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Can We Eradicate Invasive Species?

Can We Eradicate Invasive Species?

I recently attended an invasive species conference, and this topic came up.  It seems strange that it would but those who work in the invasive species world have this in the back of our heads a lot.  I mean in a lot of cases we do not bring the word up when making presentations, what some call “the E word”, because we feel in the back of our heads, we will never eradicate them, and we should not lead people on that we might.  Lionfish management is a good example.  Everyone is aware that eradication is probably not an option and so we refrain from using the term when discussing this species. 

Lionfish in tank. Photo credit: Laura Tiu

It came back a few years ago when I began working with beach vitex on Pensacola Beach.  It was a relatively new species on the radar in Florida and was not even listed as an invasive species in our state.  When we first heard about it in the Pensacola area, I checked EDDMapS to see how many records there were.  There was a total of three statewide; two in the Jacksonville area and one in Pensacola.  I conducted surveys of Pensacola Beach and found 22 additional sites where the plant existed and thought – MAYBE… if this truly ALL there was – we MIGHT eradicate this plant from the Florida panhandle.  There was a point after we had treated and removed the plants from those sites that we MIGHT have actually… dare I say it… eradicated beach vitex from Pensacola Beach.  I felt pretty good about stating this and there was even a little ceremony at a meeting to celebrated it.  Then… we found some on the north side of the Intracoastal Waterway in Gulf Breeze.  Then the plant popped in Navarre.  Then Perdido Key.  Then in Apalachicola.  And after a few years, the plant popped up again on Pensacola Beach.  We were too quick to use the term eradication and – like so many who try to manage these species – have refrained from using the term ever since. 

As I watched what was happening with beach vitex, watching what was happening with the brown anole, Chinese tallow, and what I saw in south Florida with Brazilian Pepper, I could see why many felt eradication is not part of the program.  I could see why most would immediately go into management mode and just skip the idea of eradication.  I could see why many would toss in the towel and find something else to work on. 

This yard on Pensacola Beach has become over run by vitex.

On the second day of the three-day conference the keynote speaker was Dr. Dan Simberloff.  Dr. Simberloff has been working with invasive species management since the late 1960s.  His talk was entitled Managing Invasions: What’s Worked, What Hasn’t, and What Might.  Early in his talk he asked a question… “What is our ultimate goal?”.  There was silence in the room for almost a minute.  Everyone was pondering.  In my head I was thinking “to control the species distribution as best we could and stop the introduction of anymore”.  But that was not the answer he was looking for.  After about a minute (because NO one responded 😊) he said – “our ultimate goal is eradication”. 

Again, there was silence.  He used the “E” word – out loud – in front of everyone.  I am guessing others were thinking what I was thinking.  “I didn’t think eradication was really possible?”  But his argument was that it is possible and began to run down a list of situations where it in fact HAS happened.  He also discussed new technologies that COULD allow for more. 

It was good to hear this honestly.  It felt like a locker room pep talk at half time and you are down by two touchdowns.  Your thought is that the other team has this in the box, and we should play for another half but really be thinking about how we are going to improve for the next game, so we are not in this situation.  Then “Coach Simberloff” gives his locker room talk, you go back on the field, and things turn around – you come from behind and win the game.  He made us feel like it was possible.  That we are out their fighting now but not to lose focus of the ultimate goal. 

I began to think about the beach vitex situation in the Florida panhandle again.  Maybe… just maybe…

But here’s the deal.  If you look at the invasive species curve (image provided here) you will see that your best chance at eradicating an invasive species is early in the invasion.  What people have termed EARLY DETECTION – RAPID RESPONSE (EDRR).  In my head, I think we MAY be there with beach vitex.  I do not feel the populations in the panhandle are beyond the level that eradication may now be actually achievable.  IF we know where all of the plants are.  In the back of my head, I still wonder if we have missed more than there is and that the populations may be further up the curve than we think.  BUT let’s look at this way – maybe we DO know where most of those plants are. 

The state is divided into regional management areas (CISMAS) and the western panhandle is part of the Six Rivers CISMA.  During the COVID period of 2020-2021, we developed a EDRR list for this CISMA and it is posted on our webpage (https://www.floridainvasives.org/sixrivers/).  Being a Sea Grant Extension Agent, my focus is on the coast.  The barrier islands and the waters that surround them.  We do have a few EDRR species that are popping up on, and around, our islands.  Have we detected them soon enough?  I am not sure but over the next few weeks I am going to post articles here to discuss some of them in hopes that the public will assist us in finding, reporting, and managing them.  The ultimate goal is eradication.  Let’s see if we can pull this off. 

Dealing with the Armadillo

Dealing with the Armadillo

Florida has a love-hate relationship with this animal.  Some find them cute and adorable, others find them a pest and a nuisance, either way there is no ignoring this guy.  They are everywhere and yes – they can make a mess of your lawn and garden.  So, for those who are not so in love with the creature – what can be done? 

Let’s first meet the animal. 

There are about 20 species of armadillo found in Central and South America but there is only one in the U.S., the Nine-Banded Armadillo (Dasypus novemcinctus).  The Nine-Banded Armadillo is originally from South America and there were several different species of armadillos that made the trek from South to North America prior to the ice age.  But after the ice age it seemed no armadillos were present in the U.S.  After the ice age, the Nine-Banded Armadillo expanded north into Mexico, but it seems could not cross the Rio Grande.  That is until Americans began to settle the area.  Prior to American settlement, armadillos were hunted for food, and the land on both sides of the river was regularly burned.  The American settlers ceased the burning and the Native Americans declined in numbers, so hunting pressure declined as well.  Many armadillos were probably brought across intentionally, but others who managed to swim across, and armadillos can swim, now found suitable habitat with the decreased burning.  They had arrived and began expanding both east and west across the southern U.S.  However, the Mississippi River presented another barrier they could not deal with. 

The common nine banded armadillo scurrying across the lawn. Photo: Les Harrison

The introduction in Florida was a different story.  Apparently in the 1920s and 30s they were released by humans.  One release appeared to be an escape from a small zoo.  Another was from a circus.  There are reports of armadillos riding cattle cars on trains from the west and this allowed them to cross the Mississippi.  In the 1920s bridges were built across the river for a new invention called the automobile.  All of this led to the invasion and the animals are now here, they are also expanding north. 

Armadillos like warm/wet climates.  They prefer forested areas or grasslands and, again, can swim small rivers and creeks easily.  It has been reported they can hold their breath up to six minutes and have been seen literally walking along creek bottoms. 

They feed primarily on a variety of small invertebrates such as grubs, snails, beetles, and even cockroaches (many of you will like that).  They like to feed in wet areas or loose sandy soils where digging is easier.  Unfortunately, your lawn is a good place to hunt.  They rarely, but do, feed on small reptiles and amphibians and eggs. 

They breed in the summer but delay egg implantation so that birth is in the spring.  They typically give birth to quadruplets.  The armor of the young is not hard at first but hardens over time and does provide protection from large predators like panthers, bears, and alligators.  They typically live 12-15 years, but some have reached the age of 20. 

So… now you know the animal… for those who do not want them, what can be done?

Based on an article from UF IFAS Extension, not a lot.  Typical methods of deterring wildlife have not worked.  Poisons, smells, and even using firearms has not relieved the homeowner of the problem.  One study looked at trapping and found that in general it is hard to get them to enter.  In this study they caught one armadillo every 132 trap nights – low percentages.  Another study looked at baits and found crickets and worms worked best, but the smell of other armadillos in the trap also lured them.  One colleague mentioned the need for solid wood traps and he baits them with nothing but the shells of roadkill as had good success.  He mentioned the designs of these wooden traps are online.  You can get plans to build them, and you can also purchase pre-made ones.  Once captured they can be relocated but the trapper should be aware that armadillos have many peg-like teeth and very sharp claws for digging.  HANDLE WITH CARE.  It is also known that armadillos can carry leprosy, though cases of leprosy being transmitted to humans are rare.  None the less, handle with care. 

For more information on this animal, contact your county extension office. 

Beach Vitex – Did We Get It All?

Beach Vitex – Did We Get It All?

The quick answer…

No

So, why write this?

For two reasons…

  1. To let everyone know how the battle against this invasive plant in the panhandle is going
  2. To encourage everyone along the coast to keep searching, reporting, and removing it.

Can you actually eradicate an invasive species?

MAYBE

But… you must find and begin to manage it early.  What many call Early Detection Rapid Response (EDRR) – and beach vitex is just that in the state of Florida. 

For those not familiar with the plant, it is called beach vitex (Vitex rotundifolia).  It is native to the Pacific coast of Asia, extending from North Korea to Australia.  This suggest that it can tolerate cold weather, something that has kept many south Florida invasive species at bay in the Florida panhandle, but not this one. 

Vitex beginning to take over bike path on Pensacola Beach. Photo credit: Rick O’Connor

It likes dry sandy soils and open sunny areas – our beaches are perfect.  It begins with a taproot and forms runners that cross the surface of the sand in all directions, ALMOST 360°, but not quite.  The runners are herbaceous at first and form blueish-green ovate shaped leaves and a cluster of beautiful lavender flowers in the spring and early summer.  As the plant grows it becomes more woody and can form a shrub growing between three and four feet high.  In the fall, after the cold fronts begin, the flowers become small gray seed pods.  Each pod contains four seeds, and the plant can produce up to one million seeds/m2.  These are viable for several months and can tolerate salt water for that period as well. 

The plant may have been introduced as early as 1955 but was certainly here by the 1980s.  During that period the state of South Carolina decide to try it in dune restoration after a series of strong hurricanes.  That is when it raised its ugly head and let us know that it is not a plant we want on our coast.

Beach Vitex Blossom. Photo credit: Rick O’Connor

It grows aggressively forming large monocultures within the dunes.  It is allelopathic, meaning it releases chemical compounds that can cause the decline of plants around it, this would include our beloved sea oats.  Being a taproot plant, not a fibrous one like the sea oat, the integrity of the dunes to protect from storms is weakened.  Becoming a shrub, it can also shade the sand keeping other native plants from sprouting and could impact both the survival of sea turtle hatchings and the listed beach mice around the Gulf. 

The plant was first reported to us in Pensacola around 2014 by a birding couple we know in Gulf Breeze, Florida.  It was growing on Fair Point near their home.  They told us they had it under control on their property but that it was most likely coming from Pensacola Beach on Santa Rosa Island – so, we took a look – and we found it. 

Since that time, we have found it in other coastal counties along the Florida panhandle and are trying hard to (1) remove it as fast as we find it and (2) educate others so they can help. 

We just completed our annual survey event we call HALLOWEED.  We only surveyed Pensacola Beach and the portion of the Gulf Islands National Seashore called Naval Live Oaks in Gulf Breeze.  Here are the results from the 2022 HALLOWEED…

12 volunteers worked between 2-4 hours logging 41 total hours last Friday. 

We have updates on the Pensacola Beach Survey – Naval Live Oaks results coming soon!!

95 sites of beach vitex in the bay area

57 of those (60%) are on Pensacola Beach (surveyed)  

25 (26%) are at Naval Live Oaks (will need to be updated)

6 (6%) are on Navarre Beach (were not surveyed)

3 (3%) are in Gulf Breeze (not surveyed)

2 (2%) are on Perdido Bay (not surveyed)

2 (2%) are on Perdido Key (not surveyed)

Of the 57 sites on Pensacola Beach…

30 (32% of the total; 52% of sites on Pensacola Beach) are on NE Pensacola Beach – north of Via DeLuna Drive – and east of Casino Beach

24 (25% of the total; 42% of sites on Pensacola Beach) are on SE Pensacola Beach

2 (2% of the total; 4% of sites on Pensacola Beach) are on NW Pensacola Beach

1 (1% of the total; 2% of the sites on Pensacola Beach) are on SW Pensacola Beach

All 3 sites on WEST Pensacola Beach are GREEN – have been removed and have not returned; no survey of the west end of the island was conducted today – but based on current log – there is no beach vitex on west end of Pensacola Beach. 

Of the 54 sites on the east end –

34 (63%) are on private property

20 (21%) are on public lands

Of the private properties –

24 (71%) have been either completely removed or have been treated and in the process. 

10 (29%) have not been removed or treated – it is not illegal to have beach vitex and is up to the homeowner whether they want to manage it or not.

Of the public lands –

15 (75%) have either been completely removed and have not returned; or have been treated.

5 (25%) have not been removed or treated – it is up to us to make this change – and we will next spring. 

We do hope to get a survey of Perdido Key completed by the end of the year. 

We are also planning another annual removal event we call WEED WRANGLE for early spring 2023.  We will need volunteers help to do this.  If interested in helping, contact Rick O’Connor (roc1@ufl.edu; 850-475-5230 ext.1111). 

As for the rest of the panhandle here are the records in EDDMapS as of October 2022. 

Escambia County FL – 44 records

Santa Rosa County FL – 4 records

Okaloosa County FL – 31 records

Walton County FL – 0 records

Bay County FL – 0 records

Gulf County FL – 1 record

Franklin County FL – 4 records

Wakulla County FL – 0 records

Jefferson County FL – 0 records

We are SURE this is under reported and we need your help to update these records as well as remove these plants before we are out of the EDRR phase and eradication is no longer an option.  Again, contact me (Rick O’Connor) at the contact above if you would like to help. 

How Are the Terrapins Doing in 2022?

How Are the Terrapins Doing in 2022?

Since 2005 we have been tracking and monitoring diamondback terrapins in the Florida panhandle.  For those of you who are not familiar with the animal, it is a turtle in the family Emydidae.  Emydid turtles include what we call “pond turtles” and also include the box turtles.  Terrapins differ from the others in that (a) their skin is much lighter, almost white, and (b) they like salt water – more accurately, they like brackish water. 

Diamondback terrapin (photo: Molly O’Connor)

The animals range from Massachusetts to Texas and within this there are seven subspecies.  Five of these live in Florida, and three only live in Florida.  In the Florida panhandle we have two subspecies: the Ornate terrapin (Malaclemys terrapin macrospilota) and the Mississippi terrapin (M.t. pileata).  It is believed the that the Mississippi terrapin only exist in Florida within Pensacola Bay – more on that in a moment. 

Image provided by FWC

There are literally no peer reviewed publications on terrapins from the Florida panhandle… none.  And this was how the Panhandle Terrapin Project began.  The first objective for the project was to determine if terrapins even existed here.  We began surveying for evidence of terrapins in 2005 using students from Washington High School in Pensacola.  The project quickly fell to myself and my wife due to the best time to do terrapin surveys was May and June.  And the worst time to work with high school students was May and June.  Between 2005 and 2012 we were able to verify at least one terrapin record in each of the panhandle counties.  Yes… terrapins exist in the Florida panhandle. 

The second objective was to assess their population status.  To do this we used what I call the Mann-Method.  Tom Mann, Mississippi Department of Wildlife, had developed a method of using nesting surveys to estimate relative abundance of terrapins within a population.  Terrapins tend to have strong site fidelity – they are “home bodies” – and do not move from marsh to marsh.  If you can find their marsh, you can find their nesting beaches.  If you can find their nesting beaches you can use the Mann-Method to assess their relative abundance. 

Tracks of a diamondback terrapin. Photo: Terry Taylor

There are a couple of assumptions with the Mann-Method.  (1) You are assuming every female in the population nest every year – we are not sure that is true.  (2) You are assuming that each female will lay more than one clutch of eggs each season – we do believe this is true.  (3) You are assuming that each female will not lay more than one clutch in a 16-day period – we are not sure this is true.  (4) You know where all of the nesting beaches are – we are not sure we do.  (5) The sex ratio of male to female is 1:1 – we are sure that is not the case.  One study suggested that in the panhandle the ratio may be 1:3 in favor of males, another suggested 1:5 in favor of males. 

Based off this model, and its assumptions, during a 16-day period of the nesting season, each track/nest would be an individual female.  Using 1:1, 1:3, and 1:5 as your sex ratio you can get an estimate of relative abundance. 

Another method for estimating relative abundance is counting the number of heads in a 30-minute period.  It is understood that if I see different heads during periods of the survey, I may be seeing the same head, but the argument is that if I typically see 10-15 heads during a 30-minute and over time that becomes 15-20, or 20-25, the relative abundance of terrapins is increasing – and visa versa.  

A terrapin swimming near but not entering a modified crab trap. Photo: Molly O’Connor

And we now have a third and fourth objective.  A third objective is to capture animals to place tags on them.  Doing this can give us a better idea of how these terrapins are using the habitats in the panhandle, how far they may travel and how they are getting there.  The fourth objective is to obtain tissue samples for genetic analysis.  The purpose of this is to determine whether the populations in Pensacola Bay are Mississippi terrapins, Ornate terrapins, or hybrids of the two. 

Since 2015 this work is now being conducted by trained volunteer citizen scientists – people like you – and we do the trainings in March if interested. 

So… how did things go in 2022? 

In 2022 we trained 47 volunteers to be survey beaches.  25 (53%) participated in at least one survey. 

173 surveys were conducted between April 2 and July 31 at 14 nesting beaches between Escambia and Bay counties.  Encounters with terrapins, or terrapin sign, occurred during 43 of the 173 surveys (25%) and three terrapins were captured for tissue and tagging. 

Escambia County

Number of SurveysDatesNumber of Surveys / Day
29Apr 3 – Jul 310.2
Number of EncountersFrequency of EncountersHeads / 30-minutesEstimated Relative Abundance
4.18No surveys conducted4-12

Santa Rosa County

Number of SurveysDatesNumber of Surveys / Day
58Apr 4 – Jul 50.6
Number of EncountersFrequency of EncountersHeads / 30-minutesEstimated Relative Abundance
15.26N=2, 0-49, X = 2430-90

Okaloosa County

Number of SurveysDatesNumber of Surveys / Day
43Apr 18 – Jul 150.5
Number of EncountersFrequency of EncountersHeads / 30-minutesEstimated Relative Abundance
25.58N=17, 0-32, X = 1130-90

No surveys were conducted in Walton County

Bay County

Number of SurveysDatesNumber of Surveys / Day
43Apr 2 – Jun 300.5
Number of EncountersFrequency of EncountersHeads / 30-minutesEstimated Relative Abundance
0.00No surveys conducted0

Summary of 2022 Terrapin Season

Surveys of nesting beaches occurred in four of the five counties in the western panhandle. 

Terrapins were encountered in each of these cand captured in two of them. 

The relative abundance ranged between 0 (Bay County) to between 30-90 individuals (Santa Rosa and Okaloosa counties) and was about 64-192 animals for the entire western panhandle (depending on the sex ratio you use). 

We are sure that we have not found all of the nesting beaches in this region and will continue to look for more. 

We are awaiting results from the tissue sampling to determine whether we have a distinct population of Mississippi terrapins in Pensacola Bay, but more samples will be needed. 

We need to place satellite tags on some females to get a better idea of how they travel through the system. 

And our relative abundance numbers suggest that populations in the Florida panhandle are relatively small compared to others within the terrapin range. 

More needs to be done and we will continue to survey each spring.  If you are interested in becoming a member of the Panhandle Terrapin Project, contact me (Rick O’Connor) at roc1@ufl.edu

The Eastern Indigo Snake

The Eastern Indigo Snake

Over the last few weeks, I have received several questions and comments on, and about, the eastern indigo snake.  I was curious as to why so many in such a short time – maybe a public television program on them or something? Not sure, but it is an amazing snake and I like to talk about them.  So, let’s talk about them. 

The eastern indigo (Drymarchon couperi) is the longest native snake found in North America.  It reaches a length of 9 feet and can weigh up to 11 pounds.  It is beautiful.  A shiny, iridescent black, with smooth scales that give a glossy look and emits beautiful patterns of color when the sun reflects off it that resembles the sheen you see when gasoline is spilled on water.  This beautiful coloration, being nonvenomous, and docile attitude made it very popular as a pet – except that it can reach up to 9 feet long. 

The eastern indigo snake. Photo: Molly O’Connor

Their habitat of choice are high sandy ridges along the extreme southeastern United States.  These ridges are covered with longleaf pine or turkey oak trees and provide enough space, hibernacula, and food to support them.  Though a point of origin has not been published, the historic range suggest a possible origin in Florida.  It has been suggested that there were once two distinct genetic forms of indigo snakes, one existing along the Gulf coast and another along the Atlantic coast.  It appears there was a climatic barrier separating the two which no longer exist and today it is believed that there is only one species in existence now.  The historic range of the snake included extreme southwest Mississippi, extreme coastal Alabama, extreme coastal Georgia, and all of Florida.  The most recent range shows the snake exists across the entire Florida peninsula and some portions of southern Georgia but does not include all of Georgia’s historic range.  It may be extirpated in the Florida panhandle, with a few rare reports, and believed to be completely extirpated in southern Alabama and Mississippi.    

Indigos live mainly solitary lives with large home ranges that can extend hundreds to thousands of acres.  Males have larger home ranges than females.  Indigo snakes are diurnal and forage for their food rather than sit and ambush as many snakes do.  Their diet consists of a variety of species, but diet studies show that rodents, frogs, small turtles, and snakes make up the bulk of their prey.  It also includes species of venomous snakes like the eastern diamondback and copperhead. 

Indigo snakes move between upland and lowland habitats during the warmer months.  During the winter months they are closely associated with gopher tortoise burrows where the temperature can range between 45F and 88F and average 54F.  They often emerge on sunny winter days to bask but do not move too far from the burrow.  It is not known how long indigos live in the wild, but they have lived as long as 25 years in captivity. 

During the 20th century the population of these snakes began to decrease.  As is often the case, the loss of suitable habitat was a big problem.  Longleaf pine forests where no prescribed burning was occurring as frequently as they had historically, the understory altered the habitat to a point where indigos could not support themselves.  This also led to the decrease in gopher tortoise populations along with their burrows in which the indigos needed.  The harvest of gopher tortoises as food and pets also decreased the number of burrows and thus the number of snakes.  Often people would pour gasoline into the burrows to get the tortoises out and this led to the death of many indigos.  And then there was the collection of the snakes for the pet trade.  Another problem was that they are snakes.  An eight-foot snake crawling around had little chance of escaping the wrath of scared humans. 

The eastern indigo snake is the largest nonvenomous snake in the southeast. Photo: Molly O’Connor

Today they are completely missing in Mississippi, Alabama, and the Florida panhandle.  They are listed as an endangered species under the Endangered Species Act, and there are attempts to restore their populations in Alabama and the eastern Florida panhandle.  Though there are occasional reports from the panhandle, there have been no verified records of the eastern indigo in the western panhandle since 1999.  We would like to see this animal return but to do so, the habitat will need to be restored, and head starting (releasing captive bred snakes) may be needed as well.  Though they are large, they are harmless to humans and actually provide a needed service by controlling the populations of venomous snakes in our region.  I for one would love to see them return.