Author: Gerrut Norval

A close-up of the hatchling, un-hatched egg, and the remains of the hatched egg, we recently reported on.

It is interesting that even in fairly well-studied species, we can still find new information from chance observations and carefully planned empirical studies. Recent studies have found that brown anole (Anolis sagrei) females favor nest sites that are quite moist. Losos et al. (2003) also found that the eggs of this species can survive being inundated for up to six hours by seawater. Recently we reported on an observation of brown anole eggs that remained viable after being inundated by fresh water due to heavy rains. The difference between the two conditions is, since seawater is more saline than the content of the eggs, it can be expected that the eggs would lose water, while when exposed to excessive fresh water the water gains will exceed losses, and the eggs will swell.

The observations of other researchers and ours suggest that the eggs of A. sagrei are fairly tolerant to a wide variety of environmental conditions and can remain viable when exposed (for a few hours) to excessively wet conditions. Our observations in Taiwan also reveal that unless washed away or damaged, the eggs of A. sagrei can remain viable during the high rainfall (often as a result of typhoons) of this region.

As Aristotle (384 BC – 322 BC) said, “In all things of nature there is something of the marvelous.” And I would like to encourage everyone to look into their chance observations and to describe them, not only in chat forums, but also in journals as natural history notes. That way the information is not only disseminated, but may also be accessible to a greater audience and for generations to come.

Anoles Feeding On Liquids – Please Help

By Gerrut Norval

On April 22, 2013

In Ask the Experts, Natural History Observations

Anole feeding on nectar. What about sap? Photo by Sparky Leigh.

Good day everyone. I am currently working on a short manuscript about a brown anole that I observed feeding on sap. I am aware that some anoles will feed on nectar (see list below), but I would like to know if anyone has ever observed anoles feeding on sap? If you have any references pertaining to anoles feeding on nectar or sap, and it is not listed below, would you please e-mail it to me at a_sagrei@hotmail.com, or at least provide me with the reference so that I can try to obtain it myself. Thank you very much.

Gerrut

P.S. Lizards rule!

References I am aware of:

Campbell, T. and C. Bleazy. 2000. Natural history notes: Anolis carolinensis (green anole). Nectivory and flower pollination. Herpetological Review 31: 239.

Colón Archilla A.D. 2010. Nectivory in Puerto Rican emerald anoles (Anolis evermanni). IRCF Reptiles and Amphibians 17: 144–145

Echternacht, A.C. and G.P. Gerber. 2000. Anolis conspersus (Grand Cayman Blue throated Anole). Nectivory. Herpetological Review 31:173.

Liner, E.A. 1996. Natural history notes: Anolis carolinensis carolinensis (green anole). Nectar feeding. Herpetological Review 27: 78.

Okochi, I., M. Yoshimura, T. Abe, and H. Suzuki. 2006. High population densities of an exotic lizard, Anolis carolinensis and its possible role as a pollinator in the Ogasawara Islands. Bulletin of the Forestry and Forest Products Research Institute 5: 265–269.

Perry, G. and J. Lazell. 1997. Anolis stratulus (Saddled Anole). Nectivory. Herpetological Review 28:150–151.

Perry, G. and J. Lazell. 2006. Anolis pulchellus (Grass Anole). Nectivory. Herpetological Review 37:218–219.

Rios-Lopez, N. 2004. Anolis stratulus (Saddled Anole). Extrafloral herbivory. Herpetological Review 35:386.

Timmermann, A., B. Dalsgaard, J.M. Olesen, L.H. Andersen, and A.M. Martin Gonzalez. 2008. Anolis aeneus (Grenadian Bush Anole). Anolis richardii (Grenadian Tree Anole). Nectivory/pollination. Herpetological Review 39:84–85.

Valido, A.M. 2006. Anolis allisoni (Allison’s Anole/Cameleon Azul). Nectar feeding. Herpetological Review 37:461.

When The “New World” Meets The “Old World”: Interactions Of Introduced Anoles and Native Agamids In Taiwan

By Gerrut Norval

On September 10, 2012

In Natural History Observations, Notes from the Field

The observations made on the 14th of July, 2002. A – the adult male Japalura swinhonis attempts to prey upon the crickets it can see through the plastic container; B – the Japalura swinhonis moves aside, and an adult male Anolis sagrei takes his place at the plastic container; and C – as the Anolis sagrei attempts to prey on the crickets, which it can see through the plastic, the Japalura swinhonis moves up the trunk of the betel nut palm.

On the 14^th of July, 2002, I wanted to test the possibility of using a modified funnel-trap to collect Anolis sagrei. The first lizard to respond to my trap, though, was an adult male of the agamid, Japalura swinhonis, that was attracted by the movements of the crickets in the trap. The J. swinhonis attempted to prey on the prey items for about 30 seconds. When an adult male A. sagrei approached, the J. swinhonis moved up the trunk of the betelnut palm onto which the trap was secured. No further observations were made after the A. sagrei lost interest after about one minute and moved off.

This was to date the only instance I observed in which a J. swinhonis gave way to an A. sagrei, and I am quite convinced that the J. swinhonis actually just lost interest in the possible prey in the trap, and as it moved away the A. sagrei thought he could try his luck. And this is my point concerning A. sagrei in Taiwan.

In my study area in Santzepu, Chiayi County, southwestern Taiwan, J. swinhonis males (mean ± SD = 70.5 ± 8.4 mm) and females (mean ± SD = 58.2 ± 13.9 mm) are substantially larger than A. sagrei (males; mean ± SD = 46.2 ± 9.1 mm; females; mean ± SD = 38.2 ± 5.5 mm). In most other aspects, both species are quite similar; both are diurnal trunk-ground ambush foragers and are very territorial. In a paper I am currently preparing, I compared the diet of these species and found that A. sagrei has a much wider dietary niche breadth than J. swinhonis, and that in areas where J. swinhonis and A. sagrei are sympatric, there is a substantial dietary niche overlap, and competition for prey is very likely.

Although both species are human commensals, J. swinhonis is more shade tolerant, while A. sagrei reaches higher densities in open disturbed habitats. So, my view of A. sagrei in Taiwan is that this species is here to stay, and we have to accept that it is becoming part of local ecosystems.

Is There An Alien Invasion In Taiwan?

By Gerrut Norval

On June 13, 2012

In Anole Annals Trivia

The Anolis carolinensis observed in Chiayi County, Taiwan, on the trunk of an Areca catechu.

Currently, the list of exotic invasive herpetofauna in Taiwan is fairly short:

brown anole (Anolis sagrei)

sun skink (Eutropis multifasciata)

common slider (Trachemys scripta elegans)

American bullfrog (Rana catesbeiana)

Asiatic painted frog (Kaloula pulchra pulchra)

Hong Kong whipping frog (Polypedates megacephalus)

But if the list of species permitted in the pet trade in Taiwan is not revised, and drastic steps are not taken to prevent future accidental and/or intentional introductions of exotic invasive amphibians and reptiles, that is sure to change.

There are already anecdotal accounts of green iguanas (Iguana iguana) and water dragons (Physignathus lesueurii) in the wild, and in 2011 we reported on some tokay geckoes (Gekko gecko) that we found in the wild in central western Taiwan. Earlier this year when we reported on a green anole (Anolis carolinensis) that we found in 2002 in a rural area of Chiayi County, southwestern Taiwan, we added another species to the list of species that have been recorded in the wild.

The discovery of these lizards in the wild in Taiwan is alarming. If suitable numbers of these animals are released into the wild, they very likely will establish viable populations in Taiwan.

The Reproductive Cycle Of The Brown Anole In Taiwan

By Gerrut Norval

On March 30, 2012

In All Posts

: Brown anoles mating.

Most invasive vertebrates have a high reproductive rate, and are able to build up a large population under ideal conditions. A recently published report on the reproductive cycle of the brown anole (Anolis sagrei) in Taiwan highlights this again.

This study demonstrated that the reproductive cycle of the Anolis sagrei population in Taiwan is long and cyclic, and that it is very similar to that of conspecific populations in Belize, Cuba, Florida, and Hawaii.

We found that as in Florida, the females become sexually mature at about 34 mm SVL. As in other studies, we found that Anolis sagrei females produces multiple clutches, consisting of a single egg, throughout most of the year, and that due to sperm storage, are able to produce viable eggs for a few weeks, even in the absence of males.

Unlike in other studies, we found that the males could be sexually mature at a much smaller SVL (ca. 30 mm), and that at least some males with spermatozoa, which could mate, are present throughout the year. The smaller SVL of the males mean a shorter time from hatching to the age at which mating can commence. And even though it is uncertain that such males would be able to compete with larger territorial males, these smaller males would certainly have mating opportunities in the absence of larger males in founder populations.

We found that the hatchlings have a SVL of about 18 mm, and as in other studies, they hatch after a period of about 30 days.

In view of the potential for A. sagrei taking over new territories, to prevent future introductions of this species, we strongly feel that drastic steps are merited.

A Little Worm “Told” Us …

By Gerrut Norval

On August 22, 2011

In Introduced Anoles, New Research

Studying the brown anole (Anolis sagrei) in Taiwan has presented me with numerous new opportunities, one of which is an introduction into parasitology.

A Kiricephalus pattoni nymph under the skin of a female brown anole (Anolis sagrei), collected in southwestern Taiwan.

The first parasites I found in A. sagrei in Taiwan were relatively large worm-like parasites that are often visible as a lump under the skin of the lizard. Unfortunately, my first samples were lost by the person I had sent them to for identification. But luckily, I found some more, and with the assistance of C.R. Bursey and S.R. Goldberg, the parasites were identified as the nymphs of the pentastome, Kiricephalus pattoni. Together we reported A. sagrei as a new host of this parasite in Taiwan (Norval et al., 2009).

And The Carnage Will Continue …

By Gerrut Norval

On July 1, 2011

In Anoles and Anolologists in the News, Introduced Anoles

The newspaper article to announce the actions to eradicate brown anoles (Anolis sagrei) in Santzepu, Sheishan District, Chiayi County, Taiwan.

On the 28^th of April, 2011, I posted an article here in AA about the actions of the Taiwanese authorities to try and remove Anolis sagrei in Chiayi County. On the 25^th of June, 2011, it was announced that they have acquired more funding (they ran out of funds previously) and that they will continue with these actions this year.

The alarming part is how they (whoever wrote the article) mislead the public, who believes in what is said in the newspapers, by providing incorrect information in the article.

They report that in the past two years 127,458 brown anoles were removed, and since the past winter was colder than usual, they believe they can eradicate this species by again paying the public a bounty of N.T.$ 20 (ca. U.S.$ 0.70) for every lizard they collect. I am confident they will run out of funds again, and the brown anole will persist! I am also convinced that something other than conservation is driving these actions.

Not All Lizards Attended That Lesson

By Gerrut Norval

On May 12, 2011

In Natural History Observations

: The Lizard Keeper’s Handbook. p 101

In his book, The Lizard Keeper’s Handbook (1997. Advanced Vivarium Stystems, Inc.), Philippe de Vosjoli explains at length how to select prey items of appropriate sizes to feed to pet lizards. I agree 100% with what he wrote. However, I must say that not all lizards apply these rules under natural conditions (I guess they were absent from class on the day that lesson was taught). Here are some photographs I took of brown anoles and Swinhoe’s tree lizards in my study area that preyed on prey items that most certainly did not fall within the ideal prey size categories.

1. An Anolis sagrei male with a large caterpillar.

2. An Anolis sagrei female with the remains of a grasshopper that she had had in her mouth when we captured her.

3. A Japalura swinhonis female that rushed in to grab a beetle grub that was exposed when we accidentally knocked over a dead betelnut palm (Areca catecha) in our study area.

4. A Japalura swinhonis male that captured an adult Clanis bilineata in the secondary forest in our study area.

And I believe that anyone who works with the brown anole (Anolis sagrei) would agree with me that these lizards can do some truly amazing things, as can be seen from the photos above. One of the most mind-boggling things I have found in the stomach contents of some of these lizards are centipedes. On one occasion I found a 43 mm long Chinese red-headed centipede (Scolopendra subspinipes mutilans) in the stomach of a brown anole male (SVL = 54 mm). Not only was the prey almost as long as the body length of the predator, but centipedes are venomous. It takes guts to take on such a meal!

Brown Anoles Also Eat Butterflies And Moths

By Gerrut Norval

On May 12, 2011

In All Posts, Natural History Observations

Here are three photographs I took of brown anoles preying on lepidopterans. In our diet studies lepidopterans were one of the main prey types, although, as can be expected, the larvae outnumbered the adults as prey. Amazingly, the lizards even ate larvae that had hair, which would cause an irritating burning sensation if it comes in contact with your skin.

Never Underestimate The Ability Of The Media To Make A Bad Situation Worse

By Gerrut Norval

On April 28, 2011

In Anoles and Anolologists in the News

The brown anole (Anolis sagrei) was discovered in Santzepu, Chiayi County, southwestern Taiwan, in mid 2000, and except for a few academics, most people didn’t seem to notice the existence of this exotic invasive species. That all changed when red fire ants (Solenopsis invicta) were discovered in northern parts of the island in 2003. Suddenly, invasive species became a very hot topic, and the authorities launched various projects to assess and study invasive species in Taiwan. Soon, as could be expected, A. sagrei was also in the news.