Category: Introduced Anoles Page 4 of 11

A brown anole (Anolis sagrei) male from Santzepu, Chiayi County, southwestern Taiwan.

The Taiwanese authorities will once again launch a campaign to try to eradicate the brown anole in southwestern Taiwan. By paying a bounty of N.T.D 3 per collected lizard, they hope to encourage residents to help remove these lizards. They have funds for about 100 000 lizards, but I am afraid that is most likely not enough! The known distribution of this species in southwestern Taiwan is ca. 237 hectares. In my opinion the distribution most likely exceeds that. Those in the know are aware that these lizards can attain great densities. In one study, we found that they can attain densities of about 2900 lizards / ha. So, even if the average density is just 1/10 of that they do not have enough funds.
In addition to that, some religious groups are against the killing of animals and I have found that they do not permit the capture of these lizards on their properties. Even in areas where the capturing of the lizards is permitted, it is difficult to collect all the individuals present. Anolis sagrei that have escaped after being captured tend to flee from a perceived threat at greater distances, which means that such individuals could persist in an area without the collectors being aware of them. These lizards are also opportunistic and can utilize a variety of natural and man-made structures as shelters, many of which would hinder the capture of lizards. In addition to that, some agricultural practices such as the use of greenhouses can act as reservoirs for these lizards. It is thus not surprising that in spite of the large numbers of lizards removed to date, A. sagrei still exists in the southwestern and eastern study site and seems to be expanding its distribution range in Taiwan.

An Anolis sagrei male sheltering in an electrical control unit in an agricultural area in the southwestern Santzepu, Chiayi County, southwestern Taiwan (note the sympatric Hemidactylus frenatus on one of the electrical wires).

An Anolis sagrei sheltering in a drainage pipe (right) of a concrete roadside embankment in Santzepu, Chiayi County, southwestern Taiwan.

So my money is on the lizards! Because the distribution of A. sagrei in Taiwan is fairly extensive and the species disperses very easily, the eradication of A. sagrei in Taiwan is impractical. Efforts should rather focus on managing this species.

My opinion is that one of the best ways to do so is by manipulating habitats and making them unsuitable for A. sagrei to inhabit, and so hinder the spread of this species in Taiwan and limit its population growth. The cultivation of crops such as rice (Oryza sativa) and taro (Colocasia esculenta), which are unsuitable habitats for these lizards, should be encouraged in agricultural areas where these lizards are known to occur. Also, since broadleaf forests in Taiwan are likely unsuitable habitats for A. sagrei, greater efforts should be made to re-establish and conserve large areas of broadleaf forests in disturbed lowland areas of Taiwan. This would not only contribute to the conservation of native forest species, but such areas will also function as reservoirs for species like Japalura swinhonis that can compete with A. sagrei, as well as being barriers for its spread.

Me in uniform – many years, kilograms and grey hair ago.

For many years, most units in the South African Defense Force used a plain medium brown uniform, called nutria. Soldiers commonly referred to it as “browns.” A few years before my national service, the defense force started phasing it out, replacing it with the “Soldier 2000” camouflage design. When I was conscripted to serve in the South African Medical Services (SAMS) in 1993, SAMS was the only unit that completely still used the nutria uniforms, and although not as “modern-looking” as the other uniforms, we developed a sense of pride in our “browns.”

I believe the brown anole (Anolis sagrei) needs little introduction to Anole Annals readers. I am very fortunate to have been able to do my research on the invasive population of these lizards in southwestern Taiwan. I have been a naturalist at heart since a very young age, but these lizards were my introduction to the academic side of natural history, and because of my work on them I have made numerous friends and acquaintances. So, naturally they hold a special place in my heart and mind.

A female brown anole (Anolis sagrei) from my study area in Santzepu, Sheishan District, Chiayi County, southwestern Taiwan.

Unfortunately these feelings brought a sense of guilt within me. I know all too well that they are an invasive species, which has certain impacts on native species. And yet, it is hard not to marvel at them and their ability to overcome the numerous obstacles they face in this foreign habitat.

The other day, while reading the obituary of Henry S. Fitch (1909-2009) in the 2009 issue of Herpetological Review (40[4]: 393-400), the words of Raymond B. Huey suddenly made it all so clear to me. He described an instance in which he left a meeting at which Henry Fitch was a speaker, with a haunting lesson, “We should do science because we love the process, not because we need to love the results.” I believe that for us who work with invasive species, this is also a message. So now, when I see brown anoles, I no longer have to feel guilty when I do not wish they were rather tree lizards (Japalura spp.) or grass lizards (Takydromus spp.). I admire the “browns” and I find the process of learning about their natural history truly fascinating – I love it! I wonder how many other researchers working on invasive anoles share this sentiment?