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We tested whether Porphyrio porphyrio (Purple Swamphen) in South Florida selected particular types of food and whether their diets differed among 3 geographically separate wetlands (northern Everglades, a stormwater treatment marsh, and Lake Okeechobee littoral zone). We found that the Purple Swamphens we collected from the treatment marsh were larger than those from the other sites. The primary food item of the Purple Swamphen at all 3 sites was Eleocharis cellulosa (Gulf-coast Spikerush), comprising 79%, 72%, and 49% mean dry weight of total gut contents for the northern Everglades, littoral zone, and treatment marsh, respectively. Accounting for availability, Purple Swamphens were strongly selective for Gulf-coast Spikerush, which is a common plant in the southeastern US. The availability of this plant is not likely to be a factor limiting the spread of this bird northward.
Schinus terebinthifolia (Brazilian Peppertree) is a South American plant that has become invasive in many countries around the world. It was introduced into the US about 100 years ago as an ornamental. Escaping cultivation, it now occurs in Alabama, Florida, Georgia, Texas, California, and Hawai'i. This species is one of the most invasive weeds threatening agriculture and natural areas in the Southeast. Efforts to manage Brazilian Peppertree populations with biological controls began in Hawai'i in the 1950s and resulted in the release of 3 insect species. However, the control agents have had minimal impact, and the weed continues to be a difficult problem. More recently, our international team of collaborators has discovered and tested numerous new species of potential biological control agents. These species attack different plant tissues and include defoliators, sap-suckers, stem borers, and leaf- and stem-gall formers. Despite difficulty finding an agent sufficiently specific for field release in Florida, we have narrowed the field to 2 promising species, the thrips Pseudophilothrips ichini (Hood) and the foliage-gall former Calophya latiforceps Burckhardt. Results of no-choice and choice trials conducted overseas and in quarantine indicate that both species will safely contribute to the control of this invasive weed. Herbivorous feeding by immature and adult individuals of both herbivore species stunt growth, distort leaves, and should reduce reproductive output of Brazilian Peppertree.
We describe characteristics of a Python bivittatus (Burmese Python) nest from observations made from December 2008 through August 2009 in Everglades National Park, Homestead, FL. The nest hatched on 28 July with a 77% hatching success. The female lost 54% of her body weight while breeding, laying, and incubating eggs, and abandoned the nest 3 days before eggs began hatching. Egg-mass temperature was 26.29–31.41 °C (mean = 28.07 °C), and was more stable than the temperature in direct sun above the nest, which ranged from 20.81 °C to 45.70 °C (mean = 28.45 °C). Egg-mass temperature was likely buffered from extreme heat by adjacent vegetation, where the temperature ranged from 23.19 °C to 30.48 °C (mean = 27.05 °C) and from extreme cold by shivering thermogenesis. Of successful hatchlings, 9 were male and 8 were female.
The vining fern Lygodium microphyllum (Old World Climbing Fern), which is native to the Old World tropics, has invaded central and southern Florida, disrupting native habitats, reducing biodiversity, and altering fire-line intensity and behavior. Prescribed fire, one of several methods used to manage Old World Climbing Fern infestations, reduces the fern's above-ground biomass over large areas, but its effects on spore viability are unknown. To determine the heat tolerance of spores, we exposed spores to temperatures ranging from 50 °C to 300 °C for durations of 5 sec to 1 h, then assessed their germination on agar in Petri plates. Temperatures of 50 °C had little effect; 300 °C killed spores for all durations. Results indicate that spore viability decreases with increasing temperature and duration of heat exposure, and that spores are killed at relatively low tem peratures (≥100 °C).
Several agencies and programs within the state of Florida formed the Everglades Cooperative Invasive Species Management Area (Everglades CISMA) to collaborate and share information about the invasive species that threaten the region's ecosystems. In 2010, the Everglades CISMA contracted with the Center for Invasive Species and Ecosystem Health (Bugwood) to implement EDDMapS as the database to store and share data collected by their programs and to develop and maintain a website and a smartphone application designed for professionals and citizen scientists to report invasive species. The project, IveGot1, has been a categorical success and has become a model for invasive species reporting nationwide. As of May 2015, members had submitted 3481 website records, 1178 smartphone records, and 248,571 records from bulk data-uploads.
The 2013 Python Challenge® provided an opportunity to learn more about the ecology and management of Python molorus bivittatus (Burmese Python). Goals of the 2013 Python Challenge were to raise awareness about Burmese Pythons, remove pythons, increase public participation and agency cooperation in removal and reporting of pythons, increase knowledge of python ecology, and examine effectiveness of incentives to increase public participation in invasive wildlife management. Over 1500 participants registered for the competition. Sixty-eight Burmese Pythons were removed during the Challenge. Thirteen females (19%), 54 males (79%), and 1 young-of-the-year (1%) python of undetermined sex were captured. More pythons—73 (68 from the Challenge and 5 incidental)—were removed during the 2013 Python Challenge period than during similar time periods during 2008–2012. We found no evidence of unintended consequences such as removal of native species. We identified 13 prey species: 6 mammals (46%), 6 birds (46%), and 1 alligator (8%). The potential of recreational-harvest incentive programs to impact python populations is uncertain. Incentive programs are potential tools in invasive-species management programs, but they should be managed diligently and evaluated for effectiveness.
We studied an established population of Furcifer oustaleti (Oustalet's Chameleon) in southeastern Florida to understand aspects of reproductive biology in this nonnative species. Reproduction of Oustalet's Chameleon had not been documented in the field in Florida, and limited information is available about its reproduction in its native range. We conducted surveys from July 2011 to October 2012 in the Persea americana (Avocado) grove where this species was introduced in Miami-Dade County, FL. During these surveys, we removed more than 430 chameleons. We encountered 23 gravid females from June to October. Mean clutch size was 42.3 eggs, and we recorded a new maximum clutch size of 72 eggs. Utilizing radio-telemetry, we were able to track a gravid female to a nest cavity, and herein describe the first Oustalet's Chameleon nest in Florida. Our findings suggest that management for eradication of the species should include ongoing surveys, with removal efforts intensified from June to October, when females are known to be gravid.
Citizen-science programs have the potential to contribute to the management of invasive species, including Python molurus bivittatus (Burmese Python) in Florida. We characterized citizen-science—generated Burmese Python information from Everglades National Park (ENP) to explore how citizen science may be useful in this effort. As an initial step, we compiled and summarized records of Burmese Python observations and removals collected by both professional and citizen scientists in ENP during 2000–2014 and found many patterns of possible significance, including changes in annual observations and in demographic composition after a cold event. These patterns are difficult to confidently interpret because the records lack search-effort information, however, and differences among years may result from differences in search effort. We began collecting search-effort information in 2014 by leveraging an ongoing citizen-science program in ENP. Program participation was generally low, with most authorized participants in 2014 not searching for the snakes at all. We discuss the possible explanations for low participation, especially how the low likelihood of observing pythons weakens incentives to search. The monthly rate of Burmese Python observations for 2014 averaged ∼1 observation for every 8 h of searching, but during several months, the rate was 1 python per >40 h of searching. These low observation-rates are a natural outcome of the snakes' low detectability— few Burmese Pythons are likely to be observed even if many are present. The general inaccessibility of the southern Florida landscape also severely limits the effectiveness of using visual searches to find and remove pythons for the purposes of population control. Instead, and despite the difficulties in incentivizing voluntary participation, the value of citizen-science efforts in the management of the Burmese Python population is in collecting search-effort information.
We discovered an adult female Python bivittatus (Burmese Python) coiled around a clutch of 25 eggs in a cement culvert in Flamingo, FL, in Everglades National Park. To our knowledge, this is the first record of an invasive Burmese Python laying eggs and brooding inside an anthropogenic structure in Florida. A 92% hatch-success rate suggests that the cement culvert provided suitable conditions for oviposition, embryonic development, and hatching. Given the plenitude of such anthropogenic structures across the landscape, available sites for oviposition and brooding may not be limiting for the invasive Burmese Python population.
Salvator merianae (Argentine Black and White Tegu, hereafter, Tegu) is an omnivorous, burrowing lizard native to South America. Tegus were introduced through the pet trade, and free-ranging populations now threaten many native species in Florida. As Tegu control programs expand and more traps are deployed, the need for a simple, inexpensive trap increases. To date, there has been no experimental effort to compare types of traps or alternative lures. In this study, we evaluated responses of 12 captive Tegus to several alternative trap/bait combinations. We video-recorded each of the trials and scored the outcomes based on the trap the Tegu entered first. Our results suggest that alternative trap/lure combinations, such as traps made of PVC pipe baited with commercial mouse-based trap lure, might be just as effective at capturing Tegus, and thus could be less expensive options for Tegu control programs. Trials with captive animals do not necessarily predict outcomes with free-ranging animals, and we recommend well-designed field trials as a next step.
Varanus niloticus (Nile Monitor) is a large, carnivorous lizard native to sub-Saharan Africa. A breeding population of Nile Monitors was documented in southwestern Florida (Lee County) in 2004. In 2011, the Florida Fish and Wildlife Conservation Commission began surveying the C-51 canal on the southeastern Florida coast in Palm Beach County in response to multiple reports of monitor lizards. These surveys resulted in observations of 9 Nile Monitors, including a hatchling and copulating pair. Three additional hatchlings were later reported by private citizens. These observations provide evidence of a breeding population of these non-native lizards in southeastern Florida.
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