The following copyrighted material is intended for individual use of the researcher, and may not be copied or distributed without written permission from the copyright holder. You may use it for non-profit scholarly purposes. The reference for this article is: Rivas, J. A, & S. J Corey 2008. EUNECTES MURINUS (Green Anaconda). LONGEVITY. Herptological Review. In press  Click here for a pdf

 

EUNECTES MURINUS (Green Anaconda). LONGEVITY. Anacondas and other large reptiles tend to live many years and grow slowly later in life. However, long-term data on growth rates for wild snakes are in short supply. Here we report recapture of a Eunectes murinus after 13 years. These observations were made in the course of conducting an on-going mark-recapture project (running since 1992) in the Venezuelan llanos, Distrito Muñoz, Apure State (7.5ºN, 69.3ºW). All snakes were marked using scale clipping and by copying the ventral pattern covering the first 15 subcaudal scales (Rivas et al. 2007. In Henderson and Powell [eds.], Biology of the Boas and Pythons, pp. 128138. Eagle Mountain Publishing Company, Eagle Mountain, Utah). 

On 27 August 1994 we captured a female (E548, 324 cm SVL, 21 kg). Thirteen years later on 19 March 2007, we caught E548 again and although the scale clipping mark was difficult to read, we were able to identify the individual unequivocally by comparing the subcaudal pattern with our records. Upon recapture E548 measured 366 cm SVL and 25 kg. E548 was wounded, weakened, and had a subcutaneous nematode (possibly Dracunlus sp.) which has been found in other individuals in this population (Calle et al. 1994. J. Zoo. Wild. Med. 25:53-64).

This may be the longest recapture record of any individual snake in the wild. Twelve year recaptures have been reported by Madsen and Shine (2000. J. of Animal Ecology. 69:952-958). It is surprising that in 13 years E548 only grew 42 cm. It is expected that the growth rate of large reptiles will decrease towards older age (e.g. Madsen and Shine, op. cit.), but E548 is still far from the largest size recorded for this region (exceeding 500 cm, Rivas et al. op. cit.) and even further from other records in the literature. Cursory evaluation of our mark/recapture data suggest that anacondas in the wild may take more than a decade to reach 320 cm SVL, so E548 could be in her mid-twenties or perhaps even older.

The harvest of anacondas have been present for more than two decades driven largely by an demand for luxury snakeskin products in the global market (Waller et al. 2007. In Henderson and Powell [eds.], Biology of the Boas and Pythons, pp. 340-362. Eagle Mountain Publishing Company, Eagle Mountain, Utah).  However, rural populations may also be increasing their harvest in response to changes associated with macroeconomic packages that are affecting much of South America (Rivas 2007. Iguana. 14:10-21). Nevertheless, a recent three-year study monitored the experimental harvest of wild Eunectes noteus (Yellow Anaconda) and concluded that harvest could be sustainable based primarily on high reproductive rates, large distribution, and low human density (Waller et al. op cit).  However, if the extremely slow growth rate presented here is the norm, we believe that the notion of sustainability is suspect in regions with high harvest/mortality (see Rivas, op. cit.; Rivas et al. 1999. Herpetol. Rev. 30:101; Rivas 2000. Natural History of the green anaconda with emphasis on its reproductive biology. Unpublished Ph. D. dissertation, University of Tennessee. 287 pp; Rivas et al. 2001. Herpetol. Rev. 32:107-108).

We thank the Wildlife Conservation Society, Zoo de Doue la Fontaine-France, Miami Metro Zoo, Anaconda Investments LLC, COVEGAN, J. and T. Dunbar, and T. Hughes for assistance.

 

Submitted by JESÚS A. RIVAS, Department of Math and Natural Sciences. Somerset Community College. 808 Monticello Street, Somerset, Kentucky 42501 and SARAH J. COREY, Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, 318 W. 12th Avenue, Columbus, Ohio 43210.

 

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