Your SlideShare is downloading. ×
0
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Black Ratsnake Class Presentation
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Black Ratsnake Class Presentation

1,239

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
1,239
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
0
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. The Importance of Body Size in Determining the Ecological Niche of the Black Rat Snake (Elapheobsoleta)
    Denise M. Roth
  • 2. So…Why study snakes??
    http://www.larry-adams.com/snake-check.jpg
    http://img114.imageshack.us/img114/8529/snake2tp9.jpg
    http://www.he-man.org/cartoon/cmotu-pop/snakemen1.jpg
  • 3. Snake populations are declining!
    Habitat changes
    Pet trade
    Habitat fragmentation
    Senseless killing
    “Never wound a snake; kill it.” – Harriet Tubman
    “If you see a snake, just kill it - don't appoint a committee on snakes.” – Ross Perot
    http://www.cartoonstock.com/newscartoons/cartoonists/tcr/lowres/tcrn210l.jpg
    http://magickcanoe.com/snakes/baby-gartersnake-large.jpg
  • 4. Changes in Habitat Use and Movement Patterns with Body Size in Black Ratsnakes (Elapheobsoleta)
    Gabriel Blouin-Demers, Laura P. G. Bjorgan and Patrick J. Weatherhead
  • 5. Question Addressed
    Do black ratsnakes exhibit an ontogenetic niche shift?
    In other words: Does body size influence movement patterns and use of habitat in black ratsnakes?
    Hypothesis:
    Juvenile black ratsnakes should move more often, move over longer distances and travel further from hibernacula.
  • 6. Why does body size matter?
    It influences thermoregulatory requirements
    Habitat use
    Susceptibility to predation
    Diet
  • 7. Black Ratsnake(Elapheobsoleta)
    Adult length 3.5-8 ft
    Hatchlings 11-16 in
    Live in or near woodlands (near water)
    Good climbers: competition for tree cavities
    Diet: Rodents and bird eggs
    Reproduce in early summer
    Oviparous- 12-20 eggs
    Protected in neighboring states
    Threatened in Canada
    http://www.michigan.gov/dnr/0,1607,7-153-10370_12145_12201-61209--,00.html
  • 8. Geographic Distribution
    http://www.dlia.org/atbi/species/Animalia/Chordata/Reptilia/Squamata/Colubridae/Elaphe_obsoleta.shtml
  • 9. Queen’s University Biological Station
    Study area: 30 km²
    ~36 Snakes/ 1 km²
    50 km north of Kingston, Ontario, Canada
    100 km south of Ottawa, Ontario, Canada
    http://www.dlia.org/atbi/species/Animalia/Chordata/Reptilia/Squamata/Colubridae/Elaphe_obsoleta.shtml
    http://www.queensu.ca/biology/qubs/directions.html
  • 10. Specimen Capture
    Funnel traps
    Measured for Snout-to-vent length (SVL)
    Weighed
    Sexed
    Marked with a passive integrated transponder tag
    http://icwdm.org/Images/amph-reptile/snake-nonpoison/Nonpoi10.jpg
  • 11. Distinguishing between adult and juvenile
    Juvenile
    Adult
    < 1050 mm SVL
    http://animaldiversity.ummz.umich.edu/site/resources/usfws/juvratsnake.jpg/medium.jpg
    http://www.tamssunshinehouse.com/Snakes/blackrat.jpg
  • 12. Methods
    Implanted specimens with radio-transmitters
    Used movement data of adults from previous study (n = 82)
    Additional 10 adults tracked
    35 juveniles
    Located snakes on foot and recorded location using GPS
    Also recorded behavior observed
    153 known juvenile locations
    153 random locations
    http://www.sciencedaily.com/releases/2007/07/070721200335.htm
  • 13. Classification of Variables and Statistical Analysis
    Analysis of Movement Patterns:
    Mean distance from hibernacula during active season
    Total distance travelled during active season
    Number of times individual moved when relocated
    Habitat Classification
    Forest
    Forest edge
    Open habitat
    MANOVA
    Habitat selection based on the 23 structural variables
  • 14. Results: Habitat Use
    Juveniles utilized all available macrohabitats but preferred forest
    No significant difference in microhabitat use between chosen and random locations
    Key note:
    If juveniles are in dispersal stage, they are potentially less selective for previously visited locations
    n = 306
    P = 0.11
  • 15. Results: Movement PatternsDistance Travelled vs. SVL
    All individuals followed at least 3 months during active period
    ANCOVA:
    Relationship between the total distance travelled and SVL
    Significant with SVL
    P = 0.002
    No significant relationship with sex
    P = 0.99
  • 16. Results: Movement Frequency vs. SVL
    Do smaller snakes move more often?
    Relationship between SVL and number of times snake had moved
    Significant relationship with sex
    P < 0.001
    Significant relationship with size
    P = 0.04
  • 17. Conclusion
    Juveniles and adults differed in habitat use
    Juveniles visited sites at random
    Adults seemed to have preferred habitats and locations
    Movement patterns and behavior varied with body size
    Larger snakes moved further distances
    Juveniles moved more often
  • 18. Discussion
    Possible explanations for habitat differences
    Thermoregulation strategies
    Juveniles escaping predation
    Juvenile dispersal
  • 19. Future Research
    Ontogenetic niche shifts in reptiles
    Juvenile dispersal stages?
    Is it related to body size of the individual?
    Study different land configuration
    Where do the neonates go?
    Does habitat fragmentation actually benefit the adults?
  • 20. What this means for the black ratsnake
    Ontogenetic shifts in habitat use do not seem to play a major role in species survival at this time and conservation strategies should be focused elsewhere to have an impact in sustaining populations in Ontario, Canada.
  • 21. References
    Ohio Department of Natural Resources: Division of Wildlife. Eastern Ratsnake or Black Ratsnake. Accessed from http://www.dnr.state.oh.us/Home/species_a_to_z/SpeciesGuideIndex/blackeasternratsnake/tabid/6556/Default.aspx
    http://www.washjeff.edu/Chartiers/Chartier/KEY/Reptiles/Snakes/brat.htm
    http://www.ext.colostate.edu/PUBS/natres/06501.html
    http://www.statistics.com/resources/glossary/a/ancova.php
    Blouin-Demers, Gabriel, Bjorgan, Laura P. G. & Weatherhead, Patrick J. (2007). Changes in Habitat Use and Movement Patterns with Body Size in Black Ratsnakes (Elapheobsoleta). Herpetologica, 63(4), 421-429.
    Arendt, J. D., &  Wilson, S. (1997). Optimistic growth: Competition and an ontogenetic niche-shift select for rapid growth in pumpkinseed sunfish (Lepomisgibbosus). Evolution, 51(6), 1946-1954.
    Harding, James H. (1997). Amphibians and Reptiles of the Great Lakes Region. 308-312.
    Michigan Department of Natural Resources. Black Rat Snake (Elapheobsoletaobsoleta). Accessed from http://www.michigan.gov/dnr/0,1607,7-153-10370_12145_12201-61209--,00.html
    http://thinkexist.com/quotes/with/keyword/snake/
  • 22. Questions
  • 23. Description of Microhabitats
  • 24. Distance from Hibernacula vs. Snout-to-Vent Length
  • 25. Area of Home Range vs. SVL
  • 26. Average ~ 65 snakes/ 1.8 km² (Blouin-Demers et. al 2002)
    This study (Blouin-Demers et. al 2007) was 30 km²
    Based on previous data:
    Average in this study~1087 snakes/ 30 km ² or 36 snakes/1 km²

×