Title: Alligator Presentation Script
Author: Holly
Last saved by: Mark Hostetler
Company: Tallgoof Fan Club

Effects of Invasive Plants on Wildlife

Mark Hostetler
Department of Wildlife Ecology & Conservation
Asst. Professor, Extension Wildlife Specialist
215 Newins-Ziegler Hall
PO Box 110430
Gainesville, FL 32611-0430
ph: 352-846-0568
fax: 352-392-6984
email: hostetlerm@wec.ufl.edu

Note to speaker: Bulleted text is animated in the presentation.

Slide 1: Introduction
Hi, my name is ____________ from _____________ and I’m here today to talk to you about the potential effects of invasive plants on wildife.

Slide 2: General Overview 
First, I am going to talk about basic habitat requirements of animals and work through an example of birds and their habitat requirements.
Then, I am going to talk about some invasive plants that affect the environment and how they might affect wildlife populations.  Although few specific studies exist about the effects of invasive plants on wildlife, I will discuss a few.

Slide 3: Wildlife Habitat
All animals need food, cover (or shelter), water, and space.  These are the four essentials that make up a habitat for a species.  Different species have different food, cover, water, and space requirements.  Animals use structural cues in the landscape to “evaluate” whether a particular area will provide enough food, cover, and water.  Space is the more difficult concept to understand because it encompasses food, cover, and water.  An animal will only reside or forage in an area if this area contains sufficient amounts of structural objects to satisfy its daily activities (e.g., feeding, courtship, hiding from predators, etc.). 

Slide 4: Invasive Exotic Plant?

What is an invasive exotic plant?  An invasive exotic plant is any exotic (nonindigenous) speices that has the ability to establish self-sustaining, expanding, free-living populations, and may cause economic and/or environmental harm.  A plant is categorized as invasive exotic by the 
Invasive Species Working Group http://www.dep.state.fl.us/lands/invaspec/2ndlevpgs/ISWG.htm
Florida Invasive Pest Plant Council http://www.fleppc.org/

Slide 5: Wildlife?
A variety of different animals live in different habitats and have different habitat requirements.  What is good habitat for a species?  It depends, some are specialists and require a specific habitat whereas others are more generalists.  They come in all sizes and eat a variety of different things and live in a variety of different habitats.  A flatwoods salamander (federally listed as threatened) has very specific habitat requirements whereas an alligator has more general requirements.  Many different species feed on different items in the environment.  A small hummingbird feeds on nectar and insects, many species of warblers (such as this yellow-rumped and orange-crowned warbler) feed on insects, our state bird the mockingbird - which is quite common in urban areas - eats insects and fruits, and a red-tailed hawk feeds on small animals and birds.  Invasive plant species may change habitat in such a way that negatively impacts certain species.  However, in some cases, animals may benefit.  To illustrate the different habitat requirements for different species, let’s look at habitat requirements for birds. 

Slide 6:  Habitat for Birds
For birds, different species require different types of habitat. For example, some birds prefer forested landscapes and other birds like open areas.  Some eat primarily insects and others fruit and/or seed.  Again, habitat is food, cover, water, and space.

Slide 7: Food
Let’s first talk about providing food for birds.

Slide 8: Insectivores
Many bird species eat arthropods (arthropods – a group of animals that do not have an internal skeleton of bones, examples include spiders, butterflies, beetles, and even shrimp). These species are called insectivorous (I.e., they eat insects) and they forage in areas where they suspect insects are hiding.
Many species of birds eat insects and spiders and these critters are often required to feed their baby chicks (insects have lots of fat and protein).  For example, even hummingbirds need to feed their young insects (not just nectar).  
Upper right (halictid bee)
Lower left (katydid)
Lower right (Black rattle box moth)
Center (sphinx moth)

Slide 9: Insect-eating Birds
Many species of birds eat insects and occur in habitats with abundant arthropod diversity.  Some are specialists at getting them from under the bark of trees (e.g., woodpeckers) and others glean insects from the foliage (e.g., warblers) and some fly from perches to catch flying insects (e.g., flycatchers).

Slide 10: Granivores
Many bird species are granivorous (they eat grain or seed). For example, the sweet gum tree (you know, the gum balls) produces seed that birds eat and an herbaceous plant in the genus Bidens (Spanish needles - a common white flower in Florida) produces a lot of seeds that birds eat. 

Slide 11: Seed-eating Species
Many bird species can eat seed and key on plants that produce seed.  It does not mean that they exclusively eat seed, but seed makes up a portion of their diet.

Slide 12: Frugivores
Many birds feed on plants that bear fruit.  Frugivores are birds that feed on fruit.

Slide 13: Nectivores
Nectivores are birds that feed on nectar.  Many plants produce flowers that are visited by hummingbirds.

Slide 14: Fruit- and Nectar-eating Birds
Almost no species feed exclusively on fruit or nectar, but many species are known to eat fruit at different times during the year (cedar waxwings, thrashers, mockingbirds, etc.).  Primary nectar feeders are hummingbirds (in Florida, that would be the ruby-throated hummingbird).

Slide 15: Carnivores
Many carnivorous birds eat rodents, lizards and snakes, and habitat that attracts these animals attracts birds of prey.  

Slide 16: Meat-eating Birds
Many owls and raptors (raptors are birds of prey such as hawks, eagles, falcons, ospreys) eat many different types of animals.  Some are very good at catching birds (such as the Cooper’s Hawk), others can catch a variety of rodents (such as the Red-tailed Hawk).   

Slide 17: Cover
Cover or shelter is also important component of bird habitat.  Cover is used (by birds) for protection against the elements, to raise young, and to protect themselves against predators.
For example, snags (or dead trees) are used by a vareity of birds – but they are in short supply in some habitat.  Many different species nest in cavities in dead trees and these cavities are important component for birds to raise their young in a habitat. Also, many species forage for insects on dead trees.  
For birds that raise their young in cavities (I.e., tree holes), there are two types of cavity nesters.  First, primary cavity nesters are those birds that nest in tree cavities and they make their own holes.  Examples include most all woodpeckers.  

Slide 20: Secondary Cavity Nesters
Secondary cavity nesters nest in tree holes, but they do not make their own holes.  They utilize abandoned woodpecker holes or natural holes and crevices that form in trees.  Examples include, titmice, owls, chickadees, etc.

Slide 21: Vegetation for Cover
Habitat that has understory plants (plants below the canopy) provides cover for many birds.  Some species like to hang-out in shrubs or small trees, others may like the tree canopy, and still other may like tall grass or other herbaceous vegetation found near the ground.  Several different species of birds (e.g., ground nesting warblers) will only nest in areas with lots of ground cover.

Slide 22: Water
Some birds only forage, roost, or nest near water.  Water is an important requirement for these species and vegetation in and around aquatic habitat is an important component for whether birds can forage or nest in these areas.

Slide 23: Aquatic Birds
There are a wide variety of birds that utilize aquatic habitat.  For example, the osprey and great egret nest, roost, and forage near aquatic habitats.

Slide 24: Space
Space is the more difficult concept to understand because it encompasses food, cover, and water.  An animal will only reside or forage in an area if this area contains sufficient amounts of structural objects to satisfy its daily activities (I.e., feeding, resting, courtship, hiding from predators, etc.).
1) In other words, what is the spatial geometry of a landscape needed to attract a certain species?

Slide 25: Example: Trees and a Bird
For example, lets assume a species prefers to nest in trees; the question for us is how many trees are needed on a property to attract this species?  Is one tree enough? 2 trees enough?  Or does a species need a grouping of over 50 trees that encompasses a much larger area. This is a question of scale!  In general, size of the bird may have something to do with it.  Larger birds respond to features in a landscape at broader scales than smaller birds.

Slide 26: How Do Invasive Plants Affect Wildlife?
So how do invasive plants affect wildlife?  Simply put, if invasive plants alter a species basic requirements of food, cover, water, and space – the plant may affect wildlife populations.  In many cases, it might be a negative effect, but in some cases it might be positive.

Slide 27: Effects of Invasive Plants on Wildlife Populations
Now, I am going to present some examples of invasive species and their affects on wildlife.  Invasive plants essentially impact ecosystems in two major ways: 1) they create new habitat in which wildlife species are not adapted to (often, this habitat is a monoculture and very few native species are found within this new habitat) and 2) they alter ecological processes (such as fire regimes) and many wildlife species are attuned to these disturbance regimes.  When ecological processes are altered (e.g., a fire that is more frequent), wildlife populations are affected.  For example, Burma Reed – a tall grass from Asia, is highly flammable.  Some anecdotal evidence that it promotes frequent fires and causes abnormally high mortality of slash pine. Also, some invasive plant communities may actually be affective fire breaks and in turns of managing fire-type habitats, may help preserve hardwoods in a normally fire-dominated habitat that would have very few hardwood trees.   Now, I would like to turn to some specific examples.

Slide 28: Air Potato (distribution – throughout Florida)
 Air potato – covers mature trees and shades out understory vegetation. No documented impact on wildlife but changes understory vegetation, thus probably affects wildlife populations that depend on understory plants.

Slide 29: Australian Pine (distribution – central-south Florida)
Australian pine quickly colonizes disturbed beach plant communities – thwarting the establishment of native plant species.  Invasions produce dense litter beneath trees – smothering most herbaceous vegetation.  Wildlife studies are limited but some have found small mammal population densities are less in Australian Pine habitat (that invaded eastern Florida Everglades - Mazzotti et al.; Florida Scientist 44:65-71), compared to native hammock communities.  However, impacts on vertebrate populations not well studied.  Anecdotal evidence suggests that Australian Pine dense, shallow root system interferes with sea turtles and crocodiles being able to excavate suitable nesting cavities (Jensen and Vosick 1994; DEP technical Report TSS-94-100))

Slide 30: Brazilian Pepper (distribution – primarily central-south Florida)
Brazilian pepper forms dense monospecific stands and displaces native understory plants and trees.
One study (Curnutt 1989;Florida Field Naturalist 17(3):53-60) found only 6 bird species breeding in a Everglades pepper forest compared to another study that found 28 species in a pineland (in the Everglades) and 18 species at the forest edge (Robertson 1955 phD dissertation Unv. of Illinois).  Thus,at least for this one example, it seems that fewer birds may nest in pepper forests.  However, it may be caused to the general decline of breeding birds found within the Everglades since 1955 (the comparisons were between 1955 and 1989).  Very few native amphibians and reptile species were collected in pepper forests and two nonindigenous species, Cuban frog and brown anolis lizards, were most common (Dalrymple 1988 Foest Service general tech report RM-166).  However, Dalrymple thinks this decrease of native herp fauna was due to just the closed canopy situation and soil conditions within the pepper forest and the same herp fauna could be found in southern Florida hammock communities with similar closed canopy and soil conditions.  Thus, nothing to do with the changes to plant species composition underneath the canopy, but just microhabitat requirements are not met for many herps in closed canopy conditions.

Slide 31: Chinese Tallow (distribution – primarily central-north Florida)
Chinese tallow forms dense monospecific stands and displaces native vegetation.  It is also thought to increase nutrient loadings in aquatic systems that may change aquatic vegetation composition (through leaf drop – causing higher concentrations of phosphorus).  While studies have not addressed impact on wildlife, the combination of dense monospecific stands and effects on aquatic nutrient loads is thought to affect wildlife populations.

Slide 32: Hydrilla (distribution – throughout Florida)
In many cases, thick mats of hydrilla reduce light penetration and can change plant composition and reduce dissolved oxygen in the water (see book Strangers in Paradise – Simberloff et al).  These thick mats of vegetation can cause shifts in macroinvertebrate populations – essentially open water species of zooplankton disappear and epiphytic species become more abundant because they are adapted to foraging on or around plants.  In extreme situations (> 85% of the lake is covered by hydrilla), the growth rate of many game fish (e.g., bass) is greatly reduced and you get a lot of small adult fishes.  This is because the increased amount of vegetations allows more hiding places for prey items of fish and the fish predators cannot forage efficiently.  In moderate levels, hydrilla can benefit bass.  
With birds, also in moderate levels, hydrilla is food for some species (e.g., ringed-neck ducks) and they get benefit out of hydrilla appearing in the lake. (see book Strangers in Paradise – Simberloff et al). 

Slide 33: Hydrilla (distribution - throughout Florida)
Affects can be quite dramatic – changing the look of a lake

Slide 34: Old World Climbing Fern (distribution – primarily South Forida)
Forms dense blankets over native trees – shading out native understory vegetation and native species diversity declines.  One study (University of Florida – Daniel Clark, 2002) showed insect diversity decreased in areas with the climbing fern versus native plots.  Generally, it is assumed that decreased plant diversity negatively affects wildlife diversity.

Slide 35: Melaleuca (distribution – primarily South Flroida)
Melaluca grows so thick that it almost completely displaces native vegetation.  Understory vegetation can almost be non-existent. Some evidence that it causes wetlands to dry up (more so than wetlands with native saw grass) but not fully understood. Compared to freshwater marshes, fires in melaleuca forests burn at higher temperatures, which can dry out and ignite surface organic soils (Hofstetter & Sonenshein 1990). Highly volatile oils in melaleuca leaves contribute to intense crown fires that spread rapidly over an invaded landscape (Wade 1981). The ecological ramifications of these different fire patterns are not, as yet, fully understood.  (fire blurb from Mazzotti et. al http://edis.ifas.ufl.edu/BODY_UW123)

Slide 36: Melaleuca
Wildlife studies are limited but some have found small mammal population densities are less in Melaleuca habitat that invaded eastern Florida Everglades (Mazzotti et al.; Florida Scientist 44:65-71), compared to native hammock communities. Sowder & Woodall (1985) trapped small mammals in habitats more representative of the pine flatwoods region in southwestern Florida. These authors found greater numbers of small mammals in a cypress strand than a melaleuca head, which they attributed to greater ground cover in the cypress habitat. No small mammals were captured in another melaleuca head and a powerline transmission corridor. Sowder & Woodall (1985) concluded that utilization of a particular melaleuca habitat by small mammals may depend on the area in which it is located than on characteristics of the melaleuca habitat itself. (from Mazzotti et. al http://edis.ifas.ufl.edu/BODY_UW123). 
Also, reports have suggested that melaleuca is poor forage for large vertebrates (e.g., deer)
However, these trees do provide nesting and roosting sites for some species (e.g., egrets, vultures, and hawks)
Overall, impacts on vertebrate populations not well studied and it may be more related to surrounding habitat.  Melaleuca forests are not biological deserts, and some wildlife occur in these areas.

Slide 37: Torpedo Grass (distribution – throughout Florida)
Forms extensive monospecific stands of grass; Displaces native vegetation along shorelines;
Little value for fishes, waterfowl, or songbirds (from book -  Strangers in Paradise)

Slide 38: Water Hyancith (distribution – throughout Florida)
Water hyancith forms dense aquatic plant canopy cover; Low light intensities and dissolved oxygen levels; Smothers beds of native submersed vegetation; Can cause lower fish production but not well studied.

Slide 39: Spotted Knapweed (distribution – western United States)
In other parts of the country, invasive exotics affect wildlife populations.  For example, winter forage for elk in Montana where reduced by 50 –90 % in the winter

Slide 40: Leafy Spurge (distribution – western United States)
In North Dakota, leafy spurge has reduced bison forage by 83%.

Slide 41: Impacts on Wildlife?
Overall, most of the evidence points to how invasive plants change the environment. This change ultimately is proposed to affect wildlife populations (e.g., water hyancith and reduced dissolved oxygen levels – thus less fish).
However, it is logical to assume that invasive plants affect wildlife because nothing can eat these exotic species.  It has been shown that most of the invasive plants set-up monospecific stands of exotic vegetation that displaces native plants.  Because most of the time these invasive plants are of poor forage quality, it is assumed that it impacts local wildlife diversity.  Not a bad assumption because many local species (invertebrates to vertebrates) have adapted to feeding on local plant species.  When these native plant species are replaced by an exotic plant that cannot be eaten by animals, these animals are negatively affected. In particular, insects are at the bottom of the food chain and when these animals are affected, which can affect animals that depend on them for food (e.g., birds and small mammals).  This cascades to top predators that depend on small mammals and birds for food (e.g., bobcats and hawks).
 
Slide 42: Where to Go for Info On Wildlife?

One can find wildlife information primarily on the extension web site.  One can print fact sheets and articles about wildlife issues and topics.  At the site, there are a variety of links to wildlife resources (e.g., how to identify Florida snakes).  Also, on the Web site, we have several wildlife programs that you can enroll in.  Also, call your local extension office – they have information regarding wildlife in your area.  Call Florida Fish and Wildlife Conservation Commission (FWC) or visit their web site – the FWC has a whole range of information on Florida’s wildlife. Also, Center of Aquatic Studies has info on invasive plants.

Slide 43: Where to Go for Info On Invasive Species?

Go to these Web sites to learn how to identify and remove invasive exotic plants:

http://www.dep.state.fl.us/lands/invaspec/
http://www.fleppc.org/
http://plants.ifas.ufl.edu/

Slide 44: What Can You Do? 

Learn which plant species are categorized as invasive exotic plants and remove them from your property.  The exotic plants that you have on your property may be affecting natural areas and parks far from your property.  By means of water, animals (such as birds carrying seeds), and sometimes the wind – the plants in your yard may be spreading seeds to nearby critical habitat.  It is vital that plants are removed from your property to prevent the spread of invasive species.  

Report Invasive Exotic plants – You can call the Department of Environmental Protection.  However, the easiest way is to document sightings in the Florida Exotic Pest Plant Database.  You can go online (http://www.fleppc.org/database/data_intro.htm) and report the plants that you have a positive identification for.

Educate your neighbors about eliminating invasive exotic plants in the neighborhood.  It is not enough to eliminate plants in your yard – one needs to eliminate plants in a much larger area to have an impact.

Slide 45: Summary
In closing,  
•	 Think of food, cover, water, and space when evaluating how invasive plants affect wildlife populations
•	 There are only a few studies that demonstrate how wildlife populations are affected by invasive exotics. However, it is logical to assume that invasive plants affect wildlife because nothing can eat these exotic species.  It has been shown that most of the invasive plants set-up monospecific stands of exotic vegetation that displaces native plants.  Because most of the time, these invasive plants are of poor forage quality, it is assumed that it impacts local wildlife diversity.  Not a bad assumption because many local species (invertebrates to vertebrates) have adapted to feeding on local plant species.  When these native plant species are replaced by an exotic plant (that cannot be eaten by animals), wildlife are negatively affected. 
•	 For wildlife information: go to the wildlife extension web site: www.wec.ufl.edu/extension

Slide 45: Acknowledgements

Further Reading

Simberloff, D., Schmitz, D. C., and Brown, T.C.  (Editors), Tom C. Brown (Editors).  1997. Strangers in Paradise: Impact and Management of Nonindigenous Species in Florida. Washington, D.C.: Island Press

Invasive Species Web sites

http://www.dep.state.fl.us/lands/invaspec/

http://www.fleppc.org/

http://plants.ifas.ufl.edu/