of his tracked time. He was also willing to cross a major four-lane highway during breeding season.

Living alongside AM006 was another similarly sized adult male, AM007. He was marginally longer at 2747 mm SVL,  but used a smaller area than AM006. AM007 kept entirely to the forests, not venturing into the human-dominated areas. Like AM006, AM007, shows a large increase in the area used during the breeding season - 569.95 ha to 825.80 ha.

Next up is AF010, the second female tracked. She lived almost exclusively outside of the protected area of the reserve. The agricultural areas are mainly made of cassava and rice. A interesting pattern we observed that when kings were using the agricultural areas they made extensive use of irrigation canals. The canals appear to provide safe passage across a landscape that would otherwise have very little  shelter from the sun or humans. Irrigation canal use can be seen in the restricted elongated range of AF010. Both AF010 and AF004 ranges appear to be more restricted than the adult male ranges, but further study is  required to be confident in this suggested pattern.

Another juvenile, JM013 has an interesting story attached to him. Captured very close to the reserve and release extremely close by he steadily made his way north. Over 3.5 km later he settled down and followed more expected patterns of king movements. The long distance movements made by JM013 across agriculture and through settlements highlighted how disjointed the landscape is. During this 3.5 km move JM013 had to cross six secondary roads, each one posing a serious risk.

Whereas juvenile JM013 headed north, another juvenile JM014 stayed. He lived in the reserves forested areas, often sighted moving arboreally. Kings appear to spend the earlier parts of their lives arboreally, then as they age they spend more time on the ground. That being said, the majority of our adult males have been infrequently spotted foraging arboreally.

Last, but by no means least, is AM015. He was captured right at the end of the study period so we have very limited data on his movements and range. While the area he was recorded using is only a fraction of his overall range, the pattern of habitat use is interesting. Just like AM010 in the agricultural areas, AM015 made use of the irrigation canals to traverse the landscape.

Summary - We found that king cobras use very large areas compared to other snakes. Only a couple of species come close, Drymarchon couperi (Hyslop et al. 2016) and Python bivittatus (introduced population; Hart et al 2015). Our Thai kings did not cover areas as large those tracked in India's Western Ghats. Perhaps more importantly we show that kings will not remain restricted to protected forested areas, and that breeding season may present a time of heighten movements meaning greater contact with human threats.

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Future directions - The tracking of king cobras in Thailand was difficult and as a result the data was not as well-structured and regimented as would be ideal. This prevented more sophisticated analysis. Currently, using the knowledge gained during this study, we are continuing to track king cobras aiming to produce a data-set that will be able to tease out some more nuanced information about their movements and habitat usage. Check out Silva et al. (2018) for an idea of future directions.

 

References:

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Barve, S., Bhaisare, D., Giri, A., Shankar, P. G., Whitaker, R., & Goode, M. (2013). A preliminary study on translocation of “rescued” King Cobras (Ophiophagus hannah). Hamadryad, 36(6), 80–86.

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Hart, K. M., Cherkiss, M. S., Smith, B. J., Mazzotti, F. J., Fujisaki, I., Snow, R. W., & Dorcas, M. E. (2015). Home range, habitat use, and movement patterns of non-native Burmese pythons in Everglades National Park, Florida, USA. Animal Biotelemetry, 3(8), 1–13. https://doi.org/10.1186/s40317-015-0022-2

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Hyslop, N. L., Meyers, J. M., Cooper, R. J., & Stevenson, D. J. (2014). Effects of body size and sex of Drymarchon couperi (eastern indigo snake) on habitat use, movements, and home range size in Georgia. Journal of Wildlife Management, 78(1), 101–111. https://doi.org/10.1002/jwmg.645

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Silva, I., Crane, M., Suwanwaree, P., Strine, C., & Goode, M. (2018). Using dynamic Brownian Bridge Movement Models to identify home range size and movement patterns in king cobras. PLOS ONE, 13(9), e0203449. https://doi.org/10.1371/journal.pone.0203449

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Strine, C. T., Silva, I., Crane, M., Nadolski, B., Artchawakom, T., Goode, M., & Suwanwaree, P. (2014). Mortality of a wild king cobra, Ophiophagus hannah Cantor, 1836 (Serpentes: Elapidae) from Northeast Thailand after ingesting a plastic bag. Asian Herpetological Research, 5(4), 284–286. https://doi.org/10.3724/SP.J.1245.2014.00284

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