I covered this story Mid May on WUWT.
An email today asking if this is real science or just hype prompted me to do some research. First, below, the tragic story from the lizard specialist at BYU, whose rediscovery of some old field notes apparently was enough to touch off a firestorm of press coverage. My rebuttal, with citations, follows. – Anthony
Lizard researcher dusts off 30-year-old field notes that formed foundation of the study (note these links to news stories are provided by BYU in their press release, they seem quite happy to have the coverage -A)
PROVO, Utah – When Brigham Young University biology professor Jack Sites spent summers in the late 1970s collecting lizards in Mexico, he had no idea his field notes would one day help form the foundation for a worldwide study that attributes local lizard extinctions to climate change.
Sites is the senior author on the paper published in this week’s issue of Science. Led by Barry Sinervo, professor of ecology and evolutionary biology at the University of California, Santa Cruz, the study reports a global pattern of lizard die-offs in habitats unchanged except for rising temperatures.
The researchers surveyed lizard populations, studied the effects of rising temperatures on lizards, and used their findings to develop a predictive model of extinction risk. Their model accurately predicted specific locations on five continents (North and South America, Europe, Africa, and Australia) where previously studied lizard populations have already gone locally extinct. According to the model, if current trends continue, 20 percent of lizard species could go extinct by 2080.
The disappearance of lizard populations is likely to have repercussions up and down the food chain. Lizards are important prey for many birds, snakes, and other animals, and they are important predators of insects.
The study began when Sinervo noticed local lizard extinctions, one of which was among the lizards studied by Sites between 1977 and 1991.
“I had provided a baseline data set with precise localities where the lizards were common,” Sites explained. “But Mexican ecologists were going back every few years, and pretty soon the lizards were hard to find, and then they weren’t seeing any. These are protected areas, so the habitat’s still there. So you start to think there is something else going on.”
Using Sites’ field notes for comparison, Sinervo and collaborators resurveyed 48 species of spiny lizards (Sceloporus) at 200 sites in Mexico where the lizards had been studied between 1975 and 1995. They found that 12 percent of the local populations had gone extinct.
They later connected the lizards’ decline to climate records and studied the effect of rising temperatures on lizard physiology and behavior. For example, cold-blooded lizards can’t forage for food when their bodies get too hot – they must seek shade because they can’t regulate their own temperature. The researchers found that the hours per day when the temperature allowed foraging dropped significantly.
Sites said that when the temperature increase hits during a critical month of the reproductive cycle, the lizards don’t get enough energy resources to support a clutch of eggs or embryos.
“The heat doesn’t kill them, they just don’t reproduce,” said Sites, who earned BYU’s highest honor for faculty, the Maeser Distinguished Faculty Award, in 2002. “It doesn’t take too much of that and the population starts to crash.”
But for the phenomenon to be linked to climate change, the pattern would need to be seen globally. Sites connected Sinervo with researchers in Chile and Argentina, where Sites has been working for a decade. Sinervo also worked with researchers who documented lizard declines in Africa, Australia, and Europe.
“To get this kind of pattern, on five continents in 34 different groups of lizards, that’s not random, that’s a correlated response to something big,” Sites said, adding that the effect appears to be happening too fast for the lizards to adapt.
Sites finds no joy in being part of such a significant study. “It’s a terrible sinking feeling – when I first saw the data, I thought, ‘Can this really be happening?’ It’s important to point out, but it sure is depressing.”
Sites says the model now needs detailed testing on all five continents, with a standardized protocol on lizard species that are widespread.
Read more about Sites’ exploits with reptiles in this BYU Magazine profile.
Portions of a UC-Santa Cruz news release are used here with permission.
OK here’s the money quote from the BYU press release:
Sites explained. “But Mexican ecologists were going back every few years, and pretty soon the lizards were hard to find, and then they weren’t seeing any. These are protected areas, so the habitat’s still there. So you start to think there is something else going on.”
Yes it’s climate change! That must be it! It’s the only thing that fits…or…maybe not.
The popularity of keeping lizards as pets has exploded in the last 30 years. Catch and release programs aren’t the standard for lizards, it’s more like “catch and take home”. In a poor country like Mexico, selling captured lizards, dead or alive to the gringos = easy money.
Take for example this report about lizard trade in Mexico from American University:
Reptile Trade from Mexico:
“The illegal skins trade in Mexico represents millions of dollars annually on the black market.”
Here’s a peer reviewed paper on the lizard skin trade in Mexico:
Abstract This paper examines the role of Mexico as importer, manufacturer, producer and distributor centre of reptile skins from non-native and native species, through a combination of documentary research and survey methods. A number of key findings were derived from this study. Although Mexico has adopted the “System for the Conservation, Management and Sustainable Use of Wildlife” (SUMA), the country still relies on reptile skins from non-native species. In contrast, the smaller numbers of skins used from native species mainly derive from captive breeding schemes that although biologically sustainable, provide no incentive for habitat conservation. Sustainable use of reptile skins from native species could positively encourage conservation in Mexico. However, as a megadiverse country with potential to produce wildlife, Mexico will have to implement an appropriate regulatory framework to support local communities to promote the sustainable use of native species.
Here’s a story about the explosion of exotic pets, including lizards, in the UK http://www.independent.co.uk/news/uk/home-news/the-great-british-pet-the-new-trend-gripping-the-nation-424569.html
“The British Federation of Herpetologists believes there are already more reptiles than dogs in UK homes and while the number of canines began a steady decline 10 years ago, sales of snakes, lizards, spiders and snails continue to rocket with a five-fold increase in the past 10 years.”
Here’s another from Boston.com http://www.boston.com/bostonglobe/magazine/articles/2008/07/13/leaping_lizards/
“The popularity of reptiles as pets is exploding. In 2006, 4.8 million households in the United States owned 13 million reptiles, according to the American Pet Products Manufacturers Association. That’s double the 2.4 million households that owned reptiles in 1996.”
Maybe its not the heat, but the handbags: The “endangered species handbook” says: http://www.endangeredspecieshandbook.org/trade_reptile_lizards.php
“The luxury reptile leather trade has pushed many species toward extinction, and it shows no signs of declining. Lizard and snakeskin products are now being sold in the volume that turtle and crocodilian leather once were. “
Even the WWF admits the trade is the problem: http://www.worldwildlife.org/what/globalmarkets/wildlifetrade/faqs-reptile.html
“Scientists recognize some 6,000 species of reptiles in five different groups: turtles and tortoises (order Testudines), tuataras (order Rhynchocephalia), lizards (order Sauria), snakes (order Serpentes), and crocodilians (order Crocodylia). Reptiles are traded live as pets and for their parts, particularly their skins, which are valued for certain leather items such as shoes, wallets, handbags, and watchbands. In addition, some reptiles are used as food and to make traditional medicines.”
I find the choice of lizard used by Dr. Sites in the video and press release hilarious, because it underscores his complete lack of understanding of what’s going on outside his world. He uses an Australian bearded lizard (dragon) in the video, and provide this photo in the BYU PR page:
An Australian bearded dragon.
What’s funny about using a bearded lizard? They aren’t going extinct, they are being bred to meet the popularity demand.
Bearded dragons (Pogona vitticeps) are omnivorous lizards that are native to Central Australia. These squamates have been raised in captivity with great success, with (estimates of) over 250,000 being produced in captivity per year.
Of course, with other lizards disappearing, it HAS to be climate change. There could not be any other explanation. Because, well, there just isn’t.
What a load of plonkers.
UPDATE: In comments Jimbo writes:
Here are examples of why some Mexicans and other nationals would like to catch lizards:
“Customs officers are to work with police forces worldwide to crack down on the smuggling of exotic birds and animals.
The illegal trade rakes in billions of pounds a year, making it the second most lucrative after drug smuggling, according to the intern