Download The Cache River Wetland: Are there differences in swamp rabbit

Jennifer Eagle
Scientific Research Methods for Teachers
Spring 2012
Human Alteration of Earth’s Ecosystems
Habitat Fragmentation
Source or Sink Habitats
Alteration of the Natural Flow Regime
Human Alteration of Earth’s Ecosystems
 Between one-third and one-half of the land surface has
been transformed by human action (Vitousek et al. 1997).
 Humans have cleared land plots for: cropping, logging,
grazing, urbanization, etc.
 Land transformation has become a primary force in the
loss of biological diversity and is the single most important
cause of extinction (Vitousek et al. 1997).
Human Alteration of Earth’s Ecosystems:
Habitat Fragmentation
 Native vegetation is removed or replaced with a crop
leaving behind small patches of the original vegetation.
 The fragments of habitat that are left are likely to be in a
less productive area (i.e., poorer soil, higher elevation,
partially inundated) due to nonrandom clearing choices
made by farmers (Laurance 2008).
 Fragmentation results in a reduction of the original habitat
and chops up the remaining habitat into various sizes and
degrees of isolation (Laurance 2008).
Human Alteration of Earth’s Ecosystems:
Habitat Fragmentation
 Fragmented habitats are
reduced in size and are
susceptible to edge effects:
 Changes in temperature
 Increased light
 Increased wind shear
 Increased predation
 This changes the species
composition of the habitat
area (Laurance 2008).
Habitat Fragments: Sources or Sinks?
 Patches of land that are
left behind are either
habitat sources (high
productivity), or habitat
sinks (low productivity).
 Population size and
growth rate may vary
relative to habitat types
that are available (Pulliam
& Danielson 1991).
Alteration of the Natural Flow Regime
 Land alterations have also resulted in an alteration of the
natural hydrologic flow of river ecosystems.
 The clearing and/or drainage of land for agriculture
generally results in increased overland flow, channel
incision, floodplain isolation, and headward erosion of
stream channels (Prestegaard 1988).
 Altering the natural flow can cause the degradation of
aquatic and riparian habitats (Poff 1997).
Alteration of the Natural Flow Regime
 Both high stream flows and low stream flows provide their
own benefits to riverine species, however these benefits
may only occur if the stream flow is allowed to fluctuate
naturally.
 Altering stream flow disturbs the balance of species
adaptations that are already in place, and forces organisms
to relocate or adapt to a new flow regime.
Swamp Rabbits
(Sylvilagus aquaticus)
 Swamp rabbits are habitat
specialists that live in the
bottomland forests of the
southeastern United
States.
 They are at their
northernmost reach in the
Cache River Wetland.
Swamp Rabbits
(Sylvilagus aquaticus)
 Swamp rabbits tend to rest and feed in areas with canopy
gaps (Zollner et al. 2000).
 Latrine sites, however, are more strongly correlated to the
presence of downed logs (Zollner et al. 2000).
 Swamp rabbits have been known to use upland habitat
during flooding of the bottomlands (Scharine et al. 2011).
 There is a concern for this species due to the fragmentation
and loss of the forested bottomlands.
Cache River Wetland
 CRW extends throughout four counties in Southern Illinois.
 It is comprised of forested wetlands, floodplains, upland
forests, and limestone barrens (IDNR 2007).
 Much of the bottomlands were cleared for logging or farm
land in the late 1800s.
 By the 1900s, the building of roads and other developments
fragmented much of the remaining habitat.
 Since 1905, there have been nine major alterations of the
natural drainage system to control flooding and drain
wetland for farming including dredging, levees, dams, and
channelization (IDNR 1997).
Cache River Wetland:
The Upper Cache and Lower Cache River
 The Post Creek Cutoff was
built in 1915 to divert water
from the Upper Cache
River (UCR) to the Ohio
River.
 This resulted in a split of
the river, with the Lower
Cache River (LCR) having a
reduced flow by being cut
off from its headwaters.
Our Study
 Although there have been previous studies on swamp
rabbit occupancy in southern Illinois, there has not been a
comparison of habitat in the LCR vs. the UCR.
 Our objective is to determine if there is a difference in
swamp rabbit occupancy in the LCR vs. the UCR.
 We hypothesize that there will be more swamp rabbits
occupying the UCR due to a higher quantity and quality of
suitable habitat there.
Why would more swamp rabbits
occupy the UCR than the LCR?
 A previous study (Rubert 2007) found more suitable swamp
rabbit habitat in Union and Johnson Counties (263.73 km2)
compared to Pulaski and Alexander Counties (176.75 km2).
 High flows maintain ecosystem productivity and diversity
(Poff et al. 1997), and the flow to the LCR was dramatically
reduced when it was cut off from the UCR in 1915.
 The LCR continues to accumulate excessive amounts of
sediment and is consistently flooded.
Our Methods
 We will find 10 suitable
habitat areas in the UCR and
LCR where known swamp
rabbit populations exist, and
place one artificial latrine
log (ALL) at each site.
 We will examine the ALLs
each day for 3 days and
record the number of swamp
rabbit fecal pellets on our
data sheet.
Data Analysis
 We will find the means of our artificial latrine log data
in the UCR and LCR, and run a t-test.
 From our analysis and resulting p-value we will be able
to determine if swamp rabbit occupancy rates are
significantly higher in the UCR.
Questions
???