A Guide to Invasive Species of Corkscrew Swamp Sanctuary

Feeling inspired by National Invasive Species Awareness Week, I wanted to create a guide to invasive species of Corkscrew Swamp Sanctuary. Because there are many invasives that affect the sanctuary, I decided to focus on some of the most common, most problematic, or most managed species at Corkscrew.

What is an invasive species?

According to the USDA Executive Order 13112, an invasive species is a non-native species (including seeds, eggs, spores, or other propagules) whose introduction causes or is likely to cause economic harm, environmental harm, or harm to human health.

MAMMALS

Common Name(s): Wild Hog, Wild Boar, Feral Pig

Scientific Name: Sus scrofa

Origin: Europe, Asia, North Africa

Introduction: brought by Spanish explorers and settlers in the 1500s

Ecological Impacts: compete with native animals for food, consume native plants and animals, disturb soil and ground vegetation

Management Strategies: permitted hunting on private property and in wildlife management areas

REPTILES

Common Name(s): Brown Anole, Cuban Anole

Scientific Name: Anolis sagrei

Origin: Cuba, Bahamas, Cayman Islands

Introduction: first reported in 1880s, introduced by cargo

Ecological Impacts: competes with and consumes eggs and juveniles of the native Green Anole

Management Strategies: capture and removal, public reporting


AMPHIBIANS

Common Name(s): Cuban Tree Frog

Scientific Name: Osteopilus septentrionalis

Origin: Caribbean

Introduction: 1920s by cargo

Ecological Impacts: competes with and preys on smaller native tree frogs

Management Strategies: capture and removal, public reporting

FISH

Common Name(s): Brown Hoplo

Scientific Name: Hoplosternum littorale

Origin: South America

Introduction: 1950s, aquarium release and/or aquaculture escape

Ecological Impacts: possibly competes with native fish, consumes native invertebrates

Management Strategies: capture and removal, public reporting

Common Name(s): African Jewelfish

Scientific Name: Hemichromis letourneuxi

Origin: Africa

Introduction: 1960s, aquarium release and/or aquaculture escape

Ecological Impacts: aggressive behavior, consumes small native fish and invertebrates, may compete with native fish

Management Strategies: capture and removal, public reporting

INVERTEBRATES

Common Name(s): Island Apple Snail

Scientific Name: Pomacea maculata

Origin: South America

Introduction: 1980s, pet trade

Ecological Impacts: consumes native plants, competes with the native Florida Apple Snail

Management Strategies: collection and removal of adult snails and egg masses

PLANTS

Common Name(s): Melaleuca

Scientific Name: Melaleuca quinquenervia

Origin: Australia, New Guinea

Introduction: early 1900s, landscape ornamental

Ecological Impacts: fast growing, displace native plants

Management Strategies: regiment of prescribed fires, manual removal, herbicide application

Common Name(s): Old-World Climbing Fern

Scientific Name: Lygodium microphyllum

Origin: Africa, Southeast Asia, South Pacific islands, Australia

Introduction: 1960s, landscape ornamental

Ecological Impacts: dense canopies smother native plants

Management Strategies: regiment of prescribed fires, manual removal, herbicide application

Common Name(s): Brazilian Pepper

Scientific Name: Schinus terebinthifolius

Origin: Argentina, Brazil, Paraguay

Introduction: 1800s

Ecological Impacts: produces dense canopy which shades out other plant life, poor habitat for wildlife, alters natural fire regimes, related to poison ivy and may cause allergic skin reaction

Management Strategies: regiment of prescribed fires, manual removal, herbicide application

Common Name(s): Water Hyacinth

Scientific Name: Eichhornia crassipes

Origin: South America

Introduction: 1880s

Ecological Impacts: produces dense canopy on water surface, shades out native submerged plant species, lower dissolved oxygen concentrations, can increase flooding

Management Strategies: manual removal, herbicide application

POTENTIAL THREATS (no confirmed sightings at Corkscrew Swamp Sanctuary, but may become present in the future)

Common Name(s): Burmese Python

Scientific Name: Python bivitattus

Origin: South Asia

Introduction: 1980s, pet trade

Ecological Impacts: very few predators, prey on and reduce native species populations, prey on threatened and endangered species

Management Strategies: monitoring of bird and mammal populations, capture and removal, public reporting

Common Name(s): Green Iguana

Scientific Name: Iguana iguana

Origin: Central and South America, Caribbean

Introduction: 1960s, pet trade

Ecological Impacts: consumes a wide variety of vegetation, considered a nuisance by property owners, burrows can damage infrastructure

Management Strategies: capture and removal, public reporting

Common Name(s): Argentine Black and White Tegu

Scientific Name: Salvator merianae

Origin: Argentina, Brazil, Paraguay, Uruguay

Introduction: Early 2000s, pet trade

Ecological Impacts: preys on native species, consumes the threatened Gopher Tortoise juveniles

Management Strategies: capture and removal, public reporting

HOW CAN YOU HELP?

Volunteer at Corkscrew Swamp Sanctuary

At Corkscrew, removal of non-native plants and animals is an ongoing process. One way you can help is to volunteer with our resource management team. 

Be a responsible pet owner

Before buying an exotic pet, please ask yourself a few questions. How big will this animal eventually get and what does it eat? Will you be able to care for this animal for the length of its life? If you have an exotic pet already and are no longer capable of caring for it, please don't release it. There are hobby groups, local museums, zoos, pet shops, and other programs that can assist. For additional help, contact FWC's adoption hotline at 888-IVE-GOT1.

Educate yourself

Educating yourself and others on the invasive plant and animal problem is also a great way to help. Another avenue is contacting your local, state, and/or federal representatives and voice your concerns about the impacts invasive plants and animals are having. To learn more about the Audubon Florida's efforts in the war on invasives, please visit the Florida Invasive Species Task Force page. 

Report sightings

-Amy, Education Intern

Additional resources: Corkscrew Swamp Sanctuary Invasive Species, Florida's Nonnative Fish & Wildlife, USDA National Invasive Species Information Center

Newest Intern- Kendall

Hello Everyone!

My name is Kendall Williams and I am the newest Corkscrew Conservation Intern! I am very excited to be here.

I am originally from Tampa, FL and I just graduated from the University of Florida in December of 2018 with a degree in Wildlife Ecology and Conservation. Throughout my time at UF I did some really cool things. I took a class that was all about learning wildlife techniques such as the capture of mammals, herpetofauna, and birds, and how to perform vegetation surveys. One of the highlights of this class was catching alligators off an airboat with my bare hands! This class was the thing that cemented in my head that conservation was what I wanted to do. It also opened my eyes to my true passion: Fisheries. This passion hit me so hard and so fast that the next week I had added a Fisheries and Aquatic Sciences minor to my degree. The dream right now is to work on freshwater fish in the pacific northwest of the United States.

Another cool thing I was lucky enough to do while at UF was study abroad. I went to Melbourne, Australia for a semester and absolutely LOVED it. I took mostly classes that pertained to my conservation major but also took an Australian history class that was very interesting. I traveled around the country a lot, including to Brisbane, Sydney, Cairns, Uluru, and camped under the stars in the Australian Outback. I made many good friends and many great memories. It was a trip I will never forget.

Although college and UF was a great experience, I am excited to be in the workforce and focusing on the conservation work performed here at Corkscrew. I can't wait to see where these next six months will take me!

Thanks!

Kendall

Beyond the Backcountry

One of the many rewards working for a great organization such as Corkscrew is their partnership with other conservation groups! Through the sanctuary's relationship with Rookery Bay Reserve a few other interns and myself had the opportunity to go shark tagging as well as trawling with the reserves fisheries biologist. Shark tagging involved going out about two and a half hours before sunset to get into the bay were we would be setting up our longlines and gill net. The first photo below is a gill net, a large net hanging from a line with buoys on each end and smaller floats along the length of the net to keep it at the surface of the water. The longlines are pretty much the same except instead of a net hanging from the line there are baited hooks. The deployment of these two devices is very similar. From the back end of the boat you set the anchor located on one side of the line, as the boat moves forwards you slowly let out the line or gill net making sure they are not twisted.  We set the gill net between two baited longlines. 

Once your survey equipment is all set up you sit and wait, constantly checking to see if any of the floats are bobbing or underwater. This means that something is either caught in the net or on the line. We wanted to be able to know exactly when a fish got caught so that our reaction time was quick and they wouldn't be struggling on the line or net too long helping to prevent injury and stress. After seeing a float go under, we approach a few floats away and grab the line on top of the water, slowly lifting each portion slightly out of the water to check and see if we had anything caught. Not 10 minutes after being out there we caught a smalltooth sawfish! Now, we had to be very careful when bringing this endangered species on board because they could cause injury easily with their rostrum. The sawfish was placed into a kiddie pool on the boat that was prefilled with saltwater. This is so the gills can be kept underwater allowing them to breathe. A few measurements were taken and a tag was inserted just below the dorsal fin, then the 6 foot sawfish was released back into the water a little ways away from the gill net and longlines to avoid recapture.  

After processing a captured fish the protocol is to recheck the gill net starting at the end and lifting the net up out of the water working your way through the entire length. This is to make sure no other animals were captured while processing your previous catch. Nothing was found in the gill net and none of the longline floats were down so we went back to waiting. About a half an hour before it was time to start bringing in all the equipment excitement struck! One of the floats on the gill net was frequently moving up and down. As we checked the net we found a juvenile lemon shark! This catch was exciting because after we got him into the pool we were able to see he still had his umbilical cord scar, meaning this little was only a few months old! Due to the presence of the pool this lemon shark was able to swim around in circles keeping water moving over its gills reducing the stress of processing. Again, the shark was measured and tagged before being set free and bringing an end to our evening! but not before posing for a quick snap shot :)

Benefits of Living at Corkscrew Eclipse any Downsides

One of the really interesting and unique aspects of being an intern at Corkscrew Swamp Sanctuary is that we live on the property. Our rustic cabin housing is nestled in the pine flatwood habitat near the research lab and the director’s office. Our Corkscrew home even has a name: the Gator Hole. It is an enjoyable experience working and living with my fellow interns. We all really get along and become friends during our time here.

Living at Corkscrew definitely has some perks. We have a very short commute to work, we see wildlife in our yard (one intern even saw a panther right outside the Gator Hole), and we have access to the boardwalk and other parts of the property almost all the time. This includes being able to experience Corkscrew Swamp Sanctuary at nighttime, something that is a rare opportunity for guests. The remote location of Corkscrew makes it a dark sky site and an excellent stargazing location. 

Corkscrew Swamp Sanctuary boardwalk at night. Image credit: RJ Wiley.

This past Sunday night into Monday morning we were able to observe the only total lunar eclipse that will occur this year. This lunar eclipse was only visible in North and South America as well as western parts of Europe and Africa. Lunar eclipses happen when the sun, Earth, and moon align during a full moon. The moon moves into the shadow of the Earth resulting in a lunar eclipse. The moon during this eclipse was referred to as a “supermoon” because the moon was closest to Earth in its orbit, making the moon seem larger and brighter. 

The moon orbits the earth in an ellipse shape bringing it closer and farther to Earth. The farthest point in the ellipse is called the apogee and the closest point is called the perigee. A “supermoon” appears larger because its an average of 40,000 km closer to Earth. Image source: NASA/JPL-Caltech

Lunar eclipses also turn the moon a reddish hue and people call them “blood moons.” This is caused by the same effect that gives sunrises and sunsets their reddish orange colors. Small molecules in the atmosphere scatter blue light making the sky blue, leaving behind red light that refracts in the Earth’s shadow.

As the moon is covered by the Earth’s shadow, it turns a reddish orange color. Image source: NASA.

I was able to convince interns Randi and Kendall to stay up with me and watch the eclipse. The full moon before the eclipse was beautiful in itself. It was so bright we could easily see in the dark. Around 10:40 p.m., the partial eclipse started as the Earth shadowed the moon. We periodically stepped outside every 10 to 20 minutes to watch the progress of the eclipse. As the eclipse continued, the sky became darker revealing hundreds of stars that were previously out shined by the moon. Finally, just past midnight, the full eclipse occurred with a beautiful dark red moon. 

I have always been fascinated by space and I love stargazing. I was glad I was able to see this amazing astrological event and share it with the other interns. The next total lunar eclipse won’t be visible in North America again until 2022, so we were lucky to be able to watch it and in such optimal viewing conditions. Just another benefit of living at Corkscrew Swamp Sanctuary!

-Amy, Education Intern

You can learn more about the lunar eclipse in this NASA article: How to Watch the Only Total Lunar Eclipse of 2019, Plus a Supermoon

Everyone’s Least Favorite Frog: The Story of the Cuban Treefrog

Coming to Corkscrew Swamp Sanctuary from the Rocky Mountains, I had only ever seen a handful of frogs, many of which were pets. Thus, as I began to adventure out into the swamp I became increasingly intrigued by the number of amphibians and the variety of species that were present. From treefrogs to Pig Frogs, we saw and heard many of Florida’s beloved native frog species during our field days. On one day in particular I took a look inside of a well in a back-country and much to my delight it was filled with frogs! I was so happy I began to try to grab the cute little critters to get a better look. Unfortunately these frogs were not what I had been hoping for… I quickly learned that the large, brown frogs I had first been so enamored with were actually the loathed invasive Cuban Treefrog (Ostepilus spetentrionalis).

          Cuban Treefrogs as their name suggests are native to Cuba and the West Indies. These slimy little critters first came to Florida in the 1920s as stowaways on cargo ships, making their first appearance in the Florida Keys. However, by 1952 they were spotted throughout Miami. Some 60 years later and the Cuban Treefrog has proved its dominance in Florida as it has reached even isolated pockets in the Panhandle, and survived numerous freezing events. 

          So what effect has the broadening of the Cuban Treefrog’s range had on Florida’s native ecosystems? Well, being that the Cuban Treefrog is the largest species of treefrog in North America, it has the tendency to prey upon not only insects, but other native treefrogs such as the Green Treefrog (Hyla cinerea). Eating native treefrogs is not the only issue posed by the Cuban Treefrog’s diet. Their mere consumption of insects also significantly limits resources for other native frog species making the Cuban Treefrog an all around menace to Florida’s native amphibian populations.

          But that’s not all! These sneaky little frogs have also found their way not into the hearts of local residents, but into their homes. Many Florida residents report finding Cuban Treefrogs inside of flower pots, sliding glass doors, and even in their toilets. Given their ability to hide in dark and small spaces they can be especially allusive to homeowners. However, if a Cuban Treefrog is found in your home you are advised to alert Southwest Florida’s regional invasive species managers via 1-888-IVE-GOT1  or online at IveGot1.org. Humane euthanization is also permitted through the application of benzocaine to the back of the frog, followed by freezing.

          Despite the havoc that the Cuban Treefrog has wreaked on the majority of Southern Florida, there is still much we can learn from these frogs and the effects that they are having on natural environments. Invasives are highly damaging to native ecosystems and species. Immediate identification and removal are the best ways to combat these deadly species, followed by consistent and strict management policies and practices. If the Cuban Treefrog could have been identified within the Florida Keys early on, its range could have been drastically limited and thousands of native species populations may have been preserved. Now, the Cuban Treefrog population is to a point where complete removal is not a feasible option, but that is not to say we cannot prevent the next large spread of invasive species within Florida.

           Now, as I return to that back-country well and see those slimy, brown Cuban Treefrogs I remember their story and the lessons they have taught Florida residents and wildlife managers alike about invasive species. I am not filled with a hatred for the species, but an understanding of how moving forward we must do better. So let’s all remember the story of the Cuban Treefrog and promise to always be cautious when transporting plants and animals from different regions and ecosystems, and never release domestic pets into the natural environment!

~ Evan, Conservation Intern

A Review of My Time at Corkscrew

Despite being familiar with the temporary job process, 6 months never seems as long at the end of a job as it seemed from the beginning. This month is my last here at Corkscrew, with my last day falling on February 1^st.

My internship has flown by, and over the 5 months I have lived and worked here, my appreciation for the sanctuary and its history has grown. As I type this, I can see a Red-bellied Woodpecker (Melanerpes carolinus) on a tree just outside, searching for its fill of insects. In just the second month of my internship, I briefly looked to the side out a window while processing fish in the lab, and saw nothing other than… a Florida Panther (Puma concolor coryi)!! It walked right between the lab and the intern housing, at 9 in the morning. Another intern and I ran outside for a longer look and saw it crouch in front of some bushes for about 20 seconds before chasing an Eastern Cottontail (Sylvilagus floridanus) out! Both the rabbit and the panther disappeared back into the bushes, and 2 seconds later, you would have never known they were there.

Experiences like these are inevitable at Corkscrew Swamp, and I can’t overstate how lucky we are that people in the past recognized its worth enough to protect it from development. I have enjoyed every second of my internship, from fish sampling to herp surveys! It’s hard to pick a favorite experience because I love every moment I’m out in the field. There’s always something new to see because the environment is always changing – increasing or decreasing water levels in particular determine what you might see.

The wildlife here make this place special in an ecological sense, but the people I’ve met and worked with made this place home. The friendships I made are friendships I hope last much longer than my internship. I feel incredibly lucky to have worked here with the people I’ve worked with, as all of us share a passion to preserve and protect natural areas for the benefit of future generations. Time spent in the field and lab is truly enhanced by the people that time is spent with, and I will miss working with all the wonderful people here. I have no doubt that Corkscrew will continue to flourish through their dedicated, passionate work.

As for me, I’ll be moving up to the panhandle in February to work at Florida State University’s Coastal and Marine Laboratory as a research technician. I will be working with Dr. Sandra Brooke, who will become my graduate school advisor in the fall if everything goes to plan! My intention is to study coral ecology, particularly with respect to anthropogenic impacts such as climate change. I am incredibly excited to see what changes the next year brings, but I will always be grateful for the time I spent at Corkscrew Swamp Sanctuary as an intern. J

- Randi Bowman, Research Intern

119th Annual Audubon Christmas Bird Count

History of the Christmas Bird Count

Hunters and the birds they killed during a Christmas Side Hunt.

Before the turn of the 20th century, there was holiday tradition called the Christmas Side Hunt. Groups of hunters would compete to bring home as many birds and mammals as they could. Hundreds of non-game birds were killed in a single hunt and “winners” were published in leading sportsmens' journals.

Conservation efforts were just beginning in this era, and declines in bird populations concerned early naturalists and scientists. A new Christmas tradition was proposed by ornithologist Frank M. Chapman, who was involved in the early foundation of the Audubon Society.

On Christmas Day in 1900, the first of what was then called the “Christmas Bird Census” was conducted to count birds instead of hunting them. Chapman inspired 27 birders across North America to participate in this first Christmas Bird Count where they recorded 90 bird species.

Birders from an early Christmas Bird Count.

National Audubon Society Annual Christmas Bird Count

Each year since, birders from across the Americas have come together to participate in the Christmas Bird Count that has now become an international event. Tens of thousands of people coming together, all for the love of birds.

There are count circles in the United States, Canada,
 Latin America,  the Caribbean, and the Pacific Islands. 

This year marks the 119th year for the annual Audubon Christmas Bird Count, which is the longest-running community science project in the world. Over 2,000 count circles and around 75,000 people across North, Central, and South America collect and submit data each year.

All the data is accessible on the National Audubon Society website and it has been used and referenced in several reports and studies. The data collected is used by Audubon researchers, conservation biologists, wildlife agencies, and other interested individuals to study the long-term health and status of bird populations across North America. Data from the Christmas Bird Count has been used by government agencies and non-profit organizations including the Environmental Protection Agency, U.S. Fish & Wildlife Service, North American Bird Conservation Initiative, and many more.

2018 Corkscrew Christmas Bird Count

Arial view of the Corkscrew Count Circle.

The Corkscrew Count Circle is separated into 11 sections.

The Corkscrew Christmas Bird Count is a 15 mile circle surrounding and including Corkscrew Swamp Sanctuary. Several teams divide up the count area into 11 sections, which includes a diverse array of habitats and neighborhoods. There were about 60 participants in the Corkscrew CBC this year and birders of all experience levels were welcome.   

Evan, one of our other interns, volunteered with
Team 10 and is preparing their data sheets in the
Blair Center classroom. 

Teams meet in the Corkscrew Swamp Sanctuary 

parking lot.

Meeting locations and times for each team were determined by the team captain, but most teams met at the sanctuary and got an early start at about 7:00 am. While many count circles across the country have to deal with cold winter temperatures, we had beautiful weather in the upper 70s with only a few sprinkles of rain throughout the day. Teams traveled by foot, cars, trucks, boats, and even swamp buggies while identifying and recording birds by sight and sound.

I helped lead Team 2 on the big swamp buggy.

Team 4 ready to go on their swamp buggy.

Groups began returning to the sanctuary around 3:00 pm, but some didn’t return until after sunset. Our round-up dinner was held in the classroom of the Blair Audubon Center starting at 4:30 pm that evening, where food and drinks were available. Teams either dropped off their data forms or stayed for the dinner, where we began compiling all of the data from each team. After all the data was collected, the teams said their farewells and went home for some well deserved rest after a long day.

Here are the totals from all the teams in the Corkscrew count:

- 59 participants - 103.55 hours birding - 349.80 miles covered - 114 bird species observed - 13,821 birds counted - 1 great day of birding!

I felt very honored to not only participate, but also to help lead a section of the Corkscrew count. I was able to meet some very incredible people who have a deep passion for birding and nature. Some of the participants traveled from long distances just to be a part of our count and some also participate in multiple counts around the country.

Photo taken by John Maginess, a participant in my team,
during the Corkscrew count.

Seeing this dedication reminded me of the original Christmas Bird Count and the people so committed to the conservation of birds and other wildlife that started the environmental movement so many years ago. It was an amazing feeling knowing that I was a part of an effort that has been going on for over a hundred years and that thousands people around the world were birding together for a common goal.

-Amy, Education Intern

Follow this link to learn more about the National Audubon Society Christmas Bird Count