Saturday, October 2, 2010

Declines in Snake and Lizard Populations

Recently I spent a month (mid June to mid July) in Trinidad. During those 28 days I saw eight snakes representing five species. Three were the Ratonel, Pseudoboa neuwiedii, two were the Coffee Snake, Ninia atrata, one Slug-eating Snake, Sibon nebulata, one was the the Liana Snake, Pseustes poecilonotus, and one was the Rainbow Boa, Epicrates maurus. That is one snake every 3.5 days. Checking my notes from 1982, I spent mid June to mid July in Trinidad, the same time I visited the island in 2010. During the 1982 trip I was there for 27 days and I saw 54 snakes representing 15 species or, an average of two snakes per day; and I saw three times more species in 1982 than in 2010. Given that I was spending much of my time in a heavily urban area the data may not be readily comparable to my visit in the 1982. But, I was with a relatively large group of people in 2010 who were also interested in amphibians and reptiles, and they found a few of the snakes on the list. The trend is disturbing, and unfortunately one that is supported by two recently published articles. Sinervo et al. examined 48 species of Mexican lizards at 200 localities and report that 12% of the local populations have gone missing since 1975, and they estimate that worldwide, 4% of local lizard populations have become extinct. Reading et al. (2010) examined 17 snake populations representing 8 species that had been under long term study. The populations were located in the UK, France, Italy, Nigeria, and Australia, eleven of the populations had gone into sharp decline during the same, relatively short time (from about 1995 to 2009). They suggest the declines are the result of multiple factors including habitat deterioration and prey availability, but that climate change is the root problem. Sinervo et al. came to the same conclusion for the Mexican (and global) lizard populations and propose that lizards have already crossed a threshold for extinction because of climate change. 

A juvenile Rainbow Boa, Epicrates maurus. Trinidad. JCM

Huey, R. B., J. B. Losos, and C. Moritz. 2010. Are lizards toast? Science 328:832-833.

Reading, C. J., L. M. Luiselli, G. C. Akani, X. Bonnet, G. Amori, J. M. Ballouard, E. Filippi, G. Naulleau, D. Pearson and L. Rugiero. 2010. Are snake populations in widespread decline? Biological Letters, doi:10.1098/rsbl.2010.0373

Sinervo, B., F. Méndez-de-la-Cruz, D. B. Miles, B. Heulin, E. Bastiaans, M. Villagrán-Santa Cruz, R. Lara-Resendiz, N. Martínez-Méndez, M. L. Calderón-Espinosa,  R. N. Meza-Lázaro, H. Gadsden, L. J. Avila, M. Morando, I. J. De la Riva, P. V. Sepulveda, C. F. D. Rocha, N. Ibargüengoytía, C. A. Puntriano, M.  Massot, V. Lepetz, T. A. Oksanen, D. G. Chapple,  A. M. Bauer,  W. R. Branch, J. Clobert, J. W. Sites, Jr. 2010. Erosion of Lizard Diversity by Climate Change and Altered Thermal Niches. Science 328(5980):894-899.

1 comment:

  1. It's really sad to see what humans are doing to this beautiful planet and the wildlife we share it with.