sign in sign up
<<
Home , Ani (bird), Hofstra University, Italian wall lizard, Podarcis

“Italian Immigrants” Flourish on Russell Burke Associate Professor Department of Biology

talians have made many important brought ringneck pheasants (Phasianus mentioned by Shakespeare. Also in the contributions to the culture and colchicus) to North America for sport late 1800s naturalists introduced the accomplishments of the United hunting, and pheasants have survived so small Indian mongoose (Herpestes javan- States, and some of these are not gen- well (for example, on Hofstra’s North icus) to the islands of Mauritius, Fiji, erally appreciated. Two of the more Campus) that many people are unaware Hawai’i, and much of the West Indies, Iunderappreciated contributions are that the species originated in China. Of supposedly to control the rat popula- the Italian wall , sicula course most of our common agricultural tion. Rats were crop pests, and in most and . In the 1960s and species — except for corn, pumpkins, cases the rats were introduced from 1970s, Italian wall lizards were imported and some beans — are non-native. The Europe. Instead of eating lots of rats, the to the United States in large numbers for mongooses ate numerous native ani- the pet trade. These hardy, colorful little mals, endangering many species and lizards are common in their home coun- Annual Patterns causing plenty of . They also try, and are easily captured in large num- 3.0 90 became carriers of rabies. There are 80 2.5 bers. Enterprising dealers bought 70 many more cases of introductions like them at a cut rate in and sold them 2.0 60 these, and at the time the scientific 50 1.5 to pet dealers all over the United States. 40 community has either supported or

1.0 30

Not all of these lizards made it to home Lizards/survey-NY ignored them. Lizards/survey-Italy 20 terrariums, however — in at least four 0.5 In more recent years, as the list of 10 cities in North America, lizards escaped 0.0 0 introductions with disastrous results has J FMAMJ JA SOND and survived in suburban neighbor- Month grown, many scientists have vigorously hoods. One of these populations began Number of Podarcis sicula observed in surveys by month. Italian data opposed further species introductions. in Garden City, just a few miles west of from Foà et al. (1992b); data from Burke and Ner (2005). Invasive species are now recognized as Triangles represent average number of lizards at Italian site in 1988 . This population has (Foà et al., 1992b); circles and squares represent average number of one of the most important causes of spread in all directions, and recently the lizards at New York site in 1999 and 2000, respectively. native species endangerment and extinc- Italian lizards have been seen on the tion, and a considerable portion of con- Hofstra campus. servation resources worldwide are The scientific community’s view of two most common species in the devoted to combating the spread of the release (deliberate or accidental) of United States — starlings (Sturnus vul- invasive species. Invasive species hit us and plants into new places has garis) and English sparrows (Passer in the wallets as well. For example, changed over the years. In the past, domesticus) — were both introduced zebra mussels (Dreissena polymorpha), a amateur and professional scientists often here from Europe. Starlings got their species originally from Europe, were actively promoted the introduction of beginning in Central Park in 1890, carried to the Great Lakes in the ballast foreign species into new habitats. For when someone decided that New York water of large ships. They have spread example, professional wildlife biologists should be home to all the bird species rapidly throughout lakes of the Midwest

14 HOFSTRAHORIZONS and eastern United States, now causing tions. We know Italian wall lizards are property as a safe billions of dollars of damage annually to doing very well on Long Island because corridor, and spread into neighborhoods factory and power plant water intake there are many places where they are that border the tracks. Second, there are systems. Australian melaleuca very abundant, and there must be thou- people who deliberately release lizards (Melaleuca quinquenervia) trees were sands scattered throughout Long Island. in new places. That’s almost certainly brought to southern Florida in the early This all started when a small number of how lizards got to Leeds Pond Preserve 1900s to help dry up swamps, but have lizards were released from a pet shop on the north shore, The New York spread out of control, forming thick just off Hempstead Turnpike in Garden Botanical Garden, and Planting Fields forests that exclude all native trees. City in 1966. Six years later, according Arboretum in Oyster Bay. Finally, Melaleuca forests are so successful at to a Cornell University undergraduate lizards are moved accidentally by peo- absorbing ground water that they alter student doing a research project here, ple. For example, people moving mulch local water flow patterns and regional from areas where lizards are common climate. Because melaleuca bark is are probably also moving eggs. highly flammable yet the trunk is fire Why have they done so well in resistant, lightning fires in melaleuca North America? Both species of wall forests quickly become extremely hot lizards have lived in urban and subur- crown fires that spread into natural ban parts of Italy for thousands of years, forests, clearing them of all vegetation and they really don’t live in any habitats and preparing them for further invasion in Italy that could be called natural any- by the surviving melaleucas. Gypsy more. They have adapted to living near moths (Porthetria dispar), originally humans; in fact, one of the places brought to the United States for silk they’re most common here is a nursery production, failed entirely in that school where people (especially chil- regard, but escaped from laboratories in dren) pass right in front of them all day. 1868. Since then they have become one The lizards carry on with their lives, of the most devastating forest pests in hunting and socializing, undisturbed our country, stripping the leaves of trees unless people get too close. Here on across millions of acres in the northeast Long Island, they have spread through and heading south through the neighborhoods where they can find Appalachian Mountains. As a result of shelter in which to hide, but near open these three species and many others, spaces where they can hunt for food. So U.S. taxpayers now spend $100-200 bil- far they have colonized suburban areas, lion annually to monitor, contain, and gardens and parks here — they don’t control invasive species. Scientists Photo by Bill Davis. ©2003 Newsday, Inc. Reprinted with permission. even seem to like more natural habitats today pay close attention to the spread on Long Island. of species, and work hard to limit fur- Two other reasons the lizards are ther introductions. Invasive species juvenile lizards were abundant, and the spreading quickly and building up large ecology is perhaps the most rapidly population was expanding. They had populations in their new country are growing subfield of ecology. spread out in a semicircular pattern to that they have no significant competi- Against this backdrop of introduc- about 1/4 mile from the original release tors or predators here. There are no tions causing ecological disaster, where site. Ten years later they had spread other lizard species on Long Island — do the scaly little Italian immigrants fit over 0.6 mile around the release site, none of the native species that exist in in? I am frequently asked whether the and by the early 1990s they were seen nearby New Jersey made it here, and no Italian wall lizards have a negative effect as much as 11/2 miles from the original other lizard species have been intro- on their new environment, like so many release site. Now they exist in some duced. And perhaps because there are other invasive species have. I’m asked large, more or less continuous popula- no other lizards here, there are really no this by gardeners who have them in tions spread throughout entire neigh- predators that specialize on lizards. In their gardens, homeowners who have borhoods in Nassau County, and a num- Italy, lizards are commonly eaten by a them in their basements, amateur her- ber of small isolated populations as far variety of snakes and . On Long petologists who want them in their west as The New York Botanical Garden Island, we have one snake species that backyards, and biologists who study in the Bronx and as far east as Hampton might occasionally eat lizards (milk invasive species generally. And another Bays on the beach. They are still snakes, Lampropeltis triangulum), but so common question is, How do they sur- spreading, mostly through three meth- far there is little overlap in the ranges of vive the cold Long Island winters? ods. First, they disperse on their own, milk snakes and wall lizards. I’ve seen My students and I have been work- primarily along power lines and railroad some of our common birds looking at ing on the answers to all of these ques- right-of-ways. They make good use of lizards, but there’s no evidence that

HOFSTRAHORIZONS 15 birds eat lizards here. The one predator of any consequence here is cats, which also eat wall lizards in Italy. One Long Island homeowner showed me her prize lizard catcher — and a collection of lizard tails. The cat was not always fast enough to get entire lizards, but man- aged to get the tails of its escaping prey. These lizards quickly drop their tails when that will help them get away, and the tails wiggle and squirm enticingly after detachment from the rest of the lizard. Those lizards can go on to lead long, healthy lives and regrow their tails. Do the introduced lizards have a negative effect on local species? Although I get many calls each spring and summer from frightened suburban- ites with lizards in their basements, wall Photo by Bill Davis. ©2003 Newsday, Inc. Reprinted with permission. lizards are completely harmless to humans. They won’t bite unless cap- carried diseases or parasites with them, sample of lizards is likely to carry only a tured, and only the very largest males and these had spread to species here. small sample of the total number of para- have the ability to even lightly break the There are a number of diseases known sites found in the lizard populations in skin if you let them bite. On the other to spread between different Italy, so whatever parasites they may have hand, they are voracious predators of (including birds) and mammals — some had in Italy, we should expect them to be small and other arthropods. My of the most common are bacteria in the carrying fewer parasites here. Second, students and I examined the diets of Salmonella. Salmonella outbreaks many parasites depend on multiple hosts lizards throughout their active season, are famous for popping up here and for their life cycle, and odds are low that and we found they eat a wide variety of there in human populations and quickly any parasites the colonists brought with prey species, including familiar garden disappearing, but they appear to be them would find good replacements for pests like aphids, grasshoppers, caterpil- chronic in many turtle, lizard, and bird the other hosts they need. And finally, lars, and snails. They also successfully populations. They can be quite serious, the “parasite release” hypothesis predicts tackled more formidable prey such as causing severe illness and even death in

wasps, bees, and large beetles. Male humans, and occasional massive dieoffs Mean number hours observed per day

lizards tend to reach slightly larger body in wild birds. Very little work has been 16 sizes and have larger heads than done on diseases of wild reptiles in gen- 14 eral, and no one has researched 12 females; not surprisingly they tended to 10 eat the bigger, more challenging prey, Salmonella or any other disease in wall 8 while females specialized on aphids. lizards. The possibility exists that the 6 4

One female we studied had eaten 50 lizards brought new species or new Mean number of hours active 2 strains or have become a new reservoir 0 aphids! The diversity of prey species J F M A M J J A S O N D eaten by Long Island wall lizards was for important diseases, but no evidence Month quite close to that of their Italian coun- suggests this is so, and no disease prob- Average number of hours Podarcis sicula were observed in surveys per lems have been linked in any way to day each month. Triangles represent number of hours observed at terparts, although, of course, the specif- Italian site in 1988 (Foà et al., 1992b); circles and squares represent ic prey species were different. Because these lizards. However, anyone who number of hours observed at New York site in 1999 and 2000, respec- many of the species eaten by wall lizards handles these or other reptiles should tively. Foà et al. did not report data for January and December. are also non-native, and many of their always wash carefully afterwards. prey are considered garden pests, we A bit more is known about both could conclude that the lizards have no intestinal parasites and blood parasites of that any species that does well as an negative effect on the suburban ecosys- reptiles, and wall lizards in Italy are invader does so in part because it is not tems they currently inhabit on Long known to have both kinds of parasites. held back by the parasites it faced in its Island. However, ecological theory suggests that native land. Wall lizards are certainly There are more subtle ways that we shouldn’t expect the wall lizards in doing well in North America, so they these new invaders could affect other North America to be carrying many para- probably aren’t carrying many parasites, organisms in their new home — if they sites, for three reasons. First, a small if the hypothesis applies.

16 HOFSTRAHORIZONS Our lizards can be tests of these hypotheses, but not much is known about lizard parasites. Lizard blood par- asites include the protozoans that cause malaria (genus Plasmodium); however, there are many kinds of Plasmodium, and each kind restricts itself to only a few host species. Lizard Plasmodium are not going to infect people, but they might infect some other lizards. Because there are no other lizards on Long Island, this is only a minor concern. Plasmodium also require time in a mosquito host as part of their life cycle. Given the fact that wall lizards are still not very abun- dant compared to other hosts that Long Island mosquitoes have available, the odds are low that a mosquito will pick up a Plasmodium infection from one wall lizard, and then later find another wall lizard to feed on, and infect. Thus it seems unlikely that a lizard Plasmodium Photo by Bill Davis. ©2003 Newsday, Inc. Reprinted with permission. infection could persist on Long Island, even if the original lizards were infected. probably been ingested with prey. lizards survive much colder tempera- My colleagues and I have examined Both are members of North tures on Long Island than their recent hundreds of blood samples not only American species common in birds, so ancestors experienced in Italy. How do from Long Island wall lizards, but also there’s no evidence that the wall lizards they do it? from the three other North American brought anything from Italy, and it does- They don’t do it by freezing. The populations of introduced wall lizards, n’t look like they’ve picked up much European common lizard ( vivip- and none have had any trace of blood here either. ara) is a close relative to the wall lizard, parasites. How do wall lizards survive our and it survives very cold winters by uti- Reptiles are sometimes infected winters? Wall lizards range from the lizing a series of physiological adapta- with intestinal parasites, including foothills of the Alps in extreme northern Italy all the way south to the island of trematodes, nematodes, cestodes, and Mean temperatures in Italy and New York flagellates, and these are not nearly so Palermo off the southern tip of Italy, so 25 different populations have certainly host-specific. In fact, some of these can 15 adapted to different climates. Our infect fish, turtles, birds, and mammals, 5 so there is a possibility that the intro- genetic work, however, shows that our duced lizards could have brought intes- Long Island population comes from the -5 tinal parasites that now infect local ani- vicinity of Rome. This makes sense -15 because pet wholesalers in the 1960s mals, or that local animals have intestin- -25 and 1970s were shipping animals out of J F M A M J J A S O N D al parasites that now infect wall lizards. Month Unfortunately, very little is known about Rome, and they probably obtained local Filled triangles represent average monthly temperatures (°C) for animals. Rome’s summer temperatures Rome, Italy, 1901-1930; filled squares represent mean monthly tem- the intestinal parasites of Italian wall peratures for Mineola, NY, 1948-2001; empty triangles represent lizards in their home country, so we are actually quite similar to those of extreme minimum temperatures for Rome, Italy, 1901-1930; empty Long Island — matching our average squares represent extreme minimum temperatures for Mineola, NY, can’t speculate on what the original 1948-2001. released lizards might have had with temperatures in June, July, and August them. Also, nothing is known about the almost perfectly. However, our average parasites of Long Island reptiles, so we winter temperatures are quite a bit cold- tions that allow it to freeze solid without can’t suggest what the wall lizards might er, as it rarely gets much below freezing damaging its tissues. This is a neat have been exposed to here. However, in Rome. The real differences are in trick; few other vertebrates can do it. my colleagues and I have examined the extreme temperatures. Long Island For example, when our body parts stomachs and intestines of more than often gets winter extremes of -4°F or freeze, we get frostbite and the frozen 1,000 wall lizards, from all four North even colder, whereas Rome’s coldest tissue dies, in part because the frozen American populations, and found only nights, even in very cold years, bottom cells burst. Lacerta changes its blood two parasites, and those had out around 23°F. So the Italian wall chemistry so cells don’t burst. If wall

HOFSTRAHORIZONS 17

lizards could do the same, then they when the new environment differs from could easily survive cold Long Island win- ancestral environments in only a few ters. But our laboratory work shows that factors, such as day length or minimum they don’t, so they must avoid freezing. temperature. Second, they can provide They avoid freezing on Long Island data useful for conservation. For exam- by going deep underground, and not ple, concerns about the rare Aeolian coming out until the danger of freezing wall lizard (Podarcis raffonei) have led to is long past. We have monitored the the suggestion that reintroductions may activity of Long Island wall lizards, and be needed in the future, and learning we’ve found that they’re quite different about the successful and failed introduc- from their Italian relatives. In Rome, tions of its close relatives may be help- wall lizards may be active any month of This is a cross section of a toe from an captured ful. Finally, wall lizard introductions the year, even on warm days in January. on Long Island. The image shows bone rings laid down with each have occurred only in urban or subur- In contrast, our wall lizards spend winter the lizard survived, just as a tree lays down annual growth ban areas, and these ecosystems have November, December, January and rings. This adult male has survived at least five winters. few species of native reptiles. Therefore, February deep underground, quite safe introduced wall lizards can provide from freezing. Therefore they’re active just fine on their own and don’t need excellent opportunities for study by for a much smaller fraction of each year, any help. They have not yet spread into amateur biologists, because wall lizards and we’d expect that they grow more even moderately natural habitats in often become abundantly common and slowly, reproduce less frequently, and North America, and they may yet turn they are easy to observe. For me, the reach maturity more slowly than in Italy. into a problem when they do. It is cer- opportunities to watch and handle wild Unfortunately, there’s no Italian data tainly hard to imagine how we could animals in my neighborhood played a available to test that hypothesis. I’m hop- stop them even if we wanted to. In the key role in my inclination to become a ing to spend some time in Italy next year meantime, it should be noted that the biologist. Wall lizards can provide the gathering data on their lizards, so we can introduced wall lizard populations can herpetological equivalent of watching make better comparisons with ours. have some value. First, they can pro- birds at feeders, introducing students Italian wall lizards might be an vide useful data for evolutionary and and other nonprofessionals to the basics example of an invasive species with lit- ecological model testing, especially with of scientific research. As the lizards tle impact on their new homes. That regard to theories dealing with how spread across the Hofstra campus, you doesn’t mean I advocate spreading them species will respond to new environ- can expect my students to be taking around deliberately — they’re spreading ments. This is particularly important notes.

opportunities to visit places in Florida where Because wall lizards are common close to both were abundant. Today, he continues to campus, they are an excellent species for intro- focus his research efforts largely on reptiles. ducing Hofstra undergraduates to scientific Professor Burke earned a B.S. in zoology research in the lab and in the field. Since from Ohio State University, an M.S. in wildlife 1997, 10 undergraduates have completed ecology from the University of Florida at research projects on wall lizards in Professor Gainesville, and a Ph.D. in biology from the Burke’s lab, resulting in several publications. University of Michigan. He began teaching at Despite the fact that the lizards are quite active Hofstra as an assistant professor in 1996, and around people, many Hofstra students, even was promoted to associate professor in 2002. having grown up in neighborhoods where the lizards are common, are unaware of their pres- Professor Burke teaches , ecology, ence. “One of the best things about taking stu- behavior and conservation biology. dents out in the field to study lizards is their He first began serious research on lizards surprise when they find that lizards have been while at the University of Michigan, when he around them all along and they never noticed,” recognized the advantages of lizards as study he explains. This trend is likely to continue as organisms: they are easy to observe both in the Russell Burke's longstanding interest in the lizards spread onto Hofstra campus — he’s wild and captivity, they are short-lived, and reptiles was a major influence in his decision to recently found them at the Hofstra University often abundant. These characteristics make pursue a career in biology. As a child, he Model Bird Sanctuary. He predicts that the them excellent models for studies of natural recalls collecting local snakes and keeping lizards will continue to spread over the Hofstra them in captivity. A major complaint growing selection. The abundance of Italian wall lizards campus, startling students and visitors alike. up was that there were no lizards or venomous near Hofstra University actually contributed to “That awareness of the living world around us, snakes nearby, and he seized the earliest Professor Burke’s desire to teach here. often unexpected, makes everyone a biologist.”

18 HOFSTRAHORIZONS